IJSPT
INTERNATIONAL JOURNAL OF SPORTS PHYSICAL THERAPY
An Official Publication of
A North American Sports Medicine Institute Publication Photograph by Camilla Hylleberg
IJSPT
international JOURNAL OF SPORTS PHYSICAL THERAPY
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Turner A Blackburn, APTA Life Member, AT-Ret, AOSSM-Ret President Mary Wilkinson Director of Operations and Marketing Michael Voight Executive Editor and Publisher Joe Black, PT, DPT, SCS, ATC Eric Fernandez Jay Greenstein, DC Skip Hunter, PT, ATC-Ret Sean MacNeal Russ Paine, PT, DPT Mike Reinold, PT, DPT, SCS, ATC, CSCS, C-PS Danny Smith, PT, DPT, DHSc, OCS, SCS, ATC Paul Timko Tim Tyler, PT, ATC
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Sports Legacy Advisory Board Turner A. Blackburn, PT, ATC George Davies, PT, DPT, MEd, SCS, ATC, LAT, CSCS, PES, FAPTA Terry Malone, PT, PhD Bob Mangine, PT Barb Sanders, PT, PhD Tim Tyler, PT, ATC Kevin Wilk, PT, DPT, FAPTA
Staff Executive Editor/Publisher Michael L. Voight, PT, DHSc, OCS, SCS, ATC, CSCS Director of Operations and Marketing Mary Wilkinson Editor in Chief Barbara Hoogenboom, PT, EdD, SCS, ATC Managing Editor Ashley Campbell, PT, DPT, SCS, CSCS Manuscript Coordinator Casey Lewis, PTA, ATC
NORTH AMERICAN SPORTS MEDICINE INSTITUTE Publisher Contact Information International Journal of Sports Physical Therapy 6011 Hillsboro Pike Nashville, TN 37215, US, http://www.ijspt.org IJSPT is a bimonthly publication, with release dates in February, April, June, August, October and December. ISSN 2159-2896
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IJSPT is an official journal of the International Federation of Sports Physical Therapy (IFSPT). Countries with access to IJSPT as a member benefit: Greece Argentina Hong Kong Australia Indonesia Austria Ireland Belgium Italy South Africa Bulgaria Japan South Korea Brazil Luxembourg Spain Canada The Netherlands Sweden Chile New Zealand Switzerland Cyprus Nigeria Thailand Denmark Norway Turkey Finland Portugal United Kingdom France Saudi Arabia Zambia Germany Reach us at www.ifspt.org.
IJSPT is an official journal of the ICCUS Society for Sports Rehabilitation. www.iccus.org
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1. Dima R, Tieppo Francio V, Towery C, Davani S. Review of Literature on Low-level Laser Therapy Benefits for Nonpharmacological Pain Control in Chronic Pain and Osteoarthritis. Altern Ther Health Med. 2018 Sep;24(5):8-10. PMID: 28987080. 2. Larkin KA, Martin JS, Zeanah EH, True JM, Braith RW, Borsa PA. Limb blood flow after class 4 laser therapy. J Athl Train. 2012 Mar-Apr;47(2):178-83. doi: 10.4085/1062-6050-47.2.178. PMID: 22488283; PMCID: PMC3418129. 3. Chow RT, Johnson MI, Lopes-Martins RA, Bjordal JM. Efficacy of low-level laser therapy in the management of neck pain: a systematic review and meta-analysis of randomised placebo or active-treatment controlled trials. Lancet. 2009 Dec 5;374(9705):1897-908. doi: 10.1016/S0140-6736(09)61522-1. Epub 2009 Nov 13. Erratum in: Lancet. 2010 Mar 13;375(9718):894. PMID: 19913903. 4. Alayat MS, Atya AM, Ali MM, Shosha TM. Long-term effect of high-intensity laser therapy in the treatment of patients with chronic low back pain: a randomized blinded placebo-controlled trial. Lasers Med Sci. 2014 May;29(3):1065-73. doi: 10.1007/s10103-013-1472-5. Epub 2013 Nov 2. 5. Yousefi-Nooraie R, Schonstein E, Heidari K, Rashidian A, Pennick V, Akbari-Kamrani M, Irani S, Shakiba B, Mortaz Hejri SA, Mortaz Hejri SO, Jonaidi A. Low level laser therapy for nonspecific low-back pain. Cochrane Database Syst Rev. 2008 Apr 16;(2):CD005107. doi: 10.1002/14651858.CD005107.pub4. PMID: 18425909. 6. Holanda VM, Chavantes MC, Silva DF, de Holanda CV, de Oliveira JO Jr, Wu X, Anders JJ. Photobiomodulation of the dorsal root ganglion for the treatment of low back pain: A pilot study. Lasers Surg Med. 2016 Sep;48(7):653-9. doi: 10.1002/lsm.22522. Epub 2016 May 2. PMID: 27135465. 7. Jovicić M, Konstantinović L, Lazović M, Jovicić V. Clinical and functional evaluation of patients with acute low back pain and radiculopathy treated with different energy doses of low level laser therapy. Vojnosanit Pregl. 2012 Aug;69(8):656-62. PMID: 22924260. 8. Abbasgholizadeh ZS, Evren B, Ozkan Y. Evaluation of the efficacy of different treatment modalities for painful temporomandibular disorders. Int J Oral Maxillofac Surg. 2020 May;49(5):628-635. doi: 10.1016/j. ijom.2019.08.010. Epub 2019 Sep 21. PMID: 31547949. 9. Khairnar S, Bhate K, S N SK, Kshirsagar K, Jagtap B, Kakodkar P. Comparative evaluation of low-level laser therapy and ultrasound heat therapy in reducing temporomandibular joint disorder pain. J Dent Anesth Pain Med. 2019 Oct;19(5):289-294. doi: 10.17245/jdapm.2019.19.5.289. Epub 2019 Oct 30. PMID: 31723669; PMCID: PMC6834715. 10. Roberts DB, Kruse RJ, Stoll SF. The effectiveness of therapeutic class IV (10 W) laser treatment for epicondylitis. Lasers Surg Med. 2013 Jul;45(5):311-7. doi: 10.1002/lsm.22140. Epub 2013 Jun 3. PMID: 23733499. Copyright © 2022 by DJO, LLC • MKT00-12297 Rev A Individual results may vary. Neither DJO, LLC nor any of its subsidiaries dispense medical advice. The contents of this document do not constitute medical, legal, or any other type of professional advice. Rather, please consult your healthcare professional for information on the courses of treatment, if any, which may be appropriate for you.
IJSPT
INTERNATIONAL JOURNAL OF SPORTS PHYSICAL THERAPY
Executive Editor/Publisher Michael L. Voight, PT, DHSc, OCS, SCS, ATC, CSCS Belmont University Nashville, Tennessee – USA Editor in Chief Barbara Hoogenboom, PT, EdD, SCS, ATC Grand Valley State University Grand Rapids, Michigan - USA Managing Editor Ashley Campbell, PT, DPT, SCS, CSCS Nashville Sports Medicine and Orthopaedic Center Nashville, Tennessee – USA Manuscript Coordinator Casey Lewis, PTA, ATC Nashville Sports Medicine and Orthopaedic Center Nashville, Tennessee – USA Editors Robert Manske PT, DPT, Med, SCS, ATC, CSCS University of Wichita Wichita, KS, USA Terry Grindstaff, PT, PhD, ATC, SCS, CSCS Creighton University Omaha, NE, USA Phil Page PT, PhD, ATC, CSCS Franciscan University DPT Program Baton Rouge, LA, USA Kevin Wilk PT, DPT, FAPTA Clinical Viewpoint Editor Champion Sports Medicine Birmingham, AL, USA International Editors Kristian Thorborg PT, PhD, RISPT Copenhagen University, Amager-Hvidovre Hospital Hvidovre, Denmark Colin Paterson PT, MSc PGCert(Ed), MCSP, RISPT, SFHEA University of Brighton Brighton, England, UK Luciana De Michelis Mendonça, PT, PhD UFVJM Diamantina, Brazil Chris Napier, PT, PhD Clinical Assistant Professor University of British Coumbia, Vancouver, BC, Canada Associate Editors Eva Ageberg, PT, PhD Professor, Lund University Lund, Sweden Lindsay Becker, PT, DPT, SCS, USAW Buckeye Performance Golf Dublin, Ohio, USA
Keelan Enseki, PT, MS, OCS, SCS, ATC University of Pittsburgh Pittsburgh, PA, USA John Heick, PT, PhD, DPT, OCS, NCS, SCS Northern Arizona University Flagstaff, AZ, USA Julie Sandell Jacobsen, MHSc, PhD VIA University Aarhus, Denmark RobRoy L. Martin, PhD, PT, CSCS Duquesne University Pittsburgh, PA, USA Andrea Mosler, PhD, FACP, FASMF La Trobe Sport and Exercise Medicine Research Centre, School of Allied Health, Human Services and Sport, La Trobe University Melbourne, Victoria, Australia Brandon Schmitt, DPT, ATC PRO Sports Physical Therapy Scarsdale, NY, USA Barry Shafer, PT, DPT Elite Motion Physical Therapy Arcadia, CA, USA Laurie Stickler, PT, DHSc, OCS Grand Valley State University Grand Rapids, MI, USA Editorial Board James Andrews, MD Andrews Institute & Sports Medicine Center Gulf Breeze, AL, USA Amelia (Amy) Arundale, PT, PhD, DPT, SCS Red Bull/Ichan School of Medicine Salzburg, Austria/New York, NY, USA Gary Austin, PT PhD Belmont University Nashville, TN, USA Roald Bahr, MD Oslo Sports Trauma Research Center Oslo, Norway Lane Bailey, PT, PhD Memorial Hermann IRONMAN Sports Medicine Institute Houston, Texas, USA Gül Baltaci, PT,Ph.D. Professor, CKTI, FACSM Private Guven Hospital Ankara, Turkey Asheesh Bedi, MD University of Michigan Ann Arbor, MI, USA David Behm, PhD Memorial University of Newfoundland St. John's, Newfoundland, Canada
EDITORIAL BOARD Barton N. Bishop, PT, DPT, SCS, CSCS Kaizo Clinical Research Institute Rockville, Maryland, USA
Brian Cole, MD Midwest Orthopaedics at Rush Chicago, IL, USA
Mario Bizzini, PhD, PT Schulthess Clinic Human Performance Lab Zürich, Switzerland
Ann Cools, PT, PhD Ghent University Ghent, Belgium
Joe Black, PT, DPT, SCS, ATC Total Rehabilitation Maryville, Tennesse, USA
Andrew Contreras, DPT, SCS Washington, DC, USA
Turner A. "Tab" Blackburn, APTA Life Member, ATC-Ret, AOSSM-Ret NASMI Lanett, AL, USA Lori Bolgla, PT, PhD, MAcc, ATC Augusta University Augusta, Georgia, USA Matthew Briggs The Ohio State University Columbus, OH, USA Tony Brosky, PT, PhD Bellarmine University Louisville, KY, USA Brian Busconi, MD UMass Memorial Hospital Boston, MA, USA Robert J. Butler, PT, PhD St. Louis Cardinals St. Louis, MO, USA Duane Button, PhD Memorial University St. Johns, Newfoundland, Canada
George Davies, PT, DPT, MEd, SCS, ATC, LAT, CSCS, PES, FAPTA Georgia Southern University Savannah, Georgia, USA Pete Draovich, PT Jacksonville Jaguars Footbal Jacksonvile, FL, USA Jeffrey Dugas, MD Andrews Institute & Sports Medicine Center Birmingham, AL, USA Jiri Dvorak, MD Schulthess Clinic Zurich, Switzerland Todd Ellenbecker Rehab Plus Phoenix, AZ, USA Carolyn Emery, PT, PhD University of Calgary Calgary, Alberta, Canada Ernest Esteve Caupena, PT, PhD University of Girona Girona, Spain
J. W. Thomas Byrd, MD Nashville Sports Medicine and Orthopaedic Center Nashville, TN, USA
Sue Falsone, PT, MS, SCS, ATC, CSCS, COMT Structure and Function Education and A.T. Still University Phoenix, Arizona, USA
Lyle Cain, MD Andrews Institute & Sports Medicine Center Birmingham, AL, USA
J. Craig Garrison, PhD, PT, ATC, SCS Texas Health Sports Medicine Fort Worth, Texas, USA
Gary Calabrese, PT, DPT Cleveland Clinic Cleveland, Ohio, USA
Maggie Gebhardt, PT, DPT, OCS, FAAOMPT Fit Core Physical Therapy/Myopain Seminars Atlanta, GA and Bethesda, MD, USA
Meredith Chaput, PT, DPT, SCS Ohio University Athens, OH, USA
Lance Gill, ATC LG Performance-TPI Oceanside, CA, USA
Rita Chorba, PT, DPT, MAT, SCS, ATC, CSCS United States Army Special Operations Command Fort Campbell, KY, USA
Phil Glasgow, PhD, MTh, MRes, MCSP Sports Institute of Northern Ireland Belfast, Northern Ireland, UK
John Christoferreti, MD Texas Health Dallas, TX, USA
Robert S. Gray, MS, AT Cleveland Clinic Sports Health Cleveland, Ohio, USA
Richard Clark, PT, PhD Tennessee State University Nashville, TN, USA
Jay Greenstein, DC Kaizo Health Baltimore, MD, USA
Juan Colado, PT, PhD University of Valencia Valencia, Spain
Martin Hagglund, PT PhD Linkoping University Linkoping, Sweden
EDITORIAL BOARD Allen Hardin, PT, SCS, ATC, CSCS University of Texas Austin, TX, USA
Terry Malone, PT, EdD, ATC, FAPTA University of Kentucky Lexington, KY, USA
Richard Hawkins, MD Professor of surgery, University of South Carolina Adjunct Professor, Clemson University Principal, Steadman Hawkins, Greenville and Denver (CU)
Robert Mangine, PT University of Cincinnati Cincinnati, OH, USA
John D.Heick, PT, PhD, DPT, OCS, NCS, SCS Northern Arizona University Flagstaff, AZ, USA Tim Hewett, PhD Hewett Consulting Minneapolis, Minnesota, USA Per Hølmich, MD Copenhagen University Hospital Copenhagen, Denmark Kara Mae Hughes, PT, DPT, CSCS Wolfe PT Nashville, TN, USA Lasse Ishøi, PT, MSc Sports Orthopedic Research Center Copenhagen University Hospital Hvidovre, Denmark Jon Karlsson, MD Sahlgrenska University Goteborg, Sweden Brian Kelly, MD Hospital for Special Surgery New York, NY, USA Benjamin R. Kivlan, PhD, PT, OCS, SCS Duquesne University Pittsburgh, PA, USA Dave Kohlrieser, PT, DPT, SCS, OCS, CSCS Ortho One Columbus, OH, USA Andre Labbe PT, MOPT Tulane Institute of Sports Medicine New Orleans, LA USA Henning Langberg, PT, PhD University of Copenhagen Copenhagen, Denmark Robert LaPrade, MD Twin Cities Orthopedics Edina, MN, USA Lace Luedke, PT, DPT University of Wisconsin Oshkosh Oshkosh, WI, USA Lenny Macrina, PT, SCS, CSCS, C-PS Champion Physical Therapy and Performance Boston, MA, USA Phillip Malloy, PT, PhD Arcadia University/Rush University Medical Center Glenside, PA and Chicago, IL, USA
Eric McCarty, MD University of Colorado Boulder, CO, USA Ryan P. McGovern, PhD, LAT, ATC Texas Health Sports Medicine Specialists Dallas/Fort Worth, Texas, USA Mal McHugh, PhD NISMAT New York, NY, USA Joseph Miller, PT, DSc, OCS, SCS, CSCS Pikes Peak Community College Colorado Springs, CO, USA Havard Moksnes, PT PhD Oslo Sports Trauma Research Center Oslo, Norway Michael J. Mullaney, PT, SCS NISMAT Mullaney & Associates Physical Therapy New York, NY and Matawan, NJ, USA Andrew Murray, MD, PhD European PGA Tour Edinburgh, Scotland, UK Andrew Naylor, PT, DPT, SCS Bellin Health Green Bay, WI, USA Stephen Nicholas, MD NISMAT New York New York, NY, USA John O'Donnel, MD Royal Melbourne Hospital Melbourne, Australia Russ Paine, PT McGovern Medical School Houston, TX, USA Snehal Patel, PT, MSPT, SCD HSS Sports Rehabilitation Institute New York, NY, USA Marc Philippon, MD Steadman-Hawkins Clinic Vail, CO, USA Nicola Phillips, OBE, PT, PhD, FCSP Professor School of Healthcare Sciences Cardiff University, Cardiff, Wales, UK Kevin Plancher, MD, MPH, FAAOS Plancher Orthopedics and Sports Medicine New York, NY USA
EDITORIAL BOARD Marisa Pontillo, PT, PhD, DPT, SCS University of Pennsylvania Health System Philadelphia, PA, USA
Andreas Serner, PT PhD Aspetar Orthopedic and Sports Medicine Hospital Doha, Qatar
Matthew Provencher, MD Steadman Hawkins Clinic Vail, CO, USA
Ellen Shanley, PT, PhD ATI Spartanburg, SC, USA
Charles E. Rainey, PT, DSc, DPT, MS, OCS, SCS, CSCS, FAAOMPT United States Public Health Service Springfield, MO, USA
Karin Silbernagel, PT, PhD University of Delaware Newark, DE, USA
Alexandre Rambaud, PT PhD Saint-Etienne, France Carlo Ramponi, PT Physiotherapist, Kinè Rehabilitation and Orthopaedic Center Treviso, Italy Michael Reiman, PT, PhD Duke University Durham, NC, USA Mark F. Reinking, PT, PhD, SCS, ATC Regis University Denver, CO, USA Mike Reinold, PT, DPT, SCS, ATC, CSCS, C-PS Champion Physical Therapy and Performance Boston, MA, USA
Holly Silvers, PT, PhD Velocity Physical Therapy Los Angeles, CA, USA Lynn Snyder-Mackler, PT, ScD, FAPTA STAR University of Delaware Newark, DE, USA Alston Stubbs, MD Wake Forest University Winston-Salem, NC, USA Amir Takla, B.Phys, Mast.Physio (Manip), A/Prof Australian Sports Physiotherapy The University of Melbourne Melbourne, Australia Charles Thigpen, PhD, PT, ATC ATI Spartanburg, SC, USA
Mark Ryan, ATC Steadman-Hawkins Clinic Vail, CO, USA
Steven Tippett, PT, PhD, ATC, SCS Bradley University Peoria, IL, USA
David Sachse, PT, DPT, OCS, SCS USAF San Antonio, TX, USA
Tim Tyler, PT, ATC NISMAT New York, NY, USA
Marc Safran, MD Stanford University Palo Alto, CA, USA
Timothy Uhl, PT, PhD, ATC University of Kentucky Lexington, KY, USA
Alanna Salituro, PT, DPT, SCS, CSCS New York Mets Port Saint Lucie, FL, USA
Bakare Ummukulthoum, PT University of the Witswatersrand Johannesburg, Gauteng, South Africa
Mina Samukawa, PT, PhD, AT (JSPO) Hokkaido University Sapporo, Japan Barbara Sanders, PT, PhD, FAPTA, Board Certified Sports Physical Therapy Emeritus Professor and Chair, Department of Physical Therapy Texas State University Round Rock, TX, USA Felix “Buddy” Savoie, MD, FAAOS Tulane Institute of Sport Medicine New Orleans, LA, USA Teresa Schuemann, PT, DPT, ATC, CSCS, Board Certified Specialist in Sports Physical Therapy Evidence in Motion Fort Collins, CO, USA Timothy Sell, PhD, PT, FACSM Atrium Health Musculoskeletal Institute Charlotte, NC, USA
Yuling Leo Wang, PT, PhD Sun Yat-sen University Guangzhou, China Mark D. Weber, PT, PhD, SCS, ATC Texas Women’s University Dallas, TX, USA Richard B. Westrick, PT, DPT, DSc, OCS, SCS US Army Research Institute Boston, MA, USA Chris Wolfe, PT, DPT Belmont University Nashville, TN, USA Tobias Wörner, PT, MSc Lund University Stockholm, Sweden
TABLE OF CONTENTS VOLUME 17, NUMBER 4 PAGE TITLE IN MEMORIAM INTERNATIONAL PERSPECTIVE 548 Return to Play After a Shoulder Injury: Let’s Not Put the Cart Before the Horse! Policastro PO, Camargo PR. INVITED CLINICAL COMMENTARY 551 Dry Needling: A Clinical Commentary. McAphee D, Bagwell M, Falsone S. ORIGINAL RESEARCH 556 Females have Lower Knee Strength and Vertical Ground Reaction Forces During Landing than Males Following Anterior Cruciate Ligament Reconstruction at the Time of Return to Sport. Sullivan ZB, Sugarman BS, Faherty MS, et al. 566
Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics. Martinez C, Garbett S, Hiromasa K, et al.
574
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee Valgus. Jamaludin NI, Sahabuddin FNA, Rasudin NS, Shaharudin S.
585
Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic. Weaver A, Ness B, Roman D, Giampetruzzi N, Cleland J.
593
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score. Mann KJ, O’Dwyer N, Bruton MR, Bird SP, Edwards S.
605
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players. Olson ML, Schindler G.
613
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength. Gasparin GB, Ribeiro-Alvares JBA, Baroni BM.
622
Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3 Student-Athletes. Cacolice PA, Starkey BE, Carcia CR, Higgins PE.
628
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients. Dean RS, DePhillipo NN, Kiely MT, Schwery NA, Monson JK, LaPrade RF.
636
The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in Athletic Male Individuals: An Ultrasound Investigation. Torrente QM, Killingback A, Robertson C, Adds PJ.
643
The Problem of Recurrent Injuries in Collegiate Track and Field. Hopkins C, Kanny S, Headley C.
648
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team. Buchholtz K, Barnes C, Burgess TL.
658
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage. D’Amico A, Silva K, Rubero A, Dion S, Gillis J, Gallo J.
TABLE OF CONTENTS (continued) VOLUME 17, NUMBER 4 PAGE
TITLE
669
Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User Experience Levels. Karagiannopoulos C, Griech S, Leggin B.
677
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study. McDevitt AW, Cleland JA, Addison S, Calderon L, Snodgrass S.
695
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized Clinical Trial. Howell AJ, Burchett A, Heebner N, et al.
707
Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball Seasons? Tsuruike M, Mukaihara Y, Ellenbecker TS.
715
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers. Trunt A, Fisher BT, MacFadden LN.
CASE REPORT 724 Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report. da Silva LG, Ferrer RM, de Souza JR, Gracitelli MEC, Secchi LLB. CLINICAL COMMENTARY Stride Length and Torso Biomechanics As They Relate To Medial Elbow Injuries In Adolescent Aged 732 Baseball pitchers: A Clinical Commentary. Dietz Z, DeWeese D, Shaw N, et al.
Danny D. Smith, PT, DPT, DHSc, OCS, SCS, ATC: IN MEMORIAM By Michael L. Voight
The United States Sports Physical Therapy community lost a great man on April 25, 2022, Dr. Danny Smith of Elizabethton, Tennessee. Danny Smith was not only a professional colleague to many of us - but was also a good friend to not only me, but many in our sports medicine community. John Stone a physician poet once wrote that: “I’ve seen death come on as slow as rust, or as quickly and unexpected as a doorknob coming loose in your hand”. Given the untimely passing of my good friend, this quote sticks in my head as I think about the life of Dr. Danny Smith. For those who did not know Dr. D, as he was known by so many, he was a beloved and gifted sports physical therapist who was a true asset to his community and profession as whole. Born and raised in East Tennessee, he was an outstanding baseball player for Elizabethton High School and earned a scholarship to play at Milligan College. After playing at Milligan College for three years he was accepted into Physical Therapy School at UT Memphis, graduating in 1973 with a BS in Physical Therapy. Upon graduation he moved back to east Tennessee. He continued his educational path and earned his Master’s degree at East Tennessee State University in 1978. He was the founder and owner of Physical Therapy Services for 41 years and had built this private practice clinic from scratch, and now it has become one of the most well-renown private practice clinics in the Tri-Cities, Tennessee area. He has held the title of the oldest Private Practice PT Clinic Owner in the great State of Tennessee. He did not let his education pursuits stop. Believing in the advancement of physical therapy, he later earned his Doctor of Physical Therapy, becoming the first DPT in the state of
TN. Finally, Dr. Danny Smith went on to pioneer a new degree offered by the University of St. Augustine, a DHSc degree. Dr. Smith was a servant leader in his community and his profession. He has volunteered countless hours in the community as a Sports Medicine Physical Therapist provider for Elizabethton High School sports teams, and the surrounding schools in the Tri-Cities, TN area for over 45 years. He was an advocate for quality sports care for his athletes both on and off the field. Elizabethton High School was his true pride and joy, and, often, he saw the success of many championship teams for his immediate upper east Tennessee area on several occasions. He always advocated for his players, coaches, and their families both on and off the field. He was their physical therapist and athletic trainer. His patients were his priority, and he would always say “you must put your patients first and everything else will work out.” His friendly smile, hearty laugh, and ability to talk to anyone about anything made him a true friend to his community. Danny was a great storyteller and some of his stories of patient interactions were some of the finest moments in a patient’s life when they gave credit and accountability to the physical therapy profession. He loved his community and giving back. He was inducted into the Sports Hall of Fame in the Tri-Cities area in recognition of his service. I remember watching a movie with Danny one evening about the life of Steve Jobs. During the movie, Steve Jobs said: “When you grow up, you tend to get told that the world is the way it is, and you should just live your life inside that world. Try not to bash into the walls too much. Try to have a nice family life. Have fun, save a little money. That’s a very limited life. Life can be
much broader, once you discover one simple fact, and that is everything around that you call life was made up by people who were no smarter than you. You can change it. You can influence it. You can build your own things that other people can use. Once you learn that, you’ll never be the same again”. I remember Danny looking over at me and saying, “You know, I love waking up every morning going to work as a physical therapist, because I can be that someone special in someone’s life.” In his leisure time, Danny enjoyed spending time with his family, fishing with his grandchildren, spending time at the lake, traveling, and helping others in need. Danny will be greatly missed both as a physical therapist, a mentor, a community leader, advocate for children in the community, a family man, and great friend. We will remember Dr. Danny Smith as a legacy for moving the PT profession forward in many aspects, and the APTA, the Sports Physical Therapy community, and APTA Tennessee are extremely thankful to him for the contributions and talents he gave to this great profession of ours. In his professional PT world, he had served in many roles and had been very active and engaged not only at a local and state level with the PT Association in Tennessee, but also nationally in the American Academy of Sports Physical Therapy – formerly the Sports Section, as it will always be to many of us. He served the TPTA as Chapter Vice President of the Tennessee Component, on the Legislative Committee, and did a tremendous job with the Awards Committee. On the national level, not only did Danny serve on various committees and the Executive Board for several years, Danny also embraced and established the challenges of providing the emergency first responder course for the Section, teaching countless of our developing sports physical therapists over the years. Not only was Danny my initial EMR instructor, but he also became my mentor as an instructor trainer as he did with numerous other instruc-
tors. Dr Smith was an adjunct professor within the Belmont University School of Physical Therapy teaching emergency medical response and acute illness and injury management. Danny not only helped countless students in the classroom, but he also mentored many students in his clinic throughout the years. He started the first Sports PT residency program in the state of TN in 2012. Though these interactions, he affected and shaped the careers of countless students. Once you met him, Dr D would become your friend for life and one you could always count on for whatever you might need. His service to the profession did not go unnoticed as he was the recipient of numerous awards at the State and National level. Within the State of Tennessee, he received the Mac Hensley Lifetime Achievement Award in September 2018 and one of the highest awards in the state, the Carol Liken Award in February 2021. Nationally, he received the Sports Physical Therapy Section Distinguished Service Award in 1999, the Sports Physical Therapy Section Ron Peyton Award in February of 2009, and the Turner A Blackburn Lifetime Achievement Award Hall of Fame induction in February of 2011. In 2021, the APTA recognized Dr Smith with the prestigious Lucy Blair Service Award for his many contributions to the profession. One of Danny’s favorite lines comes from John Wayne: “Courage is being scared to death and saddling up anyway”. Danny Smith’s passion for service above self leaves a legacy for all of us to find the courage to become involved and make our profession better every day. I would like to end with a quote from Emerson: “When you were born, you were crying and everyone else was smiling. Live your life so at the end, you’re the one who is smiling and everyone else is crying.” Danny, we are all much better off for knowing you and I know that you are smiling about a life well lived and one that touched so many that we are all crying. Rest in Peace, my friend. Mike Voight
Policastro PO, Camargo PR. Return to Play After a Shoulder Injury: Let’s Not Put the Cart Before the Horse! IJSPT. 2022;17(4):548-550.
IFSPT International Perspective
Return to Play After a Shoulder Injury: Let’s Not Put the Cart Before the Horse! Pablo Oscar Policastro, PT 1, Paula Rezende Camargo, PT, PhD 2 1
Laboratory of Analysis and Intervention of the Shoulder Complex, Department of Physical Therapy, Universidade Federal de São Carlos; KINÉKinesiología Deportiva y Funcional Sports Clinic, 2 Laboratory of Analysis and Intervention of the Shoulder Complex, Department of Physical Therapy, Universidade Federal de São Carlos Keywords: return to sport, reinjury, overhead sports, collision sports https://doi.org/10.26603/001c.35574
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Shoulder disorders are common in athletes who practice overhead and collision sports,1,2 and represent an important clinical problem with a high rate of recurrence.3 Return-to-sport decision-making after a shoulder injury is a significant challenge and should be a shared decision among all stakeholders due to the complexity of the process.4,5 There are currently no evidence-based criteria to be followed during the process of return-to-sport following shoulder injuries, unlike published guidelines for anterior cruciate ligament reconstruction,6 for example. Athletes should also be aware that they may be unable to return to the same level as previous to injury. Despite the lack of evidence to define return-to-play guidelines, a recent consensus statement has provided important guidance to support decision-making during the return-to-sport process after a shoulder injury.7 The authors outlined 6 domains to consider for the athlete who is in the process of returning to sport after a shoulder injury: pain, active shoulder range of motion, strength, power and endurance, the kinetic chain, psychology, and return-to-sport specific activities. This consensus may be helpful for clinicians and athletes to start gathering information to optimize the plan to return to sport. Still, additional support should be created in the near future. For now, this consensus may be used as a template for clinicians to remember that athletes with a shoulder injury should also have the other segments of the kinetic chain assessed (not only the shoulder) as well as psychological and social aspects. Shoulder functional performance tests are suggested to assess strength, power, and endurance, not only of the shoulder but also of the entire kinetic chain.8 Although several shoulder functional performance tests have been described in the literature to help in the understanding of the physical condition of the athlete, there is no battery of valid shoulder tests to guide the decision-making for return-tosport. In addition, many tests may not be specific to the functional demands of the shoulder in the athlete’s sport. The reference values for shoulder functional performance tests that are available in the current literature are not sport-specific, which makes interpretation difficult. For instance, the Y-Balance Test – Upper Quarter (YBT-UQ) is described as a quantitative analysis of an athlete’s ability to reach with the free hand while maintaining weight bearing on the contralateral upper limb.9 The performance of the athlete in the YBT-UQ may make sense for some sports
like rugby or American football where the shoulder works in open and closed kinetic chains. However, the YBT-UQ may not be relevant for overhead sports (e.g. volleyball), where the gestures are predominantly in open kinetic chain. Due to the lack of normative values, clinicians commonly use the contralateral shoulder as a reference to compare the injured shoulder. Depending on the sport, this comparison may not be appropriate if we consider the arm dominance and level of activity of the athlete. Another example is the drop catches test, which is highly influenced by the arm dominance, especially in unilateral sports. This test quantifies the number of repetitions to drop a tennis ball and quickly catch it by twisting the shoulder from an externally rotated position to an internally rotated position with 90° of arm abduction and elbow flexion.10 Therefore, it is reasonable to consider that shoulder functional performance tests may not always bring valuable information about the status of the shoulder to decide on return-to-sport readiness. Other factors should also be considered and further investigated in the return-to-play process, such as biopsychosocial context. Athletes with similar shoulder injuries and results of functional performance tests may not fully return to sports activity, especially at the same time and level.11 Factors such as fear of reinjury, apprehension during training, being involved in contact sports, and motivation may influence this process. In addition, self-report questionnaires are not enough to fully understand the athlete’s condition and context. In comparison to other body regions, we are clearly a few steps behind on decision making for the return-to-play after a shoulder injury. The scientific sports community should focus on improving the evidence to guide clinicians and all stakeholders for return-to-sport after a shoulder injury. More research exploring and combining shoulder performance tests, biopsychosocial context, sport-specific tasks and clinical information could be useful as well as high-quality longitudinal studies to determine a cluster of shoulder functional tests to guide the decision for returnto-play. Finally, we should now try to understand the value of the available performance tests instead of creating new ones. Let’s not put the cart before the horse! The process of return-to-play after an injury is challenging for both athletes and clinicians. Considering the lack of robust information to support the decision making for
Return to Play After a Shoulder Injury: Let’s Not Put the Cart Before the Horse!
shoulder injuries, the process of return-to-play is difficult and can place increased psychological pressure on athletes and sports physical therapists. As members of the sports science community, we must continue to work together to change this reality.
Submitted: April 01, 2022 CDT, Accepted: May 04, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Return to Play After a Shoulder Injury: Let’s Not Put the Cart Before the Horse!
REFERENCES 1. Fares MY, Fares J, Baydoun H, Fares Y. Prevalence and patterns of shoulder injuries in Major League Baseball. Phys Sportsmed. 2020;48(1):63-67. doi:10.10 80/00913847.2019.1629705 2. Lynch E, Lombard AJJ, Coopoo Y, Shaw I, Shaw BS. Shoulder injury incidence and severity through identification of risk factors in rugby union players. Pakistan J Med Sci. 2013;29:1400-1405. 3. Makhni EC, Lee RW, Nwosu EO, Steinhaus ME, Ahmad CS. Return to competition, re-injury, and impact on performance of preseason shoulder injuries in major league baseball pitchers. Phys Sportsmed. 2015;43(3):300-306. doi:10.1080/00913847.2015.1050 952 4. Cools AM, Maenhout AG, Vanderstukken F, Declève P, Johansson FR, Borms D. The challenge of the sporting shoulder: From injury prevention through sport-specific rehabilitation toward return to play. Ann Phys Rehabil Med. 2021;64(4):101384. doi:10.101 6/j.rehab.2020.03.009 5. Otley T, Myers H, Lau BC, Taylor DC. Return to Sport After Shoulder Stabilization Procedures: A Criteria-Based Testing Continuum to Guide Rehabilitation and Inform Return-to-Play Decision Making. Arthrosc Sports Med Rehabil. 2022;4(1):e237-e246. doi:10.1016/j.asmr.2021.09.039
6. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: The Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804-808. doi:10.1136/bjsports-2016-0960 31 7. Schwank A et al. Bern Consensus Statement on Shoulder Injury Prevention, Rehabilitation, and Return to Sport for Athletes at All Participation Levels. J Orthop Sport Phys Ther. 2022;52:11-28. 8. Wilk KE, Bagwell MS, Davies GJ, Arrigo CA. Return to sport participation criteria following shoulder injury: a clinical commentary. J Sports Phys Ther. 2020;15(4):624-642. 9. Gorman PP, Butler RJ, Plisky PJ, Kiesel KB. Upper quarter y balance test: Reliability and performance comparison between genders in active adults. J Strength Cond Res. 2012;26:3043-3048. 10. Olds M, Coulter C, Marant D, Uhl T. Reliability of a shoulder arm return to sport test battery. Phys Ther Sport. 2019;39:16-22. doi:10.1016/j.ptsp.2019.06.001 11. Higgins MJ, DeFroda S, Yang DS, Brown SM, Mulcahey MK. Professional Athlete Return to Play and Performance After Shoulder Arthroscopy Varies by Sport. Arthrosc Sports Med Rehabil. 2021;3(2):e391-e397. doi:10.1016/j.asmr.2020.10.001
International Journal of Sports Physical Therapy
McAphee D, Bagwell M, Falsone S. Dry Needling: A Clinical Commentary. IJSPT. 2022;17(4):551-555.
Clinical Viewpoint
Dry Needling: A Clinical Commentary a
Darius McAphee, PT, OCS, CSCS, CMTPT 1, Michael Bagwell, PT, DPT, OCS, CMPT 2 , Sue Falsone, PT, MS, SCS, ATC, CSCS, COMT 3 1
Atrium Health Floyd, 2 Champion Sports Medicine, 3 Houston Texans Football Team
Keywords: dry needling, trigger points, physical therapy https://doi.org/10.26603/001c.35693
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
INTRODUCTION The treatment technique called dry needling is defined by the American Physical Therapy Association(APTA) as a skilled intervention that uses a thin filiform needle to penetrate the skin and stimulate underlying myofascial trigger points, muscular, and connective tissues for the management of neuromusculoskeletal pain and movement impairments (Figure 1).1 A trigger point(TrP) is a hyperirritable spot in a taut band of skeletal muscle that is painful on compression, stretch, overload or contraction of the tissue which usually responds with referred pain that is perceived distant from the spot.2,3 Trigger points can be active, passive or latent. Active TrPs cause a reproduction of the patient’s familiar pain with or without palpation. Passive trigger points do not cause pain except when stimulated via palpation. With latent TrPs, the local and referred pain do not reproduce any symptoms familiar or usual to the patient when palpated.2,3
Figure 1. A thin filiform needle to penetrate the skin and stimulate underlying myofascial trigger points, muscular, and connective tissues for the management of neuromusculoskeletal pain and movement impairments.
HISTORY In 1938 Sir Thomas Lewis, and his fellow John Kellgren demonstrated that the injection of a saline solution into muscles led to pain being referred somewhere else.4–6 Kellgren would go on to chart zones of referred pain in neighboring and distant tissue.7 In 1942, Dr. Janet Travell–a former cardiologist- ended up publishing her first paper with several colleagues, "Pain and Disability of the Shoulder and Arm: Treatment by Intramuscular Infiltration with Procaine Hydrochloride.8 She was treating herself from shoulder and arm pain by performing injections into the muscles.8 In 1952, she would go on to identify the pain patterns of trigger points in 32 skeletal muscles.8,9 Dr. Travell would go on to meet Dr. David Simons who was interested in the science behind referred pain. They ended up publishing Myofascial Pain and Dysfunction: The Trigger Point Manual in 1983. It was divided into two volumes. Volume I covered the upper extremities and Volume II covered the lower extremities. This was a guide that was useful for the diagnosis and location of trigger points.6
a
Corresponding author: msbagwell@gmail.com
Dry needling, or using a needle without an injected anesthetic, would come into play when Karel Lewitt’s article, “The Needle Effect In The Relief Of Myofascial Pain” came out in 1979. He demonstrated analgesic effects of painful spots which came from the needle alone. The immediate analgesia has been called the, “needle effect.”10 Peter Baldry would go on in 2002 to distinguish between superficial vs deep dry needling. He found that 90 percent of his patients suffered from uncomplicated nociceptive pain from TPs.7 They could be treated with superficial dry needling which is safer and less painful to the patient when compared to deep dry needling. Deep dry needling should be reserved for those with more complicated nerve root pain with concomitant myofascial TP pain. Popularity and significant interest in dry needling didn’t grow until after the year 2000. In 2010, jurisdictions sought information from the Federation of State Boards of Physical Therapy (FSBPT) regarding the criterion for physical therapists to be able to practice dry needling.11 In 2015, the FSBPT, APTA, and seven dry needling experts composed a task
Dry Needling: A Clinical Commentary
force that set forth a final set of competencies for physical therapists for the safe and effective use of dry needling in clinical practice.11
TECHNIQUE Adept palpation skills are used to identify a trigger point. A flat or pincer grip is utilized to identify the problematic area with the palpating hand. The needling hand places the needle and guide tube at the site (Figure 2). The needle is tapped into the epidural layer of the skin and the guide tube is discarded. The dominant hand is used to insert the needle perpendicular to the muscle superficially to the subcutaneous tissue, or deep into the muscle to penetrate the trigger point. This is known as superficial (SDN) , or deep dry needling (DDN/TrP-DN) respectively.3 The needle can be left in situ for a short period of time (up to 20 minutes) or pistoned in and out of the muscle, causing a twitch response from the trigger point. During a pistoning technique, once the acetylcholine is depleted at the end plate, the twitching will stop and the needle is removed and discarded appropriately in a sharps container.
PHYSIOLOGIC EFFECTS With regards to Myofascial Pain Syndrome (MPS), Simons proposed the ‘Integrated Trigger Point’ hypothesis model.12 It is thought that at the motor end plate excessive acetylcholine is released. Acetylcholinesterase is inhibited at the end plate which leads to increased motor plate activity.3 The increased motor plate activity leads to a continual release of calcium ions(Ca +2).13 This may explain why a trigger point is present. It’s also a possibility that trigger points may also develop from repetitive low load or moderate overuse.14 This is referred to as the “Cinderella hypothesis.”14,15 Henneman’s size principle states that smaller type I fibers are recruited first and de-recruited last. These “Cinderella” fibers are recruited continuously due to the fact that the large motor fibers don’t have to work as hard.14,16 Due to the sustained muscular contractions, hypoxia may develop.14 This leads to a drop in pH. Low pH can trigger the release of inflammatory mediators and neurotransmitters such as: calcitonin gene-related peptide (CGRP), prostaglandins(PG), substance P, 5-HT, and ATP among others.3 This can cause increased nociceptive input to the spinal cord which can lead to peripheral and central sensitization.3 Sometimes the introduction of the needle into the trigger point with deep dry needling elicits a local twitch response (LTR). It’s not well understood why this occurs. After the LTR it has been observed that there is a decrease in concentrations of CGRP, substance P, interlukins, and cytokines.3 Dry needling can also be used in cases of long-standing tendinopathy. The cause of tendinopathy is not completely understood. There are three main theories in which we think they may arise. The mechanical overload theory would suggest that the tendons are repetitively overloaded in a higher end of their physiologic range causing a maladaptive response to the repetitive microtrauma. The vas-
Figure 2. The thin filiform needle in the guide tube at the site in preparation to be tapped into the epidural layer of the skin.
cular theory suggests that tendinopathies arise because tendons generally have poor blood supply making them more susceptible to vascular compromise.17 Finally, the myofascial theory associates the maladaptive tendon process to taut, shortened, muscles providing an adverse traction force to the tendon attachment site or creating unnecessary friction in the tendon sheath.18 Treating tendinopathy with dry needling has been used for decades.19 Dry needling of a tendinopathy in theory induces a microtrauma to the tendon causing a subsequent migration of inflammatory cells into the degenerative tissue as well as influx of satellite cells to promote collagen repair from the weaker type III collagen back to stronger type I collagen. This ultimately disrupts the chronic degenerative process and allows for healing of the affected tissue.19
INDICATIONS AND CONTRAINDICATIONS Dry needling may be indicated for myofascial pain with the presence of trigger points.1 Trigger points may lead to impairments in body structure, pain, and functional limitations.1 (Dry needling has been shown to be beneficial in addressing strains,20 osteoarthritis,21–23 and 24–26 tendinopathies. Dry needling is not recommended for children under the age of 12.1 There are several absolute and relative contraindications to dry needling which include but are not limited to: 1. patients with needle phobia or unwillingness to try DN.1 2. significant cognitive impairment and lack of understanding for DN parameters.1 3. local or systemic infections.1 4. localized edema1 5. Vascular disease (i.e. Varicose veins)1 6. During the 1st trimester of pregnancy 7. patients with compromised immune systems1
International Journal of Sports Physical Therapy
Dry Needling: A Clinical Commentary
OUTCOMES A systematic review and meta-analysis by Gattie et al16 revealed that dry needling is more effective for reducing pain and improving pain pressure threshold with musculoskeletal conditions, than sham treatment or no treatment at all.16 Benefits are short-term, and research methodology is low-quality to moderate-quality evidence (Figure 3).16 Uygur et al.27 compared trigger point dry needling as a first line treatment to NSAIDs, topical creams, ice, and brace use. In their study they found that dry needling was equally as effective at 3 months and significantly more effective at 6 months. This is suggestive that dry needling combined with the appropriate rehabilitation program as the potential to be even more effective without the utilization of injections or surgery. Dragoo et al.28 compared ultrasound guided PRP injections with dry needling to ultrasound and dry needling alone in patients that has failed prior conservative care. Failure was defined as symptoms persisting more than 6 weeks after working with a physical therapist for 12 visits. The study was conducted as a prospective double-blind study. They found that exercise and PRP with dry needling was superior to dry needling and exercise alone. It is important to note that both groups showed statistically significant improvement in VISA scores. The group with PRP showed greater improvement at 12 weeks but the difference in improvement between the groups disappeared after 26 weeks. Bell et al.29 conducted a double-blind randomized controlled trial evaluating the impact of autologous blood injections in the treatment of mid-portion Achilles tendinopathy. All of the participants received peritendinous injections at one month intervals using a standardized protocol along with a 12 weeks series of monitored eccentric strengthening exercises. The treatment group received 3 mL of autologous blood and the control group received needling only. The primary outcome measured was change in function and symptoms using the VISA-A questionnaire score. Secondary outcomes were patient reported perception of disability and readiness to return to sport. At 6 months clear improvements in VISA-A score were noted in both groups. No difference was noted in secondary outcomes and the authors concluded that there was no added benefit from the injection of autologous blood. A randomized controlled trial comparing ultrasound guided PRP to dry needling of the rotator cuff was conducted on 30 participants with rotator cuff disease.30 The PRP treatment group received ultrasound guided PRP twice a week with a 4 week interval between them while the needling group just received needling during those sessions. Both groups showed a significant improvement in
Figure 3. Trigger point dry needling utilized in combination with electrical stimulation.
the Shoulder Pain and Disability index. PRP provided more symptomatic relief at the six month follow up. No difference in range of motion improvement was noted between the groups. Lastly, in the Physical Therapy and Rehabilitation Journal, A RCT by Cotchett et. al24 looking at the effectiveness of dry needling vs sham needling for heel pain favored dry needling vs sham needling. Again, the duration of followup was short. Further research needs to be performed to look at the long-term effectiveness of dry needling. Strengthening and conditioning relative to the demands the athlete is placing on their body is essential component to successful athletic participation. The authors use dry needling in acute conditions when the athlete is in season and there is a need to get the athlete back as quickly and as safely as possible, with managed pain. Anecdotally the authors have seen quicker improvement in symptom reduction and function when dry needling is performed in conjunction with the appropriate rehabilitation plan versus exercises alone or dry needling alone. The authors also utilize dry needling when an athlete presents with a chronic condition that has failed to respond to prior conservative measures. Dry needling is a relatively new treatment modality used by physical therapists and other common musculoskeletal conditions seen in athletes. Dry needling is a safe, inexpensive, and minimally invasive procedure that carries a low risk. Further studies are also warranted to study the effects of different dry needling protocols for muscular, tendon, and potentially ligament conditions. Submitted: April 01, 2022 CDT, Accepted: May 01, 2022 CDT
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International Journal of Sports Physical Therapy
Dry Needling: A Clinical Commentary
REFERENCES 1. Description of Dry Needling In Clinical Practice: An Educational Resource Paper. APTA; 2013:1-7. 2. Simons DG, Travell JG, Simons LS. Myofascial Pain and Dysfunction: The Trigger Point Manual. Vol I. Lippincott William and Wilkins; 1999. 3. Dommerholt J, Fernandez-de-las-Penas C, Chaitow L, Gerwin RD. Trigger Point Dry Needling. An Evidenced and Clinical-Based Approach. 4. Lewis T. Study of Somatic Pain. Br Med J. 1938;1(4023):321-325. doi:10.1136/bmj.1.4023.321 5. Kellgren JH. Referred pains from muscle. Br Med J. 1938;1(4023):325-327. doi:10.1136/bmj.1.4023.325 6. Legge D. A History of Dry Needling. J Musculoskelet Pain. 2014;22(3):301-307. doi:10.3109/10582452.201 4.883041 7. Baldry P. Superficial versus deep dry needling. Acupunct Med. 2002;20(2-3):78-81. doi:10.1136/aim.2 0.2-3.78 8. Wilson VP. Janet G. Travell, MD: a daughter’s recollection. Tex Heart Inst J. 2003;30(1):8-12. 9. Travell J, Rinzler SH. The myofascial genesis of pain. Postgrad Med. 1952;11(5):425-434. doi:10.1080/ 00325481.1952.11694280 10. Lewit K. The needle effect in the relief of myofascial pain. Pain. 1979;6(1):83-90. doi:10.1016/0 304-3959(79)90142-8 11. Caramengo J, Adrian L, Mueller L, Purl J. Analysis of Competencies for Dry Needling by Physical Therapists. Published 2015. https://www.fsbpt.org 12. Gerwin RD, Dommerholt J, Shah JP. An expansion of Simons’ integrated hypothesis of trigger point formation. Curr Pain Headache Rep. 2004;8(6):468-475. doi:10.1007/s11916-004-0069-x 13. Koukoulithras I, Plexousakis M, Kolokotsios S, Stamouli A, Mavrogiannopoulou C. A Biopsychosocial Model-Based Clinical Approach in Myofascial Pain Syndrome: A Narrative Review. Cureus. 2021;13(4):e14737. doi:10.7759/cureus.14737 14. Shah JP, Thaker N, Heimur J, Aredo JV, Sikdar S, Gerber L. Myofascial Trigger Points Then and Now: A Historical and Scientific Perspective. PM & R. 2015;7(7):746-761. doi:10.1016/j.pmrj.2015.01.024
15. Hagg GM. Electromyographical Kinesiology. In: Anderson P, Hobart D, Danoff J, eds. Static Work Load and Occupational Myalgia: A New Explanation Model. Elsevier; 1991:141-144. 16. Gattie E, Cleland JA, Snodgrass S. The Effectiveness of Trigger Point Dry Needling for Musculoskeletal Conditions by Physical Therapists: A Systematic Review and Meta-Analysis. J Orthop Sports Phys Ther. 2017;47(3):133-149. doi:10.2519/jospt.201 7.7096 17. Rees JD, Maffulli N, Cook J. Management of tendinopathy. Am J Sports Med. 2009;37(9):1855-1867. doi:10.1177/036354650832428 3 18. Gunn C. The Gunn Approach to the Treatment of Chronic Pain. Churchill Livingstone; 1997. 19. Jacobson J, Chiavaras M. Ultrasound-guided tendon fenestration. Semin Musculoskelet Radiol. 2013;17(1):85-90. doi:10.1055/s-0033-1333942 20. Dembowski S, Westrick R, Zylstra E, et al. Treatment of hamstring strain in a collegiate polevaulter integrating dry needling with an eccentric training program: A resident’s case report. Int J Sports Phys Ther. 2013;8(3):328-339. 21. Gümü S. The Effect of Acupuncture and Physiotherapy on Patients with Knee Osteoarthritis: A Randomized Controlled Study. Pain Physician. Published online 2021:10. 22. Dunning J, Butts R, Young I, et al. Periosteal Electrical Dry Needling as an Adjunct to Exercise and Manual Therapy for Knee Osteoarthritis: A MultiCenter Randomized Clinical Trial. Clin J Pain. 2018;34(12):1149-1158. doi:10.1097/ajp.00000000000 00634 23. Weiner DK, Rudy TE, Morone N, Glick R, Kwoh CK. Efficacy of Periosteal Stimulation Therapy for the Treatment of Osteoarthritis-Associated Chronic Knee Pain: An Initial Controlled Clinical Trial: PERIOSTEAL STIMULATION THERAPY FOR KNEE OA. J Am Geriatr Soc. 2007;55(10):1541-1547. doi:10.1 111/j.1532-5415.2007.01314.x 24. Cotchett MP, Munteanu SE, Landorf KB. Effectiveness of Trigger Point Dry Needling for Plantar Heel Pain: A Randomized Controlled Trial. J Phys Ther. 2014;94(8):1083-1094. doi:10.2522/ptj.201 30255
International Journal of Sports Physical Therapy
Dry Needling: A Clinical Commentary
25. McDevitt AW, Snodgrass SC, Cleland JA, et al. Treatment of individuals with chronic bicipital tendinopathy using dry needling, eccentricconcentric exercise and stretching; a case series. Physiotherapy theory and practice. 2020;36(3):397-407.
28. Dragoo JL, Wasterlain AS, Braun HJ, Nead KT. Platelet-rich plasma as a treatment for patellar tendinopathy: a double-blind, randomized controlled trial. Am J Sports Med. 2014;42(3):610-618. doi:10.117 7/0363546513518416
26. Langberg H, Rosendal L, Kjær M. Traininginduced changes in peritendinous type I collagen turnover determined by microdialysis in humans. J Physiol. 2001;534(1):297-302. doi:10.1111/j.1469-779 3.2001.00297.x
29. Bell KJ, Fulcher ML, Rowlands DS, Kerse N. Impact of autologous blood injections in treatment of midportion Achilles tendinopathy: double blind randomised controlled trial. Br Med J. 2013;346(apr18 2):f2310. doi:10.1136/bmj.f2310
27. Uygur E, Aktas B, Özkut A, Erinc S, Yilmazoglu EG. Dry needling in lateral epicondylitis: a prospective controlled study. International Orthopaedics (SICOT). 2017;41(11):2321-2325. doi:10.1007/s00264-017-360 4-1
30. Rha DW, Park GY, Kim YK, Kim MT, Lee SC. Comparison of the therapeutic effects of ultrasoundguided platelet-rich plasma injection and dry needling in rotator cuff disease: a randomized controlled trial. Clin Rehabil. 2013;27(2):113-122. do i:10.1177/0269215512448388
International Journal of Sports Physical Therapy
Martinez C, Garbett S, Hiromasa K, et al. Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics. IJSPT. 2022;17(4):566-573.
Original Research
Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics Caitlyn Martinez, PT, DPT 1, Seth Garbett, PT, DPT 1, Kristen Hiromasa, PT, DPT 1, Rhandi Jackson, PT, DPT 1, Eric Miya, PT, DPT 1, Michelle Miya, PT, DPT 1, Joshua D White, PT, DHSc, ATC 1, Brian S Baum, PhD 2, a Mark F Reinking, PT, PhD, SCS, ATC, FAPTA 1 1
School of Physical Therapy, Regis University, 2 Lincoln Laboratory, Massachusetts Institute of Technology
Keywords: Gait analysis, loading rate, running assessment https://doi.org/10.26603/001c.34432
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Providing clinicians with an accurate method to predict kinetic measurements using 2D kinematic motion analysis is crucial to the management of distance runners. Evidence is needed to compare the accuracy of 2D and 3D kinematic measurements as well as measured and estimated kinetic variables.
Purposes The objectives of this study were to (1) compare 2D video analysis of running kinematics with gold standard 3D motion capture and, (2) to evaluate published equations which estimate running kinetics using 2D kinematic and spatiotemporal values and modify these equations based on study findings.
Design Controlled laboratory study, cross-sectional design
Methods Runners who averaged at least 20 miles per week were invited to participate. Athletes ran on an instrumented treadmill at their preferred training pace for a 6-minute warm-up. Markers were placed over designated anatomical landmarks on both sides of the pelvis as well as the left lower extremity. Subjects then ran at their preferred speed and kinematic data were recorded using both the 2D and 3D camera systems at 240 frames/second. Additionally, ground reaction forces were recorded at 1200Hz. 2D and 3D kinematic values were compared and published kinetic prediction formulas were tested. Linear regression was used to develop new prediction equations for average loading rate (AVG_LR), peak vertical ground reaction force (VERT_GRF), and peak braking force (PK_BRK). Paired t-tests were used to assess differences between the 2D and 3D kinematic variables and the measured (MEAS) and calculated (CALC) kinetic variables.
Results Thirty runners (13 men and 17 women) voluntarily consented to participate in this study and the mean age of the participants was 31.8 years (range 20 to 48 years). Although significant differences existed, all 2D kinematic measures were within 2°-5° of 3D kinematic measures. Published prediction equations for AVG_LR and VERT_GRF were supported, but new prediction equations showed higher R2 for AVG_LR (0.52) and
a
Corresponding author: Mark F. Reinking Regis University School of Physical Therapy 3333 Regis Blvd. G-4 Denver, CO 80221 mreinking@regis.edu
Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics
VERT_GRF (0.75) compared to previous work. A new prediction equation for PK_BRK was developed. No significant differences were found between the MEAS and CALC kinetic variables using the new equations.
Conclusion Accurate predictions of kinetic variables can be made using spatiotemporal and 2D kinematic variables.
Level of Evidence Level 2
INTRODUCTION Running is one of the most popular fitness activities across the world. In the United States, over 55 million individuals participate in running.1 While it is one of the most efficient ways for adults to achieve physical fitness,2 the incidence of injuries associated with running is relatively high.2 Injuries can diminish pleasure in running as a physical activity as well as contribute to medical costs and possible impact on physical fitness. Commonly reported running-related injuries (RRI) include stress fractures, medial tibial stress syndrome, patellofemoral pain, Achilles tendinopathy, iliotibial band syndrome, and plantar fasciitis.3–7 The etiology of RRI is clearly multifactorial involving runner characteristics (age, sex, nutrition), training variables (weekly mileage, training surfaces, abrupt changes in training), and biomechanical variables. The biomechanical variables that have been associated with RRI risk include kinematic variables (joint position, velocity, and acceleration), kinetic variables (force, loading rate), and temporospatial variables (cadence, stride length).8 Davis et al9 conducted a prospective study of female runners comparing kinetic variables in a never-injured group and an injured group. They found that all impact-related kinetic variables (vertical instantaneous loading rate, vertical average loading rate, vertical impact peak, and peak vertical force) were significantly higher in the injured group compared to those who have never been injured. Earlier studies have also shown that higher vertical forces may contribute to running-related injuries.9–14 Peak braking force15 and braking impulse16–18 have also been shown to be significant predictors of RRI . In well-equipped biomechanical laboratories, researchers collect kinematic and kinetic data using sophisticated 3-D motion capture systems and in-ground force plates or instrumented treadmills. However, many clinicians working in outpatient settings do not have access to such equipment. They can, however, use 2D digital video cameras to reliably collect kinematic data of runners.19 Wille et al20 conducted a study using 2D video analysis of a group of 45 runners and concluded that it is possible to estimate kinetic data using sagittal plane kinematics and temporospatial variables. In an earlier study,21 the researchers used cadence and sagittal plane kinematics collected with a 2D high speed camera to develop a prediction equation to estimate kinetic variables in high school cross country runners. Using five sagittal-plane kinematic variables (shoe angle, leg angle, knee flexion at initial contact, total knee motion, and total vertical excursion of center of mass) and cadence, 56% of the vertical ground reaction force variance
and 51% of the average loading rate variance was explained. To confirm the feasibility and improve accuracy of these estimates, further evidence is needed in the comparison of 2D and 3D kinematic measurements as well as the comparison of measured and estimated kinetic variables. The objectives of this study were (1) to compare 2D video analysis of running kinematics captured with a high-speed video camera with gold standard 3D motion capture and, (2) to evaluate equations which estimated running kinetics using 2D kinematics and spatiotemporal values and modify these equations based on study findings. The two research hypotheses were (1) 2D kinematics would not differ from 3D kinematic variables, and (2) newly developed equations would improve the accuracy of estimated kinetic variables.
METHODS This cross-sectional study was conducted at the Regis University biomechanics research lab from August through November 2019. We utilized a sample of convenience; participants were recruited from flyers posted around Regis University campus and e-mails to local running clubs. The Regis University Institutional Review Board approved the study protocol and all participants provided written informed consent prior to participating in the study. Thirty runners (13 men and 17 women) voluntarily consented to participate in this study. The mean age of the participants was 31.8 years, with a range of 20 to 48 years. All participants selected for this study met the following inclusion criteria: (1) between the ages of 18 to 50 years, (2) running on average at least 20 miles per week for one-year prior to participation in the study, (3) experience running on a treadmill, (4) no history of lower extremity congenital or traumatic deformity or previous surgery that resulted in altered bony alignment, and (5) no acute injury three months prior to the start of the study that has led to the inability to run. Upon arrival to the lab, each participant’s height, weight, shoe length, blood pressure and heart rate were measured and recorded. Participants also completed a survey regarding their history of running-related injuries. Once these data were collected, participants completed a six-minute warm-up run on the treadmill to acclimate to the treadmill (Bertec Corporation, Columbus, OH) and to determine their preferred treadmill speed described to the participants as their “normal training run pace.” During the final minute of the six-minute warmup, a member of the research team measured the cadence of each participant by counting foot strikes in a 15-second time frame and multiplying by four. After the completion of the warm-up period, one researcher
International Journal of Sports Physical Therapy
Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics
(MFR) placed reflective markers on selected anatomic landmarks including bilateral anterior superior iliac spines, bilateral posterior iliac spines, left lateral epicondyle of the knee, left lateral malleolus, left posterior lower leg over the Achilles tendon (two markers), and over the posterior midline of the left shoe (two markers). These locations are consistent with the marker set used in a previous study examining the reliability of 2-dimensional kinematic analysis.22 Another researcher (CM) placed the active marker clusters (infrared-emitting diodes) for the 3D optoelectric motion capture system (3D Investigator, Northern Digital, Inc., Ontario, Canada) on the pelvis, thigh, shank and foot. Using the digital markers and rigid body references, a digitizer was used to establish digital markers directly over the reflective markers for the 2D video. After the reflective and digital markers were placed on the participant, a one-second static trial was collected to obtain reference force plate and marker data. The participants then were asked to start running at their predetermined preferred speed on the treadmill. Digital recordings at 240 frames per sec (fps) were collected using two single high-speed cameras (SONY DSC-RX100 IV) at orthogonal angles (frontal and sagittal planes) and, concurrently, the 3D motion capture data was collected at 240 frames per second for thirty seconds. The ground reaction forces were collected at 1200 Hz through the force plates embedded in the instrumented treadmill (Bertec Corporation, Columbus, OH) and were internally synchronized with the 3D motion capture data. The following six sagittal plane kinematic variables were assessed on the left lower extremity for all 30 runners using both the 2D and 3D data: 1) angle of the shoe to treadmill at initial contact (SHOE_ANG), 2) angle of the lower leg relative to vertical at initial contact (LEG_ANG), 3) knee flexion at initial contact (KN_FL_IC), 4) knee flexion at midstance (KN_FL_MS), 5) vertical position of the estimated center of mass (center of line connecting ASIS and PSIS) at midstance, and 6) vertical position of the estimated center of mass at double float. KN_FL_IC was subtracted from KN_FL_MS to calculate total knee flexion (KN_FL_Tot). The vertical position of the estimated center of mass at double float was subtracted from the vertical position of the estimated center of mass at midstance to calculate total vertical excursion of the center of mass (COM_VtEx). All angles were measured in degrees and all distance measurements were recorded in centimeters. The fifth step was analyzed for both the 2D and 3D data. For the 2D data captured using the digital cameras, the data were analyzed using a freeaccess video analysis software program (Kinovea, version 0.8.15, http://www.kinovea.org). In a previously published study, in comparison to another rater with a similar level of experience, the investigator who measured al 2D data in this study (MFR) demonstrated high intra-rater levels of reliability ranging from 0.88 to 0.98 (ICC) for sagittal plane variables and between 0.45 and 0.96 for frontal plane variables.22 For the 3D data, joint angles were computed from a six degree of freedom rigid body model in Visual3D (C-Motion, Inc., Germantown, MD). Ground reaction force data were filtered using a fourthorder, zero-lag low-pass Butterworth filter with a 30 Hz cutoff. Similar to the Wille study,20 the peak vertical com-
ponent of the ground reaction force (Vert_GRF) and the average loading rate (AVG_LR) were measured for five consecutive running cycles for the left and right lower extremities with the average of the five cycles used for further analysis. The Vert_GRF was reported in body weight (BW) and AVG_LR was reported in BW/sec. As in the Wille et al study,20 the AVG_LR was defined as the rate of change in the vertical GRF from 20% to 80% of the period beginning with initial contact to the vertical force impact peak. Peak braking force (PK_BRK) was defined as the peak posteriorly directed ground reaction force following heel strike, reported in N/kg. In addition to descriptive statistics, t-tests were used to assess the differences between the mean 2D and 3D kinematic values. Kinematic variables collected using the 2D data were used in the prediction formula from our previous research to estimate vertical ground reaction force (VERT_GRF) and average loading rate (AVG_LR).21 A stepwise forward linear regression was used to determine if a set of kinematic and spatiotemporal variables collected in this study were predictive of VERT_GRF, AVG_LR, and PK_BRK. Differences were assessed between estimated kinetic variables using earlier published prediction equations and the new prediction equations with the actual measured kinetic variables collected with the force plate instrumented treadmill. To compare the prediction equations to those in previous published studies,20,21 the amount of variance in the kinetic parameters explained by the kinematic measures and step rate for each particular model was reported as the R2 value as well as the adjusted R2 value which adjusts for the number of terms in a model. Statistical analyses were performed using SPSS Statistics, Version 26 (IBM Corporation, Armonk, New York 10504). An alpha level of .05 was established for all tests of significance.
RESULTS Participant characteristics (mean ± SD) for the 30 runners included age (31.8 ± 8.4 years), height (174.6 ± 10.6 cm), mass (70.9 ± 14.3 kg), preferred step rate (175 ± 6.0 steps per minute), and running speed (3.15 ± 0.39 m/s). Descriptive statistics for all 2D and 3D kinematic measurements are listed in Table 1. We found that SHOE_ANG, LEG_ANG, KN_FL_IC, and KNEE_FL_MS 2D measurements were all significantly different from the 3D measurements. However, the actual mean differences between the 2D and 3D values were 2.7° for SHOE_ANG, 1.4° for LEG_ANG, 2.1° for KN_FL_IC, and 4.9° for KNEE_FL_MS. The vertical COM excursion measures using the 2D and 3D systems were not significantly different, nor was the cadence measured by a research team member and the 3D system. A correlation matrix with the correlations between the 2D and 3D kinematic and spatiotemporal variables is provided in Table 2. The prediction equations developed in the study using stepwise linear regression for VERT_GRF, AVG_LR, and PK_BRK were as follows:
International Journal of Sports Physical Therapy
Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics
Table 1. Means and standard deviations for 2D and 3D kinematic and spatiotemporal variables (units). VARIABLE
2D
3D
p-value
Angle of Shoe to Treadmill at Initial Contact (SHOE_ANG) (degs)
1.27 ± 7.78
3.96 ± 8.70
.000
Angle of Leg at Initial Contact (LEG_ANG) (degs)
4.33 ± 2.89
5.67 ± 2.27
.032
Knee Flexion Angle at Initial Contact (KN_FL_IC) (degs)
12.70 ± 4.48
10.62 ± 4.78
.006
Knee Flexion at Midstance (KN_FL_MS) (degs)
38.30 ± 4.10
33.35 ± 4.81
.000
Total Knee Flexion (KN_FL_Tot) (degs)
25.61 ± 4.84
22.74 ± 3.47
.000
Total Vertical Excursion of Center of Mass (COM_VtEx) (cm)
7.30 ± 1.53
7.26 ± 1.65
.873
174.93 ± 6.03
174.70 ± 8.94
.819
Cadence (steps/min)
Table 2. Correlation matrix of 2D and 3D kinematic and spatiotemporal variables 3Dc SHOE_ANG 2Db SHOE_ANGd
3D LEG_ANG
3D KN_FL_IC
3D KN_FL_MS
3D KN_FL_TOT
3D COM_VtEx
3D Cadence
.901a
2D LEG_ANGe
.223
2D KN_FL_ICf
.652a
2D KN_FL_MSg
.658a
2D KN_FL_Toth
.668a
2D COM_VtExi
.731a .799a
2D Cadence aCorrelation is significant at .01 b2D = two-dimensional c3D = three-dimensional dSHOE_ANG = Angle of the Shoe to Treadmill at Initial Contact eLEG_ANG = Angle of the Leg to Vertical at Initial Contact fKN_FL_IC = Knee Flexion Angle at Initial Contact gKN_FL_MS = Knee Flexion at Midstance hKN_FL_Tot = Total Knee Flexion iCOM_VtEx = Total Vertical Excursion of the Center of Mass
ference was found between the predicted VERT_GRF using the previous published21 and new equations (p=.002) and between the predicted VERT_GRF using the previous published equation21 and the measured VERT_GRF (p=.006). No difference was found between the predicted VERT_GRF using the new equation and the measured VERT_GRF. No significant differences were found between the three AVG_LR mean values (previous prediction equation,21 new prediction equation, and measured value). No significant difference was found between the PK_BRK using the new prediction equation and the measured value. Table 3 provides the predicted VERT_GRF, AVG_LR, and PK_BRK using the previously published21 and new equations as well as the measured VERT_GRF, AVG_LR, and PK_BRK from the instrumented treadmill. A significant dif-
International Journal of Sports Physical Therapy
Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics
Table 3. Means and standard deviations for predicted and actual kinetic variables (units). VARIABLE
Estimated Values Based on Previous Equation14
Estimated Values Based on New Equation
Actual Values Measured by Instrumented Treadmill
Peak Vertical Component of the Ground Reaction Force (VERT_GRF) (BW)
2.31 ± 0.16ab
2.45 ± 0.26a
2.44 ± 0.29b
Average Loading Rate (AVG_LR) (BW/sec)
48.30 ± 11.5
52.59 ± 10.08
52.59 ± 13.6
NA
-3.21 ± 0.44
-3.21 ± 0.60
Peak Braking Force (PK_BRK) (N/kg) a Significant difference p=.002 b Significant difference p=.006
DISCUSSION The objectives of this study were (1) to compare 2D video analysis of running kinematics captured with a high-speed video camera with gold standard 3D motion capture and, (2) to evaluate equations which estimated running kinetics using 2D kinematics and spatiotemporal values and modify these equations based on the current study findings. The first hypothesis was rejected as significant differences were found between the kinematic values obtained using the 2D video camera as compared to the 3D motion capture system. However, the magnitudes of these differences were 2.5° - 5°, depending on the measure. For all kinematic variables except leg angle, there were strong correlations between the 2D and 3D variables. Maykut et al23 compared 2D and 3D video analysis of frontal plane kinematics in 24 collegiate cross-country runners. They found moderate correlations between the 2D and 3D measures of peak hip adduction and peak knee abduction although they also found significant differences between the 2D and 3D measures ranging from 1° - 4°. Weber and McClinton24 compared 2D and 3D measurements of upper trunk rotation during running and found high correlations between the 2D and 3D values and did not find significant differences between the 2D and 3D values with differences ranging from 0° - 1.5°. Although significant differences were found between the 2D and 3D measures in this study, the magnitude of those differences and the high correlations between the measures suggest that 2D measures can be used clinically to approximate kinematic measures captured using 3D systems. Regarding the second research objective, data were used from the 30 runners in this study to estimate VERT_GRF and AVG_LR using previously published prediction equations.21 The comparison of the estimated kinetic values and the actual measured values showed no significant difference for AVG_LR, but there was a significant difference for VERT_GRF. In the previous work,21 peak braking force was not estimated. Using the newly developed prediction equations calculated via a stepwise forward regression analysis for AVG_LR, VERT_GRF and PK_BRK, the inputted kinematic and spatiotemporal data resulted in estimated kinetics that were not significantly different from forces measured via a 3D system with force plates. This demonstrates an improved accuracy of estimated kinetic parameters from the previous work21 and our second hypothesis was ac-
cepted. Two key differences between this study and the previous work include a greater sample size (n=30) and the use of the left limb only with 30 subjects rather than combining right and left limbs of 10 subjects. In order to translate this research into the clinical setting, it is suggested that clinicians use a procedure as outlined by Souza19 to complete a 2D digital camera video analysis of a runner. After identifying joint angles, cadence, and vertical center of mass excursion, the clinician can insert appropriate values in the equations provided in this paper to estimate loading rate, peak vertical ground reaction forces, and peak braking force. This capability increases the practicality of performing kinetic analyses in a clinical environment from cost, technical expertise, and space domains. Two-dimensional video cameras and a standard treadmill will cost far less than an instrumented treadmill and a 3D motion capture system, which together can cost $150,000-$200,000 or more. In addition, a level of expertise is required to operate and maintain these gold standard systems, which the average clinic may lack. Furthermore, 3D systems require additional infrastructure and space that would be difficult to achieve in smaller clinics. The differences in the VERT_GRF prediction equations from the previous study21 and the current study is the inclusion of speed as a variable and stride length as represented by a horizontal line from the COM line to the heel. There is evidence that these two variables, while not included in the previous published equation, do have an influence on vertical ground reaction force.25–27 The AVG_LR equation in our previous paper included SHOE_ANG, LEG_ANG, KN_FL_IC, COM_VtEx, and cadence. The new equation from the current student includes only SHOE_ANG and speed, making the equation much simpler to use while increasing its predictive abilities. An equation to estimate peak braking force was added in this study based on the evidence that excessive braking force is a runningrelated injury risk factor.15 The R2 values for the new prediction equations were 0.52 for AVG_LR, 0.75 for VERT_GRF, and 0.55 for PK_BRK. The previous published prediction equations21 had a R2 value of 0.51 for AVG_LR and 0.56 for VERT_GRF. Wille et al20 reported R2 values of 0.04 for AVG_LR, 0.48 for VERT_GRF, and 0.50 for PK_BRK. These correlation values highlight that the newly developed equations provide the best predictive abilities to date for these
International Journal of Sports Physical Therapy
Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics
variables when using 2D video data, and demonstrate a substantial improvement in predicting VERT_GRF. The results of this study support the conclusions of White et al21 and Wille et al20 that clinicians with access to a high-speed video camera and software for 2D data analysis can estimate average loading rate, vertical ground reaction force, and peak braking force in their patients who are runners. Estimation of these variables can be useful in the examination and treatment of running-related injuries, and can provide important pre-intervention and post-intervention data to assess the effectiveness of a selected intervention plan. One limitation of this study was the use of a treadmill to measure kinematic and kinetic variables. There is debate in the literature about whether kinematic and kinetic variables in overground running can be replicated on a treadmill. In a recent systematic review, van Hooren et al28 concluded, “Spatiotemporal, kinematic, kinetic, muscle activity, and muscle–tendon outcome measures are largely comparable between motorized treadmill and overground running.” (p. 785) While participants were encouraged to run as they normally would, participants may also have altered their running mechanics due to the unfamiliarity of the markers that were placed on their lower extremities. A second limitation was the brevity of the sampling window. This was done recognizing time and efficiency issues in the clinic, a realistic concern of clinicians given the additional time required for data analyis using a longer sampling window. A third and final limitation is that only the left lower extremity was used. This decision was made to not combine right and left lower extremities which complicates analyses given that the two limbs of one person are not independent of each other. Future research may include both sides assessed separately.
CONCLUSION Accurate estimations of kinetic variables can be made using spatiotemporal and kinematic variables collected using a 2D high-speed video camera. This allows clinicians without access to 3D motion capture technology and instrumented treadmills or in-ground force plates to perform running video analyses that will inform the appropriate prevention and treatment of runners.
FUNDING
This research was supported by a $1796 grant from the Regis University Research & Scholarship Committee. CONFLICTS OF INTEREST
The authors affirm that we have no financial affiliation (including research funding) or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript, and we also affirm that we have no conflicts of interest pertaining to this study. This study was approved by the Regis University Institutional Review Board on October 29, 2019 as an expedited review. Submitted: November 17, 2021 CDT, Accepted: February 08, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics
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Comparison of 2-D and 3-D Analysis of Running Kinematics and Actual Versus Predicted Running Kinetics
21. White JD, Carson N, Baum BS, Reinking MF, McPoil TG. Use of 2-Dimensional Sagittal Kinematic Variables to Estimate Ground Reaction Force during Running. Int J Sports Phys Ther. 2019;14(2):174-179. 22. Reinking MF, Dugan L, Ripple N, et al. Reliability of 2-dimensional video-based running gait analysis. Int J Sports Phys Ther. 2018;13(3):453-461. 23. Maykut JN, Taylor-Haas JA, Paterno MV, DiCesare CA, Ford KR. Concurrent validity and reliability of 2d kinematic analysis of frontal plane motion during running. Int J Sports Phys Ther. 2015;10(2):136-146. 24. Weber CF, McClinton S. Validity and Reliability of Video-Based Analysis of Upper Trunk Rotation during Running. Int J Sports Phys Ther. 2020;15(6):910-919. d oi:10.26603/ijspt20200910
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International Journal of Sports Physical Therapy
Jamaludin NI, Sahabuddin FNA, Rasudin NS, Shaharudin S. The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee Valgus. IJSPT. 2022;17(4):574-584.
Original Research
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee Valgus Nazatul Izzati Jamaludin 1, Farhah Nadhirah Aiman Sahabuddin 1, Nur Syahmina Rasudin 2, Shazlin Shaharudin 1 1
a
Exercise & Sports Science Programme, School of Health Sciences, Universiti Sains Malaysia, 2 Biomedicine Programme, School of Health Sciences, Universiti Sains Malaysia Keywords: biomechanics, human health, injury prevention, sports medicine, rehabilitation https://doi.org/10.26603/001c.35706
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background The single leg squat (SLS) motion imitates various maneuvers in sports. It is commonly used as a functional test for the lower limb. SLS with two-dimensional (2-D) video analysis is regularly performed in the clinical setting to assess dynamic knee valgus (DKV). However, 2-D video analysis may not be able to demonstrate the same level of accuracy as three-dimensional (3-D) motion analysis.
Purpose This study aimed to determine the within- and between-day reliability as well as the concurrent validity of 2-D and 3-D motion analysis of lower limb kinematics during 45° and 60° SLS among physically active females with and without DKV.
Study Design Cross-sectional study
Methods A total of 34 physically active females (17 individuals with excessive DKV and 17 without DKV) participated in the study. Their DKV was determined based on the cut-off values of knee frontal plane projection angle during drop landing. Their lower limb kinematics during SLS at 45° and 60° knee flexion were captured simultaneously by digital cameras (2-D motion capture) and infrared cameras (3-D motion capture). Intraclass Correlation Coefficient (ICC) was used as an indicator for within- and between-day reliability tests of both groups. Bland-Altman Plot and Pearson correlation were used to examine the validity of 2-D and 3-D motion capture methods in evaluating knee valgus angle.
Results Two-dimensional knee FPPA and 3-D knee angle measured during 45° and 60° SLS in normal and excessive DKV groups showed moderate to excellent within-day and between-day reliability (ICC≥ 0.50). The current study showed that the 2-D knee frontal plane projection angle (FPPA) during 45° SLS were valid for the non-dominant leg in both groups. Additionally, the 2-D knee FPPA during 60° SLS were valid for non-dominant leg in excessive DKV group and dominant leg in normal group.
Conclusion Two-dimensional knee FPPA during 45° and 60° SLS also showed high within-and between-day reliability for both groups. The validity of 2-D knee FPPA during SLS depends on the squat depth, stance leg, and presence of DKV.
a
Corresponding author: Shazlin Shaharudin, Exercise & Sports Science Programme, School of Health Sciences, Universiti Sains Malaysia, 16150 Kota Bharu, Kelantan, Malaysia shazlin@usm.my
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
Level of Evidence 2B
INTRODUCTON The single leg squat (SLS) test is a common screening tool for lower limb functional mobility.1 Individuals with patellofemoral pain syndrome (PFPS), anterior cruciate ligament (ACL) tear, or post hip arthroscopy display several distinct biomechanical characteristics when executing SLS such as greater knee valgus2 and femoral adduction.3 Therefore, the quality of SLS is affected by knee motion abnormalities and one of its quality indicators for SLS is dynamic knee valgus (DKV). DKV is defined as atypical hip and knee kinematics in the frontal and transverse planes during weight-bearing activities.4,5 DKV encompasses excessive femoral adduction, femoral internal rotation, knee abduction, and external tibial rotation.6 Excessive DKV during bilateral or unilateral landing activities, as well as during the stance phase of gait, has been linked to non-contact ACL and patellofemoral joint injuries.7,8 Hence, DKV can be screened using SLS. A three-dimensional (3-D) motion analysis system is the gold standard for assessing frontal plane knee alignment during dynamic tasks due to its high accuracy and reliability.5 However, the cost, required space, complexity in data processing and analysis may limit its usage in clinical setting.9 As a result of these limitations, SLS with 3D motion analysis is difficult to be utilized as an injury-prevention screen in routine clinical practice or in sports settings. In comparison, two-dimensional (2-D) motion analysis with kinematic analysis using software packages10 represents a portable, low-cost, and easy-to-use method to objectively evaluate clinical tests such as SLS.5,11 The usage of 2-D motion analysis can also bridge the gap between laboratory measurements and real-life motions.12 However, the clinical utility of SLS with 2-D motion analysis is highly dependent on its accuracy, reliability and validity in providing kinematics data. Therefore, the validity and reliability of 2D motion analysis in quantifying joint angles during functional tasks such as SLS need to be investigated to ensure its clinical significance.8,11 To date, no research has been conducted to compare the reliability of 2-D and 3-D motion capture and analysis among females with normal DKV versus excessive DKV. In the literature, Gwynne and Curran discovered that 2-D motion analysis during 60° SLS was reliable among male and female recreational athletes.13 Specifically, the knee frontal plane projection angle (FPPA) assessed with 2-D analysis demonstrated a good correlation with 3-D knee valgus angle (r = 0.64 to 0.78, p< 0.001). Additionally, they also found that 2-D motion analysis during 60° SLS demonstrated good within-session (0.86) and between-sessions ICCs (0.74) reliability.13 Additionally, Ortiz and colleagues14 investigated four methods of 2-D knee valgus measurement and found that all methods showed good to excellent reliability (ICC: 0.89–0.99) during 40 cm drop jump maneuver with a countermovement jump among 16 healthy participants (nine males and seven females). Knee to ankle separation ratio and knee separation distance
showed excellent correlation (ICC: 0.96; 95% CI: 0.82–0.98 and ICC: 0.94; 95% CI: 0.90–0.96, respectively) with the kinematic results from 3-D motion analysis system. On the contrary, the other two methods of measuring knee FPPA displayed poor to moderate correlation (ICC: 0–0.57) with the kinematic results from 3-D motion analysis system. One postulated reason was the inaccuracy of 2-D motion analysis in measuring the transverse plane motions.14 In addition, Ramirez et al.,15 found that 2-D mobile application (2D Spark Motion Pro™) showed excellent reliability (ICC = 0.927 and 0.792) in measuring frontal plane knee kinematics during single leg hop test among anterior knee pain patients. On a similar note, Krause et al.,16 reported that the reliability of Coach’s Eye (Tech Smith Corporation, Okemos, MI) ranged from 0.96-0.99 when measuring sagittal plane knee angle during a squat maneuver in healthy participants. In short, mobile motion capture apps can be potentially used to objectively quantify joint angles during video analysis with good reliability. On the other hand, Maykut and colleagues17 reported that 2-D kinematic variables demonstrated high reliability and intra-rater reliability for peak hip adduction angle (HADD) (ICCs: 0.951- 0.963), peak contralateral pelvic drop (CPD) (ICCs: 0.958-0.966), and peak knee abduction angle (KABD) (ICCs: 0.955-0.976) during treadmill running at self-selected speed among 24 healthy male and female collegiate cross-country runners. Their study also highlighted a significant moderate correlation between 2-D and 3-D methods for HADD in both male and female runners for both legs. However, no significant correlation existed between 2-D and 3-D motion analysis for the kinematic variables of CPD and KABD. To date, no studies have compared the reliability and validity of 2-D and 3-D motion analysis during SLS between individuals with and without DKV. Therefore, this study aimed to determine the within- and between-day reliability as well as the concurrent validity of 2-D and 3-D motion analysis of lower limb kinematics during 45° and 60° SLS among physically active females with and without DKV. The authors hypothesized a significant correlation for withinday and between-day reliability of DKV during SLS but some kinematic variables particularly those in the transverse plane may not be valid for 2-D motion analysis during SLS, as shown in previous studies.13–15,17
METHODS Initially, 44 collegiate players of various sports (handball, volleyball, frisbee, and basketball) expressed interest to participate in the study. All of them signed the informed consent form. Ethical approval was obtained from the Universiti Sains Malaysia Human Research Ethics Committee (USM/JEPeM/18070316). A priori sample size calculated by G-power software (3.0.10, Universitat Dusseldorf, Germany) for 80% power and 0.8 effect size showed that 17 participants per group were sufficient.18
International Journal of Sports Physical Therapy
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
The inclusion criteria were physically active females who participated in either handball, volleyball, frisbee, or basketball; regularly trained at least three times per week; with healthy body mass index (BMI: 18.5-24.9 kg/m2); aged between 19- to 25-years of age, with no previous injuries of the lower extremities. Only individuals with a normal BMI were recruited to limit the influence of body weight on knee biomechanics during landing.18 All anthropometric measurements including body weight and height (Seca 769, Hamburg, Germany), body fat percentage (Electronic Body Fat Percentage Analyzer (Omron HBF-360, Kyoto, Japan), and leg length (measuring tape) were measured prior to the SLS trials. DVJ SCREENING TEST
To differentiate participants with and without DKV, a screening test was conducted. Participants completed three DVJ trials with a one-minute rest interval between trials.19 The trials were recorded with a digital camera (SONY HDRCX240, Japan) from the frontal plane and evaluated with Kinovea Software (version 0.8.15, Kinovea, www.kinovea.org). The intersection of the line formed by the anterior superior iliac spine (ASIS) and the center of the knee joint with the line formed by the center of the knee joint and the center of the ankle joint was used to calculate the 2-D knee FPPA.19 For females, the average 2-D knee FPPA during DVJ is 7°-13° whereby values more than 13° are considered as excessive DKV.19 Following analysis, 17 subjects were identified as having excessive DKV while another 17 subjects recorded a normal range of DKV. SINGLE LEG SQUAT TEST
Upon arrival at the lab, the participants warmed up for five minutes by pedaling at 60 RPM with loads of 50 watts on a cycle ergometer (Cybex Inc., Ronkonkoma, NY, USA). Then, the researcher described and demonstrated the SLS test to the participants before the participants practiced the SLS test. The dominant leg was determined by observing which leg the participants used to kick a ball.20 The preferred stabilizing leg was the non-dominant limb.21 For the within-day reliability test, the SLS protocol was repeated twice a day with at least a four-hour gap between the trials. For between-day reliability, the trials were repeated twice in different days with a one-week interval. For the validity test, lower limb motions during SLS were captured simultaneously using digital cameras and infrared cameras. For 3-D motion analysis, the researcher palpated the participants to place reflective markers on the selected anatomical landmarks. A total of 35 reflective markers were affixed on both sides of the ASIS, posterior superior iliac crest, greater trochanter, medial and lateral knees, as well as medial and lateral malleoli. To capture frontal and sagittal motions during the SLS test, two digital cameras (SONY HDR-CX240, Japan) were set approximately 2.4 m in front and to the side of the participants, oriented roughly to the level of the pelvis.20 Next, the participants were asked to demonstrate double leg squat while the researcher set the angle of knee flexion (60° and 45°) with a goniometer. A clear plastic goniometer
was used to determine the desired angle. During the double limb squat, an adjustable plinth was placed at the height of the ischial tuberosity to indicate the required squat depth (60° and 45° of knee flexion).20 After that, the participants stood barefoot for ten seconds to have their static standing pose captured. The trials started with the dominant leg as the stance leg for both squat depths. During the trial, they were asked to balance on one limb (i.e., the stance leg) while keeping an erect trunk with hands on their shoulders. They were advised to perform the SLS until their knee flexed to 60°. The neutral position of the stance foot (i.e., directed forward) was maintained. To achieve the appropriate knee flexion, the participants had to touch the plinth with their buttocks each time they squatted while keeping the opposite limb facing forward and avoiding ground contact.20 The test was then repeated with SLS to 45° knee flexion for both dominant and non-dominant legs. A metronome was set to 60 beats per minute throughout the squat.20 The participants followed the rhythm of five seconds of lowering and five seconds of returning to standing. This standardized pace eliminated the influence of speed on SLS kinematics. The trials were spaced by a rest period of one minute across stance legs (i.e., dominant and non-dominant legs) and squat depths (60° and 45° knee flexion). After the experiment, the participants were instructed to stretch their legs. The marker trajectories were recorded at 100 Hz during these trials and identified using Qualisys Track Manager software (Qualisys, version 2.6.673, Gothenburg, Sweden). The raw data of the marker coordinates were then lowpass filtered using a fourth-order, zero-lag Butterworth filter with a cut off frequency of 12 Hz. Spline estimates were used to fill in the missing trajectories. Lastly, the data were imported into Visual 3D (version5, C-Motion, Inc, Rockville, MD, USA), which was used to create a bone model and calculate the lower limb joint angles. STATISTICAL ANALYSES
Data were tested for normal distribution with the Shapiro–Wilk test that was appropriate for small sample sizes (<50 samples).22 The ICC was used to assess the reliability of knee FPPA in 2-D and 3-D motion capture withinand between-days among participants with and without DKV. The ICC values were interpreted according to criteria outlined by Koo & Li,23 i.e., poor: < 0.50, moderate reliability: 0.50 to 0.75, good reliability: 0.75 to 0.90, and excellent reliability: > 0.90.23 Concurrent validity between 2-D and 3-D methods were evaluated by Pearson correlation coefficients (r) to analyze the association between the two methods. The magnitude of correlations of 0.00-0.25 was interpreted as little to no relationship, 0.25-0.50 as fair relationship, 0.50-0.75 as moderate to strong relationship, and above 0.75 as good to excellent relationship.18 In addition, the data were visualized using a Bland-Altman plot to show the direction of dispersion from the consolidated data. Any discrepancy of less than 5° between the upper and lower limits of agreement for the 2-D and 3-D analysis was deemed acceptable.13 All statistical analyses were performed using the Statistical Package for the Social Sciences
International Journal of Sports Physical Therapy
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
Table 1. Comparison of physical characteristics between participants with and without dynamic knee valgus (N=34). Mean (SD) Physical characteristics
Without DKV group (n=17)
Excessive DKV group (n=17)
Mean difference (95% CI)
tstatistic (df)
pvalue
Height (cm)
159.24 (4.27)
156.71 (5.51)
2.53 (-0.91,5.97)
1.50 (30.1)
0.14
Body weight (kg)
55.15 (7.57)
53.96 (5.77)
1.18 (-3.52,5.88)
0.51 (29.9)
0.61
Body Mass Index (BMI) (kg/m2)
21.63 (2.50)
21.97 (2.17)
-0.34 (-1.98,1.29)
-0.43 (31.4)
0.67
Body Fat Percentage (%)
20.21 (5.95)
22.32 (5.17)
-2.11 (-6.00, 1.79)
-1.10 (31.4)
0.28
Knee FPPA of dominant leg during DVJ test (°)
10.30 (1.88)
15.95 (0.76)
-5.64 (-6.63, -4.63)
-11.5 (21.4)
0.00
Pelvic width
27.29 (2.11)
27.25 (2.14)
0.04 (-1.44,1.53)
0.06 (32.0)
0.96
cm = centimeter; kg = kilogram; m = meter; % = percentage; ° = degree; FPPA= frontal plane projection angle; DKV= dynamic knee valgus; DVJ= drop vertical jump Bold indicates significantly significant difference p<0.05
Table 2. Within-day and between-day session reliability of 2-D knee frontal plane projection angle among normal group and excessive DKV at 45° and 60° SLS
Within-day session reliability
Between-days session reliability
Variables
ICC Normal (n =17)
95% CI
ICC Excessive DKV (n = 17)
95% CI
D_45°
0.98
0.96-0.99
0.75
0.31-0.91
Nd_45°
0.91
0.75-0.97
0.93
0.80-0.97
D_60°
0.71
0.21-0.89
0.91
0.73-0.97
Nd_60°
0.75
0.31-0.91
0.70
0.75-0.87
D_45°
0.84
0.14-0.92
0.88
0.67-0.96
Nd_45°
0.71
0.09-0.87
0.83
0.55-0.94
D_60°
0.75
0.28-0.91
0.83
0.55-0.94
Nd_60°
0.81
0.49-0.93
0.84
0.56-0.94
ICC = Intraclass Coefficient; CI = confidence interval; DKV = dynamic knee valgus; D = dominant leg; Nd = non-dominant leg
(SPSS) (version 24.0, IBM Inc, Armonk, NY, United States). The level of significance was set at p < 0.05.
RESULTS
nificant differences across groups. The BMI and body fat percentage of all individuals were within the normal values for physically active females. RELIABILITY WITHIN- AND BETWEEN-DAYS
From 44 interested volunteers, ten were excluded based on the exclusion criteria. The 34 volunteers who remained were divided into two groups based on their screening test results. The physical features of participants with and without DKV are shown in Table 1. The data were compared across groups were compared using the independent T-test, with alpha level of less than 0.05 indicates significant differences. The only significant difference across groups was knee FPPA of dominant leg during DVJ screening test (p≤0.05) which distinguished those with and without excessive DKV. Other physical characteristics such as height, body weight, BMI, body fat percentage and pelvic width showed no sig-
The ICC was used to determine the within- and betweenday reliability. It is a measure of the capability of a test to differentiate between two groups of participants for both within and between sessions. This study also indicates the relative reliability for 2-D knee FPPA or 3-D knee valgus measurement consistency. In other words, the ICC values represent the level of reliability. Table 2 shows the within- and between- days reliability of 2-D knee FPPA measured during 45° and 60° SLS in normal and excessive DKV groups. All the variables exhibited moderate to excellent reliability (ICC ≥ 0.50) based on the ICC value.
International Journal of Sports Physical Therapy
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
Table 3. Within-day and between-days session reliability of 3-D knee angle among normal group and excessive DKV at 45° and 60° SLS
Within-day session reliability
Between-days session reliability
Variables
ICC Normal (n =17)
95% CI
ICC Excessive DKV (n = 17)
95% CI
D_45
0.65
0.04-0.88
0.86
0.28-0.93
Nd_45
0.79
0.43-0.92
0.87
0.65-0.95
D_60
0.82
0.49-0.93
0.73
0.27-0.90
Nd_60
0.69
0.15-0.89
0.83
0.54-0.94
D_45
0.78
0.41-0.92
0.74
0.25-0.89
Nd_45
0.84
0.54-0.94
0.71
0.21-0.90
D_60
0.79
0.43-0.92
0.87
0.64-0.95
Nd_60
0.83
0.54-0.94
0.94
0.80-0.98
ICC = Intraclass Coefficient; CI = confidence interval; DKV = dynamic knee valgus; D = dominant leg; Nd = non-dominant leg
Table 4. Concurrent validity between 2-D knee FPPA and 3-D knee valgus among normal group and excessive DKV group at 45° SLS Group
Lower limb Dominant
Normal Non-dominant
Dominant Excessive DKV Non-dominant
Methods
95% CI
2-D SLS
-2.97-2.03
3-D SLS
-2.38-3.10
2-D SLS
-2.61-1.61
3-D SLS
-3.03-0.72
2-D SLS
-7.18 to -0.86
3-D SLS
-7.29 to -1.00
2-D SLS
-6.79 to -0.48
3-D SLS
-4.11 to 2.21
r-value
p-value
0.07
0.80
0.90
0.001
0.38
0.13
0.58
0.02
Abbreviation: FPPA = frontal plane projection angle; CI = confidence interval; DKV= dynamic knee valgus; 2-D= two-dimensional; 3-D= three-dimensional; SLS= single leg squat. Bolded values indicate statistically significant relationshps, p<0.05.
Table 3 shows the reliability within- and between-days of 3-D knee valgus during 45° and 60° SLS in the normal and excessive DKV groups. All the variables showed moderate to excellent reliability (ICC≥0.50). The 2-D knee FPPA acquired from video analysis during 45° and 60° SLS (r=0.78, p=0.001) were consistent with 3-D knee valgus angle of the same activities. CONCURRENT VALIDITY BETWEEN MOTION ANALYSIS
2-D AND 3-D
Table 4 presents the 2-D and 3-D measurement values in the normal and excessive DKV groups at 45° SLS. For the non-dominant leg SLS at 45°, there was an excellent positive relationship between 2-D knee FPPA and 3-D knee valgus in the normal group (r= 0.90, p= 0.001). However, no significant association between 2-D knee FPPA and 3-D knee valgus was observed during dominant leg SLS at 45°. Therefore, the validity of 2-D knee FPPA and 3-D knee valgus methods only applied for the non-dominant leg. As for the excessive DKV group, there was a moderate positive relationship between 2-D knee FPPA and 3-D knee valgus for non-dominant leg during 45° SLS (r= 0.58, p= 0.02). In contrast, there was no significant relationship for
dominant leg SLS. Therefore, the validity for 2-D and 3-D methods was only met for the non-dominant leg. Thus, Bland Altman plots were produced to compare the data of 2-D knee FPPA and 3-D knee valgus during SLS in the frontal plane for non-dominant leg in normal DKV group and excessive DKV group during 45° SLS (Figure 1 and 2). The difference between the 2-D knee FPPA and 3-D knee valgus measurement was plotted against the mean of the two measurements for each dependent variable. In the normal group, a significant moderate positive relationship was noted between 2-D knee FPPA and 3-D knee valgus during dominant leg 60° SLS (r= 0.65, p= 0.00) (Table 5). However, no significant relationship between 2-D knee FPPA and 3-D knee valgus was observed during non-dominant leg 60° SLS. Thus, the validity of 2-D knee FPPA and 3-D knee valgus for 60° SLS was met for the dominant leg only. In the excessive DKV group, non-dominant leg during 60° SLS showed a moderate positive relationship between 2-D knee FPPA and 3-D knee valgus (r= 0.48, p= 0.05). However, no significant relationship was observed between both methods on the dominant leg during 60° SLS. The examination of Bland-Altman plots and calculation of upper and lower limits of agreement indicated that variability in the
International Journal of Sports Physical Therapy
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
Table 5. Concurrent validity between 2-D knee FPPA and 3-D knee valgus among normal group and excessive DKV group at 60° SLS Group
Lower limb Dominant
Normal Non-dominant
Dominant Excessive DKV Non-dominant
Methods
95% CI
2-D SLS
-6.32-0.26
3-D SLS
-3.22-1.63
2-D SLS
-2.70-2.34
3-D SLS
-5.53-1.72
2-D SLS
-7.92 to -3.18
3-D SLS
-6.91 to 0.03
2-D SLS
-6.13 to -2.18
3-D SLS
-5.49 to 1.96
r-value
p-value
0.65
0.001
0.30
0.24
-0.05
0.86
0.481
0.05
Abbreviation: FPPA = frontal plane projection angle; CI = confidence interval; DKV= dynamic knee valgus; 2-D= two-dimensional; 3-D= three-dimensional; SLS= single leg squat. Bolded values indicate statistically significant relationships, p<0.05.
Figure 1. Bland-Altman plot demonstrating agreement between methods. The solid horizontal line represents the mean differences, and dashed lines indicate the 95% limits of agreement for non-dominant leg in normal DKV group during 45° SLS.
difference scores between 2-D knee FPPA and 3-D knee valgus measures fell within 95% limits of agreement (dashed lines). Figures 3 and 4 represent the significant results for the dominant leg in the normal DKV group and the nondominant leg in the excessive DKV group.
DISCUSSION The purpose of this study was to assess within- and between-session reliability of knee FPPA in 2-D and 3-D motion capture during 45° and 60° SLS. The validity and reliability of these methods were then compared across physically active females with and without DKV. Good within-session reliability is crucial since it ensures the con-
sistency of measuring 2-D knee FPPA during the screening test. The results showed that all the variables exhibited moderate to excellent reliability (ICC≥0.50). This indicates that 2-D and 3-D motion capture methods during SLS were reliable to be used in clinical testing to assess knee angle particularly among females with normal and excessive DKV. Similarly, Gwynne & Curran13 investigated within-session reliability of 2-D knee FPPA during 60° SLS in the same session with a one-hour break and between-session reliability with at least 48 hours interval. They reported that 2-D knee FPPA demonstrated good within-session (ICC= 0.86, 95% CI= 0.94 to 0.72) and between-session (ICC= 0.78, 95% CI= 0.18 to 0.97) reliability. When 2-D knee FPPA assessments were repeated throughout time, good between-
International Journal of Sports Physical Therapy
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
Figure 2. Bland-Altman plot demonstrating agreement between methods. The solid horizontal line represents the mean differences, and dashed lines indicate the 95% limits of agreement for non-dominant leg in excessive DKV group during 45° SLS.
Figure 3. Bland-Altman plot demonstrating agreement between methods. The solid horizontal line represents the mean differences, and dashed lines indicate the 95% limits of agreement for dominant leg in normal DKV group during 60° SLS.
session ICCs indicated good test-retest reliability values.13 However, their 18 recreationally active subjects (nine females and nine males) had not been screened for knee ab-
normalities and the SLS test was performed on dominant leg only.13 In order to avoid any bias due to knee abnormalities, the current study separated participants with normal
International Journal of Sports Physical Therapy
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
Figure 4 Bland-Altman plot demonstrating agreement between methods. The solid horizontal line represents the mean differences, and dashed lines indicate the 95% limits of agreement for non-dominant leg in excessive DKV group during 60° SLS.
and excessive DKV. Physically active females were the focus of the current study because they have been associated with an increased risk of non-contact knee injury due to excessive DKV.24 In Gwynne & Curran et al.,13 good betweensession reliability of 60° SLS (ICC= 0.74) was reported. Similarly, Munro et al. found that physically active males (ICC= 0.89) and females (ICC= 0.59) also showed good to exceptional between-session reliability for SLS at 45° knee flexion.19 Good between-session ICC indicates good test-retest reliability of observed values when 2-D knee FPPA measurement is repeated over time. Currently, there are no studies that differentiate the SLS kinematics across those with and without DKV. Most studies have compared the knee angle of healthy subjects versus those with pathological condition such as patellofemoral pain (PFP). For instance, Gwynne & Curran25 found that increased 2-D FPPA was a fair predictor of PFP as indicated by receiver operating characteristic (ROC) curve analysis during 60° SLS. The ROC curves in the study indicated that 2-D FPPA had fair specificity and sensitivity of discriminating PFP (95% CI= 0.60 to 0.86; p= 0.002). They conducted single limb stance and 60° SLS among 30 recreationally active individuals with PFP and 30 non-injured individuals. Interestingly, FPPA remained unchanged in the non-injured group during static stance and SLS. However, there was excessive frontal plane knee alignment in the PFP group (p=0.003) during the 60° SLS that demand greater neuromuscular control of the lower limb.25 Additionally, they only relied on 2-D analysis that might be less accurate than the 3-D analysis. Considering this, the knee valgus angle during 45° and 60° SLS either from 2-D or 3-D motion analysis is a valid indicator to distinguish those with exces-
sive DKV from healthy individual, particularly among physically active adults. The current study showed that the 2-D knee FPPA during 45° SLS were valid for non-dominant leg in both groups. Additionally, the 2-D knee FPPA during 60° SLS were valid for non-dominant leg in excessive DKV group and dominant leg in normal group. The differences of SLS validity across the legs may be due to the weakness of non-dominant leg, which typically being under-utilized and may be more inclined to excessive DKV than the dominant leg.13 For instance, Gwynne and Curran13 found that the 2-D knee FPPA obtained from video analysis during single limb stance (r= 0.64, p= 0.002) and 60° SLS on the dominant leg (r=0.78, p<0.001) were comparable with the 3-D knee valgus for the same task.13 However, they only studied the dominant leg, thus the validity of SLS on non-dominant leg is not known. Similar to the current results, Kingston and colleagues also observed no relationships between 2-D and 3-D knee frontal plane kinematics during SLS, drop vertical jump (DVJ), and single-leg hop (SLH) despite showing good to excellent reliability (ICC= 0.70-0.86) of the data during those taks.26 This probably is due to their participants (i.e., females with PFP ), as those with knee pain often perform functional tasks by applying increased frontal and transverse motions compared to healthy females.24 Additionally, Schurr et al.,18 observed moderate to strong correlations between the 2-D and 3-D joint angles in the sagittal plane (r = 0.51-0.093) but the knee frontal angle was poorly correlated (r = 0.308) during 90° SLS. These comparative findings indicate that the squat depths may influence the validity between the two methods.
International Journal of Sports Physical Therapy
The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
LIMITATIONS
CONCLUSION
Only physically active females were included in the study due to greater prevalence of non-contact injuries related to excessive DKV among females than males.27,28 Additionally, only females with a normal BMI were included to prevent the unwanted effects of extra weight on the participants’ motion during functional tasks.29 Therefore, the results may not be generalizable to the overweight and obese females and males. The physiological demands associated with SLS may not be of sufficient magnitude to elicit meaningful alterations in lower limb kinematics.28 Thus, future research should incorporate a wider range of complex motions such as a drop vertical jump at different heights30 and changing directions to detect any substantial changes in knee motions. Moreover, the stance foot was fixed in neutral position during SLS. It was shown that the foot position may influence knee kinematics during SLS,31 therefore future studies may include various foot positions during SLS. The sample size is within the range of previous studies’ sample size that have. investigated SLS validity and reliability.13,19 However, the ability to detect differences or relationship between variables may increase by increasing the sample size.
The results indicate that 2-D and 3-D methods of measuring knee valgus during 45° and 60° SLS are both reliable in physically active females with normal and excessive DKV. However, as validity depends on the squat depths, stance leg, and presence of DKV, clinicians should consider these factors when conducting SLS test. While 2-D knee FPPA may not be as accurate as 3-D analysis in quantifying each movement that contributes to DKV, it may provide clinicians with a useful tool that is inexpensive, portable, and readily available that can be used to assess frontal plane knee alignment during SLS.
CONFLICT OF INTEREST
None declared. FUNDING
The study was funded by Universiti Sains Malaysia RUI Grant (1001/PPSK/8012364). Submitted: September 29, 2021 CDT, Accepted: March 24, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
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The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
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10. Norris BS, Olson SL. Concurrent validity and reliability of two dimensional video analyses of hip and knee motion during mechanical lifting. Physiother Theory Pract. 2011;27(7):521-530. doi:10.3109/095939 85.2010.533745
2. Herrington L. Knee valgus angle during single leg squat and landing in patellofemoral pain patients and controls. Knee. 2014;21(2):514-517. doi:10.1016/j.kne e.2013.11.011
11. McLean SG. Evaluation of a two dimensional analysis method as a screening and evaluation tool for anterior cruciate ligament injury. Br J Sports Med. 2005;39(6):355-362. doi:10.1136/bjsm.2005.018598
3. Charlton PC, Bryant AL, Kemp JL, Clark RA, Crossley KM, Collins NJ. Single leg squat performance is impaired 1 to 2 years after hip arthroscopy. PMR. 2016;8(4):321-330. doi:10.1016/j.pmrj.2015.07.004
12. Jamaludin NI, Sahabuddin FNA, Raja Ahmad Najib RKM, Shamshul Bahari MLH, Shaharudin S. Bottomup kinetic chain in drop landing among university athletes with normal dynamic knee valgus. Int J Environ Res Public Health. 2020;17(12):4418. doi:10.33 90/ijerph17124418
4. Earl JE, Monteiro SK, Snyder KR. Differences in lower extremity kinematics between a bilateral dropvertical jump and a single-leg step-down. J Orthop Sports Phys Ther. 2007;37(5):245-252. doi:10.2519/jos pt.2007.2202 5. Willson JD, Davis IS. Utility of the frontal plane projection angle in females with patellofemoral pain. J Orthop Sports Phys Ther. 2008;38(10):606-615. doi:1 0.2519/jospt.2008.2706 6. Hewett TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med. 2005;33(4):492-501. doi:10.1177/036354 6504269591 7. Myer GD, Ford KR, Brent JL, Hewett TE. An integrated approach to change the outcome part I: neuromuscular screening methods to identify high ACL injury risk athletes. J Strength Cond Res. 2012;26(8):2265-2271. doi:10.1519/jsc.0b013e31825c 2b8f 8. Paterno MV, Schmitt LC, Ford KR, et al. Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sport. Am J Sports Med. 2010;38(10):1968-1978. doi:10.1177/03635465103760 53 9. Myklebust G, Engebretsen L, Brækken IH, Skjølberg A, Olsen OE, Bahr R. Prevention of anterior cruciate ligament injuries in female team handball players: a prospective intervention study over three seasons. Clin J Sport Med. 2003;13(2):71-78. doi:10.1097/00042 752-200303000-00002
13. Gwynne CR , Curran SR. Quantifying frontal plane knee motion during single limb squats: Reliability and validity of 2-dimensional measures. Int J Sports Phy Ther. 2014;9:898-906. 14. Ortiz A, Rosario-Canales M, Rodríguez A, Seda A, Figueroa C, Venegas-Ríos HL. Reliability and concurrent validity between two-dimensional and three-dimensional evaluations of knee valgus during drop jumps. Open Access J Sports Med. 2016;7:65. do i:10.2147/oajsm.s100242 15. Ramirez M, Negrete R, J. Hanney W, Kolber MJ. Quantifying frontal plane knee kinematics in subjects with anterior knee pain: The reliability and concurrent validity of 2-D motion analysis. Int J Sports Phys Ther. 2018;13(1):86-93. doi:10.26603/ijspt 20180086 16. Krause D, Boyd M, Hager A, et al. Reliability and accuracy of a goniometer mobile device application for video measurement of the functional movement screen deep squat test. Int J Sports Phys Ther. 2015;1(10):37-44. 17. Maykut JN, Taylor-Haas JA, Paterno MV, DiCesare CA, Ford KR. Concurrent validity and reliability of 2d kinematic analysis of frontal plane motion during running. Int J Sports Phys Ther. 2015;10(2):136-146. 18. Schurr SA, Marshall AN, Resch JE, Saliba SA. Twodimensional video analysis is a comparable to 3D motion capture in lower extremity movement assessment. Int J Sports Phys Ther. 2017;12(2):163-172.
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The Concurrent Validity and Reliability of Single Leg Squat Among Physically Active Females with and without Dynamic Knee...
19. Munro A, Herrington L, Carolan M. Reliability of two¬ dimensional video assessment of frontal plane dynamic knee valgus during common athletic screening tasks. J Sport Rehab. 2012;21:7-11. 20. Stickler L, Finley M, Gulgin H. Relationship between hip and core strength and frontal plane alignment during a single leg squat. Phys Ther Sport. 2015;16(1):66-71. doi:10.1016/j.ptsp.2014.05.002 21. DeLang MD, Hannon JP, Goto S, Bothwell JM, Garrison JC. Female adolescent soccer players utilize different neuromuscular strategies between limbs during the propulsion phase of a lateral vertical jump. Int J Sport Phys Ther. 2021;16(3):695-703. doi:10.2660 3/001c.22134 22. Ghasemi A, Zahediasl S. Normality tests for statistical analysis: A guide for non-statisticians. Int J Endocrinol Metab. 2012;10(2):486-489. doi:10.5812/ije m.3505 23. Koo TK, Li MY. A Guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016;15(2):155-163. doi:10.1016/j.jcm.2016.02.012 24. Kingston B, Murray A, Norte GE, Glaviano NR. Validity and reliability of 2-dimensional trunk, hip, and knee frontal plane kinematics during single-leg squat, drop jump, and single-leg hop in females with patellofemoral pain. Phys Ther Sport. 2020;45:181-187. doi:10.1016/j.ptsp.2020.07.006 25. Gwynne CR, Curran SA. Two-dimensional frontal plane projection angle can identify subgroups of patellofemoral pain patients who demonstrate dynamic knee valgus. Clin Biomech. 2018;58:44-48. do i:10.1016/j.clinbiomech.2018.06.021
26. Nakagawa TH, Moriya ÉTU, Maciel CD, Serrão FV. Trunk, pelvis, hip, and knee kinematics, hip strength, and gluteal muscle activation during a single-leg squat in males and females with and without patellofemoral pain syndrome. J Orthop Sports Phys Ther. 2012;42(6):491-501. doi:10.2519/jospt.2012.398 7 27. Sigward SM, Ota S, Powers CM. Predictors of frontal plane knee excursion during a drop land in young female soccer players. J Orthop Sports Phys Ther. 2008;38(11):661-667. doi:10.2519/jospt.2008.26 95 28. Wilczyński B, Zorena K, Ślęzak D. Dynamic knee valgus in single-leg movement tasks. potentially modifiable factors and exercise training options. A literature review. Int J Environ Res Public Health. 2020;17(21):8208. doi:10.3390/ijerph17218208 29. Araújo V, Souza T, Carvalhais V, Cruz A, Fonseca S. Effects of hip and trunk muscle strengthening on hip function and lower limb kinematics during stepdown task. Clin Biomech. 2017;44:28-35. doi:10.1016/ j.clinbiomech.2017.02.012 30. Sahabuddin FNA, Jamaludin NI, Shamshul Bahari MLH, Raja Ahmad Najib RKM, Shaharudin S. Lower limb biomechanics during drop vertical jump at different heights among university athletes. J Phys Edu Sport. 2021;21(4):1829-1835. 31. Mohd Azhar N, Affandi NF, Mail MSZ, Shaharudin S. The effects of foot position on lower extremity kinematics during single leg squat among adolescent male athletes. J Taibah Univ Med Sci. 2019;14(4):343-349. doi:10.1016/j.jtumed.2019.06.00 7
International Journal of Sports Physical Therapy
Weaver A, Ness B, Roman D, Giampetruzzi N, Cleland J. Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic. IJSPT. 2022;17(4):585-592.
Original Research
Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic a
Adam Weaver 1 1
, Brandon Ness 2, Dylan Roman 1 , Nicholas Giampetruzzi 1 , Joshua Cleland 2
Sports Physical Therapy, Connecticut Children's, 2 Doctor of Physical Therapy Program, Tufts University School of Medicine
Keywords: Adolescent, Anterior Cruciate Ligament Reconstruction, COVID, Strength, Rehabilitation https://doi.org/10.26603/001c.35668
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background/Purpose The COVID-19 pandemic has impacted adolescents across multiple areas of health. While many factors influence outcomes following anterior cruciate ligament reconstruction (ACLR), the impact of the COVID-19 pandemic on early patient outcomes after ACLR is currently unknown in an adolescent population. The purpose of this study was to determine if short-term clinical outcomes were different in adolescents after ACLR for those who underwent surgery pre-COVID versus during the COVID-19 pandemic timeframe.
Design Retrospective cohort
Methods A retrospective review of records occurred for patients who underwent ACLR with a quadriceps tendon autograft. Two separate review timeframes were defined according to date of surgery (control: September 2017 - October 2019; COVID: March 2020 - May 2021). Patients were classified into pre-COVID (control) and COVID groups by surgical date and were then age- and sex-matched. Three-month postoperative outcomes were included for analysis, including normalized isometric quadriceps and hamstring peak torque, Anterior Cruciate Ligament – Return to Sport after Injury (ACL-RSI), and the Pedi International Knee Documentation Committee Form (Pedi-IKDC) scores.
Results Sixty patients met the inclusion criteria (34 females, 56.7%). Follow-up testing occurred at 3.2 months (98.13 ± 14.91 days) postoperative. A significant difference was found between groups for normalized quadriceps peak torque on the uninvolved limb, with the control group (2.03 ± 0.47 Nm/kg) demonstrating decreased peak torque compared to the COVID group (2.49 ± 0.61 Nm/kg) (p =0.002, effect size (d) = 0.84). For the involved limb, no difference in normalized quadriceps peak torque was observed between the control group (1.25 ± 0.33 Nm/kg) and those who underwent surgery during the COVID-19 pandemic (1.49 ± 0.70 Nm/kg) (p = 0.09). No differences were identified between groups for any of the other strength outcomes (p = 0.31 – 0.87). Similarly, no differences in patient reported outcomes were found for Pedi-IKDC or ACL-RSI between groups (p = 0.12 – 0.43).
a
Corresponding author: Adam Weaver, PT, DPT Connecticut Children’s 399 Farmington Avenue Farmington, CT 06032 Email: aweaver@connecticutchildren.org Phone: 410-474-4550 Fax: 860-837-9341
Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic
Conclusion At roughly three months after ACLR, normalized quadriceps peak torque on the uninvolved limb was reduced by 18.5% for adolescents who underwent surgery pre-COVID versus during the COVID-19 pandemic timeframe. No group differences were observed for other isometric strength outcomes, Pedi-IKDC, or ACL-RSI scores.
INTRODUCTION Anterior cruciate ligament (ACL) rupture is one of the more common sports injuries, and 75% of high school athletes are likely to undergo surgical intervention with the aim to restore knee stability.1 Though patients who undergo ACL reconstruction (ACLR) have been shown to have superior outcomes for knee function and symptoms compared those who choose non-surgical intervention,2 outcomes are less than desirable in the young athletic population. Twelve months following ACLR, less than 50% of jumping, pivoting, and cutting athletes under the age of 25 are expected to return to sport.2 Additionally, of those that do return, one in four individuals are expected to experience either graft failure or a contralateral injury.3 The novel coronavirus (COVID-19) has impacted daily human activities around the world, and there is mounting evidence that adolescents during this time experienced increases in sedentary behavior, physical inactivity, and disrupted sleep schedules.4 Prior to the COVID-19 pandemic, less than 10% of school-aged children were achieving recommended amounts of 30-60 minutes of daily moderatevigorous physical activity.5 Since the beginning of the pandemic, only 2.6% of healthy adolescents were reaching recommended physical activity goals,6 and sedentary behaviors including television, video games and computer usage increased 20-66%.7,8 Along with these COVID-related changes in adolescent health and behavior, athletes rehabilitating from ACLR also experienced the impact of COVID-19. In the United States, state government mandates included closing of gymnasiums, fitness centers, athletic fields, and courts, as well as school systems implementing remote learning to help mitigate virus transmission. Additionally, there were significant restrictions on elective orthopedic and physical therapy services during this time period.9 COVID-19 caused rapid changes in the standard of care and implementation of telemedicine for many sports medicine providers, yet many other challenges persisted for these patients including limited access to in-person rehabilitation services, restricted access to weight rooms and training facilities, and a lack of resources to perform sport specific activities. In addition, there were other unintended consequences resulting from sheltering in place. Thirty-six percent of parents reported decreased physical activity levels in children and adolescents,10 along with higher rates of anxiety, depression, and stress.11 This is important, as stress and limited social support can negatively affect desired outcomes following ACLR.12 These new challenges during the COVID-19 pandemic added to an already complex rehabilitation process. A range of patient self-report and clinical outcome measures have been associated with the likelihood of successful return to sport after ACLR and are important to examine
throughout rehabilitation. Measurement of knee strength after ACLR is commonly used in the return to sport decision making process, as adequate strength outcomes have shown to improve the likelihood of returning to prior level of sport13,14 and reducing the risk of secondary ACL injury.15 Early functional and isolated knee extension strength at six to twelve weeks post ACLR have been predictive of hop test and knee strength outcomes at time of return to play,16–18 which highlights the importance of early strength testing after ACLR in order for clinicians to modify rehabilitation strategies accordingly. Further, psychological measures of self-efficacy, self-motivation, and optimism were predictive of an athlete’s ability to return to sport, knee symptoms, and compliance with rehabilitation.12 While many factors influence outcomes following ACLR, the impact of the COVID-19 pandemic on early patient outcomes after ACLR is currently unknown in an adolescent population. Therefore, the purpose of this study was to determine if shortterm clinical outcomes were different in adolescents after ACLR for those who underwent surgery pre-COVID versus during the COVID-19 pandemic timeframe. The authors hypothesized that strength and patient reported outcomes would be different between groups.
METHODS DESIGN
The Institutional Review Board at Connecticut Children’s approved the study. A retrospective review of records occurred for consecutive patients who underwent ACLR at the institution during the following timeframes according to date of surgery: control group between September 2017 and October 15, 2019 (pre-COVID group), and between March 2020 and May 2021 (COVID Group). The pre-COVID surgical timeframe was determined by available data that included only patients who underwent ACLR with the use of quadriceps autograft. The end date of the control group (preCOVID) was selected to ensure follow up testing did not overlap with the COVID group. The surgical date range for the COVID group was selected as this coincided with the temporary pandemic-related closure of Connecticut Children’s, as well as the many resources used during ACLR rehabilitation (physical therapy clinics, fitness centers, etc.) in the state of Connecticut. Demographic, surgical, and clinical outcome data were collected. PATIENTS
The inclusion criteria were as follows: 1) age 10-20 years old, 2) underwent primary ACLR using a quadriceps autograft, and 3) completed standard ACLR testing procedures between 60 -140 days (2 – 4.5 months) postoperative. Patients were included if a concomitant meniscal procedure was performed at the time of surgery. A prior investigation
International Journal of Sports Physical Therapy
Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic
demonstrated that the presence of meniscal repair did not influence functional outcomes after ACLR.19 Patients were excluded for any multi-ligament knee surgery and all contralateral or secondary ACLR. Groups were matched according to age and sex. In the event groups were unbalanced according to sex, randomization software20 was used to select patients for inclusion to achieve balanced groups. All patients in the sample underwent surgery with one of five different orthopedic sports medicine surgeons at a single surgical center. A standardized rehabilitation program was provided to all patients with recommendations to seek supervised postoperative rehabilitation. All strength testing was performed at Connecticut Children’s. PROCEDURES
A standardized strength testing protocol was applied for all patients within a comprehensive battery of tests, including range of motion, strength testing, dynamic movement evaluation, and patient reported outcomes in conjunction with their 3-month post-operative surgeon visit. A sports medicine trained physical therapist at Connecticut Children’s administered the tests. An isokinetic dynamometer (Humac CSMI USA, Stoughton, MA, USA) was used to measure maximum isometric muscle torque. Patients were positioned in short sitting with their trunk and thigh supported with straps and hip joint positioned in 90 degrees of flexion. The dynamometer arm was secured proximal to the ankle joint. The uninvolved limb’s quadriceps and hamstring strength were assessed prior to the involved limb. The therapist provided verbal encouragement to the patient throughout the test to deliver maximal effort. Measuring quadriceps and hamstring peak torque using this method was shown to be reliable in adults21,22 and children.23 Isometric quadriceps and hamstring torque was assessed with the knee positioned at 60 degrees of knee flexion with gravity correction applied.24 Two practice trials and five test trials were performed. Of the five trials, the maximum peak torque measurement was collected and documented in newton-meters (Nm). The limb symmetry index (LSI) was calculated as the ratio of peak torque between the involved limb and uninvolved limb and expressed as a percentage. Normalized peak torque was expressed relative to the patient’s body mass and recorded for analysis (Nm/kg).23,24 Patients completed either the Pedi International Knee Documentation Committee Subjective Knee Evaluation Form (patients under age 18)25 or the 2000 IKDC Subjective Knee evaluation form (patients 18 and older).26 The reliability and validity of the Pedi-IKDC has been shown to be acceptable in children and adolescents between the ages of 10 and 18.25 The Anterior Cruciate Ligament- Return to Sport (ACL-RSI) is a validated 12 question scale to evaluate patients’ confidence and psychological readiness related to emotions, confidence and risk appraisal after ACL injury.27,28 STATISTICAL ANALYSIS
SPSS version 26.0 (IBM Corp, Armonk, NY, USA) was used to perform the statistical analysis. Mean values, standard de-
viations, and 95% confidence intervals were calculated for all outcomes including normalized quadriceps peak torque, normalized hamstring peak torque, Pedi-IKDC, and ACLRSI. Normal distribution of the data was examined using Shapiro-Wilk tests. In cases where non-normal distribution of data was observed, the nonparametric testing equivalent was used. Group differences were evaluated using independent samples t-tests (parametric test) or Mann-Whitney U tests (nonparametric test). Chi-square tests were used to evaluate differences in group frequencies. Alpha level was set a priori to 0.05. Effect size (ES) was evaluated using Cohen’s d according to the following criteria: < 0.2 (trivial), 0.2 – 0.49 (small), 0.5 – 0.79 (medium), and ≥ 0.8 (large).29 G*Power software (Version 3.1, University of Dusseldorf, Dusseldorf, Germany) was used to perform a post hoc power analysis.30
RESULTS Sixty patients met the inclusion criteria (34 females, 56.7%) with 17 females and 13 males in each group, respectively (Table 1). No significant differences in age, height, mass, and time since surgery were observed between groups (p > 0.05). Testing occurred at roughly 3.2 months (98.13 ± 14.91 days) postoperative. Descriptive statistics are reported in Table 2. There was a statistically significant difference between groups in mean normalized quadriceps peak torque on the uninvolved limb, with those in the control group (2.03 ± 0.47 Nm/kg) demonstrating decreased peak torque compared to those who underwent surgery during the COVID-19 pandemic timeframe (2.49 ± 0.61 Nm/kg), p =0.002, effect size (d) = 0.84. For the involved limb, no difference in normalized quadriceps peak torque was observed between the control group (1.25 ± 0.33 Nm/kg) and those who underwent surgery during the COVID-19 pandemic (1.49 ± 0.70 Nm/kg), p = 0.09. No differences were identified between groups for any of the other strength outcomes (p = 0.31 – 0.87). Similarly, no differences in patient reported outcomes were found for Pedi-IKDC or ACL-RSI between groups (p = 0.12 – 0.43). A post hoc power analysis demonstrated 89% statistical power with an alpha level set to 0.05 based on the observed effect size for the group differences in normalized quadriceps peak torque on the uninvolved limb.
DISCUSSION This study sought to examine potential differences in shortterm outcomes in adolescents who underwent ACLR surgery during the COVID-19 pandemic versus the pre-pandemic timeframe. The normalized quadriceps peak torque for the uninvolved limb was significantly greater for those who underwent surgery during the COVID pandemic with a large effect size compared to those who underwent surgery preCOVID. There were no other group differences for normalized peak torque on the involved limb (quadriceps or hamstrings) or limb symmetry indices. Similarly, no differences were observed between groups for Pedi-IKDC and ACL-RSI scores. Other than the difference in quadriceps peak torque for the uninvolved limb, the results suggest similar short-
International Journal of Sports Physical Therapy
Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic
Table 1. Patient Demographics Total (n = 60)
Control (n = 30)
COVID (n = 30)
Female (%)
34 (56.7%)
17 (56.7%)
17 (56.7%)
Age (years)a
15.79 ± 1.70 (15.35, 16.23)
15.86 ± 1.52 (12.29, 16.43)
15.71 ± 1.89 (15.01, 16.41)
0.731
Height (cm)a
168.78 ± 9.77 (166.26, 171.31)
167.56 ± 10.23 (163.73, 171.38)
170.01 ± 9.23 (166.54, 173.48)
0.335
Mass (kg)a
69.04 ± 17.70 (64.46, 73.61)
68.30 ± 19.23 (61.12, 75.48)
69.78 ± 16.33 (63.68, 75.87)
0.779
Time Since Surgery (days)
98.13 ± 14.91 (94.28, 101.99)
100.50 ± 16.54 (94.32, 106.68)
95.77 ± 12.92 (90.94, 100.59)
0.137
Skeletally Immature Surgical Procedure
p value
11 (18.3%)
4 (13.3%)
7 (23.3%)
0.506
Isolated ACL reconstruction
24 (40%)
11 (36.7%)
13 (43.3%)
0.598
ACL reconstruction with medial and/or lateral meniscus repair
36 (60%)
19 (63.3%)
17 (56.7%)
Control group: pre-COVID pandemic surgical date; COVID group: surgical date occurred during COVID pandemic aValues are expressed as mean ± SD, (95% confidence interval). ACL, anterior cruciate ligament
Table 2. Short-term Outcomes after ACL Reconstruction in Adolescents Total
Control
COVID
p value
Quadriceps peak torque – Involved (Nm/kg)
1.37 ± 0.56 (1.23, 1.51)
1.25 ± 0.33 (1.12, 1.37)
1.49 ± 0.70 (1.23, 1.75)
0.087
Quadriceps peak torque – Uninvolved (Nm/kg)
2.26 ± 0.59 (2.11, 2.41)
2.03 ± 0.47 (1.85, 2.20)
2.49 ± 0.61 (2.26, 2.72)
0.002
60.75 ± 17.65 (56.19, 65.31)
62.98 ± 15.86 (57.06, 68.90)
58.52 ± 19.28 (51.32, 65.72)
0.332
Hamstring peak torque – Involved (Nm/kg)
0.95 ± 0.25 (0.88, 1.01)
0.91 ±.20 (0.84, 0.99)
0.98 ± 0.30 (0.86, 1.09)
0.323
Hamstring peak torque – Uninvolved (Nm/kg)
1.22 ± 0.30 (1.14, 1.29)
1.18 ± 0.24 (1.09, 1.27)
1.25 ± 0.35 (1.13, 1.38)
0.313
Hamstring Limb Symmetry Index (%)
79.0 ± 15.7 (74.94, 83.05)
78.67 ± 13.06 (73.80, 83.55)
79.32 ± 18.18 (72.54, 86.12)
0.873
Pedi-IKDC
69.48 ± 14.64 (65.70, 73.26)
72.59 ± 13.17 (67.68, 77.52)
66.26 ±15.57 (60.55, 72.18)
0.115
ACL-RSI
60.73 ± 22.69 (54.87, 66.59)
63.07 ± 24.74 (53.83, 72.31)
58.39 ±20.58 (50.70, 66.07)
0.429
Quadriceps Limb Symmetry Index (%)
Control group: pre-COVID pandemic surgical date; COVID group: surgical date occurred during COVID pandemic. Pedi-IKDC: (Pediatric) International Knee Documentation Committee Subjective Knee form; ACL-RSI: Anterior Cruciate Ligament- Return to Sport after Injury. Bolded values indicated significant differences between groups, p <0.05
term outcomes between patient groups who underwent surgery pre-COVID versus during the COVID-19 pandemic. These outcomes may add useful information when examining the impact of the COVID-19 pandemic on adolescents in the first three months after ACLR. This study examined differences in short-term outcomes after ACLR in adolescents with a mean follow up time of 3.2 months after surgery, but it should be recognized that ACLR rehabilitation typically lasts six to nine months (or longer). Recently, Lee et al31 showed that there were no differences in IKDC and Lysholm scores after ACLR during COVID-19 in an adult population (mean age 32.5 ± 14.5 years) with minimum one-year follow up. Further, postoperative orthopedic and physical therapy follow up visit attendance and satisfaction were reported, and further specified by in-per-
son attendance versus telehealth delivery.31 The current investigation did not examine the number of physical therapy visits, use of telehealth, or patient compliance with a home exercise program, which may be important factors for patient success, as athletes who were compliant with supervised physical therapy visits reported better function and were more than four times more likely to return to sport.32 Although a short-term postoperative timeframe was specified for this study, there are several patient and COVID-related factors that likely impacted ACLR outcomes, yet their specific influence remains unclear. As the COVID-19 pandemic continues, longer follow up timeframes of one to two years postoperative may offer additional insight. The early aims of ACLR rehabilitation are to restore range of motion, normalize gait, and regain quadriceps
International Journal of Sports Physical Therapy
Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic
function. The importance of the restoration of quadriceps strength after ACLR has been well established in its relationship to return to play,33 landing biomechanics,34 osteoarthritis35 and future re-injury.15 Better performance during early stage strength testing after ACLR has been shown to be associated with greater self-reported function and greater readiness to return to functional activities.36 Pedi-IKDC and ACL-RSI values were generally similar in both groups at three months postoperatively compared to a previous study with a similar age group (Pedi-IKDC: 64.2 ± 20.5; ACL-RSI: 69.2 ± 13.8).36 However, patients in the current cohort had quadriceps limb symmetry indices that were 18% decreased, comparatively.36 Some of the variation in strength outcomes between studies may be partly explained by differences in surgical procedures and patient group characteristics. More recent data has shown the COVID-19 pandemic has continued to impact all aspects of society, and the delivery of physical therapy services was not spared. In outpatient physical therapy settings, the frequency of visits after ACLR varies but is not uncommon for patients to attend physical therapy sessions on a weekly or biweekly basis with orthopedic surgery follow up visits occurring at sixweek and three-month postoperative timeframes. The closure and restriction of orthopedic and physical therapy services led to rapid changes in the standard of care including the stoppage of non-essential outpatient visits and the implementation of telemedicine.37,38 The height of disruption in clinical care was between March-June 2020, which led to limited physical therapy access and increased telemedicine services.9,31 However, as health care accessibility increased after June 2020, there continued to be limited patient access to important resources traditionally used during rehabilitation after ACLR (school gyms, recreational fitness centers) due to remote schooling and local governmental closures which extended into May 2021 in many parts of the United States. In contrast, upon increasing physical therapy outpatient clinic accessibility, patient visits were altered to accommodate for space restrictions, cleaning protocols and social distancing.39 One type of alteration during COVID-19 at Connecticut Children’s included increased time of each individual patient visit to accommodate social distancing and organizational protocols. It was unclear how these factors (spacing, protocols) would impact patient progress after ACLR, but the outcomes of this study were somewhat counter to the assumptions associated with restricted access to resources during COVID-19. At this point, it is unclear how specific COVID-19 restrictions may have impacted short-term outcomes after ACLR in adolescents. One notable finding from this study was those who attained surgery during the COVID pandemic timeframe, in fact, had superior quadriceps peak torque on the uninvolved limb compared to those who underwent surgery pre-COVID. It is difficult to speculate, but plausible explanations for the observed difference in uninvolved limb quadriceps peak
torque may include potential changes in rehabilitation practice patterns over time such as using the uninvolved limb for cross-education exercise strategies.40 Also, each individual patient visit was longer in duration during the COVID pandemic timeframe, which may have allowed for increased total exercise volume per session. Other than quadriceps peak torque in the uninvolved limb, postoperative strength outcomes were generally similar between groups, which may be a reflection of the relatively narrow, early postoperative window in which patient outcomes were collected. Examining patient outcomes over a longer timeframe from surgery may allow for better comparison of the trajectory for strength recovery between groups after ACLR.
LIMITATIONS This study only investigated outcomes on a single type of ACL graft within a specified timeframe of postoperative rehabilitation using isometric strength testing. Investigating patient groups with other ACL graft types, postoperative timeframes, and methods of strength assessment may offer additional means to compare patient outcomes during the COVID-19 pandemic. Finally, this study did not directly assess the influence of other areas of adolescent health that were previously reported to have been impacted during the COVID-19 pandemic, such as physical activity levels and mental health.41,42
CONCLUSION At roughly three months after ACLR, normalized quadriceps peak torque on the uninvolved limb was reduced by 18.5% for adolescents who underwent surgery pre-COVID versus during the COVID-19 pandemic timeframe. There were no other group strength differences noted on either limb, or any differences found in patient reported outcomes for Pedi-IKDC or ACL-RSI scores. Generally, changes in practice patterns due to COVID-19 did not seem to adversely impact short-term outcomes when compared to those who underwent surgery prior to the pandemic. Future investigation is warranted to examine the longer-term implications of the COVID-19 pandemic on adolescent patient outcomes after ACLR.
CONFLICT OF INTEREST STATEMENT
AW, BN DR, NG, JC have no conflicts of interest to disclose. Submitted: November 16, 2021 CDT, Accepted: March 24, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
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Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic
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3. Wiggins AJ, Grandhi RK, Schneider DK, Stanfield D, Webster KE, Myer GD. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction: a systematic review and metaanalysis. Am J Sports Med. 2016;44(7):1861-1876. do i:10.1177/0363546515621554 4. Bates L, Zieff G, Stanford K, et al. COVID-19 impact on behaviors across the 24-hour day in children and adolescents: physical activity, sedentary behavior, and sleep. Children. 2020;7(9):138. doi:10.3390/childr en7090138 5. Roman-Viñas B, Chaput JP, Katzmarzyk PT, et al. Proportion of children meeting recommendations for 24-hour movement guidelines and associations with adiposity in a 12-country study. Int J Behav Nutr Phys Act. 2016;13(1). doi:10.1186/s12966-016-0449-8 6. Moore SA, Faulkner G, Rhodes RE, et al. Impact of the COVID-19 virus outbreak on movement and play behaviours of Canadian children and youth: a national survey. Int J Behav Nutr Phys Act. 2020;17(85). doi:10.1186/s12966-020-00987-8 7. Guan H, Okely AD, Aguilar-Farias N, et al. Promoting healthy movement behaviours among children during the COVID-19 pandemic. Lancet Child Adolesc Health. 2020;4(6):416-418. doi:10.1016/s235 2-4642(20)30131-0 8. Xiang M, Zhang Z, Kuwahara K. Impact of COVID-19 pandemic on children and adolescents’ lifestyle behavior larger than expected. Prog Cardiovasc Dis. 2020;63(4):531-532. doi:10.1016/j.pca d.2020.04.013 9. Sarac NJ, Sarac BA, Schoenbrunner AR, et al. A review of state guidelines for elective orthopaedic procedures during the COVID-19 outbreak. J Bone Joint Surg Am. 2020;102(11):942-945. doi:10.2106/JBJ S.20.00510
12. Everhart JS, Best TM, Flanigan DC. Psychological predictors of anterior cruciate ligament reconstruction outcomes: a systematic review. Knee Surg Sports Traumatol Arthrosc. 2015;23(3):752-762. d oi:10.1007/s00167-013-2699-1 13. Burgi CR, Peters S, Ardern CL, et al. Which criteria are used to clear patients to return to sport after primary ACL reconstruction? A scoping review. Br J Sports Med. 2019;53(18):1154-1161. doi:10.1136/bjsp orts-2018-099982 14. Lentz TA, Zeppieri G Jr, Tillman SM, et al. Return to preinjury sports participation following anterior cruciate ligament reconstruction: contributions of demographic, knee impairment, and self-report measures. J Orthop Sports Phys Ther. 2012;42(11):893-901. doi:10.2519/jospt.2012.4077 15. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804-808. doi:10.1136/bjsports-2016-0960 31 16. Pua YH, Mentiplay BF, Clark RA, Ho JY. Associations among quadriceps strength and rate of torque development 6 weeks post anterior cruciate ligament reconstruction and future hop and vertical jump performance: a prospective cohort study. J Orthop Sports Phys Ther. 2017;47(11):845-852. doi:1 0.2519/jospt.2017.7133 17. Garrison C, Bothwell J, Wolf G, Aryal S, Thigpen C. Y balance test anterior reach symmetry at three months is related to single leg functional performance at time of return to sports following anterior cruciate ligament reconstruction. Int J Sports Phys Ther. 2015;10(5):602-611. 18. Hannon JP, Wang-Price S, Goto S, et al. Twelveweek quadriceps strength as a predictor of quadriceps strength at time of return to sport testing following bone-patellar tendon-bone autograft anterior cruciate ligament reconstruction. Int J Sports Phys Ther. 2021;16(3):681-688. doi:10.26603/001c.23421
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Short-Term Clinical Outcomes After Anterior Cruciate Ligament Reconstruction In Adolescents During The COVID-19 Pandemic
19. Casp AJ, Bodkin SG, Gwathmey FW, et al. Effect of meniscal treatment on functional outcomes 6 months after anterior cruciate ligament reconstruction. Ortho J Sports Med. 2021;9(10):232596712110312. doi:10.11 77/23259671211031281 20. Urbaniak GC, Plous S. Research randomizer (version 4.0) [computer software]. 21. Toonstra J, Mattacola CG. Test-retest reliability and validity of isometric knee-flexion and -extension measurement using 3 methods of assessing muscle strength. J Sport Rehabil. 2013;22(1). doi:10.1123/jsr.2 013.TR7 22. Hirano M, Katoh M, Gomi M, Arai S. Validity and reliability of isometric knee extension muscle strength measurements using a belt-stabilized handheld dynamometer: a comparison with the measurement using an isokinetic dynamometer in a sitting posture. J Phys Ther Sci. 2020;32(2):120-124. d oi:10.1589/jpts.32.120 23. Johnsen MB, Eitzen I, Moksnes H, Risberg MA. Inter- and intrarater reliability of four single-legged hop tests and isokinetic muscle torque measurements in children. Knee Surg Sports Traumatol Arthrosc. 2015;23(7):1907-1916. doi:10.1007/s00167-013-277 1-x 24. Undheim MB, Cosgrave C, King E, et al. Isokinetic muscle strength and readiness to return to sport following anterior cruciate ligament reconstruction: is there an association? A systematic review and a protocol recommendation. Br J Sports Med. 2015;49(20):1305-1310. doi:10.1136/bjsports-2014-09 3962 25. van der Velden CA, van der Steen MC, Leenders J, van Douveren F, Janssen RPA, Reijman M. Pedi-IKDC or KOOS-child: which questionnaire should be used in children with knee disorders? BMC Musculoskelet Disord. 2019;20(1):240. doi:10.1186/s12891-019-260 0-6 26. Logerstedt D, Di Stasi S, Grindem H, et al. Selfreported knee function can identify athletes who fail return-to-activity criteria up to 1 year after anterior cruciate ligament reconstruction: a delaware-oslo ACL cohort study. J Orthop Sports Phys Ther. 2014;44(12):914-923. doi:10.2519/jospt.2014.4852 27. Sadeqi M, Klouche S, Bohu Y, Herman S, Lefevre N, Gerometta A. Progression of the psychological ACL-RSI Score and return to sport after anterior cruciate ligament reconstruction: a prospective 2-year follow-up study from the French Prospective Anterior Cruciate Ligament Reconstruction Cohort Study (FAST). Orthop J Sports Med. 2018;6(12). doi:1 0.1177/2325967118812819
28. Webster KE, Feller JA. Development and validation of a short version of the Anterior Cruciate Ligament Return to Sport After Injury (ACL-RSI) scale. Orthop J Sports Med. 2018;6(4):2325967118763763. doi:10.1177/232596711 8763763 29. Cohen J. Statistical Power Analysis for the Behavioral Sciences. 2nd ed. Erlbaum Associates; 1988. 30. Faul F, Erdfelder E, Lang AG, Buchner A. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods. 2007;39(2):175-191. 31. Lee D, Lencer AJ, Gibbs BS, Paul RW, Tjoumakaris FP. Disruptions in standard care: anterior cruciate ligament reconstruction outcomes during the SARSCOV2 pandemic. Phys Sportsmed. Published online 2021:1-7. doi:10.1080/00913847.2021.1971494 32. Han F, Banerjee A, Shen L, Krishna L. Increased compliance with supervised rehabilitation improves functional outcome and return to sport after anterior cruciate ligament reconstruction in recreational athletes. Orthop J Sports Med. 2015;3(12):232596711562077. doi:10.1177/232596711 5620770 33. Webster KE, Feller JA, Leigh WB, Richmond AK. Younger patients are at increased risk for graft rupture and contralateral injury after anterior cruciate ligament reconstruction. Am J Sports Med. 2014;42(3):641-647. doi:10.1177/0363546513517540 34. Schmitt LC, Paterno MV, Ford KR, Myer GD, Hewett TE. Strength asymmetry and landing mechanics at return to sport after anterior cruciate ligament reconstruction. Med Sci Sports Exerc. 2015;47(7):1426-1434. doi:10.1249/MSS.00000000000 00560 35. Shimizu T, Samaan MA, Tanaka MS, et al. Abnormal biomechanics at 6 months are associated with cartilage degeneration at 3 years after anterior cruciate ligament reconstruction. Arthroscopy. 2019;35(2):511-520. doi:10.1016/j.arthro.2018.07.033 36. Burland JP, Kostyun RO, Kostyun KJ, Solomito M, Nissen C, Milewski MD. Clinical outcome measures and return-to-sport timing in adolescent athletes after anterior cruciate ligament reconstruction. J Athl Train. 2018;53(5):442-451. doi:10.4085/1062-6050-30 2-16 37. Miller MJ, Pak SS, Keller DR, Barnes DE. Evaluation of pragmatic telehealth physical therapy implementation during the COVID-19 pandemic. Phys Ther. 2021;101(1). doi:10.1093/ptj/pzaa193
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38. Parisien RL, Shin M, Constant M, et al. Telehealth utilization in response to the novel coronavirus (COVID-19) pandemic in orthopaedic surgery. J Am Acad Orthop Surg. 2020;28(11):e487-e492. doi:10.543 5/jaaos-d-20-00339
41. Guan H, Okely AD, Aguilar-Farias N, et al. Promoting healthy movement behaviours among children during the COVID-19 pandemic. The Lancet Child & Adolescent Health. 2020;4(6):416-418. doi:1 0.1016/s2352-4642(20)30131-0
39. Ditwiler RE, Swisher LL, Hardwick DD. Professional and ethical issues in united states acute care physical therapists treating patients with covid-19: stress, walls, and uncertainty. Phys Ther. 2021;101(8). doi:10.1093/ptj/pzab122
42. Xiang M, Zhang Z, Kuwahara K. Impact of COVID-19 pandemic on children and adolescents’ lifestyle behavior larger than expected. Progress in Cardiovascular Diseases. 2020;63(4):531-532. doi:10.1 016/j.pcad.2020.04.013
40. Harput G, Ulusoy B, Yildiz TI, et al. Crosseducation improves quadriceps strength recovery after ACL reconstruction: a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc. 2019;27(1):68-75. doi:10.1007/s00167-018-5040-1
International Journal of Sports Physical Therapy
Mann KJ, O’Dwyer N, Bruton MR, Bird SP, Edwards S. Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score. IJSPT. 2022;17(4):593-604.
Original Research
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score Kerry J. Mann 1
a
, Nicholas O'Dwyer 2, Michaela R. Bruton 3, Stephen P. Bird 4, Suzi Edwards 2
1
School of Allied Health, Exercise and Sports Science, Charles Sturt University, 2 The Discipline of Exercise Science, The University of Sydney, 3 School of Exercise Sciences, Australian Catholic University, 4 School of Health and Medical Sciences, University of Southern Queensland Keywords: Movement screening, injury risk, pre-elite youth athletes https://doi.org/10.26603/001c.35666
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Movement competency screens (MCSs) are commonly used by coaches and clinicians to assess injury risk. However, there is conflicting evidence regarding MCS reliability.
Purpose This study aimed to: (i) determine the inter- and intra-rater reliability of a sport specific field-based MCS in novice and expert raters using different viewing methods (single and multiple views); and (ii) ascertain whether there were familiarization effects from repeated exposure for either raters or participants.
Study Design Descriptive laboratory study
Methods Pre-elite youth athletes (n=51) were recruited and videotaped while performing a MCS comprising nine dynamic movements in three separate trials. Performances were rated three times with a minimal four-week wash out between testing sessions, each in randomized order by 12 raters (3 expert, 9 novice), using a three-point scale. Kappa score, percentage agreement and intra-class correlation were calculated for each movement individually and for the composite score.
Results Fifty-one pre-elite youth athletes (15.0±1.6 years; n=33 athletics, n=10 BMX and n=8 surfing) were included in the study. Based on kappa score and percentage agreement, both inter- and intra-rater reliability were highly variable for individual movements but consistently high (>0.70) for the MCS composite score. The composite score did not increase with task familiarization by the athletes. Experts detected more movement errors than novices and both rating groups improved their detection of errors with repeated viewings of the same movement.
Conclusions Irrespective of experience, raters demonstrated high variability in rating single movements, yet preliminary evidence suggests the MCS composite score could reliably assess movement competency. While athletes did not display a familiarization effect after
a
Corresponding author: Dr Kerry Mann School of Allied Health, Exercise & Sports Sciences Charles Sturt University Panorama Avenue Bathurst NSW 2795 Australia FAX +61 2 6338 4065 Phone +61 2 6338 4579 E-mail kmann@csu.edu.au
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
performing the novel tasks within the MCS for the first time, raters showed improved error detection on repeated viewing of the same movement.
Level of Evidence Cohort study
INTRODUCTION Due to substantial financial and social benefits in reducing injury prevalence, simple and accessible movement competency screens (MCSs) are popular among the sporting community.1 The primary aim of most screens quantifying the movement competency of athletes is to identify movement limitations that may provide indicators of injury risk.1 Early identification of risk2 may in turn allow implementation of training programs to lower injury rates among youth sporting populations.3 However, successful implementation of MCS protocols within sporting communities require them to be simple to implement, validated, reliable, cost-effective, and relevant to sport-specific injuries. Since MCSs requires the ability of raters to identify movement errors,4–7 an essential requirement is high interand intra-rater reliability.8 These factors are critical for movement screening as a result of the observational variance that can occur with subjective rating.9 Methodological limitations have cast doubt on studies that demonstrated good MCS reliability,10,11 because many of these studies11–13 have employed intra-class correlation coefficients (ICCs) to assess reliability. This statistical procedure should be applied only to continuous scalar data, not ordinal data14 such as that reported in many MCSs. A more appropriate statistical method for assessing reliability in ordinal data is the kappa score, which removes ‘chance agreement’ from the analysis.14 Although some authors have adopted the use of the kappa score to determine reliability,10,15,16 these studies have claimed high reliability despite reporting low kappa scores [e.g. inline lunge k=0.45,15 rotary stability final score k=0.43,10 hurdle step total score k=0.31].16 The way raters view the MCS also might influence the tool’s reliability, yet this appears not to have been investigated to date. Many sporting teams and clinicians have adopted simple, real-time, single-viewing and manual grading methods.4–6 However, it may be difficult to manually rate multiple error cues that occur simultaneously in real-time. While rater reliability has been widely studied, an additional consideration is the effect of familiarization of both athlete and rater. When an athlete firstly performs a MCS, they may never have performed some of the movements, while similarly, a novice rater may have no experience in rating them. Hence, familiarization effects may be present, but it is currently unknown whether athletes or raters require familiarization prior to MCS performance. This study aimed to: (i) determine the inter- and intrarater reliability of a sport specific field-based MCS in novice and expert raters using different viewing methods (single and multiple views); and (ii) ascertain whether there were familiarization effects from repeated exposure for either raters or participants. It was hypothesised that the MCS would display high inter- and intra-rater reliability for both novice and expert raters; the MCS score would change with
repeated exposure of athletes and raters due to familiarization effects; and viewing the performance of the movement multiple times while focussing on different error criteria each time would increase reliability.
METHODS SUBJECTS
Fifty-one pre-elite youth athletes who had never performed a MCS were recruited from a Regional Academy of Sport in rural Australia. Informed consent was obtained from all participants and their guardians/parents prior to data collection and all methods were approved by the Charles Sturt University Human Research Ethics Committee. EXPERIMENTAL APPROACH TO THE PROBLEM
Athletes performed a MCS on three separate occasions, with a minimal four-week wash out between testing sessions. Performances of each movement screening were recorded, then viewed and rated three times each in randomized order by 12 raters (3 expert, 9 novice), using a three-point scale. Both inter- and intra-rater reliability were calculated using; types of raters (novice and expert) and viewing type (single and multiple views). Each group of raters (Figure 1) was limited to a total of three raters, as increasing the number beyond this sample size is not suggested to affect statistical power.14 PROCEDURES
Each athlete performed a MCS comprising nine dynamic movements on three separate occasions (data trial 1, 2, 3), with a minimum four-week washout period between trials. Of the 51 athletes initially screened, 43 completed two sessions and 37 completed all three screening trials; non-participation was due to absence from training. The dynamic movements included within the screen were amended from previous screening methodologies and literature to include: Tuck Jump,6 Overhead Squat,4 Single Leg Squat (left and right),17 Dip Test (left and right),17 Forward Lunge (left and right)18 and Prone Hold19 (See Supplementary Material). Performance of each movement by each participant was videotaped in the sagittal and frontal planes at 240 Hz (ZR-200, Casio Computer Co., Ltd, Tokyo, Japan). Twelve individuals (n = 3 expert, n = 9 novice) rated the performance of the 51 athletes using the videos. Raters were divided into four groups based on three variables (Figure 1). The first variable was rater experience (expert or novice). An expert (E) rater was defined as an exercise and sport science professional with a minimum of one year of experience completing greater than 150 movement screens, while a novice (N) rater was defined as an individual with less than one year experience in screening. The second variable was method of viewing (single or multiple). A single
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Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
Figure 1. Raters divided into groups based on novice/expert status, MCS viewing method and video data viewed.
(Single) viewing involved the rater watching the sagittal and frontal plane videos of a movement task once, and assessing all the criteria during that viewing. A multiple (Multiple) viewing involved the rater watching the sagittal and frontal plane videos of a movement and assessing two criteria, then re-watching the videos and assessing two different criteria, and repeating this until all criteria were assessed. The third variable was the athlete trial data viewed, either data trial 1 viewed three times in separate rating sessions, or data trials 1, 2 and 3, each viewed once in separate rating sessions. Four rating groups were formed based on these three variables (Figure 1). Novice (n=3) and expert raters (n=3) undertook single video viewings of data trial 1 only, in three separate sessions. Different novices (n = 3) undertook single video viewings, in separate sessions, from data trials 1, 2 and 3. Different novices (n=3) undertook multiple video viewings from data trial 1 only, in three separate sessions. Novices and experts were compared to determine the effect of rating experience on detection of movement errors and reliability. MCS scores for data trials 1, 2 and 3 were compared to determine whether a familiarization effect was evident for athletes performing the movement tasks over repeated attempts. Three ratings of the video from trial 1 were carried out (in separate sessions) to determine whether a familiarization effect (increased detection of errors) was evident for the raters assessing the same movements over repeated sessions and to assess the reliability of their ratings. Single and multiple viewings of movement videos were compared to determine whether reliability was altered by simplifying the rater’s task through reducing the number of criteria assessed on each viewing session. Each rater categorized each movement task by identifying the presence of errors and counting them to yield a score of 1, 2 or 3 (1 = 3+ errors; 2 = 1-2 errors; 3 = no errors), a zero for pain is typically applied however was not applicable in this study. These individual MCS scores were then summed to give a composite score for all nine movements (maximum 27).
STATISTICAL ANALYSES
A series of repeated measures analyses of variance (ANOVAs) were conducted to determine significant differences (p<0.05) in total movement composite scores across repeated screenings by raters and repeated performances by athletes, i.e. to establish whether there was a familiarization effect for raters or athletes, respectively. Percentage agreement, kappa and intra-class correlation coefficients (ICCs) were calculated for ratings of each of the nine movements to determine intra- and inter-rater reliability as a pairwise comparison between each rater and analysis method. Kappa was defined as slight (0.00-0.20), fair (0.21-0.40), moderate (0.41-0.60), substantial (0.61-0.80) and almost perfect (0.81-1.00), with a negative Kappa representing less agreement than expected with chance.20 Percentage agreement was calculated as the proportion of occasions on which both raters agreed (i.e. the sum of the occasions the raters agreed divided by the total number of occasions), expressed as a percentage.21 To define percentage agreement, the following categories were used: poor (<50%), moderate (51-79%) and excellent (≥80%).20 Pearson’s ICC (2,1) was used to indicate the relationship between scalar data22 and defined as poor (<0.40), fair/good (0.40-0.75) and excellent (>0.75).23 Statistical procedures assessing MCS reliability often inappropriately employ ICCs to determine the reliability of ordinal (categorical) data.11,12 This is an incorrect application of ICCs, which are appropriate only for scalar data.14 The present study employed ICCs to assess the reliability of the MCS composite score, a scalar measure (as seen in Tables 1-3), however, ICCs were also presented for individual movement tasks in the MCS, only for comparison with previous research. The reliability of ordinal scores for individual movements of the MCS was assessed using both kappa scores to assess “true” agreement14 and percentage agreement.24 The measures for the nine movements were compared across sessions via t-tests to assess intra- and inter-rater reliability. Repeated measure ANOVAs and t-tests
International Journal of Sports Physical Therapy
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
Figure 2. Novice versus expert MCS score pattern across three viewing sessions. Vertical bars denote standard errors.
were performed in Statistica (v13.6, StatSoft Inc., Tulsa, OK, USA) and statistical analyses of reliability were performed using SPSS statistical package (Version 17.0.1, SPSS Inc, Chicago, IL).
RESULTS ATHLETE FAMILIARIZATION
The MCS composite scores achieved by athletes (15.0±1.6 years; n=33 athletics, n=10 BMX and n=8 surfing) for their three performance trials were analyzed separately for novices and experts because of incomplete data for one expert rater. MCS composite scores assigned by novices showed significant differences across performance trials (F2,72 = 10.89, p<0.001, η2=0.23) and between individual raters (F2,72 = 184.55, p<0.001, η2=0.84). Similarly, composite scores assigned by experts showed significant differences across trials (F2,68 = 10.18, p<0.001, η2=0.23) and between raters (F1,34 = 475.32, p<0.001, η2=0.93). Post hoc analyses for novice and expert raters revealed no clear pattern in the direction of movement competency scores across trials. INFLUENCE OF RATING EXPERIENCE
Comparison of the MCS composite scores assigned by novice and expert raters during three viewing sessions (1, 2 and 3) of the athletes Trial 1 movement performance showed novices assigned higher MSC scores than experts (F1,44 = 170.4, p<0.001, η2=0.79) (Figure 2). The mean score across all sessions and raters was 14.9 for novices and 12.8
for experts, suggesting expert raters detected more errors in athlete performances. As seen in Figure 2, the pattern of MCS scores across the three viewing sessions also differed between the rater groups, as borne out by a significant interaction between groups and sessions (F2,88 = 4.9, p<0.01, η2=0.10). Post hoc tests showed in novices, only session 1v3 scores were significantly different (15.4 vs 14.5; p=0.007), with no significant change for session 1v2 (p=0.24) or session 2v3 (p=0.74) scores. In experts, the only significant change was session 1v2 (13.7 vs 12.1; p<0.001), with session 2v3 not being different (p=0.51). INTRA-RATER RELIABILITY
- NOVICES
The novice intra-rater reliability between session 1 and 2 in the single view of the performance of the movements in Trial 1 (Table 1, left half) was shown to have fair kappa scores across all movements, except for a slight score in the tuck jump (0.18) and moderate score in the right lunge (0.43). Between session 2 and 3, there was a general increase in kappa scores compared to session 1v2 (p<0.01), with an improvement to moderate in the overhead squat (0.33 to 0.59), left lunge (0.26 to 0.52) and prone hold (0.32 to 0.45). Moderate percentage agreement was observed for all movements between session 1 and 2, with the right single leg squat scoring excellent (80%). Again, there was a general increase in scores between session 2 and 3 compared to session 1v2 (p<0.0001), with the category changing to excellent for the overhead squat (81%) and left single leg squat (83%). In contrast, the ICCs for the MCS composite score indicated excellent reliability for both sessions 1v2 (0.85) and 2v3 (0.89).
International Journal of Sports Physical Therapy
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
Table 1. Intra-rater Reliability of Trial 1 – Novice Raters. Movement
Single View Rating session 1v2 ICC
Multiple View Rating session 2v3
Rating session 1v2
Rating session 2v3
k
%
ICC
k
%
ICC
k
%
ICC
k
%
Tuck Jump
0.48
0.18
67
0.40
0.22
78
0.41
0.24
61
0.51
0.33
66
Overhead Squat
0.71
0.33
73
0.80
0.59
81
0.72
0.45
71
0.66
0.37
68
Single leg squat left
0.29
0.22
77
0.70
0.27
83
0.55
0.38
77
0.48
0.39
82
Single leg squat right
0.27
0.25
80
0.78
0.29
83
0.52
0.37
78
0.46
0.36
80
Dip test left
0.50
0.30
62
0.65
0.39
68
0.44
0.23
64
0.52
0.25
62
Dip test right
0.59
0.33
63
0.63
0.39
67
0.62
0.36
69
0.53
0.31
64
Lunge left
0.54
0.26
73
0.73
0.52
78
0.72
0.48
76
0.65
0.44
73
Lunge right
0.58
0.43
76
0.70
0.51
79
0.74
0.51
79
0.71
0.49
76
Prone hold
0.57
0.32
52
0.80
0.45
65
0.83
0.45
63
0.77
0.48
64
Total/Mean(±SD) Score
0.85
0.29 (0.07)
69 (9)
0.89
*0.40 (0.13)
*76 (7)
0.95
0.39 (0.10)
71 (7)
0.88
0.38 (0.08)
71 (7)
*p<0.01 compared with session 1v2.
International Journal of Sports Physical Therapy
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
Table 2. Inter-rater Reliability of Trial 1 - Novice Raters. Movement
Single View Rating session 1
Multiple View
Rating session 2
Rating session 3
Rating session 1
Rating session 2
Rating session 3
ICC
k
%
ICC
k
%
ICC
k
%
ICC
k
%
ICC
k
%
ICC
k
%
Tuck Jump
0.50
0.28
56
0.29
0.16
45
0.39
0.12
49
0.30
0.11
49
0.27
0.22
59
0.19
0.09
47
Overhead Squat
0.65
0.38
64
0.56
0.34
59
0.60
0.31
61
0.67
0.38
65
0.61
0.29
59
0.42
0.10
45
Single leg squat left
0.30
0.13
60
0.06
0.08
63
0.12
0.06
72
0.37
0.18
62
0.60
0.43
76
0.07
0.05
71
Single leg squat right
0.32
0.09
61
0.08
0.14
65
0.17
0.32
71
0.37
0.29
63
0.52
0.25
70
0.19
0.13
68
Dip test left
0.33
0.03
40
0.34
0.05
33
0.32
0.08
40
0.43
0.08
50
0.44
0.14
61
0.38
-0.04
36
Dip test right
0.35
0.07
44
0.50
0.11
41
0.44
0.16
49
0.45
0.09
49
0.59
0.24
62
0.28
-0.03
45
Lunge left
0.16
0.08
62
0.30
0.03
58
0.28
0.11
52
0.47
0.16
53
0.55
0.21
63
0.09
0.04
45
Lunge right
0.30
0.20
65
0.51
0.22
68
0.25
0.07
51
0.46
0.16
64
0.48
0.14
63
0.19
0.06
48
Prone hold
0.12
0.06
17
0.39
0.08
21
0.50
0.19
37
0.70
0.19
40
0.60
0.25
45
0.53
0.26
47
Total/ Mean (±SD) Score
0.75
0.15 (0.12)
52 (16)
0.85
0.13 (0.10)
50 (16)
0.73
0.16 (0.10)
54 (12)
0.84
0.18 (0.10)
55 (9)
0.91
0.24 (0.09)
62 (8)
0.70
*0.07 (0.09)
*50 (11)
*p<0.02 compared with session 2.
International Journal of Sports Physical Therapy
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
Table 3. Intra- and Inter-rater Reliability of Trial 1 - Expert Raters. *p<0.02 compared with session 1v2. Movement
Intra-rater Rating session 1v2
Inter-rater Rating session 2v3
Rating session 1
Rating session 2
Rating session 3
ICC
k
%
ICC
k
%
ICC
k
%
ICC
k
%
ICC
k
%
Tuck Jump
0.43
0.41
77
0.34
0.22
77
0.26
0.18
63
0.48
0.36
72
0.28
0.20
71
Overhead Squat
0.70
0.58
78
0.61
0.45
82
0.65
0.32
67
0.58
0.04
73
0.69
0.43
73
Single leg squat left
0.15
0.49
85
0.03
0.06
83
0.42
0.24
81
0.29
0.20
89
0.57
0.29
87
Single leg squat right
0.17
0.46
85
0.09
0.03
87
0.34
0.17
80
0.15
0.30
93
0.59
0.31
87
Dip test left
0.32
0.04
53
0.43
0.22
55
0.33
0.07
39
0.51
0.39
70
0.37
0.24
55
Dip test right
0.30
0.25
43
0.49
0.17
58
0.26
0.06
39
0.39
0.26
66
0.61
0.35
62
Lunge left
0.23
0.07
55
0.57
0.35
63
0.10
0.07
36
0.56
0.35
65
0.54
0.33
64
Lunge right
0.34
-0.10
58
0.53
0.28
68
0.19
0.05
35
0.39
0.25
62
0.52
0.31
63
Prone hold
0.46
0.24
45
0.50
0.23
57
0.25
-0.01
24
0.03
0.10
31
0.39
0.17
30
0.81
0.27 (0.23)
64 (17)
0.85
0.22 (0.13)
*70 (12)
0.71
0.13 (0.11)
52 (21)
0.88
0.25 (0.12)
##69
0.85
#0.29
##66
Total/Mean(±SD) Score
#p<0.02 compared with session 1, ##p<0.001 compared with session 1.
International Journal of Sports Physical Therapy
(18)
(0.08)
(17)
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
Multiple viewings of videos of the movements in trial 1 did not improve the intra-rater reliability of novices (Table 1, right half), either for kappa scores (p=0.41) or percentage agreement (p=0.62). Moreover, unlike the single view, there was no increase in kappa scores (p=0.99) or percentage agreement (p=0.99) for session 2v3 compared with session 1v2. As with the single view data, the reliability of the MCS composite score again indicated excellent reliability, with ICCs of 0.95 and 0.88 for session 1v2 and session 2v3 respectively. INTER-RATER RELIABILITY
- NOVICES
In viewing sessions 1, 2 and 3 of Trial 1 (Table 2, left half), the novice inter-rater reliability was poor, with kappa scores varying from slight to fair (0.03 – 0.38) and a similar pattern of poor to moderate (17% – 72%) percentage agreement across all movements. There were no significant changes in kappa (p=0.78) or percentage agreement (p=0.58) across sessions. ICCs for the MCS composite score, however, indicated excellent reliability for session 2 (0.85) with fair/good reliability in sessions 1 (0.75) and 3 (0.73). Multiple viewings of videos did not improve inter-rater reliability in novice raters (Table 2, right half). Kappa scores were slight to fair (0 - 0.38) throughout, with a moderate score, for the session 2 left single leg squat (0.43). Indeed, the reliability decreased significantly for session 3 compared to sessions 1 (p<0.02) and 2 (p<0.001). The percentage agreement scores were poor to moderate (40% - 76%) throughout, and decreased significantly in session 3 compared to session 2 (p<0.02). Intra-class correlations of MCS composite scores indicated excellent reliability in session 1 (0.84) and 2 (0.91), with fair/good reliability in session 3 (0.70). INTRA-RATER RELIABILITY
- EXPERTS
The expert intra-rater reliability (Table 3, left half), when comparing session 1v2 and session 2v3 in single views of the performance of the movements in Trial 1, varied between slight, fair or moderate kappa scores, with no significant change from sessions 1v2 to 2v3 (p=0.63). Percentage agreement scores were more consistent, with most MCS scores in the moderate range but excellent scores for single leg squats, and a significant increase from session 1v2 to session 2v3 (p<0.02). The ICCs for MCS composite scores again had excellent reliability (0.81 and 0.85). These intrarater reliability scores were not significantly different (kappa: p=0.07; percentage agreement: p=0.35) from those for the novice raters reported in Table 1 (left half). INTER-RATER RELIABILITY
- EXPERTS
The expert inter-rater reliability (Table 3, right half), in viewing sessions 1, 2 and 3 of Trial 1, varied from slight to fair kappa scores, and one moderate score for the overhead squat in session 3. Scores increased from session 1 to sessions 2 and 3, with session 3 improvement being significant (p<0.02). Percentage agreement was poor to moderate, except for the single leg squats which all had excellent
agreement. Here there was significant improvement from session 1 to sessions 2 and 3 (p<0.02). The ICCs for the MCS composite score displayed fair/good reliability for session 1 (0.71) and excellent reliability in sessions 2 (0.88) and 3 (0.85). These inter-rater reliability scores for sessions 2 and 3 were higher than those for novice raters reported in Table 2 (left half) but the difference was significant only for kappa (p<0.05) and not percentage agreement (p=0.20).
DISCUSSION Strategies to reduce prevalence of sporting musculoskeletal injuries by identifying and improving movement competency of athletes have considerable appeal due to the detrimental social and economic effects of sporting injuries.25 For such strategies to be successful, the identification of movement competency must be reliable,7 but also less costly or time-consuming than laboratory processes.26 This study highlights various factors that must be taken into account by coaches and clinicians when screening athletes. The composite score, obtained from the sum of scores for the nine movements, whether rated by novices or experts, showed no evidence of improvement across their three performance trials of the MCS. This finding indicates, contrary to previous research by Hansen et al.,27 that the athletes did not display a familiarization effect when performing a novel task over repeated attempts. The between-study difference here is likely due to differences between the tasks performed. However, given significant differences in composite score were observed between the novice and expert raters, it is suggested that a single rater should conduct repeated measures of the MCS to ensure reliable representation of the athlete’s movement competency. Analysis of assigned MCS composite score did indicate that novice raters tend to score athletes higher than expert raters, suggesting expert raters might be better able to identify errors within an athlete’s movements. Furthermore, novice and expert raters showed evidence of a small decrease in assigned MCS scores across repeated viewing of the same movements, suggesting more accurate detection of movement errors in both groups on repeated viewings. The results for both intra- and inter-rater reliability in this study showed a marked divergence between the consistently high ICCs between the composite scores and the highly variable kappa and percentage agreement scores for individual movements. Intra-rater reliability of composite scores was consistently excellent, with no effects of multiple or repeated viewings, and no differences between novices and experts. Similarly, the inter-rater reliability of composite scores was good to excellent, with no effects of multiple or repeated viewings, and no differences evident between novices and experts. These results for the reliability of the composite score in both experience conditions (i.e. novice and expert) highlight that this MCS (when considering its overall score) may be reliably replicated by both novices and experts in real-time, field-based environments in which the MCS would be typically employed. In contrast, for the individual movements, the intra-rater reliability was only fair to moderate, showed no difference between novices and experts, showed no improvement with multiple viewings of the same video sessions (task simplifi-
International Journal of Sports Physical Therapy
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
Table 4. Kappa Analysis: Crosstabulation of two raters’ scores for a left single leg squat. Rater 1
Rater 2
Movement Screen Score
1.00
2.00
(n)
1.00
48
1
49
2
0
2
50
1
51
2.00
(n)
cation), but did increase with repeated viewings of the same movements (repeat assessments). The inter-rater reliability likewise was poor to moderate for the individual movements and showed no improvement with task simplification of multiple viewings of the same video sessions. It also increased with repeated viewings of the same movements, but only in experts, and showed some evidence of higher reliability in experts than novices. These findings, that novice and expert raters (Tables 1-3) were not reliable when assessing the individual tasks in the MCS in isolation, was postulated to be due to the complex nature of evaluating multiple features at once, thought to interfere with information processing.28 Yet this study showed that simplification of the task, by providing multiple viewings and reducing the number of features evaluated at each viewing, did not improve either intra- or inter-rater reliability. Rather, it appears that becoming familiar with the movements over repeated exposure and the errors that can present is the best strategy for ensuring reliability. This was true even for the experts. It is possible that both the poor reliability for individual tasks in the MCS, and the lack of effect from reducing the complexity of assessment for raters, is confounded by the small scale on which individual tasks were scored.29 Like the Functional Movement Screen™ (FMS™),4,5 this study’s individual movement scoring system required the movement errors observed to be counted and placed into one of only three categories. Using this three-category scoring system has been suggested to reduce reliability, validity, and discrimination compared to systems with 7 to 10 categories.29 More categories could be employed by simply counting the errors instead.30 In contrast to the ratings of individual movements, the composite score displayed excellent reliability, as indicated by the ICCs for composite scores in both novice and expert raters. This discrepancy in reliability between individual movements and the composite score is likely due to the larger scale of the composite (0-27) compared to that (0-3) for individual movements.29 The reduction in statistical power due to the low number of categories was likely to be further confounded by the skewed distribution of the data for each individual movement task.14 Within this study most athletes displayed numerous movement errors, leading to ratings of category 1 or 2 for most movements. This skewed data distribution reflects the overall poor movement competency of this adolescent athlete cohort, evident in the poor MCS composite scores (mean ± SD for all raters; Session 1, 16/27 ± 4.3, Session 2, 15/27 ± 4.4, Session 3, 15/27 ± 4.1). This data distribution contributed to poor kappa scores, due to the inability to differentiate between random and systematic
agreements.14 For example, as illustrated in Table 4, the single leg squat displayed unequal data distribution, contributing to its low kappa score despite high percentage agreement (Table 2, left side; Table 3, right side). Both raters gave a categorical score of 1 for 48 athletes and only scored a discrepancy for three athletes. It is therefore critical that future research ensure normal distribution of data when assessing the reliability of a MCS. Several potential limitations of this study exist and must be considered when interpreting the results presented. The principal investigator ensured that all raters were familiar with the movement screening criteria, but because familiarization was an aspect to be analyzed for both raters and athletes through the movement screening process, no formal training was undertaken. It is possible that specific training for both novice and expert raters may have increased the reliability of individual tasks within the movement screen. Volunteer raters had many tasks and athletes to rate that could have led to reduced attention during some rating tasks due to the tedious nature of sessions. Difficulty in recruiting experts for this study led to expert raters rating only a single view session of data trial 1 over 3 sessions. Raters were defined based on their movement screening experience, not on their industry experience, which was not recorded within this study. The movement screening was recorded on two standard video cameras (frontal and sagittal views), meaning it was only possible to watch one view at a time, thereby increasing the time required to carry out each MCS. Since each rater was required to screen each athlete three times, depending on the viewing method, raters took approximately 20-40 hours to screen all participants. Watching the videos of the participants performing the movements may not reflect the real-time field-based assessment typically performed in real-world application. This study design enabled all raters to view the same data to determine rater familiarization and rater reliability of individual movements, which may have caused some confounding between the results for these two outcomes. A lack of evenly distributed individual movement scores within this study may have contributed to the lack of reliability assessed, due to an inability to distinguish between random and systematic agreements in statistical procedures.14 This study only investigated sub-elite youth athletes and thus the findings of this study cannot be extrapolated to various skill levels, age, as well as sports to see if results can be replicated and generalised to the different population cohorts.
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Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
CONCLUSION Overall results of the current study suggest that the MCS composite score can be reliably used to determine movement competency, but the individual movement scores should not be relied on. It is also recommended that a single rater should conduct any repeated measures of the MCS and the scaling range for individual movement screening scores be increased in future research to obtain more reliable individual movement scores. A familiarization session with MCS movements is not required for athletes when using the MCS composite score. It was identified that expert raters detected more errors than novices overall, however both novice and expert raters improved their detection of movement errors with repeated viewings of the same movement. Therefore, it is recommended that raters familiarize themselves with the MCS.
CONFLICTS OF INTEREST
The authors report no conflicts of interest. ACKNOWLEDGEMENTS
The authors gratefully acknowledge the Hunter Academy of Sport for providing access to the participants for this study and the contribution of the raters who generously gave their time to complete the movement screening. Submitted: November 11, 2021 CDT, Accepted: March 24, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Movement Competency Screens Can Be Reliable In Clinical Practice By A Single Rater Using The Composite Score
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International Journal of Sports Physical Therapy
Olson ML, Schindler G. Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players. IJSPT. 2022;17(4):605-612.
Original Research
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players a
Morgan L. Olson, PT, DPT 1 , Gary Schindler, PT, PhD 1 1
Department of Sports Medicine, University of North Dakota
Keywords: adductor, groin strain, weakness, ice hockey https://doi.org/10.26603/001c.34444
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Adductor strains are the most common non-contact musculoskeletal injury sustained in ice hockey. Systematic reviews have determined higher level of play and lower hip adduction to abduction strength ratios to be associated with an increased risk of adductor strain across multiple sports. Limited research exists regarding hip adduction and abduction strength profiles across various levels of ice hockey players.
Purpose To compare isometric hip adduction and abduction strength profiles among bantam, high school, tier one juniors, and NCAA Division I collegiate ice hockey players. A secondary purpose was to identify whether differences in strength profiles between dominant and non-dominant limbs exist.
Study Design Cross-sectional cohort study.
Methods A questionnaire of demographic data, hockey, and injury specific information was completed by all subjects. The mean of three reps of maximal hip isometric adduction and abduction strengths were quantified using a handheld dynamometer with external belt-fixation. Ratios of hip adduction-to-abduction strength were calculated and normalized for body weight.
Results A total of 87 uninjured skaters were included in this study with a mean age of 17 years. Mean hip adductor-to-abductor ratios for Bantam hockey players were 121% followed by collegiate (115%), Juniors (111%), and high school (109%) hockey players. No statistically significant differences were found between peak hip adduction and abduction isometric strength and playing level. In addition, there was no difference between unilateral hip strength ratios and shooting hand or leg dominance. While 34.5% of subjects reported a history of adductor injury, no significant differences existed regarding strength ratios during bilateral comparison or when compared to their team norms. Three subjects were found to have unilateral ratios of less than 80%, while two subjects demonstrated bilateral ratios of less than 80%.
Conclusions Symmetry is illustrated between dominant and non-dominant legs in ice hockey players with and without a history of adductor injury. Results align well with previously
a
Corresponding author: Morgan Olson 1129 43rd Ave W West Fargo, ND 58078 Morgan.lee.olson@gmail.com
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players
established cross-sectional data from Australian football, with ratios of 103% in high school players, 107% in semi-professional players, and 113% in collegiate players.
Level of Evidence Level 3
INTRODUCTION Hip adductor injuries account for 101 - 43%2 of all non-contact injuries among professional ice hockey players, with 23.5% of strains being recurrent injuries.3 A systematic review discovered that higher level of play and lower hip adduction and abduction strength to be associated with increased risk of adductor injuries across several sports.4 Prior research has established that ice hockey players create robust force during the glide and recovery phase of the skating motion and are at an elevated risk for non-contact musculoskeletal injuries.5 During the ice skating motion, the hip flexors and adductors are the primary stabilizers of the hip and assist with limb deceleration.6 In addition to increased eccentric forces, strength imbalances between the hip extensors and abductors (prime movers) and the hip flexors and adductors (stabilizers) can also lead to an increased risk of injury. The link between hip adductor weakness and subsequent groin injuries has been demonstrated across several sports such as rugby7 and soccer.8 Strength imbalances may present as side-to-side differences predisposing an athlete to injury, often identified during strength screenings.9 Tyler et al10 found pre-season hip adduction strength in professional hockey players to be 18% lower in those who subsequently sustained an adductor strain. In subjects without a history of adductor strains, their adduction strength was 95% of their abduction strength; compared to 78% of their abduction strength in subjects with a history of adductor injuries. The authors concluded a hip adductor-toabductor strength ratio of less than 80% was highly predictive of future injury, leading to a 17 times greater likelihood of subsequent adductor injuries in professional hockey players.10 Worner et al utilized the five-second squeeze test in 333 professional and semi-professional ice hockey players in Sweden to assess self-reported function and muscle strength, as well as to guide rehabilitative management. A significant correlation was found between hip muscle strength and the ability to discriminate between the “traffic light levels” of discomfort (Numeric Rating Scale 0-2=green, 3-5=yellow, 6-10=red). Subjects who reported discomfort in the “yellow” or “red” levels had reduced adduction and abduction strength compared to players with a “green” light.11 They advocated for frequent and routine squeeze testing to allow for early identification of groin and adductor related injuries, as well as assist with progressing the rehabilitative program. A similarly designed cross-sectional hip-strength profile study was performed in Australian footballers focused on elite, sub-elite, and amateur players. Prendergast et al7 utilized belt-fixated hand-held dynamometry (HHD) to study hip strength trends across various levels of play in Australian footballers. The authors concluded that hand-held dynamometry with external-fixation has moderate to excel-
lent intra-examiner reliability for hip muscle testing (ICC 2.1 from 0.76 to 0.95)12 as well as high correlation with isokinetic dynamometry for hip strength (r=0.60 to 0.90).13 However, no significant differences (p> 0.05) in isometric hip adduction and abduction strength or resultant strength ratios were found, regardless of leg dominance or playing level. In addition, symmetry was identified between preferred and non-preferred kicking legs at baseline.7 Tyler et al10 proposed that obtaining an adduction-toabduction strength ratio of 90% to 100% and an adduction strength equal to that of the uninjured side were suitable clinical characteristics for return to ice hockey following a hip adductor strain in professionals. Belt-fixated handheld dynamometry as described below is a clinically relevant method to assess strength at the rink-side with minimal time and equipment constraints for sports medicine staff. Therefore, the primary purpose of this study was to compare isometric hip adduction and abduction strength profiles among bantam, high school, tier one juniors, and NCAA Division I collegiate ice hockey players. A secondary purpose was to identify whether differences in strength profiles between dominant and non-dominant limbs exist.
METHODS SUBJECTS
Male ice hockey players were recruited from five separate teams representing progressively higher levels of play for a cross-sectional population. Researchers contacted coaching staff from each respective team and utilized this contact, along with parent consent for recruitment. Subjects were included if they were males ages 13 to 23 years old, had ice hockey experience of at least five years, and were currently participating in hockey activities of at least one training session and game per week during the season. Subjects were excluded if they had sustained a lower extremity injury that caused them to miss one or more games in the three months prior to testing, experienced pain during testing, or were unable to provide a maximal voluntary isometric contraction (MVIC). Ethical approval was obtained from the University Institutional Review Board, University Athletics Ethics Committee, and Public Schools Ethics Committee. All participants provided a signed informed consent form prior to participation. STUDY DESIGN
Each subject was asked to complete a voluntary questionnaire prior to testing which included their age, weight, height, competitive team level, dominant leg, hockey position, side of the ice for their position/face-offs, hours of skating during in-season and off-season, injury history, and history of adductor strains. Assessments were completed during the 2018 regular season training period. All testing
International Journal of Sports Physical Therapy
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players
occurred in the first half of the competitive season during November and December of 2018. Testing was completed independently of scheduled training sessions due to varied intensities, duration, and frequency of practices across teams. Isometric hip adduction and abduction strength was measured for both the dominant and non-dominant legs. The adduction-to-abduction ratio was calculated by dividing the mean adduction score by the mean abduction score. Data was normalized to body mass. Testing order was randomized between players via coin toss for adduction or abduction and leg dominance. Hip adduction and abduction isometric strength was measured using a hand-held dynamometer with external belt-fixation (Figures 1, 2). The HHD utilized was the MicroFET 2 © (Hoggan Scientific, LLC, Salt Lake City, UT.). Batteries were changed and both units were calibrated prior to each session of testing to ensure accurate data collection. Testing set-up also included the use of portable treatment tables, fixation-belts, and two glass suction cup handles per table. Previous studies have demonstrated HHD with external belt-fixation has excellent inter-tester reliability when assessing hip strength in strong individuals.12 Belt-fixation limits the bias of tester strength, particularly in exceptionally strong athletes such as those in this study.12 The primary (M.O) and co-researcher (G.S) performed the strength assessments. While the inter-rater reliability of the testers was not performed, the assessors completed two familiarization sessions together totaling three hours to ensure they followed the same standardized protocol. Testers measured an equivalent number of players from each team, across all levels of play. A standardized procedure was utilized with random placement of subjects between the two testers to mitigate bias. The protocol utilized was modeled after that previously described by Thorborg et. al.12 Subjects were positioned in supine with the leg in neutral, which has been found to detect larger adductor impairments at 0 degrees compared to 45 degrees.14 A fixed belt was positioned holding the HHD 10 cm proximal to the apex of the lateral malleolus with the position marked bilaterally prior to the beginning of familiarization trials. A mark was placed to ensure appropriate set-up when transitioning between adduction & abduction trials bilaterally (Figure 1, 2). Submaximal familiarization trials were provided for both adduction and abduction testing positions to ensure the correct application of force through the HHD and gradually adding tension over the five second trial and test. Five efforts were completed for each muscle group testing position: two warm-up efforts at 50% and 75% of MVIC and three efforts at 100% MVIC. All contractions were held for five seconds, with a 30-second rest between each warm-up and testing trial to avoid fatigue. The mean of three trials was used for statistical analysis. The examiners used a standardized command for encouragement given to each participant of “3-2-1 and push, push, push, push, and relax.”8 STATISTICAL ANALYSIS
Data was analyzed using IMB SPSS Statistics version 25. All data were assessed for normality using the Shapiro-Wilk test and found to be normally distributed. Demographic in-
Figure 1. Testing set-up for hip adductor strength.
Figure 2. Testing set-up for hip abductor strength.
formation was calculated and presented as means and standard deviations. A series of one-way analysis of variance (ANOVA) were used to assess if there were any significant differences in demographics between playing levels. Post hoc Bonferroni adjustments were performed for any significant main effects between tests. Data was normalized for kg of bodyweight. A series of two-way and three-way ANCOVAs were conducted to determine the effect of playing level and limb dominance on peak hip isometric strength and hip strength ratios after controlling for age and team allotment.
RESULTS Eighty-seven male ice hockey players were included with a mean age of 17.6 ±2.54 years. Bantam players (n=17) were recruited from the local youth hockey association, comprising their highest level of bantam AA ice hockey players under age 14 players. High school varsity players (n=29) were recruited from two local high schools aged 15 to 18 years. Tier one junior players (n=22) were recruited from the
International Journal of Sports Physical Therapy
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players
Table 1. Descriptive data, presented as the mean ± standard deviation or the percentage where indicated. Descriptive
Bantams
High School
Semi-Professional
Collegiate
Age (years)
14.29 (± 0.685)
16.54 (±0.95)
18.36 (±0.95)
21.11 (±1.45)
Height (inches)
68.03 (±3.023)
71.36 (±1.97)
71.48 (±2.46)
72.26 (±2.21)
Weight (lbs)
148.48 (±20.67)
169.84 (±14.92)
182.90 (±19.41)
193.74 (±12.45)
BMI
22.46 (±1.99)
23.42 (± 1.63)
25.12 (±1.86)
26.09 (±1.46)
Preferred shooting hand (R/L)
35.30% / 64.70%
41.52% / 58.48%
31.82% / 68.18%
21.05% / 78.95%
Side of ice (R/L/Not specified)
17.65% / 23.53% / 58.82%
32.01% / 20.37% / 47.62%
31.82% / 40.91% / 27.27%
26.32% / 31.58% / 42.10%
Table 2. Force in lbs to kg of bodyweight between teams, presented as the mean ± standard deviation or the percentage where indicated. Descriptive
Bantams
High School
SemiProfessional
Collegiate
Mean L abduction force to kg bodyweight
0.4370 (±0.071)
0.4520 (±0.118)
0.4441 (±0.083)
0.4428 (±0.088)
Mean L adduction force to kg bodyweight
0.5064 (±0.100)
0.4718 (±0.159)
0.4682 (±0.089)
0.5125 (±0.112)
Mean R abduction force to kg bodyweight
0.4602 (±0.084)
0.4574 (±0.109)
0.4349 (±0.086)
0.4361 (±0.074)
Mean R adduction force to kg bodyweight
0.5408 (±0.111)
0.4895 (± 0.151)
0.4868 (±0.110)
0.5114 (±0.144)
state’s United States Hockey League (USHL) team consisting of premier skaters under the age of 20, no longer playing high school hockey and hoping to play collegiately. Finally, elite division I NCAA athletes (n=19) were recruited from the state’s university, competing in the National Collegiate Hockey Conference (NCHC) with multiple players having National Hockey League commitments. Players of all positions were included, consisting of nine goalies, 28 defensemen, 11 centers, and 38 forwards. Ninety-four percent of subjects reported being right leg dominant based on their preferred leg to kick a ball, while 32.2 % reported being right-handed shooters. 34.9% reported a history of previous hip adductor injury [F(1, 87)=2.295, p=.084, power=.560]. A significant difference was found between height of the bantam players compared to all other teams, with their height being significantly less. There was no significant difference in age, height, weight, or BMI among high school, semi-professional, or collegiate players. Of the 87 ice hockey players recruited for this study, no significant difference was found between playing levels for the ratio of hip adduction-to-abduction strength profiles. The isometric hip adduction and abduction strength of each playing level are represented below (Figures 3, 4, 5). Without adjustments, the ANOVA for peak hip adduction and abduction isometric strength demonstrated no significant interaction among playing levels when normed for bodyweight. No subjects were excluded from testing due to injury, illness, or pain with maximal voluntary contraction. (Table 1). Force in pounds per kilogram of bodyweight is shown in Table 2. No significant differences in hip strength ratios were found between dominant and non-dominant kicking legs
across all levels of play. Furthermore, no significant difference was found between unilateral mean adduction or abduction strength and shooting hand or leg dominance. In this sample, 52.9% of participants played one sport competitively (ice hockey), while 47.1% competed in at least one additional sport competitively during the year. No difference in injury risk existed between ice hockey specialized and multi-sport participants. Regarding injury, 39.1% reported a past history of lower extremity injury, excluding groin injury, however, 34.9% of participants reported a history of previous groin injury. Three subjects were identified as having a unilateral adductor-to-abductor ratio of less than 80%, while two additional subjects were found to have ratios below 80% bilaterally (Table 3). These seven limbs represent 5.7% of all participants and 4% of all limbs tested. Of those identified, three were members of high school teams, one was a member of the semi-professional team, and one was a member of the collegiate team. Those with left-sided adductor-to-abductor ratios of less than 80% (four subjects) reported being right leg dominant and shot left-handed, 75% of whom reported a history of prior adductor injury. In addition, both athletes who recorded strength ratios below 80% bilaterally reported a history of prior adductor injury.
DISCUSSION This is the first study to analyze hip adduction and abduction strength profiles across bantam, high school, tier one juniors, and collegiate American ice hockey players. The primary purpose of this study was to compare the hip strength ratios among a cross-sectional group of American
International Journal of Sports Physical Therapy
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players
Table 3. History of injury data in athletes identified as “at-risk” by percentage of adductor-to-abductor strength ratio. Ratio L add-toabd
Ratio R add-toabd
History of lower extremity injury
Type of injury
History of groin injury
Athlete 1
0.77
1.15
No
NA
No
Athlete 2
0.72
1.27
Yes
B hip labral tears
Yes
Athlete 3
0.65
0.79
Yes
Ankle sprain
Yes
Athlete 4
0.83
0.69
No
NA
No
Athlete 5
0.49
0.62
No
NA
Yes
Figure 3. Mean isometric adduction strength by team in lbs.
Figure 4. Mean isometric abduction strength by team in lbs.
ice hockey players. The secondary purpose was to assess effects of limb dominance, and determine if differences existed between the dominant and non-dominant limb hip strength ratios. The results demonstrated that there were no significant differences in hip adduction or abduction strength between dominant and non-dominant legs, shooting hands, or playing level in this sample when strength was normalized to bodyweight. This indicates the potential of assuming symmetry between dominant and non-dominant
legs when it comes to tracking a player’s post-injury returnto-play progression. Utilizing average force to bodyweight regardless of age (Table 2) makes assessing hockey specific strength feasible at the rink-side. These results are in contrast with findings by Thorborg et al.8 who demonstrated that the dominant leg was significantly stronger in elite soccer players, where unilateral actions are more prevalent. The findings may be attributed to the mechanical differences between soccer and hockey
International Journal of Sports Physical Therapy
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players
Table 4. Comparison to hip adduction-to-abduction ratios across sports. Professional Hockey10
Australian Football7
Soccer8
Youth
Current study (Ice Hockey) 1.21
High School
1.03
1.09
Semi-Professional
1.07
1.11
Collegiate
1.13
Proposed ratio for return to sport
0.90-1.00
1.05
1.15
1.07
Figure 5. Mean hip adduction-to-abduction ratios by team in lbs.
players as it relates to preferred kicking leg and functional strength requirements between sports. Additionally, Tyler et al.10 reported contrasting findings in hip adduction-to-abduction strength ratios when testing professional ice hockey players using pre-season breaktesting. The authors found pre-season adduction-to-abduction ratios to be 0.95 in uninjured players compared to 0.78 in players who went on to sustain an adductor strain. The collegiate subjects in the current study demonstrated inseason adduction-to-abduction strength ratios of 1.15 to 1.17. Differences in testing position between studies may contribute, as sidelying break tests of eccentric adductor strength were used in professional ice hockey. They also demonstrated lower unilateral hip strength ratios on the side that was subsequently injured. Similar findings between players experiencing groin pain and those without groin pain have been illustrated in soccer players, with those having groin pain being nearly 50% weaker than their non-painful counterparts.8 Studies in both soccer8 and rugby7 have demonstrated elite players as being significantly stronger than their lower-level counterparts, but this was not apparent in our sample when normed for bodyweight (Table 4). The findings of the current study demonstrated bilateral adductor symmetry, similar to those found in soccer players8 and rugby players.7 While this finding is less common across other sports, it may represent a more common phenomenon in sports with high components of lateral movement, performed bilaterally and repetitively like ice skating.
Previously, researchers have suggested that adductor and abductor strength ratios were lowest during the pre-season and increase throughout the season. These same authors proposed that soccer-specific strength likely deteriorates during the off-season and may place the athlete at an increased risk of injury when resuming sport specific activity.15 This study is limited by the smaller sample size from elite and bantam players. The results may not generalize to the public and athletes of all sports but do accurately reflect the captured hockey population.
CONCLUSION The results of this study indicate that there were no significant differences in isometric hip adduction or abduction strength ratios between dominant and non-dominant kicking legs in American hockey players across various levels of play. Across all playing levels, ice hockey athletes generate approximately 0.5 lbs/kg of bodyweight with their adductors and 0.45 lbs/kg of bodyweight with their abductors.
CONFLICTS OF INTEREST
The authors report no conflicts of interest or relevant financial disclosures.
International Journal of Sports Physical Therapy
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players
STATEMENT OF IRB/ETHICS COMMITTEE APPROVAL
ACKNOWLEDGEMENT
Ethical approval was obtained from the University of North Dakota Human Research Ethics Committee, University of North Dakota Athletics Ethics Committee, and Grand Forks Public Schools Ethics Committee.
The authors thank Renee Mabey for assistance with data analysis, Cathy Ziegler and Scott “Jake” Thompson for encouragement and assistance throughout the University of North Dakota Sports Physical Therapy Residency Program. Submitted: August 20, 2021 CDT, Accepted: February 18, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Hip Adduction and Abduction Strength Profiles Among Bantam, High School, Juniors, and Collegiate American Ice Hockey Players
REFERENCES 1. Lorentzon R, Wedrèn H, Pietilä T. Incidence, nature, and causes of ice hockey injuries: a three-year prospective study of a Swedish elite ice hockey team. Am J Sports Med. 1988;16(4):392-396. doi:10.1177/036 354658801600415 2. Mölsä J, Airaksinen O, Näsman O, Torstila I. Ice hockey injuries in Finland: a prospective epidemiologic study. Am J Sports Med. 1997;25(4):495-499. doi:10.1177/03635465970250041 2 3. Emery CA, Meeuwisse WH, Powell JW. Groin and abdominal strain injuries in the National Hockey League. Clin J Sport Med. 1999;9(3):151-156. doi:10.10 97/00042752-199907000-00006 4. Whittaker JL, Small C, Maffey L, Emery CA. Risk factors for groin injury in sport: an updated systematic review. Br J Sports Med. 2015;49(12):803-809. doi:10.1136/bjsports-2014-0942 87 5. Emery CA, Meeuwisse WH. Risk factors for groin injuries in hockey. Med Sci Sports Exer. 2001;33(9):1423-1433. doi:10.1097/00005768-200109 000-00002
9. Orchard J, Best TM, Verrall GM. Return to play following muscle strains. Clin J Sports Med. 2005;15(6):436-441. doi:10.1097/01.jsm.000018820 6.54984.65 10. Tyler TF, Nicholas SJ, Campbell RJ, McHugh MP. The association of hip strength and flexibility with the incidence of adductor muscle strains in professional ice hockey players. Am J Sports Med. 2001;29(2):124-128. doi:10.1177/03635465010290020 301 11. Wörner T, Thorborg K, Eek F. Five-second squeeze testing in 333 professional and semiprofessional male ice hockey players: how are hip and groin symptoms, strength, and sporting function related? Orthop J Sports Med. 2019;7(2). doi:10.1177/232596711982585 8 12. Thorborg K, Bandholm T, Hölmich P. Hip- and knee-strength assessments using a hand-held dynamometer with external belt-fixation are intertester reliable. Knee Surg Sports Traumatol Arthrosc. 2012;21(3):550-555. doi:10.1007/s00167-012-2115-2
6. Bracko MR. Biomechanics powers ice hockey performance. Sports Medicine. 2004;47-53.
13. Martins J, Rodrigues da Silva J, Rodrigues Barbosa da Silva M, Bevilaqua-Grossi D. Reliability and validity of the belt-stabilized handheld dynamometer in hip- and knee-strength tests. J Athl Train. 2017;52(9):809-819. doi:10.4085/1062-6050-52.6.04
7. Prendergast N, Hopper D, Finucane M, Grisbrook TL. Hip adduction and abduction strength profiles in elite, sub-elite and amateur Australian footballers. Med Sci Sports Exer. 2016;19(9):766-770. doi:10.1016/ j.jsams.2015.12.005
14. Malliaras P, Hogan A, Nawrocki A, Crossley K, Schache A. Hip flexibility and strength measures: reliability and association with athletic groin pain. Br J Sports Med. 2009;43(10):739-744. doi:10.1136/bjs m.2008.055749
8. Thorborg K, Serner A, Petersen J, Madsen TM, Magnusson P, Hölmich P. Hip adduction and abduction strength profiles in elite soccer players: implications for clinical evaluation of hip adductor muscle recovery after injury. Am J Sports Med. 2011;39(1):121-126. doi:10.1177/0363546510378081
15. Wollin M, et al. In-season monitoring of hip and groin strength, health and function in elite youth soccer: Implementing an early detection and management strategy over two consec.
International Journal of Sports Physical Therapy
Gasparin GB, Ribeiro-Alvares JBA, Baroni BM. Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength. IJSPT. 2022;17(4):613-621.
Original Research
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength Gabriela Bissani Gasparin 1, João Breno Araujo Ribeiro-Alvares 1, Bruno Manfredini Baroni 1 1
a
Universidade Federal de Ciências da Saúde de Porto Alegre
Keywords: muscle injury, prevention, rehabilitation, soccer https://doi.org/10.26603/001c.34417
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background The single leg bridge test (SLBT) has been introduced in the sports context as a way of estimating hamstring muscle capacity for prevention and rehabilitation of hamstring strain injuries.
Purpose The primary aim was to examine the association between SLBT scores with concentric and eccentric knee flexor peak torques. Secondarily, this study aimed examine the association of between-limb asymmetries provided by SLBT and isokinetic tests.
Study design Cross-sectional study.
Methods One hundred male soccer players (20±3 years) performed the SLBT and the knee flexion-extension isokinetic dynamometry evaluation (60°/s) billaterally during a single visit. SLBT score (i.e., number of repetitions until failure) and concentric and eccentric knee flexor peak torques (normalized per body mass) were considered for analysis. For both SLBT and isokinetic dynamometry, between-limb asymmetry was calculated as the percentage difference between the left limb and the right limb. Associations were assessed through Pearson’s correlation coefficient.
Results The mean SLBT score was 33.6±9.6 repetitions, concentric peak torque was 2.00±0.22 Nm/ kg, and eccentric peak torque was 2.79±0.44 Nm/kg. Between-limb asymmetry was 0.4±9.6%, 1.08±8.5%, and 1.64±14.61% in SLBT, concentric, and eccentric tests, respectively. There was a poor association of SLBT score with concentric (p<0.001, r=0.275) and eccentric (p=0.002, r=0.215) peak torques. The SLBT between-limb asymmetry was poorly associated with asymmetry found in concentric peak torque asymmetry (p=0.033, r=0.213) and was not associated with eccentric peak torque asymmetry (p=0.539, r=0.062).
Conclusion The SLBT should not be used as a clinical tool to assess the maximum strength of hamstring muscles.
a
Corresponding author: Bruno Manfredini Baroni Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA) Sarmento Leite St, 245 – zipcode 90050-170 Porto Alegre, Rio Grande do Sul, Brazil Phone/fax +55 51 3303-8876 Email: bmbaroni@yahoo.com.br.
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength
Level of Evidence Level 3 PARTICIPANTS
INTRODUCTION Hamstring strain injury (HSI) is one of the most common injuries in high-speed running-based sports.1 HSI results from a complex interaction web of modifiable and nonmodifiable factors,2 and low hamstring strength has been associated with increased risk of HSI.3–6 Muscle strengthening has also been a focus of HSI rehabilitation programs, while strength recovery has been used as a milestone during treatment progression and return to sport decisions.7–9 Moreover, similar strength levels between limbs (right vs. left, dominant vs. non-dominant, or injured vs. uninjured) have been believed to reduce the risk of injury,10 and measures of between-limb asymmetry have also been commonly used as a return to sport criterion following a HSI.11 Therefore, hamstring strength assessment plays a key role in both the prevention and rehabilitation of HSI. Isokinetic dynamometry is the gold standard method to assess muscular torque production as a descriptor of strength in humans, with peak torque being the most widely used outcome.12 However, the cost (around US$ 25,000), size, non-portability, and time-consuming protocols make this option not feasible for most clinicians. In the last decade, the single leg bridge test (SLBT) has emerged as a clinical assessment of the hamstring capacity.13 This test requires a single rater and a 60 cm high box. It may be performed at the edge of the field, as well as inside the physical therapy room, gym, locker room or other sports facility. The score is given by the number of valid repetitions performed until exhaustion, and SLBT has good intra-rater reliability (intraclass correlation coefficients of 0.77–0.89 and 0.89–0.91, respectively).13 The SLBT has been introduced in the sports context as a way of estimating the hamstring capacity in a range of athletic populations,13–16 including athletes in rehabilitation following HSI.9 However, considering the nature of the SLBT (i.e., a repetition-to-failure test), it seems reasonable to hypothesize that the SLBT score would not be correlated with the maximum hamstring strength, which is the outcome mostly traditionally related to prevention and rehabilitation of HSI. Therefore, the primary aim of this study was to examine the association between SLBT scores with concentric and eccentric knee flexor peak torques. Secondarily, this study aimed examine the association of between-limb asymmetries provided by SLBT and isokinetic tests.
METHODS STUDY DESIGN
In this cross-sectional study, volunteers performed SLBT and isokinetic tests in a single visit to the laboratory. The study was approved by the Federal University of Health Sciences of Porto Alegre (Porto Alegre, Brazil) ethics committee, and all volunteers provided informed consent before starting study participation.
One-hundred male soccer players were assessed: 51 from senior teams and 49 from under-20 teams (20.06±3.41 years old; 74.81±8.59 kg; 1.79±0.07 m; 12 goalkeepers, 24 backs, 40 midfielders, and 24 forwards). All players had professional work contracts and were regularly engaged in the training routine of two football clubs from a first state division league in Brazil. Professional and under-20 players followed a routine usually encompassing one to two daily training sessions, three to five days per week, according to each team’s weekly schedule (i.e., training, games, and trips). Evaluations were carried out during the first two weeks of preseason. PROCEDURES
Coaching staffs were informed that players should not perform vigorous training sessions 24 hours prior to assessments. Players received the following recommendations: (i) not to perform high-intensity physical activities 24 hours before the tests; (ii) not to take any kind of analgesic and/or anti-inflammatory drugs 48 hours before the tests; and (iii) not to consume stimulant substances (e.g., caffeine) on the testing day. All players performed the isokinetic test first, followed by the SLBT. The side tested first was alternated between participants. Isokinetic assessment followed standardized procedures.17 After a general warm-up (five minutes of cycle ergometer exercise), players were positioned in the isokinetic dynamometer (Biodex System 4; Biodex Medical Systems, Shirley, NY) according to the manufacturer’s recommendations. Players performed 10 submaximal concentric knee flexion/extension repetitions at 90°/s for specific warm-up and familiarization with the equipment. Thereafter, two attempts of three consecutive maximum concentric contractions were executed at 60°/s, followed by two attempts of three consecutive maximum eccentric contractions at 60°/s. A one-minute rest period was allowed between attempts. The highest concentric and eccentric knee flexor peak torques were used for data analysis. Considering that body mass plays a role in SLBT performance, peak torque values were normalized by the players’ body mass to ensure a fairer comparison between tests. The SLBT (Figure 1) was performed only after the volunteer claimed to be recovered from the isokinetic assessment and was ready to perform a new maximal effort. At least a 10-minute rest period was given before performing the SLBT. During the rest period, raters introduced the SLBT to volunteers using video records and standard explanations, following recommendations by Freckleton et al.13 Players were instructed to lie down on the ground with one heel on a box measuring 60 cm high. The testing limb was positioned in approximately 20° knee flexion. Participants were instructed to cross arms over the chest and push down through the heel to lift their bottom off the ground. Players were advised that for the SLBT they should perform as many repetitions as possible until failure. Consistent feedback
International Journal of Sports Physical Therapy
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength
Table 1. Results from the single leg bridge test (SLBT) and the isokinetic dynamometry, and correlation between tests. Correlations with SLBT Mean ± SD
95% CI
Minimum
Maximum
Pearsons’s (r)
95% CI
SLBT (repetitions)
33.6±9.6
32.3;35.0
13
63
-
-
Concentric PT (Nm/kg)
2.00±0.22
1.97;2.22
1.53
2.75
0.275
0.142;0.399
<0.001
Eccentric PT (Nm/kg)
2.79±0.44
2.72;3.23
1.68
4.12
0.215
0.078;0.343
0.002
SLBT asymmetry (%)
0.4±9.6
-4.57;3.78
-50
50
-
-
-
Concentric PT asymmetry (%)
1.08±8.5%
-0.58;2.75
-20.1
20.9
0.213
0.018;0.392
0.033
Eccentric PT asymmetry (%)
1.64±14.61
-1.22;4.51
-38.3
52.6
0.062
-0.136;0.255
0.539
p-value -
CI: coefficient interval; SD: standard deviation; SLBT: single leg bridge test; PT: peak torque.
was provided throughout the procedure to ensure that the correct technique was achieved. Each trial required the participant to touch their buttock onto the ground, without resting, and then extend the hip to 0°. The target height of the upward movement was determined after a familiarization repetition to show to the volunteers the correct execution. This height was measured with a one-meter scale to be repeated during the evaluation of the opposite limb. To be considered a valid repetition, the non-working limb was required to be held stationary in a vertical position to ensure that momentum was not gained by swinging this limb and the knee had to touch the rater’s hand, placed at the target height (i.e., the tested hip at 0°), before returning to the initial position. When the correct form was lost, one warning was given and the test was ceased at the next fault in technique. Maximum valid repetitions were recorded. For both SLBT and isokinetic dynamometry, betweenlimb asymmetry was calculated considering the right limb as the reference one (i.e., between-limb asymmetry represents the left limb percentage difference to the right limb). STATISTICAL ANALYSIS
The total sample size required for a correlation study with ρH1 = 0.3, α error prob = 0.05, and power = 0.80 was 93 volunteers (G*Power 3.1.9.7). Two hundred limbs (100 on each side) were included in the analysis. Descriptive statistics (mean ± standard deviation, 95% confidence intervals, and minimum and maximum values) was used to describe the participants’ performance. Kolmogorov-Smirnov test confirmed the normal distribution of data. Associations between SBLT and isokinetic dynamometry were assessed through Pearson’s correlation coefficient. The following correlation criteria were adopted: 0, none; ≤0.2, poor; 0.2 ≤ 0.5, fair; 0.5 ≤ 0.7, moderate; 0.7 ≤ 0.9, strong; 1, perfect.18 Trend line equation and r-squared values were calculated to indicate how well the estimated trend line values fit the ac-
Figure 1. Soccer player performing the single leg bridge test (SLBT).
tual data. Statistical significance was set at 5% (p<0.05) for the comparisons.
RESULTS Table 1 summarizes the results of the study. There was a poor association of SLBT score with concentric peak torque (p<0.001, r=0.275) and eccentric peak torque (p=0.002, r=0.215) (Figure 2). The SLBT between-limb asymmetry was poorly associated with asymmetry found in concentric peak torque asymmetry (p=0.033, r=0.213) and was not associated with eccentric peak torque asymmetry (p=0.539, r=0.062) (Figure 3).
International Journal of Sports Physical Therapy
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength
Figure 2. Association of single leg bridge test (SLBT) score with concentric peak torque (top) and eccentric peak torque (bottom).
International Journal of Sports Physical Therapy
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength
Figure 3. Association of single leg bridge test (SLBT) between-limb asymmetry with concentric peak torque asymmetry (top) and eccentric peak torque asymmetry (bottom).
International Journal of Sports Physical Therapy
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength
DISCUSSION The SLBT became popular after a prospective study showed that low scores were associated with an increased risk of HSI throughout the season in Australian football players.13 Since HSI have been usually associated with low levels of maximum strength measured in isokinetic tests3–5 and Nordic hamstring exercise tests,6 interpretation of the SLBT as a new tool for assessment of maximum hamstring strength perhaps has occurred naturally in some contexts. The prospect of evaluating the hamstring capacity using a test with low technology requirements (i.e., just a box) is tempting for clinicians without access to isokinetic dynamometers or other strength assessment devices. However, the results of this study found only poor associations between SLBT scores and isokinetic dynamometry measures, suggesting that SLBT should not be used to estimate the maximum hamstring strength-related outcomes of soccer players. Maximum strength capacity is a criterion for progression of rehabilitation and return-to-sport following HSI, typically determined using isokinetic dynamometry9 and/or isometric tests performed with hand-held dynamometers.8,9 Mendiguchia et al.9 introduced SLBT as a clearance criterion for semiprofessional male soccer players with HSI. Players were required to perform >25 repetitions and have <10% asymmetry between limbs to be considered able to return to sport, in addition to a range of criteria including maximum hamstring strength asymmetry <10%.9 Findings of the present study further support that SLBT and maximum hamstring strength tests must be used in a complementary manner during the athlete’s evaluation. In other words, an athlete performing SLBT with a high number of repetitions and low between-limb asymmetry will not necessarily perform satisfactorily in some maximum strength testing such as isokinetic dynamometry. It is important to note that isokinetic dynamometry assesses the isolated action of the knee flexor muscles during concentric or eccentric contractions performed in an open kinetic chain movement. Conversely, SLBT involves maintaining a quasi-isometric knee position while the hamstrings act as hip extensors, while other muscles (i.e., glutes and trunk stabilizers) are simultaneously recruited to perform a closed kinetic chain movement. A growing body of work has emerged highlighting the heterogeneity of hamstring activation in different exercises (e.g., knee-dominant vs. hip-dominant movements),19–22 which could be a factor responsible for the poor association of SLBT scores with isokinetic peak torques. However, the poor association may also be due to the purpose of the isokinetic dynamometry (as performed in the present study) which intends to assess the individual’s capacity to produce maximum strength (i.e., peak torque), while SLBT has already been suggested as a ‘hamstring strength-endurance’ test.9,15 It is plausible that muscular endurance (i.e., resistance to fatigue) is the most dominant factor in a repetition-to-failure test such as SLBT. It is noteworthy that results of the present study do not belittle or question the usefulness of SLBT. Reliable submaximal strength endurance tests are relevant in the context of assessing the risk of orthopedic disorders (e.g., the
role of muscles engaged in core stabilization for low back pain).23 Given that male professional players cover an average total distance close to 11 km in a 90-min game, with 350 m and 1150 m performed in sprints and high-intensity running, respectively,24 fatigue-induced loss of strength in lower limb muscles is an expected phenomenon. Studies conducted with simulated and official soccer games have evidenced that hamstring strength capacity is significantly affected in those situations.25–27 Interestingly, the last third of each half in soccer games are the periods with the highest incidence of HSI.28 Although a cause-effect relationship cannot be established, it seems reasonable that hamstring fatigue may play a role in the higher susceptibility to HSI in the final parts of the game. Thus, assessing hamstring muscle function through a reproducible and feasible endurance test may be valuable and has practical implications for planning prevention and rehabilitation programmes. Clinicians must be aware of what they are measuring when using SLBT (or any other ‘strength test’ executed in the clinical setting or in the edge of the field). Results of the current study make clear that SLBT does not assess the maximum hamstring strength. Further studies are needed to address the ability of SLBT to accurately estimate the fatigue resistance of the hamstring muscles, since fatigue in other muscles involved in the movement may be responsible for the end of the test. For example, it has been shown that the gluteal musculature has important activation during the single leg bridge,29 possibly higher to that of the biceps femoris.30 Consequently, a gluteus with low fatigue resistance might anticipate the end of the SLBT. Clinicians must also keep in mind that fatigue is a task-dependent phenomenon,31 and a high score in SLBT does not necessarily transfer directly to fatigue resistance in a sporting situation. In other words, it is unknown whether a player with a higher score in a quick, cyclical, repetition-to-failure test such as SLBT responds with less hamstring fatigue to a longer, intermittent, and multicomponent exercise exposition such as a soccer game. Furthermore, despite the increased HSI risk found in Australian football players with low SLBT scores highlights the potential of this assessment tool,13 there is a lack of prospective studies evidencing the association of the SLBT with the HSI in soccer and other sports; thus, caution is recommended in considering SLBT score as a risk factor for HSI in all athletic populations. The authors acknowledge that the current study has limitations. First, the assessments took place at the first two preseason weeks, thus SLBT scores and isokinetic peak torques likely do not represent the players’ peak fitness. However, this does not compromise the objective of the study to examine the association between the two assessment tools. Second, SLBT and isokinetic dynamometry are physically demanding testing protocols, and both tests had to be carried out in a single visit to the laboratory due to the clubs’ training routine. Although a rest interval was given to volunteers to allow for recovery from the transient fatigue, a hypothetical performance impairment in the second test (SLBT) of some volunteers cannot be excluded. Third, the SLBT depends on the raters ability to perform real-time tracking of the volunteer’s movement technique during the testing execution, warning him about the first
International Journal of Sports Physical Therapy
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength
fault and ceasing assessment in the second fault. Thus, as with most field tests, some error is inherent to the SLBT, but it is not believed that this compromises the results.
CONCLUSION
maximum repetition test) instead of SLBT to evaluate their athletes.
CONFLICT OF INTEREST
In conclusion, the SLBT score of male soccer players is not associated with concentric and eccentric knee flexor peak torques obtained by isokinetic dynamometry. Between-limb asymmetry provided by SLBT is also not associated with isokinetic asymmetry. Therefore, SLBT should not be used as a clinical tool to assess the maximum strength of hamstring muscles. Clinicians interested in maximal hamstring strength-related outcomes for prevention, rehabilitation or performance purposes should use other tests (eg, isokinetic/isometric dynamometry, load cell-based devices, one-
The authors reported no potential conflict of interest. ACKNOWLEDGEMENTS
BMB thanks CNPq-Brazil for the research productivity fellowship. Submitted: August 25, 2021 CDT, Accepted: January 23, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Single Leg Bridge Test is Not a Valid Clinical Tool to Assess Maximum Hamstring Strength
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10. Helme M, Tee J, Emmonds S, Low C. Does lowerlimb asymmetry increase injury risk in sport? A systematic review. Phys Ther Sport. 2021;49:204-213. doi:10.1016/j.ptsp.2021.03.001
2. Bittencourt NFN, Meeuwisse WH, Mendonça LD, Nettel-Aguirre A, Ocarino JM, Fonseca ST. Complex systems approach for sports injuries: Moving from risk factor identification to injury pattern recognition - Narrative review and new concept. Br J Sports Med. 2016;50(21):1309-1314. doi:10.1136/bjsports-2015-09 5850
11. Buckthorpe M, Wright S, Bruce-Low S, et al. Recommendations for hamstring injury prevention in elite football: translating research into practice. Br J Sport Med Mon. 2018;0(0). doi:10.1136/bjsports-201 8-099616
3. Lee J, Mok K, Chan H, Patrick S, Chan K. Eccentric hamstring strength deficit and poor hamstring-toquadriceps ratio are risk factors for hamstring strain injury in football: A prospective study of 146 professional players. J Sci Med Sport. 2018;21(8):789-793. doi:10.1016/j.jsams.2017.11.017 4. Croisier JL, Ganteaume S, Binet J, Genty M, Ferret JM. Strength imbalances and prevention of hamstring injury in professional soccer players: a prospective study. Am J Sports Med. 2008;36(8):1469-1475. doi:1 0.1177/0363546508316764 5. Fousekis K, Tsepis E, Poulmedis P, Athanasopoulos S, Vagenas G. Intrinsic risk factors of non-contact quadriceps and hamstring strains in soccer: a prospective study of 100 professional players. Br J Sports Med. 2011;45(9):709-714. doi:10.1136/bjsm.20 10.077560 6. Timmins RG, Bourne MN, Shield AJ, Williams MD, Lorenzen C, Opar DA. Short biceps femoris fascicles and eccentric knee flexor weakness increase the risk of hamstring injury in elite football (soccer): A prospective cohort study. Br J Sports Med. 2016;50(24):1524-1535. doi:10.1136/bjsports-2015-09 5362 7. Hickey J, Timmins R, Maniar N, Williams M, Opar D. Criteria for Progressing Rehabilitation and determining return-to-play clearance following hamstring strain injury: a systematic review. Sports Med. 2017;47(7):1375-1387. 8. Medeiros DM, Aimi M, Vaz MA, Baroni BM. Effects of low-level laser therapy on hamstring strain injury rehabilitation: A randomized controlled trial. Phys Ther Sport. 2020;42:124-130. doi:10.1016/j.ptsp.202 0.01.006
12. Brown LE. Isokinetics in Human Performance. Champaign, Ill: Human Kinetics; 2000. 13. Freckleton G, Pizzari T, Cook J, Young M. The predictive validity of a single leg bridge test for hamstring injuries in football players. J Sci Med Sport. 2011;14:e17. doi:10.1016/j.jsams.2011.11.035 14. Rey E, Paz-Domínguez Á, Porcel-Almendral D, Paredes-Hernández V, Barcala-Furelos R, AbelairasGómez C. Effects of a 10-week Nordic hamstring exercise and Russian belt training on posterior lowerlimb muscle strength in elite junior soccer players. J Strength Cond Res. 2017;31(5):1198-1205. doi:10.151 9/JSC.0000000000001579 15. Macdonald B, OʼNeill J, Pollock N, Van Hooren B. Single-leg roman chair hold is more effective than the Nordic hamstring curl in improving hamstring strength-endurance in Gaelic footballers with previous hamstring injury. J Strength Cond Res. 2019;33(12):3302-3308. doi:10.1519/JSC.0000000000 002526 16. Šimenko J, Kovčan B, Pori P, Vodičar J, Vodičar M, Hadžić V. The relationship between army physical fitness and functional capacities in infantry members of the Slovenian armed forces. J Strength Cond Res. 2019;Publish Ah(Nov 27). doi:10.1519/JSC.000000000 0003344 17. Ribeiro-Alvares JB, Dornelles MP, Fritsch CG, et al. Prevalence of hamstring strain injury risk factors in professional and under-20 male football (soccer) players. J Sport Rehabil. Published online 2019:1-7. do i:10.1123/jsr.2018-0084 18. Akoglu H. User’s guide to correlation coefficients. Turkish J Emerg Med. 2018;18(3):91-93. doi:10.1016/ j.tjem.2018.08.001
9. Mendiguchia J, Martinez-Ruiz E, Edouard P, et al. A multifactorial, criteria-based progressive algorithm for hamstring injury treatment. Med Sci Sports Exerc. 2017;49(7):1482-1492. doi:10.1249/MSS.00000000000 01241 International Journal of Sports Physical Therapy
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19. Wiesinger HP, Scharinger M, Kösters A, Gressenbauer C, Müller E. Specificity of eccentric hamstring training and the lack of consistency between strength assessments using conventional test devices. Sci Rep. 2021;11(1):1-13. doi:10.1038/s41 598-021-92929-y 20. Guruhan S, Kafa N, Ecemis ZB, Guzel NA. Muscle activation differences during eccentric hamstring exercises. Sports Health. 2021;13(2):181-186. doi:10.1 177/1941738120938649
26. Rhodes D, McNaughton L, Greig M. The temporal pattern of recovery in eccentric hamstring strength post-soccer specific fatigue. Res Sports Med. 2019;27(3):339-350. 27. Bueno CA, de Araujo Ribeiro-Alvares JB, Oliveira G dos S, et al. Post-match recovery of eccentric knee flexor strength in male professional football players. Phys Ther Sport. 2021;47:140-146. doi:10.1016/j.pts p.2020.11.032
21. Marchiori C, Medeiros D, Severo-Silveira L, et al. Muscular adaptations to training programs using the Nordic hamstring exercise or the stiff-leg deadlift in rugby players. Sport Sci Heal. Published online 2021. d oi:10.1007/s11332-021-00820-0
28. Woods C, Hawkins RD, Maltby S, Hulse M, Thomas A, Hodson A. The football association medical research programme: an audit of injuries in professional football—analysis of hamstring injuries. Br J Sports Med. 2004;38(August 2007):36-41. doi:10.1 136/bjsm.2002.002352
22. Hegyi A, Péter A, Finni T, Cronin N. Regiondependent hamstrings activity in Nordic hamstring exercise and stiff-leg deadlift defined with highdensity electromyography. Scand J Med Sci Sport. 2018;28(3):992-1000. doi:10.1111/sms.13016
29. Lehecka BJ, Edwards M, Haverkamp R, et al. Building a better gluteal bridge: electromyographic analysis of hip muscle activity during modified single-leg bridges. Int J Sports Phys Ther. 2017;12(4):543.
23. Lehecka BJ, Smith BS, Rundell T, Cappaert TA, Hakansson NA. The reliability and validity of gluteal endurance measures (GEMs). Int J Sports Phys Ther. 2021;16(6):1442-1453. doi:10.26603/001C.29592
30. Ekstrom RA, Donatelli RA, Carp KC. Electromyographic analysis of core trunk, hip, and thigh muscles during 9 rehabilitation exercises. J Orthop Sports Phys Ther. 2007;37(12):754-762. doi:1 0.2519/jospt.2007.2471
24. Barnes C, Archer DT, Hogg B, Bush M, Bradley PS. The evolution of physical and technical performance parameters in the english premier league. Int J Sports Med. 2014;35(13):1095-1100. doi:10.1055/s-0034-137 5695
31. Hunter SK. Performance fatigability: Mechanisms and task specificity. Cold Spring Harb Perspect Med. 2018;8(7):1-21. doi:10.1101/cshperspect.a029728
25. Delextrat A, Gregory J, Cohen D. The use of the functional H:Q ratio to assess fatigue in soccer. Int J Sports Med. 2010;31(3):192-197. doi:10.1055/s-0029-1 243642
International Journal of Sports Physical Therapy
Cacolice PA, Starkey BE, Carcia CR, Higgins PE. Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3 Student-Athletes. IJSPT. 2022;17(4):622-627.
Original Research
Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3 StudentAthletes Paul A. Cacolice 1 1
a
, Brianna E. Starkey 2, Christopher R. Carcia 3
, Paul E. Higgins 1
Sports Medicine and Human Performance, Westfield State University, 2 University of Massachusetts Boston, 3 Kinesiology, Colorado Mesa University
Keywords: Athlete, Dominant limb, Intercollegiate, kicking, landing, lower extremity https://doi.org/10.26603/001c.35593
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background/Purpose Recent work has identified non-significant correlations of established limb dominance to the lower extremity (LE) at greater risk for Anterior Cruciate Ligament (ACL) injury in an active, non-athletic sample. The most common LE dominance definition is preferred leg to kick a ball. Athletes develop a unilaterality pattern different from their active, non-athlete peers. Therefore, the purpose of this study was to explore the correlation between the LE used to kick a ball with and the limb identified at greater risk of ACL injury in National Collegiate Athletic Association (NCAA) Division III athletes.
Design An Observational Descriptive study design
Methods Forty-six student-athletes that were active on their NCAA Division III football, field hockey, volleyball, and soccer team rosters were recruited. Upon completing consent, participants performed two tasks (kicking a ball; unilateral land) in a counterbalanced order. Data were entered into and analyzed with a commercial statistical software package where a phi coefficient and Chi-squared analysis were performed.
Results Of the 46 student athletes who participated (Female=32, Male=14, 19.48±1.26years, 171.75±10.47cm, 77.26±18.74kg), 25 participants kicked and landed with the same limb. Twenty participants chose kicking and landing with different limbs. The Phi Coefficient (Φ= 0.001; P= 0.97) indicated little to no relationship between the LE a participant kicked and landed with. Likewise, the Chi-square statistic revealed no statistical differences between observed and expected frequencies (χ2= 0.001; p= 0.97).
Discussion/Conclusion NCAA Division III athletes display a statistical absence of preferred limb predictability utilizing the most common dominance definition (kicking a ball) as it relates to identifying LE at risk of ACL injury. The results suggest that the prevalent LE dominance definition is problematic when exploring ACL injury risk in this population.
a
Corresponding author: Paul A. Cacolice, PhD., LAT, ATC, CSCS Sports Medicine and Human Performance 214 Woodward Center Westfield State University Westfield, MA 01085 Telephone 413.572.5450 Email pcacolice@westfield.ma.edu
Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3...
INTRODUCTION Decades of focused investigations have been conducted to better understand anterior cruciate ligament (ACL) injury risk factors.1 Despite this, ACL injuries remain common,2–6 costly,7 and debilitating.8 It has been estimated that 80,000 to 250,000 ACL injuries occur in the US each year,3,9,10 with an appropriated total annual cost of between $8 and $18 billion.11 ACL injury increases the likelihood of re-injury,12,13 and the risk of developing knee osteoarthritis.12 Furthermore, individuals often face psycho-sociological challenges during their time away from regular activity.14,15 A preferred strategy then, would be to prevent rather than treat ACL injuries. Injury prevention requires a precise understanding of the causal risk factor(s).16 It has been established that ACL injuries occur more frequently with non-contact mechanisms,2,4 and with single LE deceleration activities such as changing direction or landing from a jump.17 These suggest that lower extremity (LE) biomechanics are affected at ground contact to increase injury risk. As such, unilateral landing tasks are commonly utilized to study non-contact ACL risk factors.18,19 Investigation of unilateral landing behaviors commonly collects data from the participant’s dominant LE. Limb dominance is most frequently defined as the preferred LE to kick a ball.20–23 The majority of ACL injuries however occur to the plant or landing LE.21,24 It is unknown if the preferred leg to kick a ball is the lower extremity most commonly injured. Unless the preferred kicking LE is also the preferred plant or landing LE, this operational definition of LE dominance is potentially problematic. Given the epidemiological data, costs and long-term medical impacts, it is apparent choosing the appropriate LE for testing is imperative. To date, only one investigation has been published exploring the relationship between the preferred kicking LE and the preferred landing LE.25 This investigation indicated that there were weak correlations between these two measures of LE dominance in a sample of healthy, active college students. For a number of reasons explored in the literature, athletes demonstrate an elevated risk of orthopedic injury, than their healthy, but non-athlete peers.26–29 In athletes however, the strength of correlation between LE dominance measures remains unknown. Optimal prediction of LE dominance for injury risk would benefit athletes even more than the values in a general, healthy population. Therefore, the purpose of this study was to explore the correlation between the LE used to kick a ball with and the limb identified at greater risk of ACL injury in National Collegiate Athletic Association (NCAA) Division III athletes. The hypothesis was that these measures will indicate stronger correlations in athletes than reported in healthy non-athletes.25
Board approval. Inclusion Criteria required participants to be 1) between the ages of 18-25 and 2) currently active on their NCAA Division III football, soccer, field hockey, volleyball, basketball, or lacrosse team roster. Athletes from the included sports were recruited to participate as they are at increased risk for non-contact ACL injury.27–29,32,33 Participants were excluded from the study if within the prior six months they had: 1) utilized crutches for any LE injury or 2) missed a regularly scheduled intercollegiate competition due to a LE injury, 3) engaged in a rehabilitation program for a LE injury or 4) inability to demonstrate any of the required physical activities in the study. These exclusions were to assure unbiased LE function, and optimize participant safety. An a-priori power analysis using publicly available freeware (G*Power v 3.1.9.2, Düsseldorf, Germany) indicated that a minimum sample size of 34 was needed to achieve a power of 0.80. To ensure that a Type II error was not committed, forty-six student-athletes healthy, NCAA D-III participants between the age of 18 and 25 were recruited for this investigation. Data were collected during a single session in the Westfield State University Biomechanics laboratory. Upon receiving written informed consent, height, weight, age, and sport team were recorded. The participant then performed two tasks (kicking a ball; unilateral landing) in a counterbalanced order. KICKING TASK
Participants were asked to jog 300cm (3 meters) to kick a stationary soccer ball through a 100cm (1 meter) wide target, 300cm (3 meters) away. Each individual completed five trials of this activity. The LE the participant chose to kick a ball with three out of five trials was defined as their preferred kicking LE.25 Participants were asked to jog and kick the ball rather than kick it from a stationary position as we felt this methodology more realistically represented how the activity would take place. LANDING TASK
Participants were asked to stand on a box 30cm in height, and instructed to lean forward and drop from the box, landing on their preferred leg. Each individual completed five trials of this activity. The LE the participant chose to land with three out of five trials was defined as their preferred landing LE and is consistent with previous investigations.25,34,35 STATISTICAL ANALYSES
Pearson correlation coefficients were calculated (SPSS v26, IBM, Armonk, NY) to determine the relationship between preferred landing LE and preferred kicking LE. A Chi-square value was calculated to explore for observed and expected frequencies.
METHODS The authors utilized an observational, descriptive investigation design30,31 with counterbalanced, repeated measures. This investigation was granted Institutional Review
RESULTS The forty-five participants represented six sports (football= 11, men’s soccer= 1, women’s soccer= 8, women’s lacrosse=
International Journal of Sports Physical Therapy
Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3...
1, women’s volleyball= 10, field hockey= 14). Thirty-three female, and 12 male participants completed the study (19.48±1.23years, 171.75±10.47cm, 77.26±18.74kg). Twenty-five participants kicked and landed with the same limb. Twenty participants chose kicking and landing with different limbs (Table 1). The Phi Coefficient (Φ= 0.001; p= 0.97) indicated little to no relationship between the LE a participant kicked and landed with. Likewise, the Chisquare statistic revealed no differences between observed and expected frequencies (χ2= 0.001; p= 0.97).
DISCUSSION The purpose of this investigation was to correlate the preferred LE in kicking a ball, and the LE preferred from a drop landing in athletes. The investigators hypothesized the correlations would be stronger in athletes than the previous findings in healthy, active, non-athletes. The findings of this study did not support the stated hypothesis, as weaker correlations were seen in these athletes than in previous descriptions of healthy, active non-athletes. There is little discrepancy for defining upper extremity dominance.36,37 In contrast, previous investigations have utilized various definitions for LE dominance. Among the various singular strategies have been utilization of stance or weight-bearing LE,19 the preferred single LE for landing task,38 or through a battery of tests.39 The most common operational definition in the literature however, involves the preferred LE for kicking a ball.20–23 The utilization of a consistent and task specific LE selection is essential for application of any research finding. Epidemiological evidence on ACL injury incidence contrasts with the rationale for LE selection in the majority of investigations. Data show ACL injuries occur more frequently with a unilateral landing,24 during a non-contact mechanism,1–4 and do not occur as frequently to the kicking LE.17 The most frequent strategy for LE dominance selection then, seemingly is potentially problematic when attempting to understand ACL injury risk. The hypothesis was generated from the understanding that athletes demonstrate a high level of motor skills as they perform at ever higher levels of competition. These motor skills often necessitate incredible unilateral control. Indeed, prior work in dancers has suggested level of expertise may affect preferred LE for skill performance, even where bilateralism is expected.24 Previous work from two of the current investigation’s authors (PAC, CRC)25 explored the same correlation analysis in a group of healthy and active, but non-athletes. The results of that study indicated weak correlations between the preferred kicking and landing LE. The data in this study indicate even weaker, and statistically insignificant correlations in athletes. Given this, previous injury risk identification investigations may have obtained results from the LE less likely to be injured as a result. Among the premises of this investigation are that athletes differ from healthy, active non-athlete individuals of
Table 1. Frequencies of preferred dominance Preferred Kicking LE Preferred Landing LE
Left
Right
Left
3
16
Right
4
22
a similar age. Of greater concern is that athletes demonstrate an elevated risk of ACL injury than their healthy, active, but non-athlete peers.26–29 Another study limitation is that due to the selection of sport teams, data were collected on a higher number of females versus males. As females have demonstrated a greater incidence of ACL injury in the literature,33,40,41 the authors feel that the data remain consistent with the purpose of this study. Finally, the exclusion criteria were selected to investigate these skills in only those who are currently performing at high levels of function and competition. Including individuals who had returned to a full function from LE surgery is more representative of a realistic scenario in the collegiate population, and has been previously utilized for that effort.35,42 This is however, may be considered a limitation of this investigation. The findings in this investigation raise several areas of interest for future investigations. Among these are exploring any connection between upper and lower extremity dominance. Additionally, exploration of the relationship of the lower extremity with greater likelihood of injury to the operational dominance definitions as seen in sports with an elevated need for bilateralism such as lacrosse and soccer is warranted.
CONCLUSION NCAA Division III athletes display a statistical absence of predictability in definitions of LE dominance. Even though athletes develop greater unilaterality as level of competition increases, the results suggest that the most prevalent dominance definition (the limb with which one kicks a ball) may be problematic when exploring ACL injury risk in this population. As ACL injury risk is elevated in the preferred planting versus kicking limb, careful consideration should be given to the operational definition of LE limb dominance in future injury risk studies.
DISCLOSURES
There are no author disclosures regarding this investigation or preparation of this manuscript. There were no funding sources for this investigation. Submitted: October 26, 2021 CDT, Accepted: February 08, 2022 CDT
International Journal of Sports Physical Therapy
Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3...
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International Journal of Sports Physical Therapy
Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3...
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11. Mather RC, Koenig L, Kocher MS, et al. Societal and economic impact of anterior cruciate ligament tears. J Bone Joint Surg Am. 2013;95(19):1751. doi:10.2 106/JBJS.L.01705 12. Shelbourne KD, Gray T. Minimum 10-Year results after anterior cruciate ligament reconstruction: How the loss of normal knee motion compounds other factors related to the development of osteoarthritis after surgery. Am J Sports Med. 2009;37(3):471-480. d oi:10.1177/0363546508326709 13. Hewett TE, Di Stasi SL, Myer GD. Current concepts for injury prevention in athletes after anterior cruciate ligament reconstruction. Am J Sports Med. 2012;41:216-224. doi:10.1177/0363546512459638 14. Kvist J, Ek A, Sporrstedt K, Good L. Fear of reinjury: a hindrance for returning to sports after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2005;13(5):393-397. doi:1 0.1007/s00167-004-0591-8 15. Österberg A, Kvist J, Dahlgren MA. Ways of experiencing participation and factors affecting the activity level after nonreconstructed anterior cruciate ligament injury: a qualitative study. J Orthop Sports Phys Ther. 2013;43(3):172-183. doi:10.2519/jospt.201 3.4278 16. van Mechelen W. Sports injury surveillance systems, “One size fits all?” Sports Med. 1997;24(3):164-168. doi:10.2165/00007256-19972403 0-00003 17. Krosshaug T, Nakamae A, Boden BP, et al. Mechanisms of anterior cruciate ligament injury in basketball: video analysis of 39 cases. Am J Sports Med. 2006;35(3):359-367. doi:10.1177/0363546506293 899 18. Carcia CR, Kivlan B, Scibek JS. The Relationship Between Lower Extremity Closed Kinetic Chain Strength & Sagittal Plane Landing Kinematics in Female Athletes. Int J Sports Phys Ther. 2011;6:1-9. 19. Shultz SJ, Schmitz RJ, Nguyen AD, et al. ACL Research Retreat V: An update on ACL risk and prevention, March 25-27, 2010, Greensboro, NC. J Athl Train. 2010;45(5):499-508. 20. Jacobs C, Mattacola C. Sex differences in eccentric hip-abductor strength and knee-joint kinematics when landing from a jump. J Sport Rehabil. 2005;14(4):346-355.
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Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury in NCAA D3...
21. Negrete RJ, Schick EA, Cooper JP. Lower-limb dominance as a possible etiologic factor in noncontact anterior cruciate ligament tears. J Strength Cond Res. 2007;21:270-273. 22. Matava MJ, Freehill AK, Grutzner S, Shannon W. Limb Dominance as a potential etiological factor in noncontact anterior cruciate ligament tears. J Knee Surg. 2002;15:11-16. 23. Thorborg K, Couppe C, Petersen J, Magnusson SP, Holmich P. Eccentric hip adduction and abduction strength in elite soccer players and matched controls: a cross-sectional study. Br J Sports Med. 2009;45:10-13. doi:10.1136/bjsm.2009.061762 24. Brophy R, Silvers HJ, Gonzales T, Mandelbaum BR. Gender influences: the role of leg dominance in ACL injury among soccer players. Br J Sports Med. 2010;44(10):694-697. doi:10.1136/bjsm.2008.051243 25. Carcia CR, Cacolice PA, McGeary S. Defining Lower Extremity Dominance: The Relationship Between Preferred Lower Extremity and Two Functional Tasks. Intl J Sports Phys Ther. 2019;14(2):188-191. doi:10.26603/ijspt20190188 26. Arendt EA, Agel J, Dick R. Anterior cruciate ligament injury patterns among collegiate men and women. J Athl Train. 1999;34(2):86-92. 27. Agel J, Arendt EA, Bershadsky B. Anterior cruciate ligament injury in National Collegiate Athletic Association basketball and soccer: a 13-year review. Am J Sports Med. 2005;33(4):524-531. doi:10.1177/036 3546504269937 28. Agel J, Olson DE, Dick R, Arendt EA, Marshall SW, Sikka RS. Descriptive epidemiology of collegiate women’s basketball injuries: National Collegiate Athletic Association Injury Surveillance System, 1988–1989 through 2003–2004. J Athl Train. 2007;42(2):202. 29. Dick R, Ferrara MS, Agel J, et al. Descriptive epidemiology of collegiate men’s football injuries: National Collegiate Athletic Association Injury Surveillance System 1988-1989 through 2003-2004. J Athl Train. 2007;42(2):221-233.
32. Mihata LCS. Comparing the incidence of anterior cruciate ligament injury in collegiate lacrosse, soccer, and basketball players: implications for anterior cruciate ligament mechanism and prevention. Am J Sports Med. 2006;34(6):899-904. doi:10.1177/0363546 505285582 33. Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer NCAA data and review of literature. Am J Sports Med. 1995;23(6):694-701. doi:10.1177/03635465950230061 1 34. Cacolice PA, Starkey BE, Carcia CR, Higgins PE. Research Dominance Definitions May Not Identify Higher Risk Limb for Anterior Cruciate Ligament Injury. J Athl Train. 2020;55(6S):S-95. doi:10.4085/106 2-6050-55.6s.S-1 35. Cacolice PA, Carcia CR, Scibek JS, Phelps AL. The Use of Function Tests to Predict Sagittal Plane Knee Kinematics In NCAA-D1 Female Athletes. Int J Sports Phys Ther. 2015;10(4):493-504. 36. Barnes CJ, Van Steyn SJ, Fischer RA. The effects of age, gender and shoulder dominance on range of motion at the shoulder. J Shoulder Elbow Surg. 2001;10(3):242-246. 37. Laudner KG, Sipes RC, Wilson JT. The acute effects of sleeper stretches on shoulder range of motion. J Athl Train. 2008;43(4):359. 38. Padua DA, Carcia CR, Arnold BL, Granata KP. Gender differences in leg stiffness and stiffness recruitment strategy during two-legged hopping. J Motor Behav. 2005;37(2):111-126. doi:10.3200/JMBR.3 7.2.111-126 39. Newton RU, Gerber A, Nimphius S, et al. Determination of functional strength imbalance of the lower extremities. J Strength Cond Res. 2006;20(4):971-977. 40. Ireland ML. Anterior cruciate ligament injury in female athletes: epidemiology. J Athl Train. 1999;34(2):150-154.
30. Portney LG. Foundations of Clinical Research: Applications to Evidence-Based Practice. 4th ed. F.A. Davis; 2020.
41. Gwinn DE, Wilckens JH, McDevitt ER, Ross G, Kao TC. The relative incidence of anterior cruciate ligament injury in men and women at the United States Naval Academy. Am J Sports Med. 2000;28:98-102. doi:10.1177/03635465000280012901
31. Grimes DA, Schulz KF. An overview of clinical research: the lay of the land. Lancet. 2002;359(9300):57-61. doi:10.1016/S0140-6736(02)07 283-5
42. Cacolice PA, Carcia CR, Scibek JS, Phelps AL. Ground reaction forces are predicted with functional and clinical tests in healthy collegiate students. J Clin Med. 2020;9(9):2907. doi:10.3390/jcm9092907
International Journal of Sports Physical Therapy
Dean RS, DePhillipo NN, Kiely MT, Schwery NA, Monson JK, LaPrade RF. Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients. IJSPT. 2022;17(4):628-635.
Original Research
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients Robert S Dean 1, Nicholas N DePhillipo 2, Michael T Kiely 3, Nicole A Schwery 3, Jill K Monson 3, Robert F LaPrade 1 1
Twin City Orthopedics, 2 Twin City Orthopedics; Oslo Sports Trauma Research Center, 3 Twin City Orthopedics; Training HAUS
Keywords: strength deficit, sports medicine, ligament reconstruction, quadriceps strength, limb length https://doi.org/10.26603/001c.35704
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
BACKGROUND Few existing studies have examined the relationship between lower extremity bone length and quadriceps strength.
PURPOSE/HYPOTHESIS To evaluate the relationship between lower extremity, tibia and femur lengths, and isometric quadriceps strength in patients undergoing knee surgery. The null hypothesis was that there would be no correlation between lower extremity length and isometric quadriceps strength.
STUDY DESIGN Cross-sectional study
METHODS Patients with full-length weightbearing radiographs that underwent isometric quadriceps strength testing after knee surgery were included. Using full-length weightbearing radiographs, limb length was measured from the ASIS to the medial malleolus; femur length was measured from the center of the femoral head to the joint line; tibia length was measured from the center of the plateau to the center of the plafond. Isometric quadriceps strength was measured using an isokinetic dynamometer. Pearson’s correlation coefficient was used to report the correlation between radiographic limb length measurements. A Bonferroni correction was utilized to reduce the probability of a Type 1 error.
RESULTS Forty patients (26 males, 14 females) with an average age of 25.8 years were included. The average limb, femur, and tibia lengths were not significantly different between operative and non-operative limbs (p>0.05). At an average of 5.8±2.5 months postoperatively, the peak torque (156.6 vs. 225.1 Nm), average peak torque (151.6 vs. 216.7 Nm), and peak torque to bodyweight (2.01 vs 2.89 Nm/Kg) were significantly greater in the non-surgical limb (p<0.01). Among ligament reconstructions there was a significant negative correlation between both limb length and strength deficit (r= -0.47, p=0.03) and femur length and strength deficit (r= -0.51, p=0.02). The average strength deficit was 29.6% among the entire study population; the average strength deficit was 37.7% among knee ligament reconstructions. For the non-surgical limb, femur length was significantly correlated with peak torque (r = 0.43, p = 0.048).
a
Corresponding author: Robert F LaPrade, MD, PHD 4010 W. 65th St., Edina, MN 55435 Laprademdphd@gmail.com
a
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients
CONCLUSION Femur length was significantly correlated with the isometric quadriceps peak torque for non-surgical limbs. Additionally, femur length and limb length were found to be negatively correlated with quadriceps strength deficit among ligament reconstruction patients. A combination of morphological features and objective performance metrics should be considered when developing individualized rehabilitation and strength programs.
INTRODUCTION Quadriceps strength is essential in both the healthy and rehabilitating knee, and can be quantified by measuring muscle torque using isometric dynamometry.1–4 The assessment of isolated quadriceps strength serves as an important indicator of recovery and is commonly used in combination with physical performance testing to guide the decision making process for return to sport.5,6 Strength deficits following knee surgery are commonly observed and have been implicated in poorer self-reported function, gait, return to sport, athletic performance, and may lead to the development of osteoarthritis, or secondary injuries.7–15 Previous authors have advocated for minimum thresholds for quadriceps symmetry prior to returning to sport after ACL reconstruction.16,17 A variety of factors contribute to muscular strength, including genetic, developmental, endocrine, and physical activity considerations.18–21 While many of these variables are subject to change throughout one’s adult life, long bone length, and limb length remain relatively stable. Previous studies have reported that there was a significant correlation between both height, weight, and isometric quadriceps strength.22,23 However, the role of bony morphology, specifically lower extremity limb length, has scarcely been evaluated with respect to a relationship with measurements of lower extremity muscular strength. Previous authors have demonstrated that utilization of a tape measure from the anterior superior iliac spine to the medial malleolus demonstrates excellent reliability with limb length measurements compared to anterior-posterior full-length weightbearing radiographs.24 This measurement technique allows for the opportunity to obtain accurate limb length measurements in the clinical setting without necessitating full-length weightbearing radiographs to determine true limb length. Therefore, the purpose of this study was to evaluate the relationship between lower extremity length, including tibia and femur length measured radiographically, and isometric quadriceps strength in patients undergoing knee surgery. The null hypothesis was that there would be no correlation between lower extremity length and isometric quadriceps strength.
METHODS Prior to patient enrollment, the study protocol was approved by an external institutional review board (IRB) through two separate IRB protocols. Consent to participate was obtained for each IRB protocol with in-person documentation. The first IRB protocol considered the collection of lower extremity radiographs at clinic visits (#07.24.2019), while the second IRB protocol considered the collection of
isometric quadriceps strength data in the biomechanical testing facility (#10.21.2019_RL_Complex Knee). Patients from a single knee surgeon’s practice were prospectively enrolled from June 2019 until February 2020. Inclusion criteria included patients from a single knee surgeon’s practice that underwent knee surgery, who were ≥14 years and ≤65 years of age, and who obtained full length anterior-posterior weightbearing radiographs. Patients with ligamentous, meniscal, or cartilage pathologies were included. Additionally, all patients completed performance testing at a single biomechanical testing facility, using the same dynamometer (Biodex Medical Systems, Inc., Shirley, NY). Patients were excluded if they were unable to complete testing, did not obtain full length weightbearing radiographs, radiographs did not visualize the necessary anatomical landmarks (ASIS, medial malleolus, center of the femoral head, roof of the notch, center of the tibial plateau; n=2), patient was unable to bear weight, or had undergone a previous lower extremity osteotomy. Additionally, individual patient limbs were excluded from the non-operative cohort if contralateral autografts were harvested (n=2). All new patients routinely obtained long leg alignment radiographs in the senior author’s practice. Both the injured limb and the non-injured contralateral limb were used for analysis. Quadriceps strength testing was performed at a single timepoint post-operatively; this time-point was six months after ligamentous, meniscal repair, and cartilage surgeries and four months after basic knee arthroscopies.5 Weightbearing status was recorded as either weightbearing or non-weightbearing for the first six weeks following surgical intervention. Patients that underwent revision ligament reconstruction, posterior cruciate ligament reconstruction, osteochondral allograft reconstruction, isolated meniscal repair and transtibial meniscus radial or root repairs were all non-weightbearing. Primary and revision anterior cruciate ligament reconstructions with or without peripheral meniscal repairs, and diagnostic arthroscopies were allowed to weight bear immediately following surgery. RADIOGRAPH MEASUREMENT TECHNIQUE
All radiographic measurements were obtained from full length weightbearing anterior-posterior x-rays. These images were obtained using three to four individual images on a 432 cm x 43.2 cm vertical digital detector. The x-ray beam was centered at the knee at a distance of 182.9 cm. Twentyfive-millimeter sizing balls were utilized to normalize the radiographs for accurate measurements. The beam was angled independently for each shot from the hip to the ankle, with distortion corrected by processing algorithms. The length of the tibia was measured from the center of the tibial plateau, between the middle of the tibial eminences, down to the center of the most distal aspect of
International Journal of Sports Physical Therapy
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients
the tibial plafond. The femur length was measured from the center of the femoral head down to the joint line. Finally, total limb length was measured from the inferior aspect of the anterior superior iliac spine (ASIS) down to the most prominent point of the medial malleolus in a technique that was previously described (Figure 1).25,26 For the assessment of limb length correlation with strength deficit, an average of the surgical and non-surgical limb length was used for analysis. This figure depicts the measurement strategies utilized on full-length weightbearing radiographs. The image on the left (A) demonstrates to full limb length measurement: from the inferior aspect of the ASIS to the most prominent aspect of the medial malleolus. The middle image (B) depicts the measurement technique for the femur: from the center of the femoral head to the trochlea point at the top of the notch. The right image (C) demonstrated the measurement technique for the tibia: from the center of the tibial plateau to the center of the tibial plafond. QUADRICEPS STRENGTH TESTING
Quadriceps strength testing was performed at a single biomechanical testing facility, using the same dynamometer (Biodex Medical Systems, Inc., Shirley, NY) for all patients. Patients were seated on the machine with legs flexed to 90° and their back kept straight. Prior to testing, anatomical landmarks were identified. The operators ensured that the lateral femoral condyle was aligned with the dynamometer’s axis of rotation, and also that the forced arm was secured just superior to the lateral malleolus. Thigh, waist, and two chest straps were used to secure the patient to the chair. This figure demonstrates the setup for quadriceps strength testing on the dynamometer. The subject is seated on the machine with legs flexed to 90° and their back kept straight. Key anatomical landmarks are identified: the lateral femoral condyle is aligned with the dynamometer’s axis of rotation (superior arrow), and the forced arm is secured just superior to the lateral malleolus (inferior arrow). Thigh, waist, and two chest straps were used to secure the patient to the chair. STATISTICAL ANALYSIS
Because the distribution of all included datapoints was deemed to be normally distributed using a Shapiro-Wilk test, descriptive statistics were reported for all included patients using means and standard deviations. To compare values from the injured and non-surgical limbs, paired ttests were utilized. Pearson’s correlation coefficient was used to report the correlation between radiographic limb length measurements (limb, femur, and tibia length) and isometric quadriceps strength variables (peak torque, average peak torque, average peak torque to bodyweight) for both the surgical and non-surgical limb. The following guidelines were used to assess the value of the calculated correlation coefficient (r): little to no relationship (0-0.25), weak relationship (0.25-0.50), moderate to good relationship (0.50-0.75), good to excellent relationship (0.75-1.00).27 All data were analyzed using SPSS Statistics
Figure 1. Limb and Long Bone Measurement Techniques This figure depicts the measurement strategies utilized on full-length weightbearing radiographs. The image on the left (A) demonstrates to full limb length measurement: from the inferior aspect of the ASIS to the most prominent aspect of the medial malleolus. The middle image (B) depicts the measurement technique for the femur: from the center of the femoral head to the trochlea point at the top of the notch. The right image (C) demonstrated the measurement technique for the tibia: from the center of the tibial plateau to the center of the tibial plafond.
(v24; IBM), with an alpha <0.05 for statistical significance. For the correlation analysis, post-hoc testing was applied using a Bonferroni correction to reduce the probability of a type I error. The power of the current analysis was determined post hoc using the correlation coefficient of the average femur length and the surgical limb population of 40 patients. Assuming an alpha level of 0.05, it was determined that the current study achieved sufficient power (ß=81%).
RESULTS Sixty-five patients met the inclusion and exclusion criteria within the prospective enrollment period. A total of 40 patients (26 males, 14 females), with an average age of 25.8 ± 11.7 years, met the inclusion and exclusion criteria and were included in the final analysis. The average BMI of the study population was 23.9 ± 2.4 kg/m2. Two patients’ nonsurgical limb data were excluded from analysis due to patellar tendon graft harvest for a contralateral ligament reconstruction, leaving 38 knees in the non-surgical cohort. Among patients included in the final analysis, 24 had a ligamentous reconstruction procedure, six had cartilage transplant procedures, seven had isolated meniscus repairs, and three had knee arthroscopies. Isometric quadriceps strength data were collected on all patients from both their surgical limb (n=40) and non-surgical limb (n=38) in the same clinical visit at an average of 5.8 ± 2.5 months (range, 3.5-15.1 months) postoperatively. The surgical limb demonstrated significantly lower
International Journal of Sports Physical Therapy
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients
Table 1. Radiographic limb measurements in centimeters. Injured (n=40)
Non-Surgical (n=38)
p- value
Limb Length, cm ± SD
102.3 ± 6.2
102.5 ± 6.1
0.90
Femur Length, cm ± SD
49.1 ± 3.0
49.0 ± 2.7
0.99
Tibia Length, cm ± SD
40.5 ± 2.8
40.7 ± 2.9
0.81
SD: standard deviation. Cm: centimeters
Table 2. Strength testing variables based upon limb injury status Injured
Non-surgical
P value
Peak Torque, Nm ± SD
156.6 ± 68.2
225.1 ± 79.0
<0.01*
Ave. Peak Torque, Nm ± SD
151.6 ± 66.1
216.7 ± 74.9
<0.01*
Ave Peak Torque/Bodyweight, Nm/kg ± SD
2.0 ± 0.7
2.9 ± 0.7
<0.01*
Peak Torque Deficit (percentage)
29.6 ± 21.1
N/A
N/A
N: Newtons; m: meters; kg: kilograms; SD: standard deviation. *Indicates statistically significant difference (p < 0.05).
Table 3. Correlations between lower extremity bone length and included quadriceps strength metrics for entire study population. Independent Variable
Dependent Variable
Surgical, Pearson’s correlation coefficient
Surgical, p-values
Nonsurgical, Pearson’s correlation coefficient
Nonsurgical, p-values
Tibia Length
Peak Torque (Nm ± SD)
0.33
0.475
0.321
0.617
Femur Length
Peak Torque (Nm ± SD)
0.37
0.237
0.433
0.048*
Limb Length
Peak Torque (Nm ± SD)
0.36
0.238
0.390
0.14
Tibia Length
Strength Deficit
-0.19
0.99
N/A
N/A
Femur Length
Strength Deficit
-0.12
0.99
N/A
N/A
Limb Length
Strength Deficit
-0.17
0.99
N/A
N/A
N: Newtons; m: meters; kg: kilograms; SD: standard deviation. *Indicates statistically significant difference (p < 0.05). A Bonferroni correction was utilized.
peak torque, average peak torque, and average peak torque to bodyweight compared to the non-surgical limbs (p<0.001). The average strength deficit of the surgical limb compared to the non-surgical limb during strength testing was 29.6% ± 21.1% (Table 2). RELATIONSHIP BETWEEN BONE LENGTHS AND QUADRICEPS STRENGTH
Femur length in the non-surgical limb was significantly correlated with each of the quadriceps strength metrics considered: peak torque (r=0.43, p=0.048). Tibia length and limb length were not found to be significantly correlated with peak torque (r=0.32, 0.39 respectively, p>0.05). When the surgical limb was considered, femur length (r=0.37), limb length (r=0.36), and tibia length (r=0.33) were not significantly correlated with peak torque (p>0.05) (Table 3).
Among ligament reconstructions that did not utilize the contralateral patellar tendon for reconstruction (n=22), there was a significant negative correlation between both limb length and strength deficit (r= -0.47, p=0.03) and femur length and strength deficit (r= -0.51, p=0.02). There was not a significant correlation with tibia length and strength deficit (r= -0.35, corrected p=0.18).
DISCUSSION The most important finding of this study was that femur length was significantly correlated with quadriceps strength for the non-surgical limb. Additionally, among knees that underwent ligament reconstructions, there was a significant negative correlation between both lower limb and femur length, and isometric quadriceps strength deficit. This novel approach of an anthropometric specific normaliza-
International Journal of Sports Physical Therapy
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients
tion of strength values may assist in the development of performance standards following surgical intervention. These findings shed light on specific bony morphological features that may influence strength variables measured clinically and could assist in optimizing and individualizing exercise prescriptions. Physical therapists and surgeons may use the findings in the current study to individualize goal setting based on patient morphology as it relates to strength recovery and guidelines for return to activity and sport following knee surgery. While femur length was significantly correlated with quadriceps strength metrics for the non-surgical limb, after the use of the Bonferroni correction the current authors were unable to reject the null hypothesis, with respect to limb length and tibia length for either the surgical or nonsurgical limbs. Bolz et al.28 found that in eight patients with limb length discrepancies (defined in their study as > 5 mm in side-to-side difference between limbs), the shorter limb was consistently weaker with respect to knee flexion and extension strength. In addition, Hamzat et al. demonstrated a significant relationship between patient height and quadriceps strength in healthy individuals in a pilot study.23 Multiple authors have also reported that local muscle volume is significantly correlated to isometric strength.29–31 The current study was limited to measures of static bone length and the relationship with isometric quadriceps muscle torque. The current authors did not perform additional imaging to measure muscular length or calculate cross-sectional volume, so the current authors cannot extrapolate our findings to corroborate results from previous studies examining the relationship between total muscle volume and strength. However, the current study does report that femur length was statistically significantly correlated with peak torque in non-surgical limbs and that length is a contributing factor to isometric muscle strength. A significant negative correlation was identified between both overall lower limb and femur length and isometric quadriceps strength deficit between the surgical and nonsurgical limbs at an average of 5.8 months postoperatively, among knees that underwent ligament reconstructions. This may suggest that patients with longer limbs are either quicker to recover quadriceps strength symmetry or are able to retain a greater percentage of their pre-operative strength following ligament reconstruction. Additionally, femur length was significantly negatively correlated with strength deficit, while tibia length was not. While this is the first known study to consider the association of limb and bone length on strength deficit following ligament reconstruction surgery, this correlation may help inform expectations for rehabilitation timeframes. Traditionally, quadriceps strength is normalized to account for patient body weight,32–34 as was performed in the current study. However, because peak torque was shown to be significantly correlated to femur length in non-surgical limbs, it may be reasonable to add additional normalization protocols to account for an individual’s long bone length when considering isometric quadriceps strength. This suggestion was not supported by the analysis from Qazi et al.25 who found that although tibia and femur length were significantly correlated with leg extension strength, height alone is the preferred anthropometric measure for adjusting mus-
Figure 2. Strength Testing on the Dynamometer This figure demonstrates the setup for quadriceps strength testing on the dynamometer. The subject is seated on the machine with legs flexed to 90° and their back kept straight. Key anatomical landmarks are identified: the lateral femoral condyle is aligned with the dynamometer’s axis of rotation (superior arrow), and the forced arm is secured just superior to the lateral malleolus (inferior arrow). Thigh, waist, and two chest straps were used to secure the patient to the chair.
cle mass and strength. However, it should be noted that the measurement techniques in Qazi et al.25 used the greater trochanter as the superior margin of the femur measurement, which fails to account for the full length of the quadriceps muscles. The literature would benefit from further analysis considering a universal method of normalization of isometric strength data based upon femur and/ or extremity length and could look to the present study as a pilot for future reference. This further normalization could improve knee surgeons’ and therapists’ understanding of both post-surgical rehabilitation and also the effectiveness of strength training protocols, particularly when formal biomechanical testing is not available. This study was not without limitations. First, the current authors acknowledge that full-length weightbearing radiographs may not be routinely available for all patients seen in a physical therapy clinic, and as such, the tibia and femur measurement techniques may be difficult to reproduce manually. Second, the relatively low sample size from a single surgeon’s practice may limit the external validity of the testing results including strength metrics which may be related to surgical recovery and other confounding variables (e.g. pain, swelling, arthrogenic muscle inhibition). Additionally, despite the fact that this sample size was determined to achieve sufficient power (ß=81%) on post hoc analysis, the current authors unable to perform a power analysis a priori. Third, the variability in the postsurgical follow-up period may contribute to differences in surgical limb strength. However, this study attempted to control for
International Journal of Sports Physical Therapy
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients
confounding variables as all patients were recruited from the same surgeon’s clinical practice, and all quadriceps strength data was collected by the same clinicians using the same instruments.
ligament reconstruction patients. A combination of morphological features and objective performance metrics should be considered when developing individualized rehabilitation and strength programs
CONCLUSION Femur length was significantly correlated with the isometric quadriceps peak torque for non-surgical limbs. Additionally, femur length and limb length were found to be negatively correlated with quadriceps strength deficit among
CONFLICTS OF INTEREST STATEMENT
The authors report no conflicts of interest. Submitted: March 24, 2021 CDT, Accepted: March 24, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients
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2. Goetschius J, Kuenze CM, Hart JM. Knee extension torque variability after exercise in ACL reconstructed knees. J Orthop Res. 2015;33(8):1165-1170.
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3. Petersen W, Taheri P, Forkel P, Zantop T. Return to play following ACL reconstruction: a systematic review about strength deficits. Arch Orthop Trauma Surg. 2014;134(10):1417-1428. doi:10.1007/s00402-01 4-1992-x 4. Lepley LK. Deficits in quadriceps strength and patient-oriented outcomes at return to activity after ACL reconstruction: a review of the current literature. Sports Health. 2015;7(3):231-238. doi:10.1177/194173 8115578112 5. Monson J, Schoenecker J, Schwery N, Palmer J, Rodriguez A, LaPrade RF. Postoperative rehabilitation and return to sport following multiligament knee reconstruction. Arthrosc Sports Med Rehabil. 2022;4(1):e29-e40. doi:10.1016/j.asmr.2021.08.020 6. Burgi CR, Peters S, Ardern CL, et al. Which criteria are used to clear patients to return to sport after primary ACL reconstruction? A scoping review. Br J Sports Med. 2019;53(18):1154-1161. doi:10.1136/bjsp orts-2018-099982 7. Alnahdi AH, Zeni JA, Snyder-Mackler L. Muscle impairments in patients with knee osteoarthritis. Sports Health. 2012;4(4):284-292. doi:10.1177/194173 8112445726 8. Ericsson YB, Roos EM, Frobell RB. Lower extremity performance following ACL rehabilitation in the KANON-trial: Impact of reconstruction and predictive value at 2 and 5 years. Br J Sports Med. 2013;47(15):980-985. doi:10.1136/bjsports-2013-0926 42 9. Farrokhi S, O’Connell M, Fitzgerald GK. Altered gait biomechanics and increased knee-specific impairments in patients with coexisting tibiofemoral and patellofemoral osteoarthritis. Gait Posture. 2015;41(1):81-85. doi:10.1016/j.gaitpost.2014.08.014
12. Hart JM, Pietrosimone B, Hertel J, Ingersoll CD. Quadriceps activation following knee injuries: a systematic review. J Athl Train. 2010;45(1):87-97. do i:10.4085/1062-6050-45.1.87 13. Lisee C, Lepley AS, Birchmeier T, O’Hagan K, Kuenze C. Quadriceps strength and volitional activation after anterior cruciate ligament reconstruction: a systematic review and metaanalysis. Sports Health. 2019;11(2):163-179. doi:10.11 77/1941738118822739 14. Omori G, Narumi K, Nishino K, et al. Association of mechanical factors with medial knee osteoarthritis: a cross-sectional study from Matsudai Knee Osteoarthritis Survey. J Orthop Sci. 2016;21(4):463-468. doi:10.1016/j.jos.2016.03.006 15. Petersen W, Taheri P, Forkel P, Zantop T. Return to play following ACL reconstruction: a systematic review about strength deficits. Arch Orthop Trauma Surg. 2014;134(10):1417-1428. doi:10.1007/s00402-01 4-1992-x 16. Adams D, Logerstedt D, Hunter-Giordano A, Axe MJ, Snyder-Mackler L. Current concepts for anterior cruciate ligament reconstruction: a criterion-based rehabilitation progression. J Orthop Sports Phys Ther. 2012;42(7):601-614. doi:10.2519/jospt.2012.3871 17. Thomeé R, Kaplan Y, Kvist J, et al. Muscle strength and hop performance criteria prior to return to sports after ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2011;19(11):1798-1805. doi:10.1007/s0016 7-011-1669-8 18. Edwards MH, Gregson CL, Patel HP, et al. Muscle size, strength, and physical performance and their associations with bone structure in the Hertfordshire Cohort Study. J Bone Miner Res. 2013;28(11):2295-2304. doi:10.1002/jbmr.1972
International Journal of Sports Physical Therapy
Femur Length is Correlated with Isometric Quadriceps Strength in Post-Operative Patients
19. Gómez-Cabello A, Ara I, González-Agüero A, Casajús JA, Vicente-Rodríguez G. Effects of training on bone mass in older adults: a systematic review. Sports Med. 2012;42(4):301-325. doi:10.2165/1159767 0-000000000-00000 20. Karasik D, Kiel DP. Genetics of the musculoskeletal system: a pleiotropic approach. J Bone Miner Res. 2008;23(6):788-802. doi:10.1359/jbm r.080218 21. Plisky PJ, Rauh MJ, Kaminski TW, Underwood FB. Star excursion balance test as a predictor of lower extremity injury in high school basketball players. J Orthop Sports Phys Ther. 2006;36(12):911-919. doi:1 0.2519/jospt.2006.2244 22. Andrews AW, Thomas MW, Bohannon RW. Normative values for isometric muscle force measurements obtained with hand-held dynamometers. Phys Ther. 1996;76(3):248-259. doi:1 0.1093/ptj/76.3.248 23. Hamzat TK. Physical characteristics as predictors of quadriceps muscle isometric strength: a pilot study. Afr J Med Med Sci. 2001;30(3):179-181. 24. Gogia PP, Braatz JH. Validity and reliability of leg length measurements. J Orthop Sports Phys Ther. 1986;8(4):185-188. doi:10.2519/jospt.1986.8.4.185 25. Qazi SL, Rikkonen T, Kröger H, et al. Relationship of body anthropometric measures with skeletal muscle mass and strength in a reference cohort of young finnish women. J Musculoskelet Neuronal Interact. 2017;17(3):192-196. 26. Sabharwal S, Kumar A. Methods for assessing leg length discrepancy. Clin Orthop Relat Res. 2008;466(12):2910-2922. doi:10.1007/s11999-008-05 24-9
27. Portney LG, Watkins MP. Foundations of Clinical Research: Applications to Practice. Pearson/Prentice Hall; 2015. 28. Bolz S, Davies GJ. Leg length differences and correlation with total leg strength. J Orthop Sports Phys Ther. 1984;6(2):123-129. doi:10.2519/jospt.198 4.6.2.123 29. Bajaj D, Allerton BM, Kirby JT, et al. Muscle volume is related to trabecular and cortical bone architecture in typically developing children. Bone. 2015;81:217-227. doi:10.1016/j.bone.2015.07.014 30. Beck B, Middleton KJ, Billing DC, Caldwell JN, Carstairs GL. Understanding anthropometric characteristics associated with performance in manual lifting tasks. J Strength Cond Res. 2019;33(3):755-761. doi:10.1519/jsc.00000000000021 13 31. Fukunaga T, Miyatani M, Tachi M, Kouzaki M, Kawakami Y, Kanehisa H. Muscle volume is a major determinant of joint torque in humans. Acta Physiol Scand. 2001;172(4):249-255. doi:10.1046/j.1365-201 x.2001.00867.x 32. Nimphius S, McBride JM, Rice PE, et al. Comparison of quadriceps and hamstring muscle activity during an isometric squat between strengthmatched men and women. J Sport Sci Med. 2019;18(1):101-108. 33. Shultz SJ, Nguyen AD, Leonard MD, Schmitz RJ. Thigh strength and activation as predictors of knee biomechanics during a drop jump task. Med Sci Sports Exerc. 2009;41(4):857-866. doi:10.1249/mss.0b013e31 81e3b3f 34. Suchomel TJ, Nimphius S, Stone MH. Scaling isometric mid-thigh pull maximum strength in division I Athletes: are we meeting the assumptions? Sports Biomech. 2018;19(4):532-546. doi:10.1080/147 63141.2018.1498910
International Journal of Sports Physical Therapy
Torrente QM, Killingback A, Robertson C, Adds PJ. The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in Athletic Male Individuals: An Ultrasound Investigation. IJSPT. 2022;17(4):636-642.
Original Research
The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in Athletic Male Individuals: An Ultrasound Investigation Queenie Mae Torrente 1, Alban Killingback 2, Claire Robertson 3, Philip J Adds 1 1
a
Anatomy, St George's, University of London, 2 Medical Physics, St George's Hospital NHS Trust, 3 Physiotherapy, Wimbledon Clinics
Keywords: Patellofemoral pain, physiotherapy, self-myofascial release, ultrasound, vastus lateralis, vastus medialis oblique https://doi.org/10.26603/001c.35591
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Maintenance of patellar stability requires a balance between the vastus medialis oblique (VMO) and the vastus lateralis (VL). The imbalance between these muscles is thought to be implicated in the etiology of patellofemoral pain (PFP). Where there is hypertrophy of the VL in PFP patients, self-myofascial release (SMR) may be utilized for its management. However, there is no current evidence regarding SMR and its effects on VMO and VL architecture. The aim of this study, therefore, was to use ultrasound to gain further understanding of the effects of a program of SMR on the fiber angles of the VMO and VL.
Hypothesis There will be a significant decrease in the pennation angles of the VMO and VL after seven weeks of SMR using a foam roller.
Study Design Cohort Study
Methods Twenty-five young, athletic, male participants were recruited to use a foam roller, along the full length of both anterior thighs, three times weekly, on three separate days, for seven weeks. Ultrasound was used to determine the initial and final VMO and VL pennation angles on both limbs. One eligible participant was chosen as an intra-rater control and did not partake in the SMR regimen.
Results There was a statistically significant (p < 0.001) decrease in the pennation angles of the VMO and VL after the SMR regime. Mean combined right and left VL angle change was -6.65° (-18% mean change) and the mean combined right and left VMO angle change was -7.65° (-11.5% mean change). A weak negative correlation was found between initial VMO fiber angle and the angle change (Rsquared = -0.21), as well as moderate negative correlation for the VL (Rsquared = -0.51).
Conclusion A program of SMR on the anterior thighs of young, asymptomatic males resulted in changes to the fiber angles of both the VMO and VL. There was a significant decrease in pennation angle after seven weeks of SMR using a foam roller.
a
Corresponding author: Philip J Adds St George’s, University of London, Cranmer Terrace, London, SW17 0RE, United Kingdom philadds.anatomy@gmail.com
The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in...
INTRODUCTION
MATERIALS AND METHODS
The vastus medialis (VM) and vastus lateralis (VL) form part of the quadriceps femoris group in the anterior thigh. A balance between these two muscles is key to maintaining normal tracking of the patella in the trochlear groove during flexion and extension of the knee joint.1,2 The vastus medialis is located in the medial part of the thigh, and, though controversial, is generally agreed to consist of two components: the more proximal vastus medialis longus (VML) and the distal vastus medialis oblique (VMO).3–5 The VMO inserts at the medial border of the patella. Like the VM, the VL is also considered to comprise two components: the vastus lateralis oblique (VLO) and vastus lateralis longus (VLL)6–8 due to differences in their muscle fiber orientations. The VLO is analogous to the VMO in that it is orientated more horizontally at the patella.6,9 While the VMO has been the subject of much research interest, there is less in the literature regarding the VL. However, studies have been carried out, particularly using electromyography, investigating both the VMO and the VL10–13 and their respective roles in maintaining patellar alignment both in normal individuals, and in patients presenting with patellofemoral pain (PFP). The etiology of patellofemoral pain is known to be multifactorial14 and may be due to pathology or abnormalities in the regional anatomy,15 regional myofascial restrictions,16 or an imbalance between the contraction of the VMO and the VL, resulting in patellar maltracking.17 The condition is most prevalent in young, athletic individuals, with females being more affected than males.18 Treatment options for PFP include physiotherapy aimed at strengthening the VM, where VMO insufficiency is implicated, stretching exercises targeting the VL in cases of VL hypertrophy, or myofascial release where myofascial restrictions are identified.16 Previous studies have shown that it is possible to manipulate the pennation angle of the VMO and VL, either increasing the fiber angle with targeted exercises19,20 or reducing the angle by stretching,21 which has obvious implications for patellar tracking. Self-myofascial release (SMR) is a technique to reduce fascial tightening by stretching it. It is commonly performed by using a roller to apply sustained pressure to the muscle. Studies on SMR have found that foam rolling increases joint range of motion (ROM) and reduces delayed onset muscle soreness before and after exercise.22–24 There is, however, a paucity of information in the literature regarding its effect on muscle architecture. Indeed, while acknowledging the effectiveness of SMR for increasing joint range of motion, Cornell & Ebersoll25 recommended the use of ultrasound to further investigate the changes brought about by acute SMR. The aim of this study, therefore, was to explore the effects of SMR by investigating changes in the fiber angles of the VMO and VL following a seven-week program of SMR using a foam roller. Ultrasound is a safe, validated, non-invasive technique that has been used extensively to investigate the architecture of the hamstrings26 and quadriceps.19,27–30
This study received ethical approval from St George’s, University of London Ethics Committee. Participants were recruited from the University sports and athletics teams. Twenty-five young, athletic males volunteered and gave informed consent. A power calculation showed that a minimum group size of twenty-three would be needed to achieve statistical significance. Inclusion criteria were: male, age 18-35, no current knee pathology, no previous knee surgery, and a Tegner activity score ≥4.31 Using a male-only cohort provided a homogeneous sample, removing the confounding factor of sex difference. Males also have less subcutaneous fat,32 improving echogenicity of the muscle underneath.33 The volunteers underwent an initial ultrasound scan of the VMO and VL, then undertook a seven-week program of SMR, and were then re-scanned. One individual was selected at random for the intra-rater reliability study. This individual did not take part in the SMR program, and was scanned by the same operator, using the same ultrasound method, on eight different occasions during the study period. The subjects lay supine on an examination couch, with a pillow under the ankles for support. The mid-point of the patella was found using Duratool digital calipers (Duratool Corporation, Taichung City, Taiwan) and marked. A steel ruler was placed between the mid-point of the patella and the ASIS, and the femoral axis was then marked on the skin (Fig. 1a). The pennation angles of the VMO and VL were then measured on both lower limbs in turn (Fig. 1b), using a Philips iU22 ultrasound scanner with a L17-5 linear array probe (Fig. 1c). All measurements were taken by the same operator, using the same equipment. Measurements were taken three times, then averaged. Following the initial scan, volunteers commenced the seven-week SMR procedure using a 15 cm x 45 cm foam roller (PhysioRoom.Com Limited, Burnley, UK). The foam roller was to be used three times weekly, on three separate days, independent of exercise. The roller was placed under the proximal aspect of the anterior thigh while the subject was in the prone position with elbows on the ground. The contralateral limb was placed on top of the other limb (Fig. 2). Using their elbows, the subject then pushed himself back and forth so that the foam roller moved along the length of the anterior aspect of the thigh, from the top of the thigh to the upper border of the patella. Each motion was to be completed in no more than two seconds. This procedure was performed for one minute, and then repeated on the other thigh. A compliance diary was provided to monitor the subject’s activities. On completion of the seven-week SMR program, the ultrasound scans were repeated.
RESULTS INTRA-RATER RELIABILITY STUDY
The results of the intra-rater reliability study indicate good overall reliability of the measurements (Table 1). There was a substantial difference in the fiber angle of the VMO and
International Journal of Sports Physical Therapy
The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in...
Table 1. Intra-rater reliability study. Mean fiber angle, standard deviation (SD), coefficient of variance (CV) Mean°
SD
Coefficient of variation
Right VMO angle
64.6
±2.8
0.043
Left VMO angle
63.0
±2.7
0.043
Right VL angle
35.3
±4.3
0.122
Left VL angle
32.3
±2.5
0.077
Table 2. Mean change, standard deviation (SD) and range of right and left VMO fiber angles following sevenweek SMR program Mean (°)
Mean % change
SD
Range
p-value
Right VMO angle change
-7°
-10%
±9.72
-20 to 12
p < 0.001
Left VMO angle change
-8.22°
-13%
±8.22
-24 to 13
p < 0.001
Combined right and left VMO angle change
-7.65°
-11.5%
±10.16
-24 to 13
p < 0.001
Table 3. Mean change, standard deviation (SD) and range of right and left VL fiber angles following seven-week SMR program Mean (°)
Mean % change
SD
Range
p-value
Right VL angle change
-6.58
-17%
±5.58
-25 – 3
p < 0.001
Left VL angle change
-6.71
-19%
±5.45
-15 – 1
p < 0.001
Combined right and left VL angle change
-6.65
-18%
±5.56
-25 – 1
p < 0.001
the VL. The mean fiber angle of the combined right and left VMO was 63.8°, and the mean fiber angle of the combined right and left VL was 33.8°. After seven weeks of SMR, there was a significant decrease of 7.0° (±9.73) and 8.21° (±10.53) in the pennation angles of the right and left VMO, respectively (p<0.001) (Table 2). After seven weeks of SMR there was a significant decrease of 6.58° (±5.58) and 6.71° (±5.45) in the pennation angles of the right and left VL, respectively (p<0.001) (Table 3). There was a weak and non-significant inverse correlation between mean initial combined left and right VMO fiber angle and VMO fiber angle change after seven weeks of SMR (Rsquared = -0.2104, p=0.15) (Fig. 3). There was a stronger inverse correlation between mean initial combined VL fiber angle and VL fiber angle change (Rsquared = -0.5115, p<0.001) (Fig. 4). The average compliance recorded by the participants was 82%, i.e., the SMR was carried out on average 2.46 times per week by each participant.
DISCUSSION Patellar maltracking due to an imbalance between the VMO and VL is thought to be a contributor to the etiology of PFP.2,15 There is a high prevalence of PFP (also known as ‘runner’s knee’) among young athletic individuals, where the problem may be due to VMO insufficiency or a hypertrophied VL. Where myofascial tightness in the anterior thigh is suspected, SMR may be recommended in order to im-
Figure 1. The femoral axis was marked on the skin (a); VMO and VL fibre angles were identified and marked (b), using the ultrasound image (c)
prove flexibility and increase range of motion of the knee and hip.16 While several studies have shown that SMR improves joint range of motion, vascular endothelial function, flex-
International Journal of Sports Physical Therapy
The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in...
ibility, and delayed onset muscle soreness (DOMS) in athletic individuals,22,34,35 there is currently no information in the literature on the effect of SMR on the architecture of the VMO or VL, either in in asymptomatic individuals, or in patients presenting with PFP. The study reported here has shown that seven weeks of SMR using a foam roller resulted in a statistically significant reduction (p<0.001) in the pennation angles of the VMO and VL in both lower limbs. There was a greater overall percentage change for the VL (-18%) than the VMO (-11.5%), which tends to suggest that the SMR had a greater effect on the architecture of the VL than that of the VMO. This may have been due to the fact that the VL extends further along the length of the anterior thigh than does the VM, and hence was affected more by the SMR, because the subjects were required to roll from the top of the thigh down to the top of the knee. Although the subjects in this study were all asymptomatic, they were drawn from the demographic at high risk of developing PFP. The architectural changes to the VMO and VL provides clinical evidence that SMR could be effective in myofascial release in young athletic males presenting with PFP. Furthermore, a patient’s progress could be easily monitored in clinic by ultrasound scans using the method described here. However, it should be borne in mind that the subjects in this study were all asymptomatic, and, while the results were statistically significant, the clinical significance of these results is not clear: further work is needed to assess the effects of SMR on muscle architecture in patients presenting with PFP. Interestingly, there was only a weak negative correlation between the initial VMO fiber angle and the degree of change in VMO fiber angle (Rsquared = -0.21), suggesting that the initial VMO fiber angle is relatively unimportant in the likely outcome of the treatment. This is in contrast with exercises to strengthen the VMO, where a low initial fiber angle has been shown to be predictive of a greater increase in post-exercise fiber angle.31 There was a stronger negative correlation between initial VL fiber angle and change (Rsquared= -0.51), which suggests that, in cases of VL hypertrophy, patients who would benefit most from SMR might be identified in clinic by a preliminary ultrasound scan. There are some limitations to note in this study. Although volunteers were provided with a compliance diary to encourage participation, there was inevitably some variation in actual compliance. Some volunteers found initial use of the foam roller to be painful, which affected their compliance. Also, as the volunteers all took part in sports activities, some may have performed other quadriceps stretches throughout the seven-week period, which could have affected the fiber angles. Participants of this study all took part in various sports and exercise with differing levels of intensity (basketball, rugby, athletics, and cycling), which could have affected the outcomes. It would be useful to repeat this study on individuals who all participate in the same sport.
Figure 2. Roller method: the subject moved himself backwards and forwards on his elbows for one minute on each lower limb
CONCLUSION The results of this study indicate that seven weeks of SMR using a foam roller resulted in a statistically significant decrease the pennation angles of the VMO and VL in both limbs. There was, however, a greater percentage decrease in the angle of the VL. There was a moderate negative correlation between initial VL fiber angle and fiber angle change. These findings may provide information to help guide physiotherapy interventions for patients presenting with anterior knee pain.
ACKNOWLEDGEMENTS
The authors confirm that they have no conflicts of interest to declare. The study was internally funded by St George’s, University of London. Submitted: November 13, 2021 CDT, Accepted: January 23, 2022 CDT
International Journal of Sports Physical Therapy
The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in...
Figure 3. Scatter plot showing the relationship between the combined initial VMO fiber angle vs VMO fiber angle change after seven weeks of SMR
Figure 4. Scatter plot showing the relationship between the combined initial VL fiber angle vs VL fiber angle change after seven weeks of SMR
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in...
REFERENCES 1. Weinstabl R, Scharf W, Firbas W. The extensor apparatus of the knee joint and its peripheral vasti: anatomic investigation and clinical relevance. Surg Radiol Anat. 1989;11(1):17-22. doi:10.1007/bf0210223 9 2. Amis AA. Current concepts of anatomy and biomechanical of patellar stability. Sports Med Arthrosc Rev. 2007;15(2):48-56. doi:10.1097/jsa.0b013 e318053eb74 3. Lieb FJ, Perry J. Quadriceps function. An anatomical and mechanical study using amputated limbs. J Bone Joint Surg Am. 1968;50(8):1535-1548. do i:10.2106/00004623-196850080-00003 4. Smith TO, Nichols R, Harle D, Donell ST. Do the vastus medialis obliquus and vastus medialis longus really exist? A systematic review. Clin Anat. 2009;22(2):183-199. doi:10.1002/ca.20737 5. Skinner EJ, Adds PJ. Vastus medialis: a reappraisal of VMO and VML. J Phys Ther Sci. 2012;24(6):475-479. doi:10.1589/jpts.24.475 6. Hallisey MJ, Doherty N, Bennett WF, Fulkerson JP. Anatomy of the junction of the vastus lateralis tendon and the patella. J Bone Joint Surg Am. 1987;69(4):545-549. doi:10.2106/00004623-19876904 0-00011 7. Bennett WF, Doherty N, Hallisey MJ, Fulkerson JP. Insertion orientation of terminal vastus lateralis obliquus and vastus medialis obliquus muscle fibers in human knees. Clin Anat. 1993;6(3):129-134. doi:1 0.1002/ca.980060302 8. Bevilaqua-Grossi D, Monteiro-Pedro V, da Cunha Sousa G, Silva Z, Berzin F. Contribution to the anatomical study of the oblique portion of the vastus lateralis muscle. Braz J Morphol Sci. 2004;21:47-52. 9. Bose K, Kanagasuntheram R, Osman MBH. Vastus medialis oblique: an anatomic and physiologic study. Orthopedics. 1980;3(9):880-883. doi:10.3928/0147-74 47-19800901-12 10. Reynolds L, Levin TA, Medeiros JM, Adler NS, Hallum A. EMG activity of the vastus medialis oblique and the vastus lateralis in their role in patellar alignment. Am J Phys Med. 1983;62:61-70.
11. Santos EP, Bessa SNF, Lins CAA, Marinho AMF, Silva KMP, Brasileiro JS. Electromyographic activity of vastus medialis obliquus and vastus lateralis muscles during functional activities in subjects with patellofemoral pain syndrome. Braz J Phys Ther. 2008;12(4):304-310. doi:10.1590/s1413-35552008000 400009 12. Cowan SM, Bennell KL, Hodges PW, Crossley KM, McConnell J. Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome. Arch Phys Med Rehab. 2001;82(2):183-189. doi:10.1053/apmr.2001.19022 13. Tang SFT, Chen CK, Hsu R, Chou SW, Hong WH, Lew HL. Vastus medialis obliquus and vastus lateralis activity in open and closed kinetic chain exercises in patients with patellofemoral pain syndrome: an electromyographic study. Arch Phys Med Rehab. 2001;82(10):1441-1445. doi:10.1053/apmr.2001.2625 2 14. Thomeé R, Augustsson J, Karlsson J. Patellofemoral pain syndrome: a review of current issues. Sports Med. 1999;28(4):245-262. doi:10.2165/0 0007256-199928040-00003 15. Waryasz GR, McDermott AY. Patellofemoral pain syndrome (PFPS): a systematic review of anatomy and potential risk factors. Dyn Med. 2008;7(1):9. doi:10.11 86/1476-5918-7-9 16. Mullaney MJ, Fukunaga T. Current concepts and treatment of patellofemoral compressive issues. Int J Sports Phys Ther. 2016;11:891-902. 17. Chiu JKW, Wong YM, Yung PSH, Ng GYF. The effects of quadriceps strengthening on pain, function, and patellofemoral joint contact area in persons with patellofemoral pain. Am J Phys Med Rehab. 2012;91(2):98-106. doi:10.1097/phm.0b013e318228c5 05 18. Boling M, Padua D, Marshall S, Guskiewicz K, Pyne S, Beutler A. Gender differences in the incidence and prevalence of patellofemoral pain syndrome. Scand J Med Sci Sport. 2010;20(5):725-730. doi:10.111 1/j.1600-0838.2009.00996.x 19. Khoshkhoo M, Killingback A, Robertson CJ, Adds PJ. The effect of exercise on vastus medialis oblique muscle architecture: an ultrasound investigation. Clin Anat. 2016;29(6):752-758. doi:10.1002/ca.22710
International Journal of Sports Physical Therapy
The Effect of Self-Myofascial Release on the Pennation Angle of the Vastus Medialis Oblique and the Vastus Lateralis in...
20. Hilal Z, Robertson CJ, Killingback A, Adds PJ. The effect of exercise and electrical muscle stimulation on the architecture of the vastus medialis oblique - the ‘Empi’ electrotherapy system. Glob J Ortho Res. 2018;1(1). doi:10.33552/gjor.2018.01.000503
28. Engelina S, Antonios T, Robertson CJ, Killingback A, Adds PJ. Ultrasound investigation of vastus medialis oblique muscle architecture: an in vivo study. Clin Anat. 2014;27(7):1076-1084. doi:10.1002/c a.22413
21. Bethel J, Killingback A, Robertson C, Adds PJ. The effect of stretching exercises on the fibre angle of the vastus lateralis and vastus medialis oblique: an ultrasound study. J Phys Ther Sci. 2022;34(2):161-166. doi:10.1589/jpts.34.161
29. Engelina S, Robertson CJ, Moggridge J, Killingback A, Adds P. Using ultrasound to measure the fibre angle of vastus medialis oblique: a cadaveric validation study. Knee. 2014;21(1):107-111. doi:10.10 16/j.knee.2012.07.001
22. Macdonald GZ, Penney MDH, Mullaley ME, et al. An acute bout of self-myofascial release increases range of motion without a subsequent decrease in muscle activation or force. J Strength Cond Res. 2013;27(3):812-821. doi:10.1519/jsc.0b013e31825c2b c1
30. Benjafield AJ, Killingback A, Robertson CJ, Adds PJ. An investigation into the architecture of the vastus medialis oblique muscle in athletic and sedentary individuals: an in vivo ultrasound study. Clin Anat. 2015;28(2):262-268. doi:10.1002/ca.22457
23. Cheatham SW, Kolber MJ, Cain M, Lee M. The effects of self-myofascial release using a foam roller or roller massager on joint range of motion, muscle recovery, and performance: a systematic review. Int J Sports Phys Ther. 2015;10:827-838. 24. Schroeder AN, Best TM. Is self-myofascial release an effective pre-exercise? a literature review. Curr Sports Med Rep. 2015;14(3):200-208. doi:10.1249/jsr.0 000000000000148 25. Cornell DJ, Ebersole KT. Influence of an acute bout of self-myofascial release on knee extension force output and electro-mechanical activation of the quadriceps. Intl J Sports Phys Ther. 2020;15(5):732-743. doi:10.26603/ijspt20200732 26. Gérard R, Gojon L, Decleve P, Van Cant J. The effects of eccentric training on biceps femoris architecture and strength: a systematic review with meta-analysis. J Athl Train. 2020;55(5):501-514. doi:1 0.4085/1062-6050-194-19 27. Rutherford OM, Jones DA. Measurement of fibre pennation using ultrasound in the human quadriceps in vivo. Europ J Appl Physiol. 1992;65(5):433-437. do i:10.1007/bf00243510
31. Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop Rel Res. 1985;198:43-49. doi:10.1097/00003086-19850900 0-00007 32. Eisner BH, Zargooshi J, Berger AD, et al. Gender differences in subcutaneous and perirenal fat distribution. Surg Radiol Anat. 2010;32(9):879-882. do i:10.1007/s00276-010-0692-7 33. Reimers K, Reimers CD, Wagner S, Paetzke I, Pongratz DE. Skeletal muscle sonography: a correlative study of echogenicity and morphology. J Ultrasound Med. 1993;12(2):73-77. doi:10.7863/jum.1 993.12.2.73 34. Okamoto T, Masuhara M, Ikuta K. Acute effects of self-myofascial release using a foam roller on arterial function. J Strength Cond Res. 2014;28(1):69-73. doi:1 0.1519/jsc.0b013e31829480f5 35. Skarabot J, Beardsley C, Stirn I. Comparing the effects of self-myofascial release with static stretching on ankle range-of-motion in adolescent athletes. Int J Sports Phys Ther. 2015;10:203-212.
International Journal of Sports Physical Therapy
Hopkins C, Kanny S, Headley C. The Problem of Recurrent Injuries in Collegiate Track and Field. IJSPT. 2022;17(4):643-647.
Original Research
The Problem of Recurrent Injuries in Collegiate Track and Field a
Chris Hopkins 1 , Samantha Kanny 2, Catherine Headley 1 1
Department of Health Sciences, Furman University, 2 Department of Public Health Sciences, Clemson University
Keywords: sports epidemiology, injury burden, recurrent injury, track and field https://doi.org/10.26603/001c.35579
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background As with most sports, participating in Track and Field (T&F) has inherent injury risks and a previous injury often predisposes athletes to a greater future injury risk. However, the frequency and burden of recurrent injuries in collegiate T&F have not been closely examined.
Purpose The purpose of this study was to describe the frequency and burden of recurrent injuries in collegiate T&F and compare differences in the time loss associated with initial and recurrent injuries by sex and T&F discipline.
Study Design Descriptive Epidemiology Study
Methods Data from the NCAA Injury Surveillance Program were analyzed to describe the frequency and burden of recurrent injuries in collegiate T&F between 2009 and 2014. Comparisons of recurrent injury proportions by T&F discipline were made using Injury Proportion Ratios (IPR) and injury-associated time loss comparisons by injury type and sex were made using Negative Binomial Regression.
Results Four hundred and seventy-four injuries were reported, 13.1% of which were classified as recurrent injuries. T&F athletes who competed in jumps experienced a lower proportion of recurrent injuries (6.1%) than runners (14.6%) and throwers (19.2%) (Recurrent IPR 0.40, 95% CI 0.18-0.88, p<0.05). When controlling for sex and injury diagnosis, T&F athletes experienced 50% greater time loss from sport following a recurrent injury than an initial injury (95% CI 17%-107%, p<0.01).
Conclusions Recurrent injuries in T&F athletes account for greater time loss than initial injuries, despite sex or injury diagnosis. The current study indicates a need for further research to assess factors contributing to time loss.
Level of Evidence Level 3
INTRODUCTION Collegiate track and field (T&F) athletes engage in demanding aerobic and muscular-strengthening activities that can
a
improve health and well-being.1,2 However, as with most sports, T&F has inherent injury risks and the highly repetitive and intense nature of its activities may increase previously injured athletes’ risk of sustaining a recurrent in-
Corresponding author: Chris Hopkins, Department of Health Sciences, Furman University, Greenville, SC 29613; email: chris.hopkins@furman.edu; phone: 864-294-2485
The Problem of Recurrent Injuries in Collegiate Track and Field
jury.3–5 Recurrent injuries occur when an athlete experiences the same injury they have previously recovered from, either in the same season or a previous one.6 Recurrent injuries differ from initial injuries because they involve previously injured tissues that may have lingering deficits in strength, proprioception, or range of motion.6 These recurrent injuries may be associated with longer recovery times, more time away from sport, and potentially retirement from sport.6,7 While epidemiological research has evaluated injury risk in collegiate T&F, the burden of recurrent injuries has received less attention in this population.3,4 The purpose of this study was to describe the frequency and burden of recurrent injuries in collegiate T&F and compare differences in the time loss associated with initial and recurrent injuries by sex and T&F discipline.
METHODS DATA COLLECTION
This study retrieved data from the NCAA Injury Surveillance Program (ISP) to analyze injuries from Men’s and Women’s Indoor and Outdoor T&F seasons from academic year 2009-2010 through academic year 2013-2014. The ISP collects data from a convenience sample of NCAA Division I, II, and III varsity sports teams. Athletic trainers (AT) at each institution report injury and exposure data in realtime throughout the academic year. All data undergo a verification process in which data may be flagged for invalid values and then reviewed by the reporting AT and data quality assurance staff before becoming available to researchers. The methods of the ISP data collection have been previously described.8,9 When injuries were detected by or reported to an AT, the AT completed a detailed report on the athlete (eg. Sport, position, class year), their injury (eg. body region, diagnosis), and the circumstances of their injury (eg. mechanism of injury, practice or competition setting, new or recurrent). OPERATIONAL DEFINITIONS
Reportable injuries defined by the NCAA ISP are events that occurred as a result of participation in organized intercollegiate practice/competition and required examination from an AT or physician, regardless of whether the athlete missed time away from sport. However, this study only analyzes injuries that required athletes to miss at least one day from sport. This definition may not capture the entire burden of injuries in T&F; however, it reduces bias by using a more objective definition of injury and captures injuries severe enough to warrant time away from sport participation. Similarly, this study defines recurrent injuries as injuries that require athletes to miss at least one day of sport and are of the same type and site as an initial injury after an athlete has returned to full participation following their initial injury. Recurrent injuries may occur during the same season as the initial injury or in subsequent seasons. STATISTICAL ANALYSIS
The frequency and proportions of recurrent injuries were calculated by athletes’ sex and primary T&F discipline (run-
ner, jumper, or thrower) as indicated by ATs on injury reports. Injury proportion ratios (IPR) were used to compare the proportion of recurrent injuries by sex and T&F discipline. This analysis allows the comparison of recurrent injury patterns by T&F discipline to understand if certain T&F athletes experience greater proportions of recurrent injuries than others. Negative binomial regression was used to compare the number of days T&F athletes missed following an injury. This model was selected because the primary outcome of interest, number of days missed following injury, was over dispersed count data with a positive skew. Unadjusted negative binomial regression was used to compare the number of days missed after initial and recurrent injuries among each T&F discipline stratified by sex. Adjusted negative binomial regression controlling for injury diagnosis was used to compare the time loss associated with an injury by sex and injury type (initial or recurrent). All data analyses were conducted using STATA 14.2 statistical software (StataCorp LP, College Station, Texas, USA).
RESULTS Between the 2009-10 to 2013-14 academic years, there were a total of 474 injuries reported, 13.1% of which were classified as recurrent injuries. As shown in Table 1, T&F athletes whose primary discipline were jumps experienced a lower proportion of recurrent injuries (6.1%) than runners (14.6%) and throwers (19.2%) (Recurrent IPR 0.40, 95% CI 0.18-0.88, p<0.05). Table 1 also presents common examples of recurrent injury diagnoses by T&F discipline. Hamstring strains were the most common recurrent injury diagnosis among runners and jumpers. Runners also experienced recurrent injuries involving the lower leg and feet. In addition to hamstring strains, other common recurrent injury diagnoses experienced by jumpers included patellar tendinitis and lateral ankle sprains. Throwing athletes most commonly experienced recurrent injuries involving the spine and upper extremities. On average, T&F athletes missed 15.6 days following an initial injury and 24.2 days following a recurrent injury. Using unadjusted negative binomial regression to account for overdispersion, T&F athletes missed 55% more time following a recurrent injury than an initial injury (95% CI 17%-107%, p<0.01). When stratified by sex, this difference was greater in Women’s T&F with recurrent injuries requiring 75% more time loss than initial injuries (95% CI 16%-167%, p<0.01) compared to Men’s T&F where recurrent injuries only required 34% more time loss, however, this difference in Men’s T&F was not statistically significant (95% CI -9%-96%, p=0.14). Table 2 provides the average number of days missed from initial and recurrent injuries for each discipline in Women’s and Men’s T&F. There was no sex difference in the proportion of injuries classified as recurrent (IPR 0.96, 95% CI: 0.7-1.3), however, Women’s T&F athletes experienced 27% more time loss across all injuries than Men’s T&F athletes (95% CI 5%-55%, p=0.02). With this difference in mind, sex and injury diagnoses were included as covariates in an adjusted negative binomial regression analysis. The results of this model are listed in Table 3, where recurrent injuries account for 50% more time loss (95% CI 13%-98%, p<0.01) but no
International Journal of Sports Physical Therapy
The Problem of Recurrent Injuries in Collegiate Track and Field
Table 1. Recurrent Injuries by Track and Field Discipline (n=474) Proportion of Injuries Reported as Recurrent
Recurrent Injury Proportion Ratioa (95% CI)
Examples of Recurrent Injuries in Sample
Runners
14.6%
1.43 (0.82-2.49)
Hamstring strain, Medial Tibial Stress Syndrome, Plantar Fascia strain
Jumpers
6.1%
0.40 (0.18-0.88)
Hamstring strain, Patellar tendinitis, Lateral ankle sprain
Throwers
19.2%
1.56 (0.79-3.07)
Ulnar collateral ligament strain, Sacroiliac dysfunction, Paralumbar muscle strain
Discipline
a Injury Proportion Ratio (e.g. Proportion of Recurrent Injury among Runners / Proportion of Recurrent Injury among non-Runners)
significant difference persisted between sexes (95% CI -6%-41%, p=0.18).
Table 2. Time loss by Injury Type and Track and Field (T & F) Discipline (n=474) Time loss from initial injuries
DISCUSSION The aim of this study was to describe the frequency and burden of recurrent injuries on collegiate T&F athletes. The main findings of the study indicate that recurrent injuries are associated with a greater amount of time loss compared to initial injuries and that T&F disciplines experience differing proportions of recurrent injuries with jumpers having a lower proportion than runners and throwers. Regardless of injury diagnosis or sex, athletes who experienced a recurrent injury experienced greater time loss from the sport than those who experienced an injury for the first time. While previous injury is a commonly discussed risk factor for future injury, the elevated burden or increased time loss associated with recurrent injuries has received less attention.6 There may be physiological and psychosocial factors related to the extended time loss observed after a recurrent injury. The goal of this discussion is to describe these factors.
Women’s T&F (n=259) 18.4 days (n=151)
32.6 days (n=21)
Throwers
14.3 days (n=21)
25.2 days (n=5)
Jumpers
14.5 days (n=56)
23.2 days (n=5)
17.0 (n=228)
29.9 (n=31)
Runners
Total
Men’s T&F (n=215) 14.7 days (n=112)
20.9 days (n=24)
Throwers
12.9 days (n=21)
14.2 days (n=5)
Jumpers
12.5 days (n=51)
2.00 days (n=2)
13.9 (n=184)
18.6 (n=31)
Runners
Total
Table 3. Rate ratio of days missed following injury (n=474)
PHYSIOLOGICAL REASONS FOR EXTENDED TIME LOSS
Athletes who have previously experienced an injury may have neuromuscular deficits such as decreased strength and proprioception that could predispose them to a recurrent injury.6,10 These deficits can decrease athletes’ abilities to appropriately respond to changing stimuli in sport and not only increase their risk of injury, but potentially result in more severe injuries with longer healing duration. It is unclear if anatomical changes following an initial injury contribute to increased injury severity of recurrent injuries. The formation of less functional scar tissue following a muscle injury may generate more strain on adjacent muscle fibers and result in a greater risk of recurrent injury.11 This continued development of scar tissue following a recurrent injury may make it more difficult for athletes to regain appropriate strength, delaying their return to sport. It is unclear whether previously injured tissues experience delayed healing if injured again. In the first study of its kind, Sevick et al. compared the mechanical properties of injured and reinjured rabbit ligaments and found little difference in the structural and material properties of single- and re-injured ligaments of similar severity, however, more severely re-in-
Time loss from recurrent injuries
Ratio of Time Lost Following Injury^
95% CI
pvalue
Injury Type New Injury Recurrent Injury
Referent 1.50
1.13-1.98
<0.01
Sex Male Female
Referent 1.15
0.94-1.41
0.18
^Negative Binomial Regression controlling for injury diagnosis, injury type, and sex
jured ligaments were inferior in ligament failure stress and creep strain.12 Future research should compare the structural properties of initial and recurrent injuries to better understand physiological factors that may delay healing or prolong an injured athlete’s return to sport.
International Journal of Sports Physical Therapy
The Problem of Recurrent Injuries in Collegiate Track and Field
PSYCHOSOCIAL REASONS FOR EXTENDED TIME LOSS
Athletes who have previously recovered from an injury may delay their return to sport following a recurrent injury because of psychosocial reasons. Athletes recovering from injury might display fear avoidance behaviors which can delay their recovery and require extended time loss from sport.13,14 However, athletes with recurrent injuries may be more vulnerable to these fear avoidance beliefs than athletes with a single injury.15 Conversely, athletes with high athletic identity may exhibit poor psychosocial outcomes following an injury and be more prone to not report injury symptoms to coaches or trainers in the hopes of uninterrupted sport participation.16 Since they have already recovered from an initial injury, these athletes may feel more knowledgeable about injury management practices and seek to self-manage a recurrent injury rather than report it to coaches or athletic trainers. They may only choose to report the recurrent injury if their symptoms worsen beyond their initial injury. This delay in injury reporting could result in a more severe injury that requires greater time to fully recover. Lastly, the athlete’s medical team may take a more conservative approach following a recurrent injury if they feel the athlete’s previous recovery timeline was inadequate and thus contributed to their recurrent injury. Future research should evaluate these psychosocial correlates of time loss following recurrent and initial injuries. LIMITATIONS
The findings from the current study may not be generalizable to other competition levels such as high school, professional, or recreational track and field athletes. Additionally, the NCAA ISP uses a convenience sampling method, so participating schools may not be representative of the entire NCAA. This surveillance study also did not account for the many individual- or institutional-related factors that may have contributed to injury risk and time loss. Examples of these factors may include athletes’ specific training loads or different injury-prevention or management practices implemented by coaching and training staff at each college.
Lastly, the “Runner” position category did not differentiate between sprinters and distance runners, so differences in their injury patterns and recovery times could not be accounted for in this study. CONCLUSION
This study provides an assessment of the frequency and burden of recurrent injuries in collegiate track and field using data from a large injury surveillance program. The results of this study indicate that regardless of injury diagnosis or sex, recurrent injuries required greater time loss from sport participation than initial injuries. Both physiologic and psychosocial factors may contribute to the extended time loss associated with recurrent injuries, however, further research is necessary to assess their contributions to time loss and better prepare student-athletes for a safe return to sport.
ACKNOWLEDGMENT
This publication contains materials created, compiled or produced by the Datalys Center for Sports Injury Research and Prevention, Inc. on behalf of the National Collegiate Athletic Association. The NCAA Injury Surveillance Program data were provided by the Datalys Center for Sports Injury Research and Prevention. The Injury Surveillance Program was funded by the National College Athletic Association (NCAA). The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the Datalys Center or the NCAA. We thank the many athletic trainers who have volunteered their time and efforts to submit data to the NCAA Injury Surveillance Program. Their efforts are greatly appreciated and have had a tremendously positive effect on the safety of collegiate athletes. Submitted: October 20, 2021 CDT, Accepted: February 18, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
The Problem of Recurrent Injuries in Collegiate Track and Field
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9. Kerr ZY, Dompier TP, Snook EM, et al. National Collegiate Athletic Association injury surveillance system: review of methods for 2004– 2005 through 2013–2014 data collection. J Athl Train. 2014;49(4):552-560. doi:10.4085/1062-6050-49.3.58 10. McCall A, Carling C, Davison M, et al. Injury risk factors, screening tests and preventative strategies: a systematic review of the evidence that underpins the perceptions and practices of 44 football (soccer) teams from various premier leagues. Br J Sports Med. 2015;49(9):583-589. doi:10.1136/bjsports-2014-09410 4 11. Opar DA, Williams MD, Shield AJ. Hamstring strain injuries: factors that lead to injury and reinjury. Sports Med. 2012;42(3):209-226. doi:10.2165/1 1594800-000000000-00000 12. Sevick JL, Heard BJ, Lo IK, et al. Are re-injured ligaments equivalent mechanically to injured ligaments: The role of re-injury severity? Proc Inst Mech Eng H. 2018;232(7):665-672. doi:10.1177/09544 11918784088 13. Fischerauer SF, Talaei-Khoei M, Bexkens R, Ring DC, Oh LS, Vranceanu AM. What Is the Relationship of Fear Avoidance to Physical Function and Pain Intensity in Injured Athletes? Clin Orthop Relat Res. 2018;476(4):754-763. doi:10.1007/s11999.000000000 0000085 14. Hsu CJ, Meierbachtol A, George SZ, Chmielewski TL. Fear of Reinjury in Athletes. Sports Health. 2017;9(2):162-167. doi:10.1177/1941738116666813 15. Houston MN, Hoch JM, Hoch MC. College Athletes With Ankle Sprain History Exhibit Greater FearAvoidance Beliefs. J Sport Rehabil. 2018;27(5):419-423. doi:10.1123/jsr.2017-0075 16. Renton T, Petersen B, Kennedy S. Investigating correlates of athletic identity and sport-related injury outcomes: a scoping review. BMJ Open. 2021;11(4):e044199. doi:10.1136/bmjopen-2020-0441 99
International Journal of Sports Physical Therapy
Buchholtz K, Barnes C, Burgess TL. Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team. IJSPT. 2022;17(4):648-657.
Original Research
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team a
Kim Buchholtz 1
, Curt Barnes 2 , Theresa L. Burgess 3
1
Health, Physical Activity, Lifestyle, and Sport (HPALS) Research Centre, University of Cape Town; Department of Physiotherapy, LUNEX International University of Health, Exercise and Sports, 2 Division of Physiotherapy, University of Cape Town, 3 Division of Physiotherapy, University of Cape Town; Centre for Medical Ethics and Law, Stellenbosch University Keywords: epidemiology, rugby union, football, sprains and strains https://doi.org/10.26603/001c.35581
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Professional rugby presents significant injury and illness risks to players, which need to be regularly assessed to monitor the effects of interventions and competition rules changes.
Hypothesis/Purpose The purpose of this study was to determine the incidence and nature of time-loss injuries and illness during the pre-season and competition period of the 2017 Super Rugby tournament in a single South African team.
Study Design Descriptive Epidemiology Study
Methods Forty-five adult players were recruited from one 2017 Super Rugby South African team, with 39 included in the final data set. Daily injury and illness data were routinely collected during the season by support staff over a 28-week period (January to July 2017), based on standardized injury and illness definitions. Retrospective analyses of the data were performed.
Results The incidence of match injuries (241.0 per 1000 player hours) was significantly higher than training injuries (3.3 per 1000 player hours). Twenty one percent of all injuries occurred during the tackle; 37.5% of all injuries were of a “moderate” severity. The proportion of players who sustained a time-loss injury was 76.9% (n=30). The overall incidence of illness was 1.8 per 1000 player days. Acute respiratory tract infection (28.6%) was the most common diagnosis, and the majority of illnesses (64.3%) did not result in time-loss.
Conclusion This study presented a longer study period than previous research by including the pre-season training, but represented only one single team. The incidence of match injuries was significantly higher than previously reported in Super Rugby tournaments, whereas illness rates were significantly lower. Support staff in professional rugby need to be trained on the standardized Orchard System of Classifications to ensure good quality data that can be compared to other teams within the same or other sporting codes.
a
Corresponding author: Kim Buchholtz, Department of Physiotherapy, LUNEX International University of Health, Exercise and Sports, 50 Avenue du Parc des Sports, Differdange, L-4671, Luxembourg (kim.buchholtz@lunex-university.net)
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
Level of evidence Level 3
INTRODUCTION In professional team sports, rugby union has one of the highest reported incidences of injury and illness.1 The combination of high physical demands, together with repetitive collisions and contact, means the inherent risk of injury is substantial in rugby union.1 Previous studies on rugby union and Super Rugby have reported a match injury incidence between 66 and 107 per 1000 player hours.1–4 Between 48 and 64% of players in Super Rugby will sustain a time-loss injury during the tournament.2 The lower limb has previously been the most commonly injured region (48-57%), and injuries are most frequently reported as “minimal” severity (2-3 days time loss).2–4 The Super Rugby tournament is played annually between professional rugby union teams from Japan, South Africa, Argentina, New Zealand and Australia, and is considered to be one of the most competitive rugby competitions in the world.2 Between 2006 and 2016, there has been an increase in the number of teams, weekly matches, bonus incentives and demanding travel schedules in the Super Rugby tournament. These factors have been associated with insufficient recovery times, reduction in game-related key performance indicators, and an elevated risk of injury and acute illness.5,6 The demanding nature of the Super Rugby tournament provides an opportunity to further investigate the incidence and nature of injury and illness in rugby union. To improve inter-study comparisons, in 2007 the Rugby Injury Consensus Group (RICG) standardized the definitions and methodologies for recording and reporting of injuries.3 Recent research has focused on improving both quality and quantity of epidemiological data on injuries and illness in professional rugby union. Understanding the burden of both injury and illness within the context of rugby union will facilitate the development of preventative measures.7 Previous epidemiological studies have not included the pre-season phase of training in the study period, which contribute to overall load. Injuries and illnesses that occur in the pre-season have not previously been considered recurrent if they reoccur later in the season due to this omission. The objectives of this study were to determine the incidence and nature of time-loss injuries and illness during the 2017 Super Rugby tournament in a single South African team, including the pre-season training period.
MATERIALS AND METHODS This study had a retrospective surveillance design. Fortyfive adult male professional Rugby Union players from one South African team participating in the 2017 Super Rugby tournament over a complete season (including pre-season) were recruited for this study. The team selected was based on the availability of previously collected (prospective) data from consistent, ongoing recordings of injury and illness over a 28-week period by team management staff. Ethical approval was granted by the Human Research Ethics Com-
mittee (HREC) of the Faculty of Health Sciences, University of Cape Town (HREC REF: 124/2018) and permission was granted by the Chief Executive Officer of the relevant Rugby Union. Players were not involved in planning and/or conducting the study. Although the players were previously aware of, and participated in ongoing daily monitoring, written informed consent was additionally obtained to use these previously collected data in this study. Players with complete datasets of training loads, injury, and illness records over the complete 2017 Super Rugby tournament were included. Players who were released from their contract during the monitoring period or had not been contracted for the full 2017 Super Rugby tournament were excluded. Players who did not consent to participate or who withdrew from the study were not included. INJURY AND ILLNESS DATA COLLECTION
Training and match-related injury data were collected daily by the team physician and physiotherapist. The inclusion of injuries was based on the time-loss definition of an injury according to the 2007 Consensus Statement.3 A ‘time-loss’ injury was an injury preventing a player from participating fully in all training activities planned for that day and/or match for more than one day following the day of injury.3 The Orchard Sports Injury Classification System 10.1 was used to code injury diagnosis.8 Injury classifications including location (match or training), anatomical site, type, mechanism, and time-loss were used.2,3 The severity of time-loss injuries was classified as minimal (2-3 days), mild (4-7 days), moderate (8-28 days) and severe (≥ 28 days).2,3 The main player position (forwards or backs) was recorded for the injured player. More than one time-loss injury in the same player was recorded as a separate injury. Illness events were recorded by the team physician. Illness data included the presenting symptoms, diagnosis, suspected cause of illness, and time-loss from training and/or matches.5 A recurrent illness was defined as an additional onset of the same illness within the 2017 season.5 A randomized number was assigned to each player once injury and illness data were recorded to ensure confidentiality. STATISTICAL ANALYSIS
The team strength and conditioning coach routinely recorded information on daily squad size, the type of training day (match, training, or rest day), team, and individual training minutes. Training exposure was calculated by multiplying the number of players on a training day to have completed the training session by the session’s duration in minutes.2 Match player hours were calculated per player as the exact number of minutes of participation in each match.2 Data on the number of injuries and players injured, and the number of illnesses and players who experienced illness were collected. Injuries were classified as match or training related injuries. The incidence of injury was calculated per
International Journal of Sports Physical Therapy
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
Table 1. Number of injuries, player hours and the incidence of time-loss injuries for all, match, and training injuries, presented as injuries per 1000 player hours (95% confidence intervals). Time-loss injuries (n)
Player hours
Incidence of injury
All injuries
80
6277
12.7 (10.0-15.8)
Match injuries
60
249
241.0 (185.5-308.0)
Training injuries
20
6028
3.3 (2.1-5.0)
Table 2. Injury incidence for overall, training and matches per season phase presented as number, percentage, and injuries per 1000 player hours (95% confidence intervals). Overall injuries
Season Phase (weeks)
Training injuries
Matches injuries
Injury (%)
Incidence
Injury (%)
Incidence
Injury (n)
Incidence
Preseason (weeks 1-7)
7 (8.7%)
3.6 (1.6-7.2)
7 (35%)
3.6 (1.6-7.2)
-
-
Early (weeks 8-17)
39 (48.8%)
18.0 (13.7-25.7)
7 (35%)
3.6 (1.6-7.2)
32 (53.3%)
237.0 (165.0-331.0)
Late (weeks 18-28)
34 (42.5)
14.9 (10.5-20.1)
6 (30%)
2.8 (1.1-5.7)
28 (46.7%)
245.0 (166.0-350.0)
1000 player hours of exposure.2,9 Illness incidence was calculated per 1000 player-days and time-loss was classified as “illness resulting in one or more lost training and/or match days”.5 The total player-days were calculated by the total team tournament days multiplied by the daily squad size.5 Total player-days included training and match days from the first day of pre-season training until the last match day of the 2017 season.
lower limb had the highest proportion of match (60%) and training (70%) related injuries (Table 3). According to specific anatomical location, the thigh region had the highest frequency of injuries (20%), followed by the knee (12.5%). No specific information on the injury related to structure, grade, or diagnosis was available in the dataset.
RESULTS
From the total squad, 30 players sustained at least one time-loss injury (76.9%). Twenty-eight percent (n=11) experienced a minimal severity injury (2-3 days time-loss). This was followed by mild (4-7 days) 23% (n=9), moderate (8-28 days) 23% (n=9), and severe (≥ 28 days) 3% (n=1). Therefore, 26% of the total squad sustained an injury severe enough to prevent eight days or more of participation in training and/or matches.2,3
Forty-five players were recruited for this study. Thereafter six players were excluded based on the exclusion criteria, resulting in a sample of 39 players. Data on the players’ descriptive characteristics were limited to age to protect confidentiality of individual players given the small and potentially identifiable study cohort. The mean age of the overall squad was 25.3 ± 4.0 years. A total of 6277 player hours of exposure were recorded with a mean per player of 160.9 hours. Total, match and training hours, and injury incidence are shown in Table 1. The overall incidence of injury was 12.7 per 1000 player hours (95% CI: 10.0-15.8) with 241.0 injuries per 1000 player hours (95% CI: 185.5-308.0) and 3.3 per 1000 player hours (95% CI: 2.1-5.0) during matches and training, respectively. Injury incidence per season phase is shown in Table 2. A total of 80 injuries were recorded over the season. The highest percentage of injuries were reported in the early competition phase (48.8%). MAIN AND SPECIFIC ANATOMICAL LOCATION
INJURED PLAYER PROPORTION
INJURY TYPES
Injuries to the soft tissues combined (muscle/tendon, joint/ ligament, brain and skin) accounted for 95% of all injuries (Table 3). Of the soft-tissue injuries, the majority occurred in muscles or tendons (62.5%), followed by joints or ligaments (25%). In matches, the incidence of muscle or tendon injuries was 148 per 1000 player hours (95% CI: 106-203) and joint or ligament injuries was 60 per 1000 player hours (95% CI: 35-97). During training, the incidence of muscle or tendon injuries was 2.2 per 1000 player hours (95% CI: 1.2-3.6) and joint or ligament injuries was 0.8 per 1000 player hours (95% CI: 0.3-1.8) (Table 4).
The majority of the injuries occurred in the lower limb (62.5%), followed by the head or neck region (15%). The
International Journal of Sports Physical Therapy
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
Table 3. The number, percentage, and incidence of all, training, and match related injuries for all players by main anatomical location, and anatomical type. Incidence is presented per 1000 player hours (95% confidence intervals). All injuries
Main Anatomical Region
Anatomical type
Match injuries
Training injuries
Injury (%)
Player hours
Incidence
Injury (%)
Player hours
Incidence
Injury (%)
Player hours
Incidence
All players
80 (100.0%)
6277
12.7 (10.0-15.8)
60 (100.0%)
249
241.0 (185.5-308.0)
20 (100.0%)
6028
3.3 (2.1-5.0)
Head/neck
12 (15.0%)
6277
1.9 (1.0-3.3)
10 (16.7%)
249
40.1 (20.4-71.6)
2 (10.0%)
6028
0.3 (0.06-0.10)
Upper limb
10 (12.5%)
6277
1.6 (0.8-2.8)
10 (16.7%)
249
40.1 (20.4-71.6)
-
6028
-
Trunk
8 (10.0%)
6277
1.3 (0.6-2.4)
4 (6.6%)
249
16.1 (5.1-38.8)
4 (20.0%)
6028
0.6 (0.2-1.6)
Lower limb
50 (62.5%)
6277
8.0 (6.0-10.4)
36 (60.0%)
249
145.0 (103.0-198.0)
14 (70.0%)
6028
2.3 (1.3-3.8)
All injuries
80 (100.0%)
6277
12.7 (10.0-15.8)
60 (100.0%)
249
241.0 (185.5-308.0)
20 (100.0%)
6028
3.3 (2.1-5.0)
Muscle/ tendon
50 (62.5%)
6277
8.0 (6.0-10.4)
37 (61.7%)
249
148.0 (106.0-203.0)
13 (65%)
6028
2.2 (1.2-3.6)
Joint/ ligament
20 (25.0%)
6277
3.2 (2.0-4.8)
15 (25.0%)
249
60.0 (35.0-97.0)
5 (25%)
6028
0.8 (0.3-1.8)
Skin
2 (2.5%)
6277
0.3 (0.1-1.1)
1 (1.7%)
249
4.0 (0.2-20.0)
1 (5%)
6028
0.1 (0-0.8)
Bone
3 (3.8%)
6277
0.5 (0.1-1.3)
3 (5.0%)
249
12.0 (3.0-32.0)
-
6028
-
Brain
4 (5.0%)
6277
0.6 (0.2-1.5)
4 (6.6%)
249
16.0 (5.1-3.9)
-
6028
-
Unspecified
1 (1.2%)
6277
-
-
249
-
1 (5%)
6028
0.1 (0-0.8)
International Journal of Sports Physical Therapy
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
Table 4. The incidence and percentage for all, match and training injuries according to time-loss severity. Incidence is presented per 1000 player hours (95% confidence intervals). Injury (n)
Percent (%)
Time-loss (days)
Incidence (95% CI)
Total:
80
100
736
12.7 (10.0-15.8)
Minimal (2-3 days)
24
30
44
3.8 (2.5-5.6)
Mild (4-7 days)
24
30
134
3.8 (2.5-5.6)
Moderate (8-28 days)
30
37.5
414
4.8 (3.3-6.7)
Severe (≥28 days)
2
2.5
144
0.3 (0.1-1.0)
Total:
60
100
557
241.0 (185.5-308.0)
Minimal (2-3 days)
18
30
35
72.3 (44.0-112.0)
Mild (4-7 days)
17
28
95
68.3 (41.0-107.0)
Moderate (8-28 days)
24
40
336
96.4 (63.0-141.0)
Severe (≥28 days)
1
2
91
4.0 (0.2-19.8)
Total:
20
100
179
3.3 (2.1-5.0)
Minimal (2-3 days)
6
30
9
0.9 (0.4-2.0)
Mild (4-7 days)
7
35
39
1.1 (0.5-2.3)
Moderate (8-28 days)
6
30
78
0.9 (0.4-2.0)
Severe (≥28 days)
1
5
53
0.2 (0-0.8)
Injury severity
All injuries
Match injuries
Training injuries
INJURY SEVERITY
A total of 736 days of time-loss occurred due to injury over the 28-week period (Table 4). The most frequent severity was “moderate” for all injuries (37.5%) and match-related injuries (40%). The most frequent severity recorded for training injuries was “mild” severity (35%). INJURY MECHANISMS
The most common mechanism for all injuries was “other” (32.5%) followed by 28.8% occurring in the tackle (including being tackled or being the tackler) (Table 5). The “other” category represented grappling or wrestling, landing from a jump, punching, or a mechanism that the player or data collector were unable to recall. Being tackled (including being tackled side on, front on and from behind) contributed to 21.3% of all injuries. From the match injuries, the mechanism of being tackled accounted for 26.6%. The most common mechanism for training injuries were “other” (60%) as defined above. From the overall injuries, contact injuries (37.5%) were greater than non-contact injuries (30.0%) with “other” accounting for 32.5% of all injuries. INCIDENCE OF ILLNESS
Illness incidence was calculated using player-days (Table 6). Over the 28-week period, 7644 player-days were recorded. The overall incidence of illness was 1.8 per 1000 player days (95% CI: 1.0-3.0). ILLNESS PLAYER PROPORTION
The proportion of players who acquired an illness was 28.2% (n=11). From the total number of illnesses (n=14),
new illnesses accounted for 93.0% (n=13) and recurrent illnesses accounted for 7.0% (n=1). BODILY SYSTEMS AFFECTED AND SYMPTOMS
The respiratory system (50%) was the most commonly affected bodily system followed by the digestive system (43%) (Table 6). An incidence of 0.9 per 1000 player days (95% CI: 0.4-1.8) and 0.7 per 1000 player days (95% CI: 0.3-1.6) were demonstrated for the respiratory and digestive system, respectively. Diarrhea (28.7%) was the most commonly presented symptom followed by symptoms listed as “other” (21.4%), sore throat (14.3%) and fatigue (14.3%). Acute upper respiratory tract infections (URTI) were the most common specific diagnosis (28.6%) followed by noninfective gastroenteritis (21.4%). Infection (n = 5) was the most common suspected cause of illness (35.6%) respectively followed by environmental (21.5%). Of the total illnesses, 64.3% resulted in no time-loss, 21.4% in one day of time-loss and 14.3% more than one day of time-loss (Table 6).
DISCUSSION In this study, the aim was to investigate the training and match related injuries in a South African Super Rugby Team during the 2017 tournament including the pre-season training period. The match related injuries were significantly higher than in previous studies, but the area, type and severity of injury were comparable. Epidemiological studies provide the information required to develop and implement injury prevention strategies within sports teams. The epidemiological findings presented below can guide the future injury prevention and training programs within this
International Journal of Sports Physical Therapy
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
Table 5. The mechanism and frequency of all, match, and training injuries. Mechanism
All injuries
Match injuries
Training injuries
Injury (n)
Percentage (%)
Injury (n)
Percentage (%)
Injury (n)
Percentage (%)
Total:
80
100
60
100
20
100
Other*
26
32.5
14
23.3
12
60.0
Being tackled (total)
17
21.3
16
26.6
1
5.0
Tackled side on
10
12.5
6
10.0
0
0.0
Tackled front on
5
6.3
8
13.3
1
5.0
Tackled from behind
2
2.5
2
3.3
0
0
Collision
7
8.8
6
10.0
1
5.0
Acceleration
6
7.5
4
6.7
2
10.0
Tackling (total)
6
7.5
6
10
0
0
Tackling front on
5
6.3
5
8.3
0
0
Tackling side on
1
1.2
1
1.7
0
0
Twisted
5
6.3
5
8.3
0
0
Sidestep
3
3.8
3
5.0
0
0
Deceleration
3
3.8
0
0
0
0
Kicked
2
2.5
1
1.7
1
5.0
Conditioning
1
1.2
0
0
1
5.0
Landing
1
1.2
1
1.7
0
0
Weight training
1
1.2
0
0
1
5.0
Slipped
1
1.2
1
1.7
1
5.0
Kneed
1
1.2
1
1.7
0
0
* Other = grappling or wrestling, landing from a jump, punching, or a mechanism that the player or data collector were unable to recall
Table 6. The overall number, percentage, incidence per 1000 player-days and time-loss of illness per bodily system. Incidence is presented per 1000 player hours (95% confidence intervals). Bodily System
Illnesses (n)
All systems
Respiratory
Digestive
Other
No timeloss
Percentage (%)
Incidence
Illnesses (n=14)
100
1.8 (1.0-3.0)
9
3
2
All respiratory system illnesses (n=7)
50.0
0.9 (0.4-1.8)
4
2
1
Acute upper respiratory tract infection (n=4)
28.6
0.5 (0.2-1.3)
1
2
1
Allergic rhinitis (n=2)
14.3
0.3 (0-0.9)
2
-
-
Allergic sinusitis (n=1)
7.1
0.1 (0-0.6)
1
-
-
All digestive system illnesses (n=6)
43.0
0.7 (0.3-1.6)
4
1
1
Non-infective gastroenteritis (n=3)
2.1
0.4 (0.1-1.0)
3
-
1
Other (n=3)
2.1
0.4 (0.1-1.0)
3
1
-
Eye (n=1)
7.1
0.1 (0-0.6)
1
-
-
International Journal of Sports Physical Therapy
One day time-loss
> One day time-loss
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
franchise (considering the specific setting of the team) and in rugby union in general. The sample size in this study is comparable to studies in general professional Rugby Union, but notably smaller than previous Super Rugby studies covering multiple teams.2,4,5,10 The data from six Super Rugby franchises in South Africa including 482 players between 2012 and 2016 has been previously reported.10 The use of independent data collection procedures from the team’s support staff in a standardized prospective manner resulted in accurate recording of routinely collected data. This study included preseason, early, and late competition phases for 28 weeks which is longer than reported in previous studies.2,4,5,10 The overall injury incidence of 12.7 per 1000 player hours (95% CI: 10.0-15.8) was higher than reported in five Super Rugby tournaments from 2012 to 2016 with 10.0 per 1000 player hours (95% CI: 9.4-10.7).10 The high overall injury incidence could hypothetically be related to differences in training methods like the volume of contact and non-contact training, coaching techniques, conditioning, injury prevention strategies, travel schedules in the expanded tournament format, and rotational player systems.2 The incidence of match injuries of 241.0 per 1000 player hours (95% CI: 185.5-308.0) was notably higher than previously reported in the Super Rugby tournament and in general professional Rugby Union ranging from 66.1 to 107.0 per 1000 player hours.1,2,4,5,10–13 The incidence of match injuries were 73 times higher in comparison to training injuries. The precise reason for the high incidence of match injuries is unclear but could be related to the strongest teams participating against each other in the 2017 tournament format, or the smaller sample size in this study. Findings in this study were consistent with several studies showing a higher incidence of injuries in matches in contrast to training.2,4,5,10 The high incidence of injury in matches could be related to contact events during matches which occur at a higher rate than in training, but the high percentage recorded in the “Other” category make it difficult to determine which contact events present the greatest danger. In the match setting these could include ‘dangerous play’, side-stepping, punching, static grappling, landing from a jump, ‘grass cutter’ tackle and twisting related mechanisms. In this study, 76.9% (n=30) of the squad sustained at least one time-loss injury which was greater than the 1999 (64%) and 2012 to 2016 Super Rugby tournaments with an average of 48% over the five Super Rugby tournaments.10,14 However, the proportion of injured players reported in this study was lower than the 2008 Super Rugby tournament (82%) which only reported match injuries.12 Again, the authors hypothesize that changes in training methods, training environments due to travel, the implementation of new game laws and individual injury prevention in teams over a fiveyear period may have contributed to the difference. Calculating the injured player proportion must be applied with caution as the number of players with more than one injury is not included in the calculation. The 2007 Consensus Statement does not include the reporting of the injured player proportion but authors have recommended exploration using this method.2,3 Overall, the lower limb was the most frequently injured anatomical location (62.5%). This finding is higher than
previously reported in the 2012 (48.1%) and 2014 (57.1%) Super Rugby tournaments.2,9 Results from this study are consistent with previous studies which report the lower limb as the most commonly injured anatomical location.1,10,11 Soft-tissue injuries (95%) represented a large proportion of all injuries with 62.5% in muscles or tendons and 25% in joints or ligaments. This was similar to findings from the 2012 Super Rugby tournament and across five Super Rugby tournaments reporting on match injuries.2,10 The most frequent severity of injury in this study was “moderate,” which accounted for 4.8 per 1000 player hours (95% CI: 3.3-6.7) in contrast to “minimal” reported in five Super Rugby tournament studies with 3.9 per 1000 player hours (95% CI: 3.5-4.4).10 The high incidence of “moderate” severity for match injuries found in this study was contrary to the “minimal” severity reported in five Super Rugby tournament studies.10 The increased severity of match injuries over time could be related to numerous factors such as an increase in the “level of play” over time, changes in game laws, the format of contact training, or fatigue and technique related mechanisms.15 In this study, the incidence of illness was 1.8 per 1000 player days (95% CI: 1.0-3.0) was lower than previously reported.5 The reason for the greater illness rates reported in the previous studies in comparison to this study could be related to the larger cohort of players (range: 259-736) in the previous studies.5,16 This study also focused solely on South African players whereas previous studies used various populations.5 Population differences in lifestyle and behavioural factors could be related to the difference in illness incidence.5 Over a seven-year period, strict hygiene protocols and illness prevention strategies within this team could have contributed to minimizing the incidence of illness. The proportion of players that acquired an illness (28%) in this study was lower than previously reported (72%).5 However, the authors reported a higher frequency of new illnesses with 93% in contrast to 88%, and a lower frequency of recurrent illnesses of 7% in comparison to 12% in the 2010 Super Rugby tournament.5 The high incidence of new illness could be related to the environment in which teams make use of communal facilities which could facilitate the spread of infection.5 The lower incidence of recurrent illness could indicate sufficient prevention strategies such as probiotics, vaccines, and additional supplementation. Results from this study concur with the main findings in Rugby Union and across sporting codes that most of the reported illnesses affected the respiratory (50%) and digestive systems (43%).5,16–19 Prolonged competition load and insufficient recovery have been linked with immune changes associated with an increased risk of illness.5 Prolonged training and competition load as demonstrated in the Super Rugby tournament has been linked to an increase in the risk of sub-clinical immunological changes that may increase the risk of illness.5 LIMITATIONS AND RECOMMENDATIONS
Epidemiological data are essential as part of the injury prevention process as described by van Mechelen et al.20 They provide the basis upon which injury prevention programs
International Journal of Sports Physical Therapy
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
may be developed and evaluated over future seasons in the same sport. The challenge with descriptive epidemiological studies is the inability to describe cause-and-effect relationships, and results in authors having to create hypotheses to explain findings. In rugby, there have many changes in game laws, travel, and match schedules, as well as increase in professionalism of players and format of contact training, and it is challenging to establish which individual factors may contribute to changes in the injury rates over time. While a smaller sample was used in comparison to previous studies on the Super Rugby tournament, data over a 28-week period represented an extended period in comparison to previous studies. The inclusion of the preseason phase in the Super Rugby tournament and general professional rugby union is recommended as it contributes to the overall epidemiological data on injury profiles and illness rates across entire seasons. The authors acknowledge that data on a single team remains a limitation. The lack of anthropometric data like body mass, height and body mass index limits population specific comparisons to previous study populations in general professional Rugby Union and the Super Rugby tournament but these details were removed from the dataset in this study to prevent identification of individual players. Data collected by medical and support staff were limited to the routinely collected data, and resulted in a large number of “other” injury and illness mechanisms. Training the medical staff to adopt data collection methods according to the 2007 Consensus Statement could prevent non-specific categories like “other” under injury mechanism and causes of illness. This category requires further investigation as it represents a high proportion of injuries and illness.
CONCLUSION The overall injury incidence in the 2017 Super Rugby tournament was higher than previously reported. The incidence
of match injuries specifically was higher than in previous studies. The illness rates in the 2017 Super Rugby tournament were lower than reported in Rugby Union and across sporting codes. Use of the Orchard system of diagnostic categories should be encouraged to prevent the use of the “other” classification under mechanism of injury as this cause of injury accounted for many of the reported mechanisms. Injury prevention strategies should target match related causes of soft-tissue injury to the lower limb to reduce the time-loss and severity of injury in-season. Clinical staff and team management can use epidemiological data of this nature to anticipate the potential burden of injuries and illness in their squads and therefore make the required planning regarding squad dynamics and prevention strategies.
ACKNOWLEDGEMENTS
The authors would like to extend their gratitude and acknowledgement of the Rugby Union staff for their support of this research project. The authors would like to acknowledge the players for their willingness to participate in the research project. We would like to extend gratitude to Dr Alan Kourie for his support in the study and thank Professor Martin Schwellnus for his assistance with the illness data. COMPETING INTERESTS
CB was employed by the rugby franchise at the time of the study, but was working with the junior teams, and not involved in the care of the Super Rugby team. He was also not involved in the data collection during this study and therefore would not be considered to have a conflict of interest. The other authors declare no conflicts of interest exist. Submitted: August 17, 2021 CDT, Accepted: April 09, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
REFERENCES 1. Williams S, Trewartha G, Kemp S, Stokes K. Metaanalysis of injuries in senior men’s professional Rugby Union. Sports Med. 2013;43(10):1043-1055. do i:10.1007/s40279-013-0078-1 2. Schwellnus MP, Thomson A, Derman W, et al. More than 50% of players sustained a time-loss injury (>1 day lost training or playing time) during the 2012 Super Rugby Union Tournament: a prospective cohort study of 17340 player hours. Br J Sports Med. 2014;48(17):1306-1315. doi:10.1136/bjsports-2014-09 3745 3. Fuller CW, Molloy MG, Bagate C, et al. Consensus statement on injury definitions and data collection procedures for studies of injuries in rugby union. Br J Sports Med. 2007;41(5):328-331. doi:10.1136/bjsm.20 06.033282 4. Whitehouse T, Orr R, Fitzgerald E, Harries S, McLellan CP. The epidemiology of injuries in Australian professional Rugby Union 2014 Super Rugby competition. Orthop J Sports Med. 2016;4(3):1-10. doi:10.1177/2325967116634075 5. Schwellnus M, Derman W, Page T, et al. Illness during the 2010 Super 14 Rugby Union tournament – a prospective study involving 22 676 player days. Br J Sports Med. 2012;46(7):499-504. doi:10.1136/bjsport s-2012-091046 6. Lo M, Aughey RJ, Hopkins WG, Gill N, Stewart AM. The longest journeys in Super Rugby: 11 years of travel and performance indicators. J Sports Sci. 2019;37(18):2045-2050. doi:10.1080/02640414.2019.1 618533 7. Bolling C, van Mechelen W, Pasman HR, Verhagen E. Context matters: Revisiting the first step of the ‘Sequence of prevention’ of sports injuries. Sports Med. 2018;48(10):2227-2234. doi:10.1007/s40279-01 8-0953-x 8. Rae K, Orchard J. The Orchard Sports Injury Classification System (OSICS) Version 10. Clin J Sports Med. 2007;17(3):201-204. doi:10.1097/jsm.0b013e318 059b536 9. Gabbett TJ, Domrow N. Relationships between training load, injury, and fitness in sub-elite collision sport athletes. J Sports Sci. 2007;25(13):1507-1519. do i:10.1080/02640410701215066
10. Schwellnus MP, Jordaan E, Janse van Rensburg C, et al. Match injury incidence during the Super Rugby tournament is high: a prospective cohort study over five seasons involving 93 641 player-hours. Br J Sports Med. 2019;53(10):620-627. doi:10.1136/bjsports-201 8-099105 11. Fuller CW, Laborde F, Leather RJ, Molloy MG. International Rugby Board Rugby World Cup 2007 injury surveillance study. Br J Sports Med. 2008;42(6):452-459. doi:10.1136/bjsm.2008.047035 12. Fuller CW, Raftery M, Readhead C, et al. Impact of the International Rugby Board’s experimental law variations on the incidence and nature of match injuries in southern hemisphere professional rugby union. S Afr Med J. 2009;99(4):232-237. 13. Fuller CW, Sheerin K, Targett S. Rugby World Cup 2011: International Rugby Board injury surveillance study. Br J Sports Med. 2013;47(18):1184-1191. doi:1 0.1136/bjsports-2012-091155 14. Targett SGR. Injuries in Professional Rugby Union. Clin J Sports Med. 1998;8(4):280-285. doi:10.1097/000 42752-199810000-00005 15. Hendricks S, Lambert MI. Theoretical model describing the relationship between the number of tackles in which a player engages, tackle injury risk and tackle performance. J Sci Med Sport. 2014;13:715-717. 16. Dvorak J, Junge A, Derman W, Schwellnus M. Injuries and illnesses of football players during the 2010 FIFA World Cup. Br J Sports Med. 2011;45(8):626-630. doi:10.1136/bjsm.2010.079905 17. Alonso JM, Tscholl PM, Engebretsen L, Mountjoy M, Dvorak J, Junge A. Occurrence of injuries and illnesses during the 2009 IAAF World Athletics Championships. Br J Sports Med. 2010;44(15):1100-1105. doi:10.1136/bjsm.2010.07803 0 18. Engebretsen L, Steffen K, Alonso JM, et al. Sports injuries and illnesses during the Winter Olympic Games 2010. Br J Sports Med. 2010;44(11):772-780. do i:10.1136/bjsm.2010.076992 19. Cunniffe B, Griffiths H, Proctor W, Davies B, Baker JS, Jones KP. Mucosal immunity and illness incidence in elite Rugby Union players across a season. Med Sci Sports Exerc. 2011;43(3):388-397. doi:10.1249/mss.0b 013e3181ef9d6b
International Journal of Sports Physical Therapy
Injury and Illness Incidence in 2017 Super Rugby Tournament: A Surveillance Study on a Single South African Team
20. van Mechelen W, Hlobil H, Kemper HCG. Incidence, severity, aetiology and prevention of sports injuries. A review of concepts. Sports Med. 1992;14(2):82-99. doi:10.2165/00007256-19921402 0-00002
International Journal of Sports Physical Therapy
D’Amico A, Silva K, Rubero A, Dion S, Gillis J, Gallo J. The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage. IJSPT. 2022;17(4):658-668.
Original Research
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage Anthony D'Amico 1 1
a
, Kevin Silva 1, Alejandro Rubero 1, Steven Dion 1, Jason Gillis 1, Joseph Gallo 1
Sport and Movement Science Department, Salem State University
Keywords: exercise recovery, low-level laser therapy, muscular soreness, photobiomodulation https://doi.org/10.26603/001c.34422
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Intense physical activity can result in exercise-induced muscle damage, delayed-onset muscle soreness, and decrements in performance. Phototherapy (PhT), sometimes referred to as photobiomodulation or low-level laser therapy, may enhance recovery from vigorous exercise.
Purpose The purpose of this study was to assess the influence of phototherapy on functional movements (vertical jump, agility), and perceptions of muscle soreness following exercise-induced muscle damage caused by high volume sprinting and decelerations.
Methods In a between-group design, 33 participants performed 40x15m sprints, a protocol intended to cause muscle damage. Immediately following sprinting and in the four days following, vertical jump and agility were assessed, as well as calf, hamstring, quadriceps, and overall perceptions of soreness. Sixteen subjects (age 20.6±1.6 yrs; BMI 25.8±4.6 kg.m-2) received PhT prior to testing each day, while 17 (age 20.8±1.3 yrs; BMI 26.2±4.5 kg.m-2) received sham PhT and served as a control (CON). Measurements were recorded during five days of recovery from the repeated sprint protocol, then compared to those recorded during three baseline days of familiarization. Area under the curve was calculated by summing all five scores, and comparing those values by condition via a two-tailed unpaired t-test for normally distributed data, and a two-tailed Mann-Whitney U test for nonparametric data (alpha level = 0.05).
Results Calf soreness was lower in PhT compared to CON (p = 0.02), but no other significant differences were observed between groups for vertical jump, agility, quadriceps, hamstring, and overall soreness (p > 0.05).
Discussion Phototherapy may attenuate soreness in some muscle groups following exercise-induced muscle damage, but may not enhance recovery after explosive, short-duration activities.
Conclusion Phototherapy may not be a useful recovery tool for those participating in explosive, short-duration activities.
a
Corresponding author: Anthony D’Amico Salem State University 352 Lafayette Street, Salem, MA, USA 01970 P: 978-542-2904 F: 978-542-6554 adamico@salemstate.edu
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
Level of evidence 2c
INTRODUCTION Physical activity that is novel, demanding, and high in volume often results in exercise-induced muscle damage (EIMD).1 Eccentric muscle actions appear especially likely to induce damage.1 Exercise of this nature may cause intracellular muscle damage, impair muscle function, lead to swelling and inflammation, and cause delayed onset muscle soreness (DOMS).2,3 While the exact mechanisms of EIMD are unclear, both metabolic and mechanical pathways are likely contributory.4 Tee et al. suggested that oxidative stress, a delayed inflammatory response, and impairment of excitation-contraction coupling represent a metabolic cascade resulting in EIMD.4 Proske and Morgan described a mechanical pathway where sarcomere disruption occurs via high myofibrillar tension.5 Moderate EIMD is a normal outcome following vigorous activity, and can play a role in beneficial physiological adaptations.6 Excessive EIMD, however, may hinder training and performance.6 Therefore, reducing EIMD symptoms may prove beneficial. Phototherapy (PhT), a non-thermal process where chromophores react to light, inducing photochemical and photophysical responses in varied tissues,7 may help athletes reduce the detrimental effects of EIMD. Phototherapy, otherwise referred to as photobiomodulation, light-emitting diode therapy, or low-level laser therapy, is a non-ionizing light therapy. Phototherapy may employ light emitting diodes, lasers, and broadband light ranging on the spectrum from visible to infrared.7 Phototherapy has been shown to potentiate aerobic performance,8–14 increase the number of muscular contractions that can be performed prior to fatigue,15–23 and hasten recovery following exercise-induced muscle damage.10,16,21,24–31 While tenets of the treatment vary (dosage, pre vs. post exercise application, pulsed vs. continuous application), PhT generally appears to enhance some types of performance. While the efficacy of PhT toward aerobic performance potentiation and recovery appears well established, the influence on strength performance and recovery is unclear. Reduced decrements in strength following EIMD as measured by maximal voluntary contraction (MVC)10,16,24–27,30 or repetitions until exhaustion31 have been reported. These investigations have primarily used single joint assessments of strength. Malta et al.32 performed the lone investigation where short-burst, anaerobic tests were used to assess the influence of PhT on recovery from EIMD. The countermovement jump (CMJ), a multi-joint movement, was included as a dependent variable. The authors reported no difference between groups, though while there was little previous evidence to suggest that PhT may minimize decrements in CMJ following EIMD, the lack of difference in any recovery marker whatsoever appeared to conflict with most of the literature. The authors acknowledged as much, and called for further investigation.32 Given the preponderance of athletic activities which rely primarily on multi-joint, functional movements, it is im-
portant to investigate how these are influenced by PhT during recovery from EIMD. The improvements in recovery observed in slower, isolated assessments of MVC are suggestive of potential benefits toward recovery of functional movements, but this requires confirmation. Therefore, the purpose of this study was to assess the influence of PhT on functional movements (vertical jump, agility), and perceptions of muscle soreness following EIMD caused by high volume sprinting and decelerations. The null hypothesis was that following EIMD, PhT would not expedite recovery for agility and VJ, or decrease perceptions of muscle soreness compared to CON.
METHODS PARTICIPANTS
Six healthy, college-aged females (age 20.3 ± 1.2 yrs; BMI 23.7 ± 4.8 kg.m-2) and 10 males (age 20.8 ± 1.7 yrs; BMI 23.7 ± 4.8 kg.m-2) received PhT on each testing day, following EIMD at the start of the testing period. Seven healthy, college-aged females (age 20.7 ± 1.0 yrs; BMI 27.3 ± 5.5 kg.m-2) and 10 males (age 20.9 ± 1.4 yrs; BMI 25.3 ± 3.1 kg.m-2) served as a control (CON), receiving sham PhT on each testing day, following EIMD at the start of the testing period. Participants were informed of all procedures, potential risks, and benefits of the study, and if willing to participate, read and signed an informed consent form prior to participation. All procedures were approved by the Salem State University Review Board (IRB # 103117-1). Participants were 18 years of age or older (range; 18-25 yrs). Based upon previous investigations, approximately eight to 20 participants per condition were determined as adequate to observe a significant difference in the primary dependent variable of muscle soreness.16,21,23 Potential participants were excluded if they 1) were injured, or 2) had received PhT in the last 30 days, or 3) had already completed the repeated sprinting protocol. Each participant was instructed to refrain from strenuous physical activity and alcohol consumption during the study. Data collection for this investigation was conducted between December 2018 and February 2020. PROCEDURES
During the first session of week one in this two-week investigation, participants were assigned to either PhT or CON in a counter-balanced fashion. Following group assignment, participants completed a standardized, pre-testing battery warm-up (50 jumping jacks, 30 high knees [15 per leg], 10 push-ups, and 10 squats), followed by a non-fatiguing testing battery that included assessments of muscle soreness, VJ, and the Agility T-Test (described below). This protocol was repeated during all three familiarization sessions in week one. All testing took place at the same time of day throughout the study. During week two, participants attended the lab five consecutive days, henceforth described as POST, +24hrs, +48hrs, +72hrs, and +96hrs. Prior to the
International Journal of Sports Physical Therapy
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
Table 1. Phototherapy/Light Emitting Cluster Applicator Diode Parameters. Laser Classification
IIIb (therapeutic) GaAlAs
Number of Laser Diodes
5
Laser Diode Wavelength
850 nm (infrared)
Laser Power output per diode
200 mW (total of 1000 mW)
Laser Frequency
Continuous output
Laser Spot Size per diode
0. 1041cm2
Laser Power density per diode
1.92 W/cm2
Laser Energy density (J/cm2) per diode
57.64 J/cm2
Laser Energy (J) per diode
6J
Total Laser Energy for 5 diode cluster
30 J
Total Laser Energy per site
60 J
Treatment Time
30 seconds
Number of LED diodes
4
LED Diode wavelength
650 nm
LED Power output
10 mW (total of 40 mW)
LED Frequency
Continuous output
LED Spot Size per diode
0.3948 cm2
LED Power density per diode
0.0253 W/cm2
LED Energy density (J/cm2) per diode
0.7599 J/cm2
LED Energy (J) per diode
0.3 J
Total LED Energy for 4 diodes
1.2 J
Total LED Energy per site
2.4 J
Treatment Time
30 seconds
Target Tissue Sites
Vastus Medialis, Rectus Femoris, Vastus Lateralis, Semitendinosus, Gastrocnemius - 2 point per muscle
Application Technique
Cluster diode is held firmly to each location on the target tissue at a 90o angle
first testing battery at POST, participants underwent a repeated sprinting protocol (described below). Participants in the experimental group then underwent the PhT intervention while CON received a sham PhT treatment. Both groups then performed the testing batteries. At each session from +24 to +96hrs, both CON and PhT performed the previously described standardized, pre-testing battery warm-up. DESCRIPTION OF BLINDING PROCEDURE
Upon entry to the study each participant was assigned a code by a researcher, reflecting their experimental or control status, participant number, and sex. The researcher applying the PhT treatment was informed of the participant’s condition, in order for the PhT treatment or sham therapy to be applied (described below). Participants were kept unaware of their group assignment throughout the investigation. The researcher applying the intervention was different from the researcher that assessed participant’s vertical jumping ability, agility, and perceptions of muscle soreness.
DESCRIPTION OF THE PHOTOTHERAPY INTERVENTION
Phototherapy was delivered using a Richmar Theratouch LX2 device (St Louis, MO). A nine-diode cluster applicator, consisting of five laser diodes and four light emitting diodes (LEDs), was used to deliver the PhT treatment. The PhT parameters are presented in Table 1. The nine-diode cluster was selected over a single diode due to its efficiency in delivering the desired joules to a larger area and its ability to simultaneously deliver Laser energy and LED energy. All participants wore protective goggles and lay supine when anterior sites were irradiated and prone when posterior sites were irradiated. The PhT device was placed at participant’s feet during all treatments. This ensured that participants in both groups were unable to see the applicator or device screen. The PhT device was set to provide no audible sounds during the placebo or PhT treatment. Phototherapy treatments were delivered with the cluster applicator in direct contact with the skin using firm, but comfortable pressure at each of the predetermined sites on the quadriceps, hamstring, and gastrocnemius. Phototherapy was delivered to a total of 10 sites on both legs (Figure
International Journal of Sports Physical Therapy
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
Figure 1. Phototherapy application sites.
1). A researcher trained in PhT treatment was responsible for delivering each treatment. The placebo group did not receive any PhT irradiation from the device. The placebo treatment consisted of the same physical set up, however the applicator was not armed for treatment. The PhT device was set to 0 Joules for the placebo treatment. The clinician held the cluster applicator in direct contact with the skin using firm, but comfortable pressure on all of the previously described sites. The clinician simulated activation of the cluster applicator and held it in place for 30 seconds. DESCRIPTION OF MUSCLE DAMAGE PROTOCOL
Prior to performing the repeated sprint protocol, participants completed a general warm-up of five laps around a basketball court, followed by a sprinting-specific warm-up butt kicks, high knees, soldier walks, toe walking, carioca, and sidesteps with a squat. Participants then completed four 15 m sprints accelerating from 25 % of maximal speed, to 50 %, 75 %, to 100 %, throughout the four sprints. The sprinting-specific warm-up, different than the pre-testing battery warm-up, was used to decrease the likelihood of a participant incurring an injury while sprinting. The warmup was followed by a repeated sprinting protocol, which involved 40, 15 m sprints and a 5 m deceleration zone to accentuate eccentric muscle actions. Participants were instructed to exert maximal effort on each sprint. Woolley et al.33 observed that this protocol triggered muscle damage in physically active adults. This protocol has been used to elicit muscle damage in previous, similar research.34
PERCEPTION OF MUSCLE SORENESS
A PainTest™ FPN 100 Algometer (Wagner Instruments, Greenwich, CT, USA) was used to assess muscle soreness of the quadriceps, hamstrings, and gastrocnemius muscles on the right leg of each participant. Thirty N of force was applied to the mid-point of the muscle belly of each with the algometer. Participants verbally reported a pain rating which ranged from zero (no pain) to 10 (most painful) using a categorical pain scale, and those values were used for analysis.35 A categorical scale is limited in that it only allows inferences to be made about the rank-order of the varying sensations. In light of these limitations, Green et al.36 developed a scale of sensory magnitude with apparent ratio properties called the general labeled magnitude scale (gLMS). The gLMS generates ratio-level values in sensory modalities36 and was used in the present investigation, and in similar research34 as a further assessment of muscle soreness. Participants were provided with a visual aid attaching verbal descriptors to numeric soreness values, and those numerical values were used for analysis. VERTICAL JUMP
Vertical jump testing followed the protocol outlined in The Canadian Physical Activity, Fitness and Lifestyle Approach (CPAFLA) manual,37 using a commercial Vertec (Vertec, North Easton, MA, USA). While instructed not to use a preparatory step, participants flexed their hips and knees into a partial squat, stopping fully in this position and pausing in order to eliminate any influence from the stretch reflex. Participants then jumped up, reaching up with their dominant arm, and pushed the highest vane possible. Three trials were performed with at least 60 s rest between each
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The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
Table 2. Mean (SD) subject characteristics at baseline (Values reported as mean ± SD). Variable
CON (n=17)
PhT (n=16)
Weight (kg)
76.7 (13.3)
74.1 (16.4)
Age (yrs)
20.8 (1.3)
20.6 (1.6)
Height (m)
1.7 (0.1)
1.7 (0.1)
BMI (kg.m-2)
26.2 (4.5)
25.8 (4.6)
Muscle soreness (gLMS)
2.0 (5.5)
7.7 (14.8)
Muscle pain: Quadriceps (VAS)
0.2 (0.5)
0.6 (1.3)
Muscle pain: Hamstrings (VAS)
0.3 (0.6)
0.4 (0.9)
Muscle pain: Calf (VAS)
0.3 (0.6)
0.6 (1.7)
Vertical Jump height (inches)
20.4 (3.2)
21.6 (4.8)
Agility (s)
13.1 (1.4)
13.0 (1.4)
PhT= Phototherapy condition. CON= Control condition. gLMS= General labelled magnitude scale. VAS= Visual analog scale. No significant differences found between groups at baseline (p > 0.05).
attempt, the average was recorded to the nearest 0.5 in, and used for analysis. AGILITY
For the Agility T-Test, four cones were arranged in a T shape. Starting at the bottom of the T, participants sprinted 10 yards forward, then shuffled five yards to the right, then shuffled ten yards to the left, then shuffled five yards to the right, then backpedaled 10 yards to the initial starting point, touching each cone outlining the T as they went. The average of three trials was recorded to the nearest 0.1 seconds, and used for analysis. Trials were performed with at least 120 s rest between each attempt. A trial was disqualified if the participant neglected to touch a cone, crossed their feet during a lateral shuffle, turned their body sideways while shuffling, slipped, fell, or stumbled.38 STATISTICAL ANALYSES
The three values for each assessment collected during week one were used to calculate baseline scores. The five values for each assessment collected during week two were then compared to baseline values (Δ). Area under the curve (AUC) was calculated for each participant by summing week two scores collected from POST to +96hrs. Normality of distribution was assessed via the Kolmogorov Smirnov test. Normally distributed data were compared between conditions with a two-tailed independent t-test. Nonparametric data were compared using the two-tailed Mann-Whitney U test. Alpha level was set at 0.05. Data analysis was completed with GraphPad Prism 5.0 (GraphPad Software San Diego, CA, USA). Additionally, the magnitude of effect was calculated for significant treatment effects. Mean differences were first calculated between condition means as they changed (Δ) from baseline. Ninety-percent confidence intervals were then calculated to surround mean differences (presented as mean difference, ±CI90%), in accordance with the approach of Hopkins et al.39 Confidence intervals were then calculated using the formula: Standard error of the mean, with the standard error of the mean calculated us-
ing the formula:
The thresholds for
small, moderate, and large effects were calculated as 0.3, 0.9, and 1.6 of the standard error of the measurement.39 The standard error of the measurement was calculated with the formula: where Rtest equated to the mean intra-class correlation coefficient (ICC) obtained from familiarization session two vs. familiarization session three. A learning effect would likely increase variability across familiarization sessions; thus, this may be described as a conservative assessment. Lastly, SDtest equated to the standard deviation of the values collected during familiarization sessions.
RESULTS PARTICIPANT CHARACTERISTICS
The mean (SD) participant baseline scores are displayed in Table 2. No significant differences were observed between conditions for baseline participant scores or characteristics (p > 0.05). PERCEPTIONS OF MUSCLE SORENESS VIA ALGOMETRY
Mean (SD) perception of calf soreness by condition, assessed via an algometer, is displayed in Figure 2. Calf soreness in response to 30 N of pressure applied by an algometer was significantly lower in PhT compared to CON (p = 0.02). For CON, mean changes from baseline were 1.6, 2.3, 1.6, 0.8, and 0.1 on the day muscle damage was induced, and over the four days following, respectively. For PhT, mean changes from baseline were 0.8, 1.0, 0.5, 0.1, and -.1, respectively. No significant differences were observed between groups for hamstrings or quadriceps soreness in response to 30 N of pressure applied by an algometer (p > 0.05) The mean (SD) pain response did not exceed 2.7 ± 2.3 across all conditions and muscle bellies, which equates to a location roughly halfway between ‘no pain’ at point zero, and ‘moderate pain’ at point five on the zero to VAS 10 scale. Additionally, the magnitude of effect was calculated by finding the mean difference in the Δ perception of calf sore-
International Journal of Sports Physical Therapy
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
Figure 2. Perceptions of calf soreness in phototherapy (PhT) and control (CON) conditions. A) Mean change in perceptions of calf soreness B) Area under the change (Δ) in gLMS curve. A two-tailed Mann Whitney U test showed a significant difference by condition (p > 0.05) in the area under the curve, with PhT resulting in lower perceptions of calf soreness compared to CON.
ness between CON and PhT, then building a 90 % confidence interval (±CI90%) around the mean difference for each of the five testing days (Figure 3). The magnitudebased approach suggests with a 90 % certainty that true change in perception of calf soreness between the two conditions will fall within the ‘small’, ‘medium’ or ‘large’ effect ranges. Additionally, should there be no real difference between the two conditions, the mean difference, ±CI90% will overlap zero, represented by a solid line in the figure’s center. The reader will observe that immediately post-sprint, the mean difference overlaps zero, indicating that there may be no real effect of the intervention. Further, the right border of the confidence interval extends into the positive region of the figure, suggesting possible performance impairment with PhT compared to CON. At 24 to 48 hours post sprinting, the confidence interval borders ‘medium effect’ at its lower bound to ‘large effect’ at its upper bound, suggesting a beneficial effect of the intervention. At 72 hours post sprinting, the confidence interval borders ‘small effect’ at its lower bound, and ‘large effect’ at its upper bound, suggesting a beneficial effect of the intervention for some, but possibly no effect for others. At 96 hours post sprinting, the confidence interval borders ‘no effect’ at its lower bound, and ‘medium effect’ at its upper bound. These data suggest with 90% certainty that the true change in perception of calf soreness after exercise-induced muscle damage measured between conditions will fall in the “small,” “medium,” or “large” effect ranges. If there is no real difference between conditions, the mean difference, ±CI90% will overlap zero. The data show favor for phototherapy (left of zero), indicating a benefit toward reducing perceptions of muscle soreness.
PERCEPTIONS OF MUSCLE SORENESS VIA GENERAL LABELLED MAGNITUDE SCALE
No significant differences were observed between groups for overall lower body muscle soreness as measured by gLMS (p > .05). VERTICAL JUMP
Vertical jumping height (inches) did not significantly differ between conditions (p > 0.05). The mean (SD) vertical jump height measured across both conditions fell from 21.0’’ ± 4.0’’ at baseline to 19.2’’ ± 4.0" at POST, 19.6’’ ± 3.9’’ at +24hrs, 19.4’’ ± 4.0’’ at +48hrs, 19.8’’ ± 4.2’’ at +72hrs, and 20.0’’ ± 4.3’’ at +96hrs. AGILITY
Agility T-Test time (s) did not significantly differ between conditions (p > 0.05). The mean (SD) Agility T-Test time across both conditions fell from 13.0 ± 1.4 s at baseline to 13.6 ± 1.6 s at POST, 13.5 ± 1.5 at +24hrs, 13.3 ± 1.7 s at +48hrs, 13.4 ± 1.5 s at +72hrs, and 13.3 ± 1.5 s at +96hrs.
DISCUSSION The present investigation assessed whether PhT influences soreness perception and recovery of multi-joint, functional movements following EIMD caused by repeated sprinting. An important finding is that the repeated sprint protocol induced muscle soreness in both conditions. Participants in both PhT and CON experienced moderate perceptions of muscle soreness as indicated by the gLMS scale. Another important finding is that PhT appeared to expedite calf soreness recovery following EIMD, as measured by an algometer (Figure 2). Calf soreness was lower in the PhT group compared to CON. Thus, while both groups experienced calf soreness following EIMD, PhT reported lower
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The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
Figure 3. Mean difference, ± CI90% for the perception of calf soreness compared by condition (CON vs. PhT) across the testing week.
soreness values throughout the week. Mean values for calf soreness changes from baseline in CON were 1.6, 2.3, 1.6, 0.8, and 0.1 on the day muscle damage was induced, and over the four days following, respectively. Mean values for calf soreness changes from baseline in PhT on those days were 0.8, 1.0, 0.5, 0.1, and -.1, respectively. These findings indicate that PhT may reduce calf soreness following EIMD. Phototherapy appears to generally aid recovery of performance variables following EIMD,10,16,21,24–31 but the influence on soreness is unclear, with both positive24,29 and null findings25,27,30,32 reported in previous investigations. Three different algometry sites and a global measure of lower body muscle soreness, the gLMS, were used in the present investigation. Quadriceps and hamstrings soreness, as measured by an algometer, and overall lower body soreness, as measured by the gLMS scale, were not different between groups. Calf soreness, measured with an algometer, was the only measure where PhT reported significantly lower soreness through the week. While the between-group area under the curve reached significance, it is reasonable to question whether these statistically significant differences hold any practical meaning. The largest difference between groups was observed at +24hrs post EIMD, where CON reported a 2.3 out of 10 on the soreness scale, and PhT reported 1.0 out of 10, equating to a mean difference between conditions of 1.3 units. Given this difference approaches the limits of the sensitivity of the scale, coupled with the scale’s inherent lack of verbal descriptors, assigning meaning to the difference is difficult. It is unclear whether an athlete would meaningfully benefit from a soreness reduction of this magnitude. Aver Vanin et al.25 did not observe reductions in soreness with PhT, and suggested that the use of high-level athletes in that study versus the
use of untrained volunteers in others (as in the present investigation) may explain the differing outcomes. While PhT may offer modest reductions in soreness following EIMD, it is unclear whether these contribute to performance recovery, or can even be expected in a trained population. Vertical jump height was not different between PhT and CON in the present investigation. To date, researchers have identified PhT’s benefit toward improving muscular force as measured by repetitions to fatigue,31 and MVC.10,16,24–30 There has been little investigation into PhT’s influence on power-oriented activities, such as jumping. Malta et al. reported that PhT did not expedite recovery of VJ following EIMD.32 In light of the findings by Malta et al.32 and those of the present investigation, it appears that PhT may not enhance recovery of short-burst, explosive activities with a considerable neurological component, compared to more prolonged activities where fatigue may be a factor. Agility recovery was also not enhanced by PhT in the present investigation. Pinto et al. reported that repeated sprint ability recovery was enhanced after PhT was applied following EIMD, further indicating that PhT may benefit activities posing an endurance challenge.21 The Agility T-Test used herein was performed in a non-fatigued state, and was typically completed in 10-13 seconds. Thus, the test’s duration was potentially too short for any benefits of PhT to be apparent. However, previous investigations have reported improved recovery of MVC, indicating PhT’s possible benefit toward recovery of certain short-duration performance measures. Maximal voluntary contraction assessment can be classified as a high-force, low-velocity activity. Alternatively, VJ and the Agility T-Test are best classified as low-force, high-velocity. The latter two are likely limited by neurological factors, more so than the former.38 Thus, it is possible that PhT
International Journal of Sports Physical Therapy
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
may not benefit activities where limitations to performance are primarily pre-synaptic. A strength of this study was the existence of a true placebo condition. Investigations of other popular recovery methods (foam rolling, massage, ice baths) do not lend themselves to blinding of the control group. Another strength was the relevance of the muscle damage protocol and testing battery to many popular sporting activities. A weakness of this study was the lack of physiological assessment, which precludes any insight into potential mechanisms. There were several important limitations of this study. First, participants were healthy, young adults. Trained athletes, children, individuals with chronic musculoskeletal injuries, or older adults may respond differently to PhT following EIMD. Second, the present findings may be unique to the particular PhT protocol used in this investigation. At this time, no standard method, duration, or frequency of PhT exists. Third, the findings of the present investigation are limited to recovery from EIMD following a repeated sprint protocol. Individuals experiencing EIMD brought on by other forms of exercise may respond to PhT in a different manner. CONCLUSIONS
The results of the present investigation support the null hypotheses that PhT would not decrease perceptions of hamstring, quadriceps, and general soreness, or increase VJ and agility compared to CON following EIMD. The results do support the alternative hypothesis that calf soreness would
differ between CON and PhT following EIMD caused by sprinting. Following EIMD, PhT may offer a modest benefit toward calf soreness recovery, but the meaningfulness of this finding is unclear. Additionally, the findings of the present investigation do not suggest a benefit toward low force, high velocity anaerobic activities. Future studies should investigate precisely which type of activities and/or populations benefit from PhT. Further, future studies should investigate the optimal dose, timing and general best practices concerning the use of PhT.
ACKNOWLEDGMENTS
These results were presented in an oral presentation at the New England American College of Sports Medicine Fall Meeting in November 2019. No financial support was received. CONFLICT OF INTEREST STATEMENT
Co-author Joseph A. Gallo, DSc, ATC, PT has served as a consultant or received honoraria from Richmar/Compass Health Brands, DJO, Zimmer MedizinSysteme, and Dynatronics Corporation. Submitted: September 02, 2021 CDT, Accepted: February 08, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
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International Journal of Sports Physical Therapy
The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
17. Hemmings TJ, Kendall KL, Dobson JL. Identifying dosage effect of light-emitting diode therapy on muscular fatigue in quadriceps. J Strength Cond Res. 2017;31(2):395-402. doi:10.1519/jsc.00000000000015 23 18. Leal Junior ECP, Lopes-Martins RÁB, Dalan F, et al. Effect of 655-nm low-level laser therapy on exercise-induced skeletal muscle fatigue in humans. Photomed Laser Surg. 2008;26(5):419-424. doi:10.108 9/pho.2007.2160 19. Leal ECP Jr, Lopes-Martins RÁB, Frigo L, et al. Effects of low-level laser therapy (LLLT) in the development of exercise-induced skeletal muscle fatigue and changes in biochemical markers related to postexercise recovery. J Orthop Sports Phys Ther. 2010;40(8):524-532. doi:10.2519/jospt.2010.3294 20. Leal Junior ECP, Lopes-Martins RÁB, Rossi RP, et al. Effect of cluster multi-diode light emitting diode therapy (LEDT) on exercise-induced skeletal muscle fatigue and skeletal muscle recovery in humans. Lasers Surg Med. 2009;41(8):572-577. doi:10.1002/ls m.20810 21. Pinto HD, Vanin AA, Miranda EF, et al. Photobiomodulation therapy improves performance and accelerates recovery of high-level rugby players in field test: A randomized, crossover, double-blind, placebo-controlled clinical study. J Strength Cond Res. 2016;30(12):3329-3338. doi:10.1519/jsc.00000000000 01439 22. Rossato M, Dellagrana RA, Lanferdini FJ, et al. Effect of pre-exercise phototherapy applied with different cluster probe sizes on elbow flexor muscle fatigue. Lasers Med Sci. 2016;31(6):1237-1244. doi:1 0.1007/s10103-016-1973-0 23. Rossato M, Dellagrana RA, Sakugawa RL, Lazzari CD, Baroni BM, Diefenthaeler F. Time response of photobiomodulation therapy on muscular fatigue in humans. J Strength Cond Res. 2018;32(11):3285-3293. doi:10.1519/jsc.0000000000002339 24. Antonialli FC, De Marchi T, Tomazoni SS, et al. Phototherapy in skeletal muscle performance and recovery after exercise: effect of combination of super-pulsed laser and light-emitting diodes. Lasers Med Sci. 2014;29(6):1967-1976. doi:10.1007/s10103-0 14-1611-7 25. Aver Vanin A, De Marchi T, Silva Tomazoni S, et al. Pre-exercise infrared low-level laser therapy (810 nm) in skeletal muscle performance and postexercise recovery in humans, what is the optimal dose? A randomized, double-Blind, placebo-controlled clinical trial. Photomed Laser Surg. 2016;34(10):473-482. doi:10.1089/pho.2015.3992
26. Borges LS, Cerqueira MS, dos Santos Rocha JA, et al. Light-emitting diode phototherapy improves muscle recovery after a damaging exercise. Lasers Med Sci. 2014;29:1139-1144. 27. Baroni BM, Leal Junior ECP, De Marchi T, Lopes AL, Salvador M, Vaz MA. Low level laser therapy before eccentric exercise reduces muscle damage markers in humans. Eur J Appl Physiol. 2010;110(4):789-796. doi:10.1007/s00421-010-1562-z 28. De Marchi T, Leal-Junior ECP, Lando KC, et al. Photobiomodulation therapy before futsal matches improves the staying time of athletes in the court and accelerates post-exercise recovery. Lasers Med Sci. 2019;34(1):139-148. doi:10.1007/s10103-018-2643-1 29. de Paiva PRV, Tomazoni SS, Johnson DS, et al. Photobiomodulation therapy (PBMT) and/or cryotherapy in skeletal muscle restitution, what is better? A randomized, double-blinded, placebocontrolled clinical trial. Lasers Med Sci. 2016;31(9):1925-1933. doi:10.1007/s10103-016-207 1-z 30. Fritsch CG, Dornelles MP, Severo-Silveira L, Marques VB, Rosso I de A, Baroni BM. Effects of lowlevel laser therapy applied before or after plyometric exercise on muscle damage markers: randomized, double-blind, placebo-controlled trial. Lasers Med Sci. 2016;31(9):1935-1942. doi:10.1007/s10103-016-207 2-y 31. Larkin-Kaiser KA, Christou E, Tillman M, George S, Borsa PA. Near-infrared light therapy to attenuate strength loss after strenuous resistance exercise. J Athl Train. 2015;50(1):45-50. doi:10.4085/1062-605 0-49.3.82 32. Malta E de S, Lira FS de, Machado FA, Zago AS, Amaral SL do, Zagatto AM. Photobiomodulation by led does not alter muscle recovery indicators and presents similar outcomes to cold-water immersion and active recovery. Front Physiol. 2019;9(1948). doi:1 0.3389/fphys.2018.01948 33. Woolley BP, Jakeman JR, Faulkner JA. Multiple sprint exercise with a short deceleration induces muscle damage and performance impairment in young, physically active males. J Athl Enhancement. 2014;03(02). doi:10.4172/2324-9080.1000144 34. D’Amico AP, Gillis J. Influence of foam rolling on recovery from exercise-induced muscle damage. J Strength Cond Res. 2019;33(9):2443-2452. doi:10.151 9/jsc.0000000000002240 35. Bijur PE, Silver W, Gallagher EJ. Reliability of the visual analog scale for measurement of acute pain. Acad Emergency Med. 2001;8(12):1153-1157. doi:10.11 11/j.1553-2712.2001.tb01132.x
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The Influence of Phototherapy on Recovery From Exercise-Induced Muscle Damage
36. Green BG, Shaffer GS, Gilmore MM. Derivation and evaluation of a semantic scale of oral sensation magnitude with apparent ratio properties. Chem Senses. 1993;18(6):683-702. doi:10.1093/chemse/1 8.6.683 37. Canadian Society for Exercise Physiology (CSEP) The Canadian Physical Activity, Fitness & Lifestyle Approach (CPAFLA): CSEP-Health & Fitness Program’s Health-Related Appraisal and Counselling Strategy. 3rd ed. Canadian Society for Exercise Physiology and Health Canada; 2003:8.
38. Deonese B, Nimphius S. Essentials of Strength Training and Conditioning. 4th ed. Human Kinetics; 2016:522-548. 39. Hopkins WG, Marshall SW, Batterham AM, Hanin J. Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc. 2009;41(1):3-12. doi:10.1249/mss.0b013e31818cb278
International Journal of Sports Physical Therapy
Karagiannopoulos C, Griech S, Leggin B. Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User Experience Levels. IJSPT. 2022;17(4):669-676.
Original Research
Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User Experience Levels Christos Karagiannopoulos 1 1
a
, Sean Griech 1
, Brian Leggin 2
Doctor of Physical Therapy Program, DeSales University, 2 Penn Therapy and Fitness, Good Shepherd Penn Partners
Keywords: ActivForce, microFET2, hand-held dynamometer, psychometric properties, clinical experience https://doi.org/10.26603/001c.35577
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Currently available hand-held dynamometers (HHD) offer a more objective and reliable assessment of muscle force production as compared to a manual muscle test (MMT). Yet, their clinical utility is limited due to high cost. The ActivForce (AF) digital dynamometer is a new low-cost HHD with unknown psychometric properties, and its utilization may benefit clinical practice.
Hypothesis/Purpose This study aimed to determine the AF intra- and inter-tester reliabilities, standard error of measurement (SEM), minimal detectable change (MDC), and criterion validity for assessing shoulder isometric force as compared to the microFET2 (MF2) across testers with different experiences.
Design Descriptive observational study.
Methods A convenience sample of 29 healthy adults were assessed twice by each of three testers (two experienced clinicians and a novice PT student) on shoulder external rotation (ER), internal rotation (IR), and forward elevation (FE) using both the AF and MF2 devices. Tester, HHD, and shoulder motion assignment orders were randomized. All testing was performed in a standardized seated position. ER and IR were tested with the shoulder fully adducted. FE was tested at 45° at the scapular plane. All testing and rest periods between testers and tested motions were standardized and monitored via a stopwatch.
Results Both devices had high intra- [ ER (.95-.98), IR (.97 - .99), FE (.96 - .99)] and inter-tester [ ER (.85-.96), IR (.95 - .97), FE (.88 - .95)] intraclass correlation coefficient (ICC) with comparable intra- (1.68-1.80) and inter-tester (2.36-2.98) SEM, and intra- (4.64-4.97) and inter-tester (6.50-8.24) MDC values across all motions. Tester experience did not affect these values. High (.89-.93) statistically significant Pearson correlations were found between HHDs for all shoulder motions.
Conclusion Both the AF and MF2 HHDs were found to have high reliability levels across all shoulder motions regardless of tester clinical experience. The AF was also found to be valid for
a
Corresponding author: Christos Karagiannopoulos, MPT, MEd, PhD, ATC, CHT Doctor of Physical Therapy Program, DeSales University 2755 Station Avenue, Center Valley, Pennsylvania, United States. Tel: 610 282 1100, Ext 2142, E-mail: Christos.Karagiannopoulos@desales.edu
Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User...
measuring shoulder isometric force production compared to the criterion standard device, the MF2. Its low-cost and electronic accessibility features may promote better compliance for clinicians using dynamometry to objectively assess and store muscle force data in a cost-effective manner.
Level of Evidence 3
INTRODUCTION Accurate quantification of muscle force production is important in clinical practice. It allows clinicians to identify limitations as well as track the progression of muscle strength over time, which has shown to be a strong predictor for functional gains.1–3 Manual muscle testing (MMT) has been commonly used clinically to evaluate muscle strength.4,5 However, MMT for strength assessment has been criticized for its subjectivity and low reliability in quantifying muscle force production.6,7 The continued clinical use of MMT can be justified due to ease of performance and lack of cost. Hand-held dynamometers (HHD) quantify muscle force production accurately8 and offer an alternative to MMT for objectively monitoring patients’ strength progress over time.8,9 HHD isometric testing can encompass a “maketest” technique, where the subject exerts muscle force against a stationary dynamometer. This method involves less measurement error than a MMT “break test”.10,11 Various HHDs have been studied for use in the upper extremity with good-to-excellent reliability [Intraclass Correlation Coefficient (ICC) >.75], and concurrent validity when compared to the isokinetic dynamometry.9,12 HHDs appeal to clinicians due to their portability, ease of use, and lower cost, as compared to isokinetic devices. However, the price (> $1,000) of currently available HHDs may be cost-prohibitive for some clinicians.10,12 The microFET2 (MF2; Hoggan Scientific, Salt Lake City, UT) is a commonly used HHD with high (>.85) reliability in assessing muscle force production across various injury populations3,10,13,14 that include shoulder patients.3,13,14 Similarly, the MF2 has been found to be highly reliable among healthy adults.15 Its moderate-to-high (r ≥.50) concurrent validity has also been established against isokinetic testing16–20 among injury populations16,21 that include the shoulder17,18,20 as well as in healthy adults.19 Thus, it can be considered a criterion-standard for assessing muscle force production. The ActivForce (AF; Activbody, San Diego CA) digital dynamometer is a newly available HHD, which is marketed as both an exercise monitoring tool and isometric muscle force testing instrument. It was manufactured to be a clinically useful tool for establishing muscle strength impairment baselines and tracking the progress of strengthening programs among patients with various pathologies. The AF is smaller, lighter, and less expensive (priced at < $200.00) as compared to other HHDs. However, to the best of the authors’ knowledge, its psychometric properties have yet to be established. Additionally, the effect of tester clinical experience on the psychometric properties of both the MF2 and AF HHDs has not been established. Knowledge of tester experience on the clinometric properties of these HHDs may
advance their clinical utility and implementation among more clinicians with diverse clinical backgrounds. This study aimed to determine: 1) the intra- and intertester reliability for novice and experienced clinicians when testing shoulder isometric muscle force [external rotation (ER), internal rotation (IR), and forward elevation (FE) at the scapular plane] of the MF2 and AF HHDs in healthy adults, 2) the standard error of measurement (SEM) and the minimal detectable change (MDC) values for both HHDs when assessing shoulder isometric muscle force in healthy adults, and 3) the criterion validity of the AF compared to the MF2 HHD on testing shoulder isometric muscle force in healthy adults.
METHODS This was an observational study, which was approved by the DeSales University Institutional Review Board. Participants were recruited via word of mouth and electronic communication (social media and emails) within the DeSales University community. All participants signed informed consent, their rights were protected, and were screened for eligibility. Inclusion criteria included being at least 18 years of age with no history of shoulder surgery at the dominant arm within two years, no shoulder pain within the prior six months, and pain-free functional shoulder active range of motion. Hand dominance was determined as the participant’s preferred side for writing.22 Functional shoulder motion in ER, IR, and FE were defined as being able to reach with the dominant hand behind the head, up the spine behind the back, and overhead midway between the sagittal and frontal planes, respectively. Exclusion criteria consisted of inability to speak or read in English, cognitive impairment impacting the safety of the participant, any painful shoulder pathology with muscle weakness at the dominant arm, and pregnancy. INSTRUMENTATION
Muscle force production of each participant’s dominant shoulder ER, IR, FE was measured using the MF2 and AF HHDs (Figure 1). A standardized testing position was adopted for both devices with the participants in a seated position (Figure 2). Shoulder ER and IR were tested with the participant’s arm fully adducted, the elbow at 90°, and the forearm in a neutral position. Shoulder FE was tested at 45° in the plane of scapula,23 which was defined as a participant’s natural shoulder upward motion that occurs between the frontal and sagittal plane (halfway between the coracoid process and posterolateral acromion corner), identified via palpation.24 To minimize error and maximize testing standardization efficiency, the tester passively placed the participant’s arm in each test position while the HHD
International Journal of Sports Physical Therapy
Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User...
was placed at the volar distal forearm for IR, the dorsal distal forearm for ER, and the distal lateral humerus for FE.23 Before data collection, a small (n=10) pilot training was performed to ensure consistency on the study’s protocol. All three testers were present during this training session. Important feedback was shared between testers, which was used constructively towards establishing inter-tester agreement and consistency across all testing steps. PROCEDURES
Three testers assessed each participant with each HHD. Two testers were experienced clinicians (>20 years of experience) and one tester was a third-year physical therapy student with only novice HHD skills. Both expert clinicians held advanced Physical Therapy certifications in the Orthopedic, Upper Extremity, and Manual Therapy. The tester, device, and motion assignment order were randomized. An investigator not performing the testing read each device and recorded the data, thus, both the participant and tester blinded to the results. The MF2 device offers a digital display at its side, which was blocked from the tester’s view during testing. The AF device does not display the force. It allows for a remote connection with a cell phone where the test score is displayed. After each test trial, the independent reader who stood next to each tester read and recorded each HHD. Testing consisted of two trials of a maximal isometric “make test” with a 30-sec rest period between trials. Standardized verbal commands were utilized for each trial (“push as hard as possible, push, push, push”), which lasted for three seconds. This protocol was repeated with all testers using both HHDs for each motion assessed. A three to five min rest period was given between motions and testers, respectively. All time periods of the study were monitored by a stopwatch. At the end of each testing session, participants were asked to report which device felt most comfortable during testing. DATA ANALYSIS
Descriptive and inferential statistical analysis was performed using SPSS version 25 (IBM Corp., Armonk, NY). ICC (2,2) was used to determine the intra-tester reliability within each tester based on the two trials each tester competed for each shoulder motion. ICC (2,1) was used to determine the inter-tester reliability across testers of similar and different clinical experience levels based on the mean value of the two trials each tester completed for each shoulder motion. ICCs were interpreted as ≥.75 high, .40 -.75 moderate, and <.40 poor.24,25 SEM and MDC values were determined for both HHDs. The SEM represented the within and between testers’ HHD measurement error for each shoulder motion.25 SEM was calculated as SD x √1-ICC, where SD is the measurement standard deviation within and between each tester.24 The MDC, which is a measure of test-responsiveness,26 represented the minimum test-score change for a statistically significant difference, taking into account variation between subjects, raters, and SEM.21,24 MDC was calculated as z x SEM x √2, with a z score of 1.96 reflecting a 95% confidence level.24 Concurrent validity was determined via Pearson correlation coefficient statistics by comparing
Figure 1. The HHDs used in this study: MF2 (A) and AF (B).
the AF to its criterion-referenced MF2 HHD in all 3 shoulder motions. Pearson correlations were interpreted as: >.75 good-high, 0.50 - 0.75 moderate-good, and <.50 fair-poor.24 Participants’ preferences on instrument comfort levels during testing were reported via frequency statistics.
RESULTS Among 30 recruited participants, only one was excluded due to shoulder pain during testing. The final analysis included 29 healthy participants (17 females and 12 males) with a mean age of 30 ±11.4 years. The majority (25/29) of participants were right-hand dominant. Descriptive intraand inter-tester reliability statistics for both devices across all three testers and shoulder motions are shown in Tables 1 and 2. Results demonstrated high intra- (.95 - .99) and intertester (.85 - .97) ICCs for both devices, all testers, and all shoulder motions. Table 3 shows the average ICC, SEM, and MDC values for both devices and all testers when all shoulder motions were combined. Pearson correlation analysis indicated strong correlations between the MF2 and AF for the ER (r =.89, p=0.000), IR (r =.93, p=0.000), and FE (r =.91, p=0.000) shoulder motions. These correlations were found statistically significant at the 0.01 level. The AF was reported as the preferred HHD by the majority (86%) of the participants based on comfort levels during testing.
DISCUSSION To the best of the authors’ knowledge, this is the first study to determine the AF psychometric properties. This HHD was found to be a highly reliable and valid tool for assessing shoulder muscle force in ER, IR, and FE motions in healthy adults as compared to the gold-standard MF2. Like the MF2, the AF demonstrated excellent levels of intra- and intertester reliability and criterion validity for all tested motions amongst both experienced and novice testers. In this study, tester clinical experience differences minimally influenced the AF intra- and inter-tester reliability, concurrent validity, and SEM and MDC values, demonstrating comparable psychometric stability to the MF2. The intra- and inter-tester reliability ICCs were high (.85-.99) for both the new AF and MF2 without noticeable differences among the three shoulder motions. These ICCs
International Journal of Sports Physical Therapy
Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User...
Table 1. Intra-tester descriptive statistics for both HHDs and all three testers and motions. Tester
Instrument/Motion
ICC (2,1)
(95% CI)
SEM
MDC95
Expert 1
MF2/FE MF2/IR MF2/ER AF/FE AF/IR AF/ER
0.98 0.97 0.98 0.99 0.99 0.98
(0.97, 0.99) (0.94, 0.98) (0.97, 0.99) (0.97, 0.99) (0.98, 0.99) (0.95, 0.99)
1.60 2.14 1.06 1.36 1.36 0.91
4.43 5.93 2.92 3.75 3.75 2.51
Expert 2
MF2/FE MF2/IR MF2/ER AF/FE AF/IR AF/ER
0.96 0.97 0.97 0.97 0.98 0.97
(0.91, 0.98) (0.94, 0.98) (0.93, 0.98) (0.94, 0.98) (0.97, 0.99) (0.93, 0.98)
1.75 1.93 1.25 1.86 1.88 1.39
4.83 5.32 3.45 5.13 5.18 3.83
Novice
MF2/FE MF2/IR MF2/ER AF/FE AF/IR AF/ER
0.96 0.98 0.97 0.96 0.98 0.95
(0.92, 0.98) (0.96, 0.99) (0.94, 0.98) (0.93, 0.98) (0.97, 0.99) (0.91, 0.98)
2.19 1.82 1.23 2.82 1.95 1.68
6.04 5.02 3.39 7.78 5.38 4.63
ICC = Intraclass Correlation Coefficient; CI = Clinical Interval; SEM = Standard Error of Measurement; MDC95 = Minimal Detectable Change; MF2 = microFET2; AF = Active Force; FE = Forward Flexion; IR = Internal Rotation; ER = External Rotation.
Table 2. Inter-tester descriptive statistics for both HHDs, and all three testers and motions. Testers
Instrument/Motion
ICC (2,2)
(95% CI)
SEM
MDC95
Exp 1 vs. Exp 2
MF2/FE MF2/IR MF2/ER AF/FE AF/IR AF/ER
0.92 0.96 0.93 0.89 0.95 0.85
(0.84, 0.96) (0.92, 0.98) (0.85, 0.96) (0.94, 0.94) (0.83, 0.98) (0.05, 0.96)
2.78 2.28 1.93 4.01 2.99 2.77
7.67 6.29 5.32 11.06 8.25 7.64
Nov vs. Exp 1
MF2/FE MF2/IR MF2/ER AF/FE AF/IR AF/ER
0.93 0.97 0.91 0.93 0.96 0.94
(0.80, 0.97) (0.93, 0.98) (0.81, 0.95) (0.85, 0.96) (0.92, 0.98) (0.87, 0.97)
2.91 2.13 2.17 3.63 2.73 1.68
8.03 5.87 5.98 10.01 7.53 4.63
Nov vs. Exp 2
MF2/FE MF2/IR MF2/ER AF/FE AF/IR AF/ER
0.88 0.96 0.96 0.95 0.95 0.89
(0.76, 0.94) (0.93, 0.98) (0.90, 0.98) (0.90, 0.97) (0.85, 0.98) (0.03, 0.97)
3.34 2.38 1.42 2.74 3.01 2.53
9.21 6.56 3.91 7.56 8.30 6.98
ICC = Intraclass Correlation Coefficient; CI = Clinical Interval; SEM = Standard Error of Measurement; MDC95 = Minimal Detectable Change; Exp = Expert; Nov = Novice; AF = Active Force; MF2 = microFET2; FE = Forward Flexion; IR = Internal Rotation; ER = External Rotation.
are in agreement with previous studies that have found high (.82-.99) intra- and inter-tester ICCs for HHDs, including the MF2, on assessing shoulder strength in patients with shoulder pathology,14 swimmers,13 and healthy adults.3,15,20 All the previously referenced studies3,13–15,20 were affected by a lack of standardization in body and shoulder positioning during testing. The current study’s HHD isometric strength-testing process adapted the same test positions as previous studies,23,24 which reported high (.79-.96) intra- and inter-tester ICCs when assessing shoulder strength in ER, IR, and FE with a HHD.23 The advantage of the selected shoulder-testing positions was thought to be the ease of instrument stabilization against the body, better representation of functional shoulder positions, and test standardization consistency. Muscle force testing in ER, IR,
and FE at below shoulder-level positions could also more readily apply in patients with shoulder pain. This study’s high ICCs confirmed the Leggin et al23 study results for these AF and MF2 testing positions. The other variable in this study was tester clinical experience. The initial hypothesis was that a tester with novice clinical experience would be less reliable in HHD testing than the experienced testers. To the best of the authors’ knowledge, this is the first study to investigate the influence of clinical experience on the reliability of shoulder isometric muscle force HHD testing. Thus, it is not feasible to compare this study’s findings to previous studies that have utilized testers with advanced clinical skills or did not report instrument reliability differences based on tester-experience levels. This study has shown that the AF is as re-
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Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User...
Table 3. Average intra- and inter-tester descriptive statistics for both HHDs and clinical experience levels with all shoulder motions combined. MF2
AF
Conditions
Testers
ICC
SEM
MDC95
ICC
SEM
MDC95
Intra-tester
Exp
.97
1.62
4.48
.98
1.46
4.02
Nov
.97
1.74
4.81
.96
2.15
5.93
All
.97
1.68
4.64
.97
1.80
4.97
Exp-Exp
.93
2.33
6.42
.89
3.25
8.98
Nov-Exp
.93
2.39
6.59
.93
2.72
7.50
All
.93
2.36
6.50
.91
2.98
8.24
Inter-tester
MF2 = microFET2; AF = Active Force; ICC = Intraclass Correlation Coefficient; SEM = Standard Error of Measurement; MDC95 = Minimal Detectable Change; Nov = Novice Tester; Exp = Experienced Tester.
Figure 2. Shoulder testing positions for IR (A), ER (B), and FE (C).
liable as other commonly utilized HHDs such as the MF2, in assessing shoulder isometric muscle force, regardless of tester experience. In this study, both devices were found to have small intra- (1.68 - 1.80 lbs.) and inter-tester (2.36 - 2.98 lbs.) SEM values for all shoulder motions combined (Table 3). The AF had slightly higher inter-tester SEM values than the MF2 HHD, a difference that was not statistically analyzed. Clinical experience and shoulder motion did not have a noticeable effect on the SEM values of these devices with the novice tester having slightly higher SEM values than the experienced clinicians. The observed SEM variability could be attributed to potential instrumentation error sources such as slight inconsistencies in verbal cueing, participants’ body compensation patterns, and muscle fatigue. Although a small amount of instrumentation error is considered inevitable, testing randomization and standardization were expected to keep this study’s SEM at low levels. The MDC values of both HHDs followed a similar pattern to their SEM levels. The AF had slightly higher MDC values compared to the MF2 potentially due to higher SEM levels. Based on their MDC values, score changes of 5-6 lbs. and
5-8 lbs. are required to measure statistically significant differences in muscle force production with the MF2 and AF HHD, respectively. Yet, tester clinical experience did not noticeably influence the instruments’ MDC values (Table 3). Among the three shoulder motions, slightly higher MDC values existed for the FE and IR than for ER across all testers and both HHDs. Based on MDC averaged values from Tables 2 and 3, a test-score change of near 7 lbs. implies a statistically significant difference in muscle force production for FE and IR. The comparable test-score change in muscle force production for ER is near 4 lbs. These findings are consistent with previously reported HHD SEM and MDC values for shoulder ER, IR,3 and flexion in healthy adults.27 Regarding the concurrent validity of the AF as it compares to a criterion-standard dynamometer on shoulder muscle force production, the current results are also in agreement with previous research.12 In this study, the criterion-standard device was the MF2, which has been strongly validated against an isokinetic device for testing shoulder isometric strength in healthy adults.17,18,20 This study’s results confirmed that the AF strongly correlates (r =.89 -.93) with its counterpart MF2 HHD in testing shoulder ER, IR,
International Journal of Sports Physical Therapy
Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User...
and FE muscle force. These results are slightly higher than the correlation values (r=.76 -.78) previously reported between the MF2 and isokinetic machines.17,18,20 Such strong correlations strengthen the external validity and clinical utility of this new AF and are in line with recent claims in the literature that HHD muscle force testing should be considered a valid and an acceptable, clinically meaningful alternative to other externally fixed and expensive isokinetic dynamometers.28 This study is strengthened by both its observational design and methodological approach. In terms of its design, the aim to determine intra- and inter-tester reliabilities among multiple testers with different experience levels strengthened the study’s utility and extrapolation in clinical practice. In today’s clinical arena, where HHD devices are used regardless of clinical experience levels, an instrument’s psychometric properties should be established for all users. Likewise, the study’s aim to determine the AF concurrent validity via comparing it to an established criterion-standard HHD is consistent with current research standards. It also warrants the new instrument’s external validity and clinical credibility.12 The AF is pocket-sized, lightweight, easy to use, and more affordable HHD than others available on the market with unique advanced features to electronically measure, monitor, and store isometric muscle force data remotely. It can measure up to 200 pounds of muscle peak force. The standardized data collection process with randomization and blinding for both the testers and the participants, and the well-delineated recruitment process via specific inclusion and exclusion criteria strengthened the study. Data collection for each participant was completed within a single session to prevent possible confounding variables (activity, fatigue, diet, hydration, and motivation level differences) that may induce muscle force production variability with different-day testing. Although muscle fatigue was a concern in this study, the incorporation of consistent breaks between testers and test repetitions and the randomized assignment process should have offset any fatigue effects related to same-day testing. Study results should be generalized with caution due to some methodological limitations. This was an exploratory study, which utilized a sample of convenience of 29 participants. This study utilized a single data-collection site and recruited only healthy adults, limiting its ability to gener-
alize its findings among patients with shoulder pathology. However, the inclusion of only healthy participants allowed for determining the psychometric properties of this new AF among a more stable population, avoiding confounding influences from musculoskeletal injury (pain and muscle weakness). Also, no attempts were made to diversify the sample beyond the available participants’ gender and age. This study presents useful preliminary data on the AF psychometric properties and how clinical experience might influence its clinometric levels. Future studies should establish the AF psychometric properties in assessing patients with musculoskeletal pathologies.
CONCLUSION The results of this study indicate that the AF is a highly reliable (i.e., ICC, SEM, and MDC clinometric properties) and valid tool for assessing shoulder isometric muscle force in ER, IR, and FE as compared to its criterion-standard MF2 in healthy adults, regardless of tester clinical experience. Evidence from this study implies that the AF might offer clinicians an objective, and cost-effective HHD option for assessing shoulder muscle force production.
ACKNOWLEDGEMENTS
We are grateful to our DeSales DPT students: Michael Mathis, Sara Cinelli, Joshua Anderson, Cortlyn Van Deutsch, Kaylie Vrabel, and Thomas Epsaro, for their vital contributions and commitment during the entire data collection process. We are thankful to Wendy Thomas for her imperative assistance to the study scheduling process along with all our volunteer participants. DISCLOSURES
The authors report no present or future financial disclosures. Submitted: October 22, 2021 CDT, Accepted: February 08, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User...
REFERENCES 1. Capodaglio P, Capodaglio Edda M, Facioli M, Saibene F. Long-term strength training for community-dwelling people over 75: impact on muscle function, functional ability and life style. Eur J Appl Physiol. 2007;100(5):535-542. doi:10.1007/s0042 1-006-0195-8 2. Rantanen T, Guralnik JM, Foley D, et al. Midlife hand grip strength as a predictor of old age disability. JAMA. 1999;281(6):558-560. doi:10.1001/jama.28 1.6.558 3. Cools AMJ, Vanderstukken F, Vereecken F, et al. Eccentric and isometric shoulder rotator cuff strength testing using a hand-held dynamometer: reference values for overhead athletes. Knee Surg Sports Traumatol Arthrosc. 2016;24(12):3838-3847. doi:10.10 07/s00167-015-3755-9 4. Avers D, Brown M. Daniels and Worthingham’s Muscle Testing: Techniques of Manual Examination and Performance Testing. 10th ed. Elsevier Health Sciences; 2018. 5. Kendall FP, McCreary EK, Provance PG, Rodgers MM, Romani WA. Muscles: Testing and Function, with Posture and Pain. 5th ed. Lippincott Williams & Wilkins; 2005. 6. Bohannon RW. Manual muscle testing: does it meet the standards of an adequate screening test? Clin Rehabil. 2005;19(6):662-667. doi:10.1191/0269215505 cr873oa 7. Cuthbert SC, Goodheart GJ. On the reliability and validity of manual muscle testing: a literature review. J Chiropr Med. 2007;15(1):1-23. 8. Kolber MJ, Cleland JA. Strength testing using handheld dynamometry. Phys Ther Rev. 2005;10(2):99-112. doi:10.1179/108331905x55730 9. Sørensen L, Oestergaard LG, Van Tulder M, Petersen AK. Measurement properties of handheld dynamometry for assessment of shoulder muscle strength: a systematic review. Scand J Med Sci Sports. 2020;30(12):2305-2328. doi:10.1111/sms.13805 10. Schrama PPM, Stenneberg MS, Lucas C, Van Trijffel E. Intraexaminer reliability of hand-held dynamometry in the upper extremity: a systematic review. Arch Phys Med Rehab. 2014;95(12):2444-2469. doi:10.1016/j.apmr.2014.05.019
11. Stratford PW, Goldsmith CH. Use of the standard error as a reliability index of interest: an applied example using elbow flexor strength data. Phys Ther. 1997;77(7):745-750. doi:10.1093/ptj/77.7.745 12. Stark T, Walker B, Phillips JK, Fejer R, Beck R. Hand-held dynamometry correlation with the gold standard isokinetic dynamometry: a systematic review. Arch Phys Med Rehabil. 2011;3(5):472-479. do i:10.1016/j.pmrj.2010.10.025 13. Conceicao A, Parraca J, Marinho D, et al. Assessment of isometric strength of the shoulder rotators in swimmers using a handheld dynamometer: a reliability study. Acta Bioeng Biomech. 2018;20(4):113-119. 14. Kilmer DD, McCrory MA, Wright NC, Rosko RA, Kim HR, Aitkens SG. Hand-held dynamometry reliability in persons with neuropathic weakness. Arch Phys Med Rehabil. 1997;78(12):1364-1368. doi:1 0.1016/s0003-9993(97)90311-7 15. Cools AM, De Wilde L, Van Tongel A, Ceyssens C, Ryckewaert R, Cambier DC. Measuring shoulder external and internal rotation strength and range of motion: Comprehensive intra-rater and inter-rater reliability study of several testing protocols. J Shoulder Elbow Surg. 2014;23(10):1454-1461. doi:10.1 016/j.jse.2014.01.006 16. Deones VL, Wiley SC, Worrell T. Assessment of quadriceps muscle performance by a hand-held dynamometer and an isokinetic dynamometer. J Orthop Sports Phys Ther. 1994;20(6):296-301. doi:10.2 519/jospt.1994.20.6.296 17. Johansson FR, Skillgate E, Lapauw ML, et al. Measuring eccentric strength of the shoulder external rotators using a handheld dynamometer: reliability and validity. J Athl Train. 2015;50(7):719-725. doi:1 0.4085/1062-6050-49.3.72 18. Karabay D, Yesilyaprak SS, Picak GS. Reliability and validity of eccentric strength measurement of the shoulder abductor muscles using a hand-held dynamometer. Phys Ther Sports. 2020;43:52-57. doi:1 0.1016/j.ptsp.2020.02.002 19. Keep H, Luu L, Berson A, Garland SJ. Validity of the handheld dynamometer compared with an isokinetic dynamometer in measuring peak hip extension strength. Physiother Can. 2016;68(1):15-22. doi:10.3138/ptc.2014-62
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Reliability and Validity of the ActivForce Digital Dynamometer in Assessing Shoulder Muscle Force across Different User...
20. Vermeulen HM, de Bock GH, van Houwelingen HC, et al. A comparison of two portable dynamometers in the assessment of shoulder and elbow strength. Physiotherapy. 2005;91(2):101-112. d oi:10.1016/j.physio.2004.08.005 21. Reinking MF, Bockrath-Pugliese K, Worrell T, Kegerreis RL, Miller-Sayers K, Farr J. Assessment of quadriceps muscle performance by handheld, isometric, and isokinetic dynamometry in patients with knee dysfunction. J Orthop Sports Phys Ther. 1996;24(3):154-159. doi:10.2519/jospt.1996.24.3.154 22. Adamo DE, Taufiq A. Establishing hand preference: why does it matter? Hand. 2011;6(3):295-303. doi:10.1007/s11552-011-9324-x 23. Leggin BG, Neuman RM, Iannotti JP, Williams GR, Thompson EC. Intrarater and interrater reliability of three isometric dynamometers in assessing shoulder strength. J Shoulder Elbow Surg. 1996;5(1):18-24. do i:10.1016/s1058-2746(96)80026-7 24. Pearl ML, Jackins S, Lippitt SB, Sidles JA, Matsen FAI. Humeroscapular positions in a shoulder rangeof-motion-examination. J Shoulder Elbow Surg. 1992;1(6):296-305. doi:10.1016/s1058-2746(09)8005 6-6
25. Stratford PW, Balsor BE. A comparison of make and break tests using a hand-held dynamometer and the Kin-Com. J Orthop Sports Phys Ther. 1994;19(1):28-32. doi:10.2519/jospt.1994.19.1.28 26. Lehman LA, Velozo CA. Ability to detect change in patient function: responsiveness designs and methods of calculation. J Hand Ther. 2010;23(4):361-371. doi:10.1016/j.jht.2010.05.003 27. Dollings H, Sandford F, O’Conaire E, Lewis JS. Shoulder strength testing: the intra- and inter-tester reliability of routine clinical tests, using the PowerTrackTM II Commander. Shoulder Elb. 2012;4(2):131-140. doi:10.1111/j.1758-5740.2011.001 62.x 28. Holt KL, Raper DP, Boettcher CE, Waddington GS, Drew MK. Hand-held dynamometry strength measures for internal and external rotation demonstrate superior reliability, lower minimal detectable change and higher correlation to isokinetic dynamometry than externally-fixed dynamometry of the shoulder. Phys Ther Sports. 2016;21:75-81. doi:1 0.1016/j.ptsp.2016.07.001
International Journal of Sports Physical Therapy
McDevitt AW, Cleland JA, Addison S, Calderon L, Snodgrass S. Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study. IJSPT. 2022;17(4):677-694.
Original Research
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study Amy W. McDevitt 1
a
, Joshua A. Cleland 2 , Simone Addison 3, Leah Calderon 3, Suzanne Snodgrass 4
1
Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus; The University of Newcastle, 2 Department of Public Health and Community Medicine, Doctor of Physical Therapy Program, Tufts University School of Medicine, 3 Department of Physical Medicine and Rehabilitation, University of Colorado Anschutz Medical Campus, 4 School of Health Sciences, University of Newcastle Keywords: biceps tendon, tendinopathy, Delphi study, physical therapy, intervention, sports physical therapy https://doi.org/10.26603/001c.35256
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Shoulder pain related to the long head of the biceps tendon (LHBT) tendinopathy can be debilitating and difficult to treat especially in athletes who often elect for surgical intervention. Conservative management is recommended but there are limited established guidelines on the physical therapy (PT) management of the condition.
Hypothesis/Purpose The purpose of this study was to establish consensus on conservative, non-surgical physical therapy interventions for individuals with LHBT tendinopathy using the Delphi method approach.
Study Design Delphi Study
Methods Through an iterative process, experts in the PT field rated their agreement with a list of proposed treatment interventions and suggested additional interventions during each round. Agreement was measured using a four-point Likert scale. Descriptive statistics including median and percentage agreement were used to measure agreement. Data analysis at the end of Round III produced, by consensus, a list of PT interventions recommended for the management of individuals with LHBT tendinopathy. Consensus was defined as an a priori cutoff of ≥75% agreement.
Results The respondent group included 29 international experts in the PT management of individuals with shoulder pain. At the conclusion of the study 61 interventions were designated as recommended based on consensus amongst experts and 9 interventions were not recommended based on the same criteria, 15 interventions did not achieve consensus.
Conclusion There is a lack of well-defined, PT interventions used to treat LHBT tendinopathy. Expert respondents reached consensus on multimodal interventions including exercise, manual therapy and patient education to manage LHBT tendinopathy.
a
Corresponding author: Amy McDevitt PT, DPT, OCS, FAAOMPT University of Colorado School of Medicine 13121 E 17th Avenue C-244 Aurora, Colorado 80045 amy.mcdevitt@cuanschutz.edu 303-902-3312
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Level of Evidence 5
INTRODUCTION Shoulder pain related to pathology of the long head of the biceps tendon (LHBT) can be debilitating and often interferes with an individual’s activity and participation.1–3 The biceps tendon and labral complex is a potential pain generator in overhead throwing athletes.4–6 Anterior shoulder pain caused by tenosynovitis of the LHBT in athletes can lead to decreased performance and persistent pain.4,7,8 LHBT “tendinopathy” may start as an inflammatory condition or tenosynovitis of the LHBT1–3 and progress to a degenerative tendinopathy of the LHBT (characterized by tendon thickening, disorganization and irregularity of the tissue including the presence of hemorrhagic adhesions and scarring).3 The incidence of LHBT tendinopathy remains unclear as it is often considered a secondary shoulder condition associated with other conditions including rotator cuff disease and subacromial impingement.1,8 However, the reported incidence of tendinopathies in sports appears to be rising due to increased participation and training frequency.9 Overall, the literature regarding diagnosis, appropriate management of disorders related to the LHBT, including physical therapy (PT) management and surgical intervention, especially in the younger, athletic population remains controversial.1,4,8,10 Management of LHBT tendinopathy may include rest, activity modification, non-steroidal anti-inflammatory drugs, corticosteroid injections and tendon fenestration.1,8,11 More invasive, surgical interventions include biceps tendon distal reattachment (tenodesis) or release (tenotomy).1,12 However, there is little consensus regarding the ideal approach to treating chronic pain related to the LHBT.2,3 Conservative management including PT is often recommended prior to more invasive interventions,3,13,14 yet conservative management may be suboptimal in relieving symptoms and many individuals go on to seek more invasive treatment alternatives including surgical intervention. Conservative PT management of shoulder pain including LHBT pathology may involve a multimodal approach addressing associated impairments of the shoulder, scapular region and cervicothoracic spine with the application of exercise, joint and soft tissue mobilization as well as retraining dysfunctional movement patterns.3 A search of the literature revealed that most randomized controlled trials exploring PT management for LHBT conditions involved the utilization of biophysical agents including ultrasound, electrotherapy, extracorporeal shockwave therapy and iontophoresis however, there remains a paucity of high quality literature outlining the conservative management of LHBT tendinopathy in isolation.15–20 Considering chronic biceps tendinopathy often leads to invasive surgical intervention it is essential for physical therapists to recognize interventions that can be potentially effective in treating LHBT tendinopathy to avoid such procedures.21 Currently no quality studies have identified the most effective interventions for treating individuals with LHBT tendinopathy. Ex-
pert opinion in the form of the Delphi method is an important tool in fostering decision making when evidence is lacking.22 Therefore, the purpose of this study was to perform a Delphi study on common PT interventions utilized to treat individuals with biceps tendinopathy in order to generate expert consensus on recommended PT interventions.
MATERIALS AND METHODS STUDY DESIGN
This study used a Delphi method to elicit opinions and determine consensus from targeted content experts.23 This design allowed for the recruitment of international content experts without constraints of geography, offered anonymity, and avoided the dominance of opinion by a minority. The web-based Delphi consists of three rounds of surveys with both a panelist (respondent) group and a work group (investigators) in order to answer the following question: Which conservative interventions are effective in treating individuals with long head of the biceps tendon tendinopathy? The three-step Delphi method took place between February and June of 2021. This research received exempt status by the University of Colorado Multiple Institutional Review Board (COMIRB) and was approved by the Human Research Ethics Committee (HREC) at the University of Newcastle; all participants provided informed consent prior to participation. The study was performed in line with the Conducting and Reporting Delphi Studies (CREDES) recommendations to assure study rigor.23 PARTICIPANTS AND RECRUITMENT
In line with CREDES recommendations, experts were sought globally23 and were defined and agreed upon by the work group. Experts on shoulder pain were systematically identified using three methods. First, experts were identified as clinicians and/or researchers who had international and nationally recognized training and experience in the PT management of shoulder pathology or experience in research related to specific PT interventions utilized to treat individuals with shoulder pain and/or pathology. Relevant manuscripts and abstracts were collected utilizing electronic libraries including PubMed, CINAHL and Google Scholar. Investigators composed a list of potential panelists consisting of physical therapists and researchers listed as first/last authors of peer-reviewed publications on the PT management of individuals with shoulder pathology. Second, experts were identified through presentation abstracts and records of conference programming specifically, individuals who had presented on shoulder pathology at the 2019 and 2020 American Physical Therapy Association (APTA) Combined Sections Meeting (CSM) specifically in the Orthopedics, Research, and Sports Sections. Third, experts were identified by searching the grey literature through Google to include additional conference proceedings, textbooks and non-peer-reviewed nationally or inter-
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Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
nationally published material. Experts were invited via email to participate in the study. WORK GROUP
The work group consisted of the five authors of the study: the lead investigator (AM, a board-certified orthopedic specialist and a fellow in the American Academy of Orthopaedic and Manual Physical Therapists), two senior academics (SS and JC), with experience in the Delphi technique, quantitative research methods and 50 years of combined experience in musculoskeletal medicine, and two research assistants (SA, LC) completing doctoral training in PT. The work group was responsible for study design, recruiting content experts, and circulation and analysis of the questionnaire data. Additionally, the work group made decisions regarding methodology, data analysis and quality assurance. SYSTEMATIC REVIEW OF THE LITERATURE
A systematic review of the literature was performed prior to questionnaire development to identify best practice for the PT management of LHBT tendinopathy. The electronic databases MEDLINE, CINAHL, Cochrane Library, PubMed and Physiotherapy Evidence Database (PEDro) were searched from inception to June 20, 2020. The search was developed and performed with assistance from a research librarian. The search strategy combined headings and keywords for “biceps tendinopathy” or “biceps tendinitis” and “physical therapy” or “management” or “rehabilitation.” Individuals from the work group screened titles and abstracts to discard irrelevant ones. Articles from the literature search were included if they described or recommended PT interventions. Articles discussing medical or surgical interventions were excluded. Full-text publications were searched for information relevant to PT interventions used to treat individuals with LHBT tendinopathy. Data extracted from the full-text publications were then used to guide development of general themes presented in the Round I Delphi survey. PROCEDURE
This Delphi consisted of a preparatory phase by the work group and three rounds of electronic surveys conducted via the Qualtrics (Qualtrics, Provo, UT) online platform. An email was sent to 136 potential panelists inviting them to participate in the Delphi survey, including a link with information about the study, informed consent, privacy, and a link to complete the Round 1 survey online. Email invitations generated from Qualtrics with links for Rounds II and III were sent to all respondents who completed Round I. Each Delphi round was conducted over a four-week period with three reminder emails to ensure survey completion. Between each round, investigators performed data management, analysis, subsequent survey creation, and survey testing for two weeks. An introductory invitation containing the link to the consent and Round I questionnaire was sent to the list of identified experts to inform them of the study and request their participation via email. Two weeks
later, the invitation to participate was sent again to all experts who did not decline participation. Three follow up emails were sent to non-responders at intervals of one week. Throughout the entire Delphi process, all participants were blinded to the identity of the other participants in the respondent group. Details of participant recruitment can be found in Figure 1. INSTRUMENT ROUND I OF DELPHI
The first instrument consisted of an information statement describing the study, informed consent, demographic questions, and nine open-ended questions on the conservative management strategies that the participants believe are most common and effective for the physical therapy treatment of individuals with LHBT tendinopathy (Appendix 1). The first two open-ended questions inquired about general interventions followed by six open-ended questions on interventions including exercise-based interventions, manual therapy, and biophysical agents. The last question asked for further comments on PT interventions used to treat individuals with LHBT tendinopathy. The purpose of Round I was to gather information and inform investigators of the most common and effective interventions utilized, or believed to be utilized, to treat individuals with LHBT tendinopathy. The use of open-ended questions was intentional to reduce the potential for bias and allow individuals to describe interventions openly. Definitions of all terms were provided upon initiation of the survey to assure familiarity and congruence with the terms. The definition of LHBT tendinopathy used for the purpose of the study was: an inflammatory condition or tenosynovitis, occurring in the path of the LHBT as it courses in the intertubercular or bicipital groove of the humerus.1,2 The continuum of clinical pathology ranges from acute inflammatory tendonitis to degenerative tendinopathy.1,2 Without the use of imaging, LHBT pathology is typically diagnosed through a combination of patient identified location, palpation, special tests and other provocative maneuvers.24 The term manual therapy was defined as skilled hand movements and skilled passive movements of joints and soft tissue intended to improve tissue extensibility; increase range of motion; induce relaxation; mobilize or manipulate soft tissue and joints; modulate pain; and reduce soft tissue swelling, inflammation, or restriction. Techniques may include manual lymphatic drainage, manual traction, massage, mobilization/manipulation, and passive range of motion.25 Manual therapy was also defined in terms of non-thrust manipulation (mobilization) or thrust manipulation. Non-thrust manipulation was defined as a passive procedure which involves a low velocity, low to high amplitude force to a targeted region which is modified based on clinician assessment and patient feedback; thrust manipulation was defined as a passive procedure which involves a high velocity, low amplitude force to a targeted region which is modified based on clinician assessment and patient feedback.25 The term intervention was defined as the purposeful interaction of the physical therapist with an individual to produce changes in the condi-
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Figure 1. Flow recruitment and study respondents. (Abbreviations: APTA=American Physical Therapy Association; CSM=Combined Sections Meeting; AAOMPT=American Academy of Orthopaedic Manual Physical Therapists; AOPT=Academy of Orthopedic Physical Therapy; LHBT=Long Head of Biceps Tendon)
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
tion that are consistent with the diagnosis and prognosis.25 Lastly, the term biophysical agents was defined as a broad group of agents that use various forms of energy and are intended to assist muscle force generation and contraction; decrease unwanted muscular activity; increase the rate of healing of open wounds and soft tissue; maintain strength after injury or surgery; modulate or decrease pain; reduce or eliminate edema; improve circulation; decrease inflammation, connective tissue extensibility, or restriction associated with musculoskeletal injury or circulatory dysfunction; increase joint mobility, muscle performance, and neuromuscular performance; increase tissue perfusion and remodel scar tissue; and treat skin conditions.25 Subsequent rounds were used to reach a consensus among reported recommendations while incorporating modifications and inclusion of new items. ROUND II OF DELPHI
From the qualitative analysis of responses from Round I, themes were identified and subsequently coded to present themes in Round II. A qualitative, thematic analysis approach was used to interpret, construct, and develop themes summarizing the participants’ recommended interventions.26,27 Using this approach, thematic interpretations remain close to participants’ words. Themes and subthemes were identified and subsequently coded by A.M. and L.C. and disputes were settled by S.A. The purpose of Round II was to achieve consensus on intervention strategies identified in Round I. Additionally, Round II included questions regarding the stage of healing (acuity) in which each intervention would be utilized. Identified themes and subthemes included: Resistance Exercise/Muscle Performance (subthemes: tendon loading techniques, progressive resistance exercises, open/closed kinetic chain exercises, task specific/functional activities), Stretching and Flexibility, Manual Therapy (subthemes: non-thrust manipulation, thrust manipulation, soft tissue techniques), Patient Education, Biophysical Agents, Dry Needling, Other and Treatment Statements. Questions were organized using a 4-point Likert scale ranging from 1 (“strongly agree”) to 4 (“strongly disagree”). Participants were also asked to rate through multiple choice questions, the stage(s) of tissue healing they would recommend each intervention be used with options of “acute”, “subacute”, “chronic”, or “I would not use or recommend this intervention”. Common definitions of the stages of healing were included again for standardization.28 Finally, respondents were asked to report their level of agreement with statements regarding clinical decision making (which resulted from Round 1 open ended statements) pertaining to treating individuals with LHBT tendinopathy using the Likert scale described above. ROUND III OF DELPHI
The questionnaire for Round III contained the same questions that were presented in Round II, including all definitions, intervention techniques, and stages of acuity. Each question was accompanied by tables and figures illustrating the results of Round II. The respondents were asked to re-
view the feedback from Round II and rescore each intervention. DATA ANALYSIS
The survey instrument was built on Qualtrics survey software (Qualtrics, Provo, UT). After Round I was complete, data were exported from Qualtrics to an excel sheet for analysis. Three investigators completed the theme and coding synthesis process individually. The 3 investigators (A.M., L.C., and S.A.) then came together to reach consensus for themes to advance into Round II. After the completion of Round III, data were exported from Qualtrics to an excel sheet for further analysis by the workgroup. For Round III, a benchmark of ≥75% agreement as an a priori cutoff was utilized, as seen in similar study designs.23,29 Recommendations rated as 3 (disagree) or 4 (strongly disagree) by ≥75% of the panelists were collapsed into “disagree” and not considered recommended interventions. Intervention recommendations rated as a 1 (strongly agree) or 2 (agree) by ≥75% of the panelists were collapsed into “agree” and included as recommended in the final consensus. Scores were tallied for each intervention including the frequency of respondents and corresponding percentages.
RESULTS RESPONDENT CHARACTERISTICS
A total of 136 potential participants were contacted via email. Ten potential participants had email addresses that were currently not active, leaving 126 eligible participants. One expert declined to participate due to a disagreement in the definition of biceps tendinopathy utilized in our study. One hundred and five experts did not respond to the invitation to participate or the reminders. Thirty-one (24.6%) participants completed the consent form and responded to Round I (Figure 1). The respondent group consisted of experts from the United States (n = 19), United Kingdom (n=2), Australia (n=2), Sweden (n=2) and one from each of the following countries: Spain, New Zealand, Turkey, Canada, Italy, and the Netherlands. Thirteen respondents were female (41.9%), eighteen were male (58.1%), and 0% responded as non-binary. Respondents had a variety of degrees, including Masters, Doctorate, Doctor of Science (DSc), and Doctor of Philosophy (PhD), in addition to other specialty certifications. Twenty-six of 31 (83.9%) of the respondents in Round I were clinicians. Of those clinicians, fifteen (48.4%) had 20 or more years of clinical practice. Twenty-seven of 31 respondents (87.1%) consented to be acknowledged for their participation (Table 1). ROUND I
Comments from Round 1 were summarized and statements containing similar constructs were grouped and reduced for each theme. For example, the following five items were originally included in the list of statements for Round 1: 1) common and effective interventions used to treat LHBT tendinopathy 2) common and effective exercise-based interventions used to treat LHBT tendinopathy 3) common and effective manual therapy-based interventions used to
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Table 1. Descriptive characteristics of the Delphi expert panel Demographic characteristics
Value
Percentage
20-30
0
0.00%
30-40
10
31.30%
40-50
11
34.40%
50-60
8
25.00%
60-70
3
9.40%
70+
0
0.00%
Total
32
100%
Male
19
59.40%
Female
13
40.60%
Non-binary
0
0.00%
Prefer not to say
0
0.00%
Total
32
100.00%
United Kingdom
2
6.30%
Spain
1
3.10%
Australia
2
6.30%
New Zealand
1
3.10%
United States
20
62.50%
Turkey
1
3.10%
Canada
1
3.10%
Sweden
2
6.30%
Italy
1
3.10%
Netherlands
1
3.10%
Total:
32
100.00%
South Atlantic (DE, DC, FL, GA, MD, NC, SC, VA, WV)
3
15.00%
Middle Atlantic (NJ, NY, PA)
2
10.00%
East North central (IL, IN, MI, OH, WI)
3
15.00%
West North Central (IA, KS, MN, MO, NE, ND, SD)
1
5.00%
New England (CT, ME, MA, NH, RI, VT)
1
5.00%
Pacific (AK, CA, HI, OR, WA)
1
5.00%
East South Central (AL, KY, MS, TN)
0
0.00%
Mountain (AZ, CO, ID, MT, NV, NM, UT, WY)
9
45.00%
Total:
20
100.00%
None
0
0.00%
Clinician
27
84.40%
Researcher
13
40.60%
Academic
18
56.30%
Management
4
12.50%
None
0
0.00%
0-5
2
6.30%
Age (years)
Gender
In what country do you currently reside?
If you reside in the US, in which region do you currently reside?
Describe your current role?
How many total years have you been in clinical practice?
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Demographic characteristics
Value
Percentage
5-10
2
6.30%
10-15
9
28.10%
16-20
4
12.50%
20+
15
46.90%
Total
32
100.00%
None
2
6.30%
0-5
9
28.10%
5-10
7
21.90%
10-15
7
21.90%
15-20
3
9.40%
20+
4
12.50%
Total
32
100.00%
MSPT/MPT
12
37.50%
DPT
15
46.90%
ATC
1
3.10%
DSc
2
6.30%
PhD
8
25.00%
OCS
17
53.10%
SCS
4
12.50%
Other: FAAOMPT, TDN, PhD(c), OMPT, DSc student, BSc
21
65.60%
United Kingdom
2
6.30%
Spain
1
3.10%
Australia
1
3.10%
New Zealand
1
3.10%
United States
19
59.40%
Turkey
1
3.10%
Canada
1
3.10%
Sweden
2
6.30%
Morocco
1
3.10%
Italy
1
3.10%
Netherlands
1
3.10%
Wales
1
3.10%
Total
32
100.00%
No
24
75.00%
Yes
8
25.00%
Total
32
100.00%
No
17
53.10%
Yes
15
46.90%
Total
32
100.00%
How many total years have you been involved in research?
Degrees and/or certifications
In what country did you receive your degree(s)?
Have you completed a residency in physical therapy?
Have you completed a fellowship in physical therapy?
Abbreviations: US=United States, DE=Delaware, DC=District of Columbia, FL=Florida, GA=Georgia, MD=Maryland NC=North Carolina, SC=South Carolina, VA=Virginia, WV=West Virginia, NJ=New Jersey, NY=New York, PA=Pennsylvania, IL=Illinois, IN=Indiana, MI=Michigan, OH=Ohio, WI=Wisconsin, IA=Iowa, KS=Kansas, MN=Minnesota, MO=Missouri, NE=Ne-
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
braska, ND=North Dakota, SD=South Dakota, CT=Connecticut, ME=Maine, MA=Massachusetts, NH=New Hampshire, RI=Rhode Island, VT=Vermont, AK=Arkansas, CA=California, HI=Hawaii, OR=Oregon, WA=Washington, AL=Alabama, KY=Kentucky, MS=Mississippi, TN=Tennessee, AZ=Arizona, CO=Colorado, ID=Idaho, MT=Montana, NV=Nevada, NM=New Mexico, UT=Utah, WY=Wyoming, MSPT=Master of Science in Physical Therapy, MPT=Master of Physical Therapy, DPT=Doctor of Physical Therapy, ATC=Certified Athletic Trainer, DSc=Doctor of Science, PhD=Doctor of Philosophy, OCS=Orthopedic Certified Specialist, SCS=Sports Certified Specialist, FAAOMPT=Fellow of the American Academy of Orthopaedic Manual Physical Therapists, TDN=Trigger point Dry Needling, PhD(c)=Candidate Doctor of Philosophy, OMPT=Orthopedic Manual Physical Therapist, BSc=Bachelor of Science
treat LHBT tendinopathy 4) common and effective biophysical agents used to treat LHBT tendinopathy 5) other common and effective interventions used to treat LHBT tendinopathy. Across all five item categories, 217 initial statements from the open-ended responses specific to physical therapy interventions were provided in Round 1 and condensed into 47 intervention-based statements across eight newly formed themes (resistance exercise/muscle performance, stretching and flexibility, manual therapy, patient education, biophysical agents, other, dry needling, and treatment statements).
MANUAL THERAPY
One respondent did not complete the survey from Round II despite weekly reminders; therefore 30 of 31 of the respondents participated in Round II (96.7% retention rate between Round I and Round II; Figure 1). Retention rates for respondents were reduced from 30 to 29 from Round II to Round III (96.6% retention rate between Round II and Round III); (Figure 1). Twenty-nine respondents completed Round III (93.5% retention rate between Round I and Round III). A detailed description of consensus for “agree” and “disagree” per intervention category for Round III is reported beginning with Table 2.
Non-thrust manipulation techniques (five of five) achieved consensus “agree” by respondents in Round III with techniques to the acromioclavicular joint and scapulothoracic joints not reaching the threshold for agreement by respondents in Round II. Four thrust manipulation techniques were included in the questionnaire with only two of four regions (thoracic spine and cervicothoracic junction) achieving overall consensus “agree” by respondents in Round III (Table 3 and Figure 2). Intervention to the thoracic spine region received the highest level of consensus “agree” in both non-thrust and thrust manipulation techniques; 89.65% and 83.34% respectively in Round III. Specific thrust and non-thrust manipulation techniques included Grade I-II and Grade III-IV non-thrust, Grade V thrust and mobilization with movement (MWM) all of which achieved consensus “agree” in Round II and III. Soft tissue techniques were included in the manual therapy category and two of 11 techniques (soft tissue mobilization of the biceps brachii and trigger point therapy to the rotator cuff muscles) achieved consensus “agree” in Round II compared to seven of 11 techniques in Round III. All other soft tissue techniques to specified regions (six of 11) did not reach consensus for “agree” or “disagree” (Table 3 and Figure 3).
INTERVENTION THEMES
PATIENT EDUCATION
RESISTANCE EXERCISE/MUSCLE PERFORMANCE
Patient education concepts related to advice achieved eight of eight consensus “agree” in Round III. Concepts that achieved 100% consensus included: activity and occupational modification, training/loading modification and education surrounding the PT treatment plan and pain neuroscience education (Table 4).
ROUNDS II AND III
Among respondents there was strong consensus in favor of tendon loading techniques as an effective intervention for treating individuals with LHBT tendinopathy. Consensus “agree” was reached for five of five tendon loading techniques in Round II and Round III (Table 2). Respondents reached consensus “agree” that progressive resistance exercises would be prescribed for nine of 11 muscles/muscle groups not including upper trapezius and pectoralis major muscles. Consensus “agree” was also established across six of six open and closed chain kinetic chain exercises including minimal change in consensus between Rounds II and III. Task specific functional activities (reaching, lifting, overhead activity, and occupation and sport specific tasks) reached consensus “agree” with all respondents in Round II and III (Table 2).
BIOPHYSICAL AGENTS
Respondents reached consensus “disagree” on seven of nine biophysical agents including iontophoresis, phonophoresis, three forms of electrical stimulation, ultrasound and lowlevel laser therapy (LLLT), (Table 4 and Figure 4). Therefore, thermal agents including cryotherapy and moist heat did not reach consensus agree or disagree. Additionally, there was no change in consensus “agree” in the seven of nine categories between Round II and Round III.
STRETCHING/FLEXIBILITY
DRY NEEDLING
Respondents demonstrated consensus “agree” in favor of stretching/flexibility for five of seven identified muscles/ muscle groups in Round II increasing to seven of seven muscles/muscle groups in Round III with four participants changing to agree in Round III to include upper trapezius as a target muscle for stretching (Table 2).
Among respondents there was consensus “agree” on dry needling to the biceps brachii muscle in Round II and Round III. In Round II respondents reached consensus “agree” on needling the rotator cuff muscles but consensus “agree” was not achieved in Round III (Table 4).
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Table 2. Results from Round III, Themes: Resistance Exercise/Muscle Performance, Stretching/Flexibility Theme Resistance Exercise/Muscle Performance
Agree, n (%)
Disagree, n (%)
Consensus
Isometric tendon loading - Biceps brachii muscle
26 (89.66%)
3 (10.35%)
CA
Concentric tendon loading - Biceps brachii muscle (shoulder flexion)
29 (100%)
0 (0%)
CA
Concentric tendon loading - Biceps brachii muscle (elbow flexion)
29 (100%)
0 (0%)
CA
Eccentric tendon loading- Biceps brachii muscle (shoulder flexion)
28 (96.55%)
1 (3.45%)
CA
Eccentric tendon loading - Biceps brachii muscle (elbow flexion)
29 (100%)
0 (0%)
CA
Pectoralis major muscle
19 (65.52%)
10 (34.48%)
NC
Latissimus dorsi muscle
22 (75.86%)
7 (24.14%)
CA
Deltoid muscle
28 (96.55%)
1 (3.45%)
CA
Biceps brachii muscle
29 (100%)
0 (0%)
CA
Upper trapezius muscle
15 (51.72%)
14 (48.28%)
NC
Middle trapezius muscle
27 (93.10%)
2 (6.90%)
CA
Lower trapezius muscle
27 (93.10%)
2 (6.90%)
CA
Serratus anterior muscle
29 (100%)
0 (0%)
CA
Rhomboid major/minor muscles
23 (79.31%)
6 (20.69%)
CA
Rotator cuff internal (medial) rotation muscles
28 (96.55%)
1 (3.45%)
CA
Rotator cuff external (lateral) rotation muscles
28 (96.55%)
1 (3.45%)
CA
Rotator cuff muscles-open chain
29 (100%)
0 (0%)
CA
Rotator cuff muscles-closed chain
28 (96.55%)
1 (3.45%)
CA
Scapular stabilizers-open chain
29 (100%)
0 (0%)
CA
Scapular stabilizers-closed chain
29 (100%)
0 (0%)
CA
Biceps brachii muscle-open chain
29 (100%)
0 (0%)
CA
Biceps brachii muscle-closed chain
28 (96.55%)
1 (3.45%)
CA
Reaching
29 (100%)
0 (0%)
CA
Lifting
29 (100%)
0 (0%)
CA
Overhead activity
29 (100%)
0 (0%)
CA
Occupation specific
29 (100%)
0 (0%)
CA
Sport specific
28 (96.55%)
0 (0%)
CA
Pectoralis major muscle
28 (96.55%)
1 (3.45%)
CA
Pectoralis minor muscle
28 (96.55%)
1 (3.45%)
CA
Upper trapezius muscle
25 (86.20%)
4 (13.79%)
CA
Biceps brachii muscle
23 (79.31%)
6 (20.69%)
CA
Latissimus dorsi muscle
26 (89.66%)
3 (10.35%)
CA
Posterior rotator cuff muscles
27 (93.10%)
2 (6.90%)
CA
Glenohumeral medial/internal rotators
25 (86.20%)
4 (13.79%)
CA
Subtheme: Tendon Loading Techniques
Subtheme: Progressive Resistance Exercise (PRE)
Subtheme: Open/Closed Kinetic Chain Exercises
Subtheme: Task-specific Functional Activities
Theme: Stretching/Flexibility
Abbreviations: CA=consensus agree; NC=non consensus; n=number of participants
OTHER
The other category included additional interventions that respondents commented on by providing free text answers to open-ended questions in Round I. Respondents reached consensus “agree” on two of five items to include cognitive
behavioral therapy and non-steroidal anti-inflammatory drugs (NSAIDs) and consensus “disagree” on two of five items including extracorporeal shock wave therapy (ESWT) and dry cupping therapy (Table 4).
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Table 3. Results from Round III, Theme: Manual Therapy Theme: Manual Therapy
Agree, n (%)
Disagree, n (%)
Consensus
Glenohumeral joint
24 (82.76%)
5 (17.24%)
CA
Thoracic spine
26 (89.66%)
3 (10.35%)
CA
Cervical spine
24 (82.76%)
5 (17.24%)
CA
Scapulothoracic "joint"
22 (75.86%)
7 (24.14%)
CA
Acromioclavicular joint
22 (75.86%)
7 (24.14%)
CA
Thoracic spine
25 (86.20%)
4 (13.79%)
CA
Cervical spine
21 (72.41%)
8 (27.58%)
NC
Cervicothoracic junction
23 (79.31%)
6 (20.69%)
CA
Glenohumeral joint
11 (37.93%)
18 (62.07%)
NC
Grade I-II non-thrust
23 (79.31%)
6 (20.69%)
CA
Grade III-IV non-thrust
25 (86.20%)
4 (13.79%)
CA
Grade V thrust
22 (75.86%)
7 (24.14%)
CA
Mobilization with movement (MWM)
27 (93.10%)
2 (6.90%)
CA
Deep transverse friction (long head of the biceps tendon)
9 (31.03%)
20 (68.96%)
NC
Deep transverse friction (biceps brachii muscle belly)
9 (31.03%)
20 (68.96%)
NC
Deep transverse friction (bicipital groove)
9 (31.03%)
20 (68.96%)
NC
Trigger point therapy (biceps brachii muscle)
22 (75.86%)
7 (24.14%)
CA
Trigger point therapy (rotator cuff muscles)
22 (75.86%)
7 (24.14%)
CA
Soft Tissue Mobilization (biceps brachii muscle)
25 (86.20%)
4 (13.79%)
CA
Soft tissue mobilization (periscapular muscles)
22 (75.86%)
7 (24.14%)
CA
Soft tissue mobilization (scapular muscles)
23 (79.31%)
6 (20.69%)
CA
Soft tissue mobilization (rotator cuff muscles)
26 (89.66%)
3 (10.35%)
CA
Soft tissue mobilization (cervical region)
24 (82.76%)
5 (17.24%)
CA
Instrument-assisted soft tissue mobilization
16 (55.17%)
13 (44.82%)
NC
Subtheme: Non-thrust Manipulation (Region)
Subtheme: Thrust Manipulation (Region)
Subtheme: Thrust & Non-thrust Manipulation (Techniques)
Subtheme: Soft-Tissue Techniques
Abbreviations: C=consensus; CA=consensus agree; NC=non consensus; n=number of participants
TREATMENT STATEMENTS
Respondents reported their level of agreement with treatment-based statements in terms of intervention (which resulted from Round 1 open ended questions) and consensus “agree” was reached in six of eight statements with one statement (clinical decision making should be prescriptive) reaching consensus “disagree” and the other reaching non consensus (Table 5). Statements that were consensus “agree” included utilization of a pragmatic and multimodal approach to intervention following clinical practice guidelines when available. Additional statements are included in Table 5.
DISCUSSION The primary purpose of this Delphi study was to identify experts in the PT management of shoulder pain and utilize their experience and expertise to identify interventions that
are common and effective in treating individuals with LHBT tendinopathy. For the 29 expert respondents who contributed to the final results, findings demonstrated that 61/ 86 interventions across seven intervention themes met the criteria of 75% consensus of being effective for the treatment of LHBT tendinopathy; conversely, 9/86 interventions across seven themes reached a 75% consensus of being ineffective for the treatment of LHBT tendinopathy. These findings suggest there are several physical therapy interventions across multiple intervention themes (with high consensus) including resistance exercise, stretching and flexibility, manual therapy, and patient education that are recommended by experts to treat individuals with LHBT tendinopathy. These interventions may serve as a proposed guideline of interventions to be investigated in clinical trials and trialed with patients clinically due to a lack of additional evidence to guide optimal management. One noteworthy finding was the overall high consensus with the intervention of exercise including the themes of resistance exercise/muscle performance and stretching/flexi-
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Table 4. Results from Round III, Theme: Patient Education, Biophysical Agents, Dry Needling, Other Theme: Patient Education
Agree, n (%)
Disagree, n (%)
Consensus
Activity modification
29 (100%)
0 (0%)
CA
Occupation modification
29 (100%)
0 (0%)
CA
Training/loading modification
29 (100%)
0 (0%)
CA
Medication
25 (86.20%)
4 (13.79%)
CA
Physical therapy treatment plan
29 (100%)
0 (0%)
CA
Pain neuroscience education
29 (100%)
0 (0%)
CA
Long head of the biceps tendon (LHBT) pathoanatomy
28 (96.55%)
1 (3.45%)
CA
Postural control
24 (82.76%)
5 (17.24%)
CA
Iontophoresis
2 (6.90%)
27 (93.10%)
CD
Phonophoresis
1 (3.45%)
28 (96.55%)
CD
Interferential current (IFC)
1 (3.45%)
28 (96.55%)
CD
Neuromuscular electrical stimulation (NMES)
3 (10.34%)
26 (89.65%)
CD
Transcutaneous electrical nerve stimulation (TENS)
3 (10.34%)
26 (89.65%)
CD
Ultrasound
3 (10.34%)
26 (89.65%)
CD
Laser Therapy
5 (17.24%)
24 (82.76%)
CD
Cryotherapy
17 (58.62%)
12 (41.38%)
NC
Moist Heat
13 (44.83%)
16 (55.17%)
NC
Dry Needling (long head of the biceps tendon)
15 (51.72%)
14 (48.28%)
NC
Dry Needling (biceps brachii muscle)
22 (75.86%)
7 (24.14%)
CA
Dry Needling (upper trapezius)
19 (65.52%)
10 (34.48%)
NC
Dry Needling (rotator cuff muscles)
21 (72.41%)
8 (27.58%)
NC
Dry Needling with electrical stimulation
15 (51.72%)
14 (48.28%)
NC
Taping
20 (68.96%)
9 (31.04%)
NC
Non-steroidal anti-inflammatory drugs (NSAIDs)
24 (82.76%)
5 (17.24%)
CA
Extracorporeal shock wave therapy (ESWT)
4 (13.79%)
25 (86.21%)
CD
Dry cupping therapy
5 (17.24%)
24 (82.76%)
CD
Cognitive behavioral therapy
22 (75.86%)
7 (24.14%)
CA
Theme: Biophysical Agents
Theme: Dry Needling
Theme: Other
Abbreviations: CA=consensus agree; NC=non consensus; CD=consensus disagree; n=number of participants
bility and subthemes of tendon loading techniques (including isometrics, concentric and eccentrics), progressive resistance exercises, open/closed kinetic chain exercises and task-specific functional activities (Table 2). These findings are not surprising considering strong recommendations in the literature for including exercise therapy as the first-line treatment to improve pain, mobility, and function in patients with subacromial shoulder pain.30 Studies specific to tendinopathies describe exercise therapy, specifically eccentric exercise, as an effective component of an exercise program in treating individuals with tendinopathy.31–33 Respondents agreed that “progressive loading of the LHBT should be matched to tissue capacity and pain severity/irritability” based on consensus with those treatment statements, combined with a consensus on the recommendation of five of five tendon loading techniques. Respondents also demonstrated consensus on nine of 11 progressive resistance exercises, and con-
sensus on all interventions in the theme of stretching/flexibility and subthemes of open/closed kinetic chain exercises and task-specific functional activities. Krupp and colleagues3 state that a comprehensive rehabilitation program should focus on restoring dynamic stability to the shoulder and rehabilitation may vary depending on clinical presentation. Further, according to Krupp et al.3 patients may progress through four phases (pain management and restoration of range of motion (ROM), active range of motion (AROM) and early strengthening, rotator cuff and periscapular strengthening, return to sport) which may explain why respondents recommended 32 of 34 exercise interventions and included the use of exercise interventions across all stages of tissue healing (acute, subacute, chronic). A second noteworthy finding was the lack of agreement among respondents on interventions within the dry needling theme and the manual therapy subthemes of
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Table 5. Results from Round III, Theme: Treatment Statements Theme: Treatment Statements
Agree, n (%)
Disagree, n (%)
Consensus
Interventions selected should be multimodal in nature.
28 (96.55%)
1 (3.45%)
CA
Clinical decision making should be based on a pragmatic/ICF and impairment-based approach.
29 (100%)
0 (0%)
CA
Clinical decision making should be based on a prescriptive/protocol-based approach.
5 (17.24%)
24 (82.76%)
CD
Clinical decision making should be based on following related clinical practice guidelines (region or pathology).
28 (96.55%)
1 (3.45%)
CA
Progressive loading of the LHBT should be matched to tissue capacity.
29 (100%)
0 (0%)
CA
Progressive loading of the LHBT should be matched to pain severity/ irritability.
29 (100%)
0 (0%)
CA
LHBT tendinopathy is often a primary shoulder pathology.
12 (41.38%)
17 (58.62%)
NC
LHBT tendinopathy is often a secondary shoulder pathology (accompanying other primary shoulder pathologies).
28 (96.55%)
1 (3.45%)
CA
Abbreviations: LHBT=Long head of the biceps tendon; ICF=International Classification of Functioning, Disability and Health; CA=consensus agree; NC=non consensus; CD=consensus disagree; n=number of participants
Figure 2. Consensus agree (≥75%) for interventions in the theme manual therapy and subthemes of non-thrust and thrust manipulation by region.
thrust manipulation and soft tissue techniques (Table 3). Respondents reached consensus on non-thrust manipulation interventions to the glenohumeral joint, cervical and thoracic spines, scapulothoracic and acromioclavicular joints and thrust manipulation interventions to the cervicothoracic regions (Figure 2) but did not meet the a priori consensus of 75% for thrust manipulation of the glenohumeral joint or cervical spine. Therefore, it is possible the respondents were familiar with literature surrounding manual therapy interventions known to be more effective in treating individuals with shoulder pain. Well described in the literature are the effects of cervicothoracic and thoracic manipulation in individuals with shoulder pain34,35 demonstrating findings of reduced pain and disability immediately and up to 52
weeks.36,37 However, there is overall less evidence to support thrust manipulation to the cervical spine and glenohumeral joint for the management of shoulder pain. Respondents did not reach consensus on instrumented soft tissue mobilization or deep transverse friction techniques (Table 3). Deep transverse friction techniques have been recommended for the treatment of various tendinopathies,38,39 however, evidence is anecdotal40 and the authors are not aware of studies investigating these techniques specifically for treating individuals with LHBT tendinopathy. The subtheme of dry needling did not reach consensus on four of five interventions, with dry needling to the biceps brachii muscle being the only intervention reaching consensus (Table 4). Recent research recommends
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
Figure 3. Consensus agree (≥75%) for interventions in the theme manual therapy and subtheme of soft tissue techniques by region or muscle.
Figure 4. Consensus disagree (≥75%) for interventions in the theme biophysical agents.
needling for the treatment of tendinopathy,41–43 but only a single case series specific to dry needling of the LHBT for the treatment of LHBT tendinopathy was identified.21 A third notable finding was the consensus “disagree” in the theme of biophysical agents on seven of nine items including iontophoresis, phonophoresis, electrical stimulation (interferential current, neuromuscular electrical stimulation and transcutaneous electrical nerve stimulation), ultrasound, and low-level laser (Figure 4). In the theme of other there was also consensus “disagree” on shock wave
therapy. Findings from a recent review of systematic reviews, specific to tendinopathies, found moderate-quality evidence to support the use of low level laser for pain and disability in the short-term and shock wave therapies showed a statistically significant improvement in pain and function at all follow-up periods.33 However, the opinion persists that most of the available therapeutic modalities are only supported by weak evidence44 with moderate evidence of no effect for interventions, such as laser therapy, extracorporeal shockwave therapy, pulsed electromagnetic
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
energy, and ultrasound.30 Additionally, based on the systematic review of the literature performed prior to the study, only low quality randomized controlled trials exist specifically outlining meaningful improvements using biophysical agents to treat LHBT tendinopathy. Overall, the pooled recommendations of the respondents are consistent with current recommendations that a multimodal approach is optimal for the management of shoulder pain.37,45–48 Physical therapy management of LHBT tendinopathy may involve a multimodal approach addressing associated impairments of the shoulder, scapular region and cervicothoracic spine with the application of exercise, joint and soft tissue mobilization as well as retraining dysfunctional movement patterns.3 As such, the respondents reached consensus on a number of interventions across different themes and subthemes supporting a multimodal approach to treatment. Preliminary evidence on the PT management of LHBT tendinopathy is not robust enough to draw strong conclusions1,2,13,16,19–21 and few studies focus on a multimodal approach. Therefore, obtaining international expert consensus on a multimodal treatment approach further informs treatment recommendations, which could potentially be utilized prior to electing for surgical options. Surgery (biceps tenodesis) may be a safe option and may offer a satisfactory rate of return to sport in young athletes,4 however, according to Frank et al.49,50 there is an increased risk of surgical revision in athletes under 20 years old with a history of throwing activity. Therefore, based on the results of this Delphi study conservative PT based management prior to individuals electing for more aggressive surgical intervention for the management of LHBT tendinopathy may be recommended based on these expert opinions.
ipate in the study, thus the expressed opinions may not be fully representative of all experts in the field. Further, any recommendations made as a result of this Delphi, warrant further investigation in trials as evidence of effectiveness of the recommended interventions is still lacking in this specific patient population.
LIMITATIONS
ACKNOWLEDGEMENTS
There were several limitations to this Delphi study. First, the respondents included in this study were those willing to participate and may not reflect all clinicians and researchers with expertise in treating shoulder pathologies. Additionally, the respondent group consisted of individuals from various countries. Although this diversity was also seen as a strength, the definitions that were used in this study may not have been commonly used by all respondents. Further, the views of the Delphi panelists may differ from other content experts who declined the offer to partic-
The authors would like to thank all the respondents who participated in the study. The authors would like to thank Cardon Rehab (Ontario, Canada) and the American Academy of Orthopaedic Manual Physical Therapists for the Cardon Research Grant which supported this work.
CONCLUSION The results of this study highlight the current absence of well-defined, PT interventions used to treat LHBT tendinopathy. Expert respondents reached consensus that a multimodal approach including exercise, manual therapy and patient education could be used to manage LHBT tendinopathy. Given the chronic nature of the condition combined with the lack of established guidelines for PT intervention, future research is needed to guide physical therapists who manage the condition.
CONFLICTS OF INTEREST
All authors do not have conflicts of interest to report. GRANT SUPPORT
This work was supported by The American Academy of Orthopedic Manual Physical Therapists (AAOMPT) under a grant from Cardon Rehabilitation (Ontario, Canada). Neither AAOMPT nor the funding agency had any role in the study design, analysis, interpretation, or decisions about publication.
Submitted: November 22, 2021 CDT, Accepted: March 24, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
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International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
21. McDevitt AW, Snodgrass SJ, Cleland JA, Leibold MBR, Krause LA, Mintken PE. Treatment of individuals with chronic bicipital tendinopathy using dry needling, eccentric-concentric exercise and stretching; a case series. Physiother Theory Pract. 2020;36(3):397-407. doi:10.1080/09593985.2018.1488 023 22. Powell C. The Delphi technique: myths and realities. J Adv Nurs. 2003;41(4):376-382. doi:10.1046/ j.1365-2648.2003.02537.x 23. Jünger S, Payne SA, Brine J, Radbruch L, Brearley SG. Guidance on Conducting and REporting DElphi Studies (CREDES) in palliative care: Recommendations based on a methodological systematic review. Palliat Med. 2017;31(8):684-706. d oi:10.1177/0269216317690685 24. Gazzillo GP, Finnoff JT, Hall MM, Sayeed YA, Smith J. Accuracy of palpating the long head of the biceps tendon: an ultrasonographic study. PM R. 2011;3(11):1035-1040. doi:10.1016/j.pmrj.2011.02.02 2 25. Guide to Physical Therapist Practice 3.0. American Physical Therapy Association; 2014. Accessed December 17, 2020. http://guidetoptpractice.apta.org/ content/1/SEC1.body 26. Braun V, Clarke V. One size fits all? What counts as quality practice in (reflexive) thematic analysis? Qual Res Psychol. 2021;18(3):328-352. doi:10.1080/14 780887.2020.1769238 27. Braun V, Clarke V. (Mis)conceptualising themes, thematic analysis, and other problems with Fugard and Potts’ (2015) sample-size tool for thematic analysis. International Journal of Social Research Methodology. 2016;19(6):739-743. doi:10.1080/136455 79.2016.1195588 28. Kisner C, Colby LA, Borstad J. Therapeutic Exercise: Foundations and Techniques. F.A. Davis; 2017. 29. Teo PL, Hinman RS, Egerton T, Dziedzic KS, Bennell KL. Identifying and Prioritizing Clinical Guideline Recommendations Most Relevant to Physical Therapy Practice for Hip and/or Knee Osteoarthritis. J Orthop Sports Phys Ther. 2019;49(7):501-512. doi:10.2519/jospt.2019.8676 30. Pieters L, Lewis J, Kuppens K, et al. An Update of Systematic Reviews Examining the Effectiveness of Conservative Physical Therapy Interventions for Subacromial Shoulder Pain. J Orthop Sports Phys Ther. 2020;50(3):131-141. doi:10.2519/jospt.2020.8498
31. Andres BM, Murrell GAC. Treatment of tendinopathy: what works, what does not, and what is on the horizon. Clin Orthop Relat Res. 2008;466(7):1539-1554. doi:10.1007/s11999-008-026 0-1 32. Jayaseelan DJ, Kecman M, Alcorn D, Sault JD. Manual therapy and eccentric exercise in the management of Achilles tendinopathy. J Man Manip Ther. 2017;25(2):106-114. doi:10.1080/10669817.201 6.1183289 33. Girgis B, Duarte JA. Physical therapy for tendinopathy: An umbrella review of systematic reviews and meta-analyses. Phys Ther Sport. 2020;46:30-46. doi:10.1016/j.ptsp.2020.08.002 34. Sueki DG, Chaconas EJ. The effect of thoracic manipulation on shoulder pain: a regional interdependence model. Phys Ther Rev. 2011;16(5):399-408. doi:10.1179/1743288x11y.00000 00045 35. McDevitt A, Young J, Mintken P, Cleland J. Regional interdependence and manual therapy directed at the thoracic spine. J Man Manip Ther. 2015;23(3):139-146. doi:10.1179/2042618615y.00000 00005 36. Peek AL, Miller C, Heneghan NR. Thoracic manual therapy in the management of non-specific shoulder pain: a systematic review. J Man Manip Ther. 2015;23(4):176-187. doi:10.1179/2042618615y.000000 0003 37. Mintken PE, McDevitt AW, Cleland JA, et al. Cervicothoracic manual therapy plus exercise therapy versus exercise therapy alone in the management of individuals with Shoulder Pain: A multicenter randomized controlled trial. J Orthop Sports Phys Ther. 2016;46(8):617-628. doi:10.2519/jospt.2016.631 9 38. Dimitrios S. Exercise for Patellar Tendinopathy. Austin Sports Med. 2016;1(2):1010. 39. Hunter G. Specific Soft Tissue Mobilisation in the Treatment of Soft Tissue Lesions. Physiotherapy. 1994;80(1):15-21. doi:10.1016/s0031-9406(10)6124 0-0 40. Joseph MF, Taft K, Moskwa M, Denegar CR. Deep friction massage to treat tendinopathy: a systematic review of a classic treatment in the face of a new paradigm of understanding. J Sport Rehabil. 2012;21(4):343-353. doi:10.1123/jsr.21.4.343 41. Stoychev V, Finestone AS, Kalichman L. Dry Needling as a Treatment Modality for Tendinopathy: a Narrative Review. Curr Rev Musculoskelet Med. 2020;13(1):133-140. doi:10.1007/s12178-020-09608-0
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Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
42. Nagraba Ł, Tuchalska J, Mitek T, Stolarczyk A, Deszczyński J. Dry needling as a method of tendinopathy treatment. Ortopedia Traumatologia Rehabilitacja. 2013;15(2):1-10. doi:10.5604/1509349 2.1045947 43. Jayaseelan DJ, T. Faller B, H. Avery M. The utilization and effects of filiform dry needling in the management of tendinopathy: a systematic review. Physiother Theory Pract. 2021;2021:1-13. doi:10.1080/ 09593985.2021.1920076 44. Cardoso TB, Pizzari T, Kinsella R, Hope D, Cook JL. Current trends in tendinopathy management. Best Pract Res Clin Rheumatol. 2019;33(1):122-140. doi:1 0.1016/j.berh.2019.02.001 45. Page MJ, Green S, McBain B, et al. Manual therapy and exercise for rotator cuff disease. Cochrane Database Syst Rev. 2016;(6):CD012224. doi:10.1002/1 4651858.cd012224 46. Page MJ, Green S, Kramer S, et al. Manual therapy and exercise for adhesive capsulitis (frozen shoulder). Cochrane Database Syst Rev. 2014;(8):CD011275. doi:1 0.1002/14651858.cd011275
47. Braun C, Hanchard NCA. Manual therapy and exercise for impingementrelated shoulder pain. Phys Ther Rev. 2010;15(2):62-83. doi:10.1179/174328810x1 2786297204675 48. Bang MD, Deyle GD. Comparison of supervised exercise with and without manual physical therapy for patients with shoulder impingement syndrome. J Orthop Sports Phys Ther. 2000;30(3):126-137. doi:10.2 519/jospt.2000.30.3.126 49. Belk JW, Jones SD, Thon SG, Frank RM. Trends in the Treatment of Biceps Pathology: An Analysis of the American Board of Orthopaedic Surgery Database. Orthop J Sports Med. 2020;8(12):232596712096941. doi:10.1177/232596712 0969414 50. Frank RM, Nho SJ, McGill KC, et al. Retrospective Analysis of Arthroscopic Superior Labrum Anterior to Posterior Repair: Prognostic Factors Associated with Failure. Advances in Orthopedics. 2013;2013:1-7. doi:1 0.1155/2013/125960
International Journal of Sports Physical Therapy
Physical Therapy Interventions for the Management of Biceps Tendinopathy: An International Delphi Study
SUPPLEMENTARY MATERIALS Appendix 1 Download: https://ijspt.scholasticahq.com/article/35256-physical-therapy-interventions-for-the-management-ofbiceps-tendinopathy-an-international-delphi-study/attachment/89838.docx?auth_token=kr1FEsVmdNxwv8c7xJac
International Journal of Sports Physical Therapy
Howell AJ, Burchett A, Heebner N, et al. Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized Clinical Trial. IJSPT. 2022;17(4):695-706.
Original Research
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized Clinical Trial Alan J Howell, PT, ATC 1, Andrew Burchett, DPT, ATC 1, Nicholas Heebner, PhD, ATC 2, Cody Walker, MS, LAT, ATC 3, a Alec Baunach, SPT 4, Asia Seidt, SPT 4, Tim L Uhl, PT, ATC, PhD 4 1
FYZICAL Therapy & Balance Centers, 2 Sports Medicine Research Institute, University of Kentucky, 3 Department of Athletic Training and Clinical Nutrition, University of Kentucky, 4 Department of Physical Therapy, University of Kentucky Keywords: posterior shoulder tightness, therapeutic exercise, shoulder pain, scapular stabilization https://doi.org/10.26603/001c.34439
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background Previous research has demonstrated the benefits of both stabilization and non-stabilization of the scapula during stretching in individuals with posterior shoulder tightness, but limited evidence exists in patients with shoulder pain.
Hypothesis/Purpose The aim of this study was to determine the effect of stabilized scapular stretching on patients with shoulder pain. The primary hypothesis of this study is that stabilized scapular stretching will improve glenohumeral motion and pain compared to non-stabilized stretch program. A secondary hypothesis of this study is that stabilized scapular stretching will produce greater improvement in function compared to the non-stabilized stretching program.
Study Design Randomized Clinical Trial
Methods Sixteen patients with sub-acromial pain associated with tendinopathy and associated pathologies presenting to physical therapy were randomized into two groups (stabilized or non-stabilized scapular stretching). Baseline pain and range of motion were measured prior to and following each treatment session for three visits that occurred over the course five to seventeen days depending on the patients availability. The dependent measurements were stabilized horizontal adduction, stabilized internal rotation, stabilized shoulder flexion, non-stabilized shoulder flexion, and current pain level.
Results Patients in the scapular stabilization stretching group increased horizontal adduction 40° (CI95 31, 48°) compared to the non-stabilization stretching group increase of 8° (CI95 0, 17°) over the course of the three treatments (p<0.001). Similarly, the stabilized stretching group increased internal rotation 48° (CI95 26, 69°) compared to the non-stabilized stretching group increase of 26° (CI95 4, 48°) (p=0.001). Pain decreased in the stabilized stretching group by 1.4 points (CI95 -0.4, 3.2) but increased slightly in non-stabilized
a
Corresponding author: Tim L. Uhl Uinversity of Kentucky, Room 210C C.T. Wethington Building 900 South Limestone Lexington, KY 40536-0200 email: tim.uhl@uky.edu
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
group by -0.5 points (CI95 -2.3, 1.3) which was not a clinically meaningful change. (p=0.03)
Conclusion Stabilized scapular stretching was more effective than non-stabilized stretching at gaining shoulder mobility in patients with shoulder pain. Benefits were immediate and sustained between treatment sessions. Stretching interventions improved range of motion but had limited effect on shoulder pain.
Level of Evidence 2
INTRODUCTION Shoulder range of motion deficits often arise from various shoulder pathologies and occur in multiple planes.1–5 Patients with signs consistent with general shoulder pain, including internal impingement6,7 or superior labral pathology2 commonly have associated loss of both internal rotation and horizontal adduction.2,6 This common physical limitation in patients with shoulder pain necessitates that interventions are utilized to effectively improve shoulder range of motion, pain, and function. Assessment and treatment of shoulder mobility is critical to improved patient outcomes as many diagnoses have identified shoulder mobility deficits as a common impairment. Two recent clinical reasoning algorithms for managing patients with shoulder pain recommend that shoulder soft-tissue limitations be assessed and treated to effectively manage these patients.8,9 Morrison recommends treating mobility deficits prior to strength deficits in patients with rotator cuff impingement.3 Several interventions, such as the sleeper stretch, the cross-body stretch, and joint mobilization have demonstrated increased shoulder mobility in individuals with posterior shoulder tightness.10–14 Recently, Salamh et al.12 investigated the immediate effects of scapula stabilized vs. non-stabilized stretching in volleyball players with tight posterior shoulder tissues and found that scapular-stabilized stretching was most effective. A common limitation of these studies is that they were conducted on healthy individuals with posterior shoulder tightness, creating a paucity in the literature to support the use of these stretching interventions in patients with shoulder pain. Stretching interventions combined with other interventions have been successful improving mobility,6,13–15 function,6,13–15 and pain13,14 in patients presenting with symptoms of internal impingement and mobility deficits. Multi-modal interventions of stabilized scapula stretching, joint mobilization, and scapular strengthening have demonstrated improvements in mobility, function and pain reduction over the course of three to seven weeks.6,15 Patients with rotator cuff tendinitis who do not receive therapy for a month have shown no improvement in the same measures, indicating that no treatment does not seem to resolve symptoms.4 Multi-modal interventions are effective yet limit our understanding which intervention affects a particular impairment. There is limited evidence to demonstrate that patients with a painful shoulder who seek medical care can benefit from an intervention focusing primarily on posterior shoul-
der stretching alone to positively impact range of motion, pain and function. Limited evidence exists on the effect of stretching with scapula stabilized compared to non-stabilized in a population with shoulder pain. The aim of this study is to determine the effect of stabilized scapular stretching on patients with shoulder pain. Therefore, the primary hypothesis of this study is that stabilized scapular stretching will improve glenohumeral motion and pain compared to non-stabilized stretch program. A secondary hypothesis of this study is that stabilized scapular stretching will produce greater improvement in function compared to the non-stabilized stretching program.
METHODS A single-blinded randomized clinical trial was used to compare two shoulder stretching techniques performed over the course of three treatment sessions in patients with shoulder pain (Figure 1). SUBJECTS
Potential participants were recruited between June 2015 and July 2017. A total of 16 patients with shoulder pain were enrolled in this study that were seeking treatment at the Howell Rehab Centers outpatient physical therapy clinic for shoulder pain. Informed consent was obtained for all participants in accordance with the procedures approved by the University of Kentucky Institutional Review Board prior to participation in the study. All of the participants were screened by a licensed physical therapist and excluded from participating if reporting pain originating from peripheral neurological disorder (such as cervical radiculopathy or thoracic outlet syndrome), determined to have adhesive capsulitis defined as range of motion limitation in external rotation or elevation of 50% or more compared to the uninvolved side, pain greater than or equal to 8/10. Patients with a history of shoulder surgery in the last three months were excluded. Patients were included in the study if shoulder pain was provoked with active, passive or resistive testing of shoulder elevation, external rotation or internal rotation regardless of pain duration or source of pain. Patient’s referring physicians were primary care and sports orthopedic surgeons and the patients had the following referring diagnoses: rotator cuff tendinopathy (n=10), non-specific shoulder pain (n=4), superior labral pathology (n=1), and acromioclavicular joint sprain (n=1). Patients were randomly assigned to one of two stretching groups: stabilized scapular stretching (n=8) or non-stabi-
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
Table 1. Subject baseline characteristics comparing stabilized versus non-stabilized groups. Values are represented as a mean (standard deviations). Not Stabilized Stretching Control (n=8)
Stabilized Stretching (n=8)
Level of significance
Sex (male, female)(n)
4,4
3,5
p=0.61
Age (years)
52 (16)
45 (18)
p=0.41
Height (cm)
174 (19)
173.0 (16)
p=0.94
Body Mass (kg)
80 (18)
78 (22)
p=0.80
Non-stabilized Flexion
141 (13)
150 (10)
p=0.30
Stabilized Flexion
108 (11)
103 (10)
p=0.41
Stabilized Horizontal Adduction
-21 (5)
-25 (5)
p=0.05
Stabilized Internal Rotation
16 (12)
24 (10)
p=0.23
Penn Shoulder Score
61 (24)
52 (16)
p=0.25
Pain
2 (2)
3 (2)
p=0.16
Symptomatic Shoulder Stretched (right, left)(n)
4,4 (8)
4,4 (8)
p=1.0
Figure 1. Consort Flow Diagram for group allocation
lized scapular stretching (n=8), using a block randomization process. The physical therapist was blinded until all initial assessments and measurements were completed. An opaque envelope was opened to indicate treatment assignment. The patient was blind to group membership as all patients were given a stretching intervention. No differences in baseline measures as determined by independent T-test and Chi-square analysis except for horizontal adduction (Table 1). A priori power analysis was performed using Nquery Advisor 7.0 (Statistical Solutions, Ltd, Boston, MA) using previous data of stabilized vs non-stabilized horizontal adduction range of motion.12 A sample size of 12 in each group
would have 80% power to detect a mean difference of 18° assuming a common standard deviation of 15° using a two sided independent t-test with a p = 0.050. These differences were calculated to have an effect size of 1.2. MEASUREMENT PROCEDURES
During the initial visit, measurements were taken bilaterally; subsequent assessments were only taken on the symptomatic side. The physical therapist was blinded to the results using a two-person assessment to minimize bias. A digital inclinometer (Baseline Digital Inclinometer, White Plains, NY) was used to measure all motions described below. The physical therapist and assistant performing all
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
measurements’ reliability was evaluated and found to be excellent. ICC’s ranged from 0.87 to 0.99 with minimal detectable changes with 90% confidence interval ranging from 2° - 4° for all measurement which is consistent with previous research.16,17 Non-stabilized passive flexion was measured with the patient lying supine, and their arm passively elevated in the sagittal plane to the point of pain or resistance, whichever came first. The angle between the arm relative to the horizontal surface of the plinth was recorded. The patient was not allowed to arch their back ensuring that their trunk was in line with the table. Stabilized supine passive flexion was measured in the same manner except that the physical therapist stabilized the lateral border of the scapula with the heel of their hand before passively elevating the patient’s arm into flexion. Stabilized supine horizontal adduction was measured with the patient lying supine.17,18 Their arm was abducted to 90° and elbow flexed to 90°. The physical therapist blocked the lateral border of the scapula with the heel of their hand before passively elevating the patient’s arm transversely across their chest into adduction to the point of pain or resistance, whichever came first. The inclinometer was zero referenced perpendicular to the plinth such that if the humerus was pointing directly toward the ceiling that would be zero degrees. Measures less than vertical were recorded in negative degrees and measurement angles greater than zero degrees were recorded as positive values (Figure 2).7,18,19 Stabilized supine internal rotation was measured with the patient lying supine. The patient’s arm was abducted to 90° and elbow flexed to 90°. The physical therapist blocked the scapula anteriorly over the coracoid process and clavicle to prevent scapular substitution. The patient’s forearm was passively rotated forward toward the table in the sagittal plane to the point of pain or resistance with the scapular stabilized by the physical therapist. The inclinometer was zero referenced as described previously. The angle between the forearm relative to the horizontal surface of the plinth was recorded using a digital inclinometer (Figure 3). All measurements were taken in the same manner before and after each treatment intervention for the three sessions of treatment, as was reported level of pain, using a numeric pain rating scale from 0= no pain to 10= worst possible pain. Single measurements were recorded as all data were collected in an outpatient clinic by the therapist during the standard course of patient care. It was not feasible or consistent with the standard of care to take multiple measurements. The physical therapist had 30 plus years of experience and excellent reliability outcomes supports this measurement approach. It was not feasible to blind the treating physical therapist from group membership as this was a single physical therapist practice. The physical therapist was blinded to measurement values by performing the passive movements while an assistant would zero and align the inclinometer to the humerus, to minimize evaluator bias. Data were recorded by the assistant on the data collection form and recorded in the chart. Measurements were not seen by the physical therapist until the patient had left to attempt to minimize bias.
Figure 2. Measurement technique of stabilized supine horizontal adduction
Figure 3. Measurement technique of stabilized scapular internal rotation
Prior to the initial evaluation and following the final treatment visit, patients were asked to complete the Penn Shoulder Score, a self-reported measure of shoulder function, pain, and satisfaction.20 The Penn Shoulder Score total score ranges from 0-100 with 100 indicating no pain, full
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
satisfaction and normal function. The retest reliability of this self-reported functional outcome tool has been found to have an ICC with 95% confidence interval of (.89-.97) with a minimal clinically important difference at a 90% confidence interval of 12.1 points.20 STRETCHING INTERVENTION
All patients regardless of group, received high voltage pulsed (galvanic) electrical stimulation prior to stretching. The bipolar electrodes were placed on the anterior and posterior aspect of the shoulder with a dispersive pad placed over the lumbar spine with the parameters set at 80 pulses per second for 20 minutes. The intensity was set to the point of a strong sensation but no muscle contraction in order to facilitate the gate control theory of pain management.21 After all patients completed the electrical stimulation treatment, they were split into their designated groups: stabilized or non-stabilized scapular stretching intervention. STABILIZED SCAPULAR SHOULDER STRETCHING
The patient was lying supine for all stretches. The treating physical therapist had the patient perform 10 repetitions of passive shoulder flexion in the supine position with the scapula manually stabilized on the lateral portion to restrict scapular motion to focus stretch on scapulohumeral tissues. The patient performed a self-stretching technique by slowly lifting arm overhead into shoulder flexion to the point of tightness but with no pain using their opposite arm or stick to perform the passive motion. The therapist reminded the patient to stop stretching shoulder into flexion right before the point of pain. The patients held this position for five seconds and then relieved the tension by lowering the arm back to neutral. The treating physical therapist re-applied manual stabilization to the scapula, as needed, during the 10 repetitions to minimize scapular motion. This procedure of stabilized scapular self-stretching was repeated in the transverse plane for horizontal adduction. The patient was instructed to slowly pull their humerus across their body with their elbow flexed to the point of tightness but again not to induce any shoulder pain while the physical therapist applied resistance to the lateral scapular border to minimize scapular motion. Passive shoulder internal rotation at 90° of abduction was performed with use of a stick while the physical therapist stabilized the scapula anteriorly over the acromion and coracoid to prevent anterior tilting. The stretching parameters for duration and frequency were the same for all of 10 repetitions with five second holds below the pain threshold. NON-STABILIZED SHOULDER STRETCHING
The patient was lying supine for all stretches with direct supervision of the treating physical therapist. All stretching parameters were exactly the same as described above without the scapula being blocked. The patient was still instructed to perform self- stretching exercises and stop prior to inducing pain while holding for five seconds.
Post-intervention measurements occurred immediately after stretching routine was completed and followed the same procedures as described previously. After, all patients received 15 minutes of cryotherapy using a commercial cold pack with toweling placed between the skin and cold pack with a wrap securing the position. The participants returned for two more sessions based on the participant’s schedule and treating physical therapist’s schedule. Patients are typically seen two-times per week. The average duration was 9 days (range 5-17 days) to complete the study. HOME EXERCISE PROGRAM
Patients were instructed in-home exercises of shoulder flexion and internal rotation three times per day for 10 repetitions with a three-second hold for each stretch. Both groups were given the same home program. Shoulder flexion was performed with the assistance of the opposite arm or with a stick. Shoulder internal rotation was performed with the assistance of a towel either pulling across their back or up their back to induce a non-painful stretch. Each participant was given a home exercise log to monitor adherence to program and asked to return at the end of the study. Self-reported compliance was 85% in the stabilized group and 92% in the non-stabilized group resulting in no difference between the groups (p=0.58). STATISTICAL ANALYSIS
The data was examined for normality using a Shapiro-Wilks test and found to be normally distributed. A fixed two factor linear mixed model analysis was performed with significance set at (p<0.05). The fixed factors were group (stabilized group and non-stabilized stretching groups) and time (pre and post measurements for the three visits). The dependent measures were the four range of motion measures and current level of pain. The same mixed model analysis for the Penn Shoulder Scores was carried out but with only two time points pre-intervention on Day 1 and post-intervention on Day 3. If a significant interaction between group and time were observed Bonferroni post-hoc analysis was carried out with significance set at (p<0.05). IBM SPSS Statistics for Windows (Version 23.0; Armonk, NY; IBM Corp.) was used to analyze the data.
RESULTS Significant interactions between group and time were found for three of the four range of motion measurements indicating that the stabilized group improved more: stabilized flexion (Figure 4, p<0.001), stabilized horizontal adduction (Figure 5, p<0.001) and stabilized internal rotation (Figure 6, p < 0.001). Bonferroni post-hoc analyses correcting for multiple comparison reduced the critical value (p ≤0.008). For both stabilized flexion and stabilized horizontal adduction, measures at post-treatment visit 1 through post-treatment visit 3 were found to be both significantly greater and beyond measurement error in the stabilized group compared to the non-stabilized group (Figures 4 and 5). Stabilized internal rotation measures at post-treatment visit
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
Figure 4. Results of stabilized vs. non-stabilized shoulder flexion.
Figure 5. Results of stabilized vs non-stabilized horizontal adduction.
1 through pre-treatment visit 3 were found to be significantly greater and beyond measurement error in the stabilized group compared to the non-stabilized group (p<0.008, Figure 6). Only non-stabilized flexion did not have a significant interaction (p = 0.38) but demonstrated a significant main effect of greater motion in the stabilized stretching group
(164° CI95 157°,171°) compared to the non-stabilized stretching group (150° CI95 142°,158°) (P= 0.033). There was a main effect for time, indicating that regardless of group membership non-stabilized shoulder flexion increased over time. A Bonferroni post-hoc analysis for multiple pairwise comparisons with an adjusted critical value of (p ≤0.003) for time revealed that at final post-treatment
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
Figure 6. Results of stabilized vs non-stabilized internal rotation.
visit 3 measure of non-stabilized flexion (164° CI95 157°, 171°) was found to be greater than the first three measurements (Table 2). Current pain level analysis revealed a significant interaction between group and time (p =0.026) (Figure 7). Post-hoc analysis was performed with pairwise comparisons using a Bonferroni correction for multiple comparisons adjusting the critical value to (p ≤0.008). Pairwise comparisons between groups did not reach this level of significance at any time point. The linear mixed model ANOVA for the Penn Shoulder Score total score did not reveal a significant interaction between group and time (p =0.64). However, there was a main effect for time, indicating that both stretching groups significantly improved the Penn Shoulder Score total score. The baseline Penn Shoulder Score was 56.3 (CI95 47.3, 65.4) and progressed to 73.0 (CI95 64.5, 81.5) at the end of treatment. (p <0.001), surpassing the minimally clinically important difference.
DISCUSSION
Table 2. Main effect results for non-stabilized flexion measurements Time
Mean
CI95
1. Pre-intervention Visit 1
146*,†
(139, 153)
2. Post-intervention Visit 1
155*
(150, 161)
3. Pre-Intervention Visit 2
155*
(148, 161)
4. Post-intervention Visit 2.
160
(154, 165)
5. Pre-intervention Visit 3.
159
(153, 166)
6. Post-intervention Visit 3.
164
(157, 171)
* = indicates that time point is significantly lower than time point 6 † = indicates that time point is significantly lower than time point 4
function, following pain-free stabilized scapular stretching and simple home program, were achieved in 5-17 days. These results support the concept of re-establishing normal shoulder mobility initially in the rehabilitation process.3,9 INTERVENTIONS TO IMPROVE POSTERIOR SHOULDER MOBILITY
Stabilization of the scapula during stretching improved mobility in patients with shoulder pain in three of the four directions evaluated compared to patients without scapular stabilization. This supports the primary hypothesis that stabilized scapular stretching is more effective than nonstabilized scapular stretching in restoring passive shoulder mobility. However, the hypothesis that stabilized scapular stretching would reduce pain more than non-stabilized stretching was not supported. Based on previous literature, an improvement of 9 degrees in shoulder ROM is determined to be clinically significant.16 Significant and clinically meaningful changes in passive shoulder mobility and
Posterior shoulder stretching to improve mobility is wellestablished.6,10–12,14,15,22–24 However, most research has focused on stretching subjects that had restricted shoulder mobility without shoulder pain. Three previous studies have examined the stretching effect on posterior shoulder tightness (PST) in symptomatic patients.6,14,15 Posterior shoulder mobility improved over the course of multiple visits across three to seven weeks using a multi-modal approach of stretching, strengthening and educational techniques.6,15 The current study focused on only stretching
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
Figure 7. Results of stabilized vs non-stabilized pain scale.
interventions to improve mobility, pain, and function in three visits across nine days on average. A multimodal approach to treating (PST) in patients with shoulder pain improves mobility and function,6,14,15 however, determining which intervention caused what effect can be difficult to ascertain. Tyler et al.,6 enrolled 22 patients with posterior impingement into an prospective cohort study of physical therapy three times per week, including daily home exercises that included stabilized scapular stretching, joint mobilizations, self-stretching, and shoulder strengthening. The interventions demonstrated significantly increased horizontal adduction by 28 ± 22° and internal rotation by 26 ± 20°.6 These improvements are comparable to the current study which was achieved in three treatments. Cools et al.,15 undertook a similar study enrolling thirty competitive overhead athletes with impingement signs and posterior shoulder tightness. Patients were randomized into either glenohumeral joint mobilization or scapula stabilized stretching. Each group underwent 30-minute treatments, three times per week for three weeks. Half of each treatment focused on scapular stabilized cross body stretching and half on sleeper stretch while the joint mobilization group spent half of their time on posterior and inferior mobilization interventions.15 No differences were seen between groups, but both groups saw improvement of passive internal rotation (12 ± 10°).15 Tahran et al.,14 explored the difference between modified crossbody stretching and modified sleeper stretching in combination with therapeutic exercise on subjects with impingement signs and GIRD, compared to a control group only receiving the therapeutic exercise over 20 treatment sessions. No significant difference was found between stretching groups, improving internal rotation by 22 ± 9°.14 Unfortunately, weekly measurements were not captured in these
studies so it is unclear when these changes occurred. It is possible that changes occurred early as seen in the current study but were just not recorded. The effectiveness of scapular stabilization versus no scapular stabilization during stretching was observed after a single treatment intervention and progressed over the three visits spanning a mean of nine (range 5-17) days. These changes occurred earlier than in previous reports.6,14,15 Potential explanation for the large and early increase in mobility may be due to the stabilized stretching in three differing planes of motion. The therapists in comparable studies stabilized cross-body adduction in similar manners,6,14,15 internal rotation using the plinth6,14 or therapist hand15 but neither intervention incorporated scapular stabilized flexion stretching, which may target different portions of the posterior soft tissue that were restricting motion accounting for the dramatic improvement. The large change in range of motion may be due to the current subjects having a larger mean deficit in internal rotation at baseline, measuring 10° less than Tyler et al.6 and 30° less than Cools et al.15 and Tahran et al.,14 allowing for greater change in motion to occur. Three of the four motions were positively affected by stabilized scapular stretching with the exception in the nonstabilized flexion, which improved in both groups. Stabilized scapular stretching during flexion targets scapulohumeral tissues while non-stabilized flexion allows the scapula to move therefore stretching multiple tissues in the shoulder region. Both groups performed non-stabilized flexion at home at a similar adherence rate which may account for lack of differences observed in this measurement.
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
DOSING PARAMETERS AND MECHANISM
Dosing parameters and effectiveness is varied in previous research. The current study used a dosing parameter of ten stretches, holding for five seconds, in three planes of motion for a total stretching time of 150 seconds. A systematic review of the effectiveness of stretching on PST demonstrated that interventions for PST have stretching parameters that range from ninety seconds to fifteen minutes in healthy populations with posterior shoulder tightness.25 Previous research focusing on duration parameters in hamstring muscles identified thirty seconds as an optimal stretch duration.26 However, applying a passive stretch of fifteen seconds or for two minutes did not demonstrate significant improvements in hip abduction range of motion.27 Stretch duration research has predominantly been studied in patients without pain. In this study’s results suggest short duration holds repeated 10 times in multiple planes were effective to improve motion in a painful population. Connective tissue restrictions of both musculotendinous and capsular structures in the shoulder have been implicated as a mechanism causing shoulder pathologies and altering shoulder joint arthrokinematics.28–30 As this was a clinical study, the authors were unable to discern if the adaptations were muscular or capsular but likely muscular due to early changes. Stretching and soft-tissue mobilization have demonstrated reduced muscular stiffness31 but the viscoelastic changes are temporary and baseline measures return within an hour.32 In the current study changes occurred during treatment and were maintained between treatments beyond the reported viscoelastic affects. Neurophysiologic changes may attribute to range of motion gains as static stretching has been shown to minimally decrease the time required for an H-reflex through diminished motor neuron pool excitability promoting increases in muscle extensibility.33 However, these results were determined from single stretching sessions and current research utilizing long-term protocols have determined no significant neurological adaptations to repeated stretching.34 Therefore, another explanation for these results is due to increased tolerance to stretching.32,34–36 Perhaps through the short yet repetitive stretching performed, tolerances improved in this study, accounting for the improved measures. Proposed mechanisms of increased range of motion following stretching include increases in elasticity of connective tissue and myofibrils, neurophysiological effects, and increased tolerance to stretching.31,32,34,35 FUNCTION AND PAIN IMPROVEMENTS NOT DUE TO STABILIZED SCAPULAR STRETCHING
Patient reported outcomes are critical measures of patient improvement as they evaluate patient’s perception of function and pain. Direct comparisons between studies was not feasible due to frequency of measurement and tools used. To compare the current results to others the percent improvement in the functional score per visit was calculated. The current study had a 12%/visit improvement in function over three visits, as measured by the Penn Shoulder Score, and was most similar to Tyler’s results, a 6%/visit improvement in function over 21 visits.6 It is likely that other stud-
ies have similar or perhaps greater improvement but were not measured as frequently.6,14,15,37 Early changes in perceived function have been seen in previous research and is a strong indicator of successful intervention.37,38 In the current study both stretching groups improved with most of the change occurring in the function component of the Penn score. The increased mobility may have allowed patients to perform functional tasks easier accounting for the perceived improvement. Prior to and following each treatment day pain was measured with a numeric pain rating scale. Previous research has found that two points represents a clinically meaningful change in pain.39 Pain demonstrated a significant interaction but the clinical meaningfulness of a one point change should be questioned (Figure 7). The study duration was short and focused on mobility potentially explaining these findings. The relatively low self-report of current pain level and low number of subjects may also account for the lack of difference. It is also reasonable to interpret this finding that stretching alone does not reduce shoulder pain. Multimodal interventions have shown 30% reductions in pain.6 However, any study without a control group, cannot rule out that pain reduction did not occur naturally over time. LIMITATIONS
An obvious limitation of this study is the small sample size. The a priori power analysis estimated that 12 subjects in each group would be needed to achieve at least 80% power. However, the authors were only able to recruit a total of 16 subjects (8 in each group) over a two-year recruitment process. The estimated effect size used in the original power analysis was 1.2 based on an 18° difference comparing stabilized and non-stabilized stretching interventions to gain horizontal adduction.12 Effect size was calculated after visit 1 (time point 2) and after visit 3 (time point 6) to compare observed versus estimated effect sizes (Table 3). The average effect size was 2.6 which is twice as much change as would have been expected with a fully powered study. A post-hoc power analysis using this new effect size of 2.6 resulted in an achieved power of 99%. Based on the time spent recruiting, and that stabilized scapular stretching was the standard clinical procedures in the clinic where the study took place, the study was discontinued even though it was underpowered. The statistical analysis supported this decision as greater changes were observed in motion using the stabilized stretching intervention for three directions measured. Another limitation is that this study was performed in a single privately owned physical therapy clinic which reduces the external validity as other clinicians may not have the same technique. The clinician has over 30 years of experience and has used this technique in multiple patients with a positive response. This potentially biases the study as the clinician was interested in the effectiveness of this approach. However, the clinician was willing to expose his patients to another treatment approach of non-stabilized stretching during the course of his typical clinical practice. The implication of this treatment intervention is that it was applied to patients seeking physical therapy for shoulder pain in a clinical environment which enhances its external
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
Table 3. Effect Sizes for Stabilized Scapula Stretching Group Results
Change in power (effect size-estimated power [1.2])
Post-visit 1
Post-visit 6
Post-visit 1
Post-visit 6
Stabilized Horizontal Adduction
2.079
2.306
0.879
1.106
Stabilized Flexion
2.576
4.009
1.376
2.809
Stabilized IR
3.391
1.279
2.191
0.079
validity to patients seeking medical care. The therapist was not completely blinded from the data as he documented patient records after care was provided. The inclinometer was recorded by an assistant to minimize bias, but it is possible that the same force applied was not consistent between groups as the therapist was aware of group membership. No long-term follow up to measure motion following the intervention was carried out. Cools et. al.15 demonstrated that range of motion gains were maintained at three weeks following a multimodal intervention approach. The current study was only carried out for three treatments to evaluate immediate effects of a specific stretching intervention on mobility, pain, and function. Follow up assessment was not feasible as other treatment interventions were applied to all patients as determined appropriate by the therapist following the third visit.
CONCLUSION Re-establishing normal pain free mobility is a common goal in shoulder rehabilitation and typically precedes re-establishment of strength and function. The results of this study indicate that patients in with shoulder pain that have range of motion deficits benefit the most from stabilized scapular stretching addressing internal rotation, horizontal adduction, and flexion. The results of the current study further
indicate that improvements can be observed after a single treatment and can be maintained between visits with a home stretching program. Function was improved with both approaches. Pain improved in the stabilized scapular stretching group but did not reach clinical significance in this short duration intervention.
STATEMENT OF IRB APPROVAL
This study was approved by the University of Kentucky Institutional Review Board: 15-0223-P1H FINANCIAL DISCLOSURE
The authors affirm that they have no financial affiliation (including research funding) or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript, except as disclosed in an attachment and cited in the manuscript. Any other conflict of interest (ie, personal associations or involvement as a director, officer, or expert witness) is also disclosed in an attachment. Submitted: July 21, 2021 CDT, Accepted: February 18, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Effectiveness of Scapular Stabilization Versus Non-Stabilization Stretching on Shoulder Range of Motion, a Randomized...
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International Journal of Sports Physical Therapy
Tsuruike M, Mukaihara Y, Ellenbecker TS. Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball Seasons? IJSPT. 2022;17(4):707-714.
Original Research
Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball Seasons? Masaaki Tsuruike, PhD, ATC 1
a
, Yohei Mukaihara, MA, ATC, CSCS 2, Todd S. Ellenbecker, DPT, MS, SCS, OCS, CSCS 3
1
Department of Kinesiology, College of Health and Human Sciences, San José State University, CA, 2 Oji Baseball Club, Kasugai, Aichi, Japan, 3 Rehab Plus Sports Therapy Scottsdale and ATP Tour, AZ Keywords: scapular dyskinesis, collegiate baseball pitchers, throwing-related shoulder injury https://doi.org/10.26603/001c.34676
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background A pattern of scapular dyskinesis on the dominant side has been demonstrated to be associated with a decrease in throwing arm conditions identified by a self-report outcome assessment in collegiate baseball pitchers during the course of a single season. However, it is unclear if symptomatic shoulders in baseball pitchers may be associated with the presence of scapular dyskinesis.
Purpose To study the relationship between the presence of scapular dyskinesis and throwing-related injury in collegiate baseball pitchers during each respective course of up to four subsequent seasons.
Methods A single Division 1 National Collegiate Athletic Association team participated in this study over a four-year-period. The scapular dyskinesis test was implemented during the preseason for baseball pitchers. Players were followed throughout each respective season to track the incidence of throwing-related upper extremity injuries.
Results A total of 36 collegiate baseball pitchers (height: 185.3 ± 5.6 cm, weight: 88.8 ± 7.8 kg, age: 20.0 ± 1.5 years) consisting of 57 pitcher seasons were followed in this study, in which 18 pitchers remained with the team for more than one year. Twenty-seven of the 57 pitchers were classified as having scapular dyskinesis demonstrated at around 90° of shoulder flexion on the throwing side. Five injuries (13.2% of a total of 38 injuries) were diagnosed as throwing-related shoulder injuries during the course of the intercollegiate baseball seasons. Four of the five throwing-related shoulder injuries occurred in pitchers who had scapular dyskinesis on their dominant side. Consequently, the odds ratio was 5.04 for the collegiate pitchers with scapular dyskinesis on the throwing arm side associated with a throwing-related shoulder injury compared to those with no scapular dyskinesis (p = 0.16). No relationship was identified between scapular dyskinesis on the throwing arm side and throwing-related elbow injury. Eighty-one percent of the scapular dyskinesis test results were not changed on the throwing side from the previous to the following year for those 18 pitchers who were followed for more than one season, whereas 42.9% of the results remained unchanged on the non-throwing side.
a
Corresponding author: Masaaki Tsuruike, PhD, ATC Department of Kinesiology, San José State University One Washington Square, San Jose, CA 95192-0054 email: masaaki.tsuruike@sjsu.edu
Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball...
Conclusion The results suggest that collegiate baseball pitchers with dominant arm scapular dyskinesis likely are at increased risk of throwing-related shoulder injury.
Level of evidence Level 2, Prospective Cohort Study
INTRODUCTION A previous study has reported that there was no difference in draft rank, games missed, or performance across uninjured, nonoperative, and operative players for those who were drafted by Major League Baseball (MLB) organizations.1 However, only 59% of the 216 high school to professional level pitchers could return to play at the same level or higher after superior labrum (SLAP) repairs.2 Indeed, overhead throwing athletes who underwent SLAP repairs on the throwing side had at least a two times less likely to return to their previous level activity, compared to non-overhead athletes.3 Consequently, it is critically important to identify the factors that predispose baseball pitchers to increased shoulder injury risk. The scapular dyskinesis test has been implemented in visual dynamic assessment schemes that seek to classify altered scapular motion, which has been intriguing to clinicians and researchers.4–15 Previous meta-analyses have demonstrated that asymptomatic athletes with the presence of scapular dyskinesis at baseline increased their risk of developing shoulder injury by 25% to 43%, compared to their counterparts without scapular dyskinesis.16,17 However, no significant relationship was observed between scapular dyskinesis and throwing-related shoulder injury.17 Those meta-analyses included heterogenous subjects in a variety of sports from preadolescent to elite cohorts, whereby adverse internal variability should be considered. In contrast, scapular dyskinesis on the dominant side has been demonstrated to be associated with a decrease in throwing arm conditions identified by a self-report outcome assessment for collegiate baseball pitchers during the course of a single season, while no difference was found in the throwing arm conditions for position players regardless of scapular dyskinesis.13 Additionally, Tsuruike et al14 reported that a collegiate baseball pitcher with the history of SLAP repair showed moderate scapular dyskinesis, in which the medial border of the scapula was abruptly protruded on the throwing arm side during weighted arm lowering in the sagittal plane. The protocol of the scapular dyskinesis test has been demonstrated to vary with different weight loads ranging from no external weight to the use of 5 kg held in both hands. Bilateral arm movement speed also varies with different instructions ranging from two to five seconds to complete each elevation and lowering phase, and multiple planes of motion have been used including the sagittal, coronal, and scapular plane.4–14,17 Tsuruike et al12 demonstrated that EMG activity of the anterior deltoid and upper trapezius decreased during arm lowering from full flexion (eccentric contraction), compared to arm elevation (concentric contraction) during the scapular dyskinesis test. This physiological research provides rationale for the clini-
cian to utilize the addition of weight in order to structurally stress the stability of scapulae as there appears to be less muscular activation during the arm lowering phase. Furthermore, the authors12 observed that collegiate baseball players developed an adaptation in periscapular muscle activity during the scapular dyskinesis test in which the upper trapezius muscle was less activated on the dominant side than on the non-dominant side, while the lower trapezius muscle was more activated compared to the non-dominant side. Few prospective cohort studies have investigated whether the presence of scapular dyskinesis identified during the preseason in baseball pitchers may predispose them to throwing-related injuries during the course of intercollegiate baseball seasons. Therefore, the purpose of this study was to study the relationship between the presence of scapular dyskinesis and throwing-related injury in collegiate baseball pitchers during each respective course of up to four subsequent seasons. The authors hypothesized that collegiate pitchers with scapular dyskinesis would have an increased incidence of throwing-related injury during the course of intercollegiate baseball seasons.
METHODS PARTICIPANTS
A single Division 1 National Collegiate Athletic Association team participated in this study over a four-year-period. All subjects met during preseason meetings in January and gave informed consent to the procedures as approved by the Institutional Review Board in the Office of Research at San José State University prior to data collection each year. This study prospectively followed these players throughout each respective season pertaining to incidence of upper extremity injury. The inclusion criteria were that the subjects had to be asymptomatic competitive baseball pitchers, free from neurologic or physiologic conditions in their upper body prior to each upcoming season. Pitchers were excluded from participation if they appeared in two games or less during each season. Each season typically consisted of 56 (± 1.3) official games over an average of 95 (± 3.7) days. PROCEDURES
The scapular dyskinesis test was conducted in the second week of January during the preseason each year. The subjects were asked to in the standing position, simultaneously lower both arms from full flexion with a 3.2 kg wrist cuff worn on both extremities over a five-second period while following a metronome set at 60 beats per minute.12–14 The amount of weight used during the scapular dyskinesis test was based on previous studies.12–14 The scapular dyskinesis test was recorded with a digital video camera (Panasonic
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Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball...
Camcorder HC-V770, Osaka, Japan) that was mounted level on a tripod four feet from the floor and set seven feet behind the subject. The videotape was copied and distributed to one physical therapist (PT) and two athletic trainers (AT) who determined the Kibler scapular classification types at around 90° of shoulder flexion on both sides during the lowering phase of the arm movement.6 All three of the examiners had two-to 10 or more years of experience in the performance and interpretation of the scapular dyskinesis test in clinical practice with overhead athletes including baseball players and had published in this area. Player’s hand dominance was not disclosed to the examiners throughout the scapular dyskinesis assessments. Subsequently, this study classified the athletes into four patterns of scapular kinesis: 1) both sides with scapular dyskinesis, 2) scapular dyskinesis on the throwing side but not on the non-throwing side, 3) scapular dyskinesis on the non-throwing side but not on the throwing side, 4) neither side with scapular dyskinesis. DATA ANALYSIS
Athlete-exposures (AEs) were calculated for each of the throwing-related shoulder and elbow injuries with the number of pitchers involved during the course of the respective season over the four year-period including both practices and games. The team had one no-practice day every week for 14 weeks or the average of 95 days during the respective season, leading to the average of 81 days which were used to calculate AEs. Odds ratios were calculated to describe the association of throwing-related injury between pitchers with and without scapular dyskinesis along with descriptive statistics for incidence of injuries. Also, the pvalue of the odds ratio was calculated as the area of the normal distribution that fell outside ± z value.18 The initial scapular dyskinesis assessments were analyzed using the four-type Kibler classification system.6 In the Kibler classification all Type I, Type II and Type III findings were transposed and recorded as a “yes” value for scapular dyskinesis and all Type IV findings were transposed and recorded as a “no” value for no presence of scapular dyskinesis.5,13,15 The inter-rater reliability of scapular dyskinesis was then calculated using the yes/no classification system15 that was used to identify the degree of agreement between two examiners in terms of the presence of scapular dyskinesis.
RESULTS A total of 36 male collegiate baseball pitchers (height: 185.3 ± 5.6 cm, weight: 88.8 ± 7.8 kg, age: 20.0 ± 1.5 years) were included; 18 pitchers who were rostered for only one season, 18 pitchers remained with the team for more than one year and were subsequently tested each year they were active on the roster. Fifteen out of the 18 were rostered for two seasons, and three were rostered for three seasons (Figure 1). The inter-rater reliability yielded an 92% agreement, resulting in a kappa (κ) correlation of 0.81 between the PT and AT1 on the throwing side of 13 pitchers while it was a 77% agreement with a κ correlation of 0.55 for the non-throwing side. Similarly, the inter-rater reliability yielded an 84% agreement with a κ correlation of 0.68 between AT1 and
AT2 for the throwing side of 44 pitchers while it was a 77% agreement with a κ correlation of 0.56 for the non-throwing side. In the case of disagreement, two examiners reviewed the video together and obtained a consensus. As a result, 27 pitchers were classified as having scapular dyskinesis on the throwing side during the lowering phase of arm movement. For those 18 pitchers who remained with the team for more than one year, 81.0% of the scapular dyskinesis test results were not changed on the throwing side from the previous to the following year, whereas 42.9% of the results remained unchanged on the non-throwing side. Examples of scapular presentations are provided in Figures 2a and 2b. Thirty-eight injuries were diagnosed by the team physician over the four year-course of seasons. This included eight shoulder injuries. Three shoulder injuries were subsequently excluded from analysis due to nonthrowing-related mechanisms: two injuries occurred during batting practice (biceps subluxation) and weightlifting (biceps tendinitis), and the other injury occurred on the non-throwing side (anterior instability) (Table 1). As a result, five injuries (13.2% of a total of 38 injuries) were described as throwing-related shoulder injuries, which occurred during the course of the intercollegiate baseball seasons. None of the five throwingrelated shoulder injuries occurred in the same pitcher. All of the injuries were diagnosed as overuse or chronic injuries, including three cases of subacromial impingement syndrome (SIS), one SLAP lesion, and one case of thoracic outlet syndrome (Table 1).19 None of the injuries were acute or of sudden onset. The incidence rate of throwing-related shoulder injury for the pitchers was 1.04 per 1,000 AEs during the course of the season. The five injured pitchers were disabled from throwing until each of them was re-evaluated and allowed to pitch by the team physician during each respective course of season. The number of days at the onset of injury from the first day of game were 30 (± 14) on average for those pitchers with scapular dyskinesis while the number of days to return to play from the onset of injury were 19 (± 14) on average. Ten throwing-related elbow injuries were diagnosed by the team physician over the four seasons (26.3% of a total of 38 injuries). The incidence rate of throwing-related elbow injury was 2.08 per 1,000 AEs during the course of season. Those injuries included seven ulnar collateral ligament (UCL) sprains, two medial muscle-tendon strains, and one case of lateral epicondylitis without throwing-related shoulder injury (Table 1). One pitcher who had a history of UCL sprain in the previous year developed another UCL sprain in the following year. The rest of the throwingrelated elbow injuries occurred in nine different pitchers. Also, one pitcher who suffered SIS also developed a mild UCL sprain. Four of the five pitchers with throwing-related shoulder injuries were classified with the presence of scapular dyskinesis on their throwing side (Table 2). The odds of shoulder injury for the pitchers with the presence of scapular dyskinesis on their throwing side was 0.174 (4 divided by 23 pitchers), compared to the odds of 0.034 for the pitchers without the presence of scapular dyskinesis (1 divided by 29 pitchers). Subsequently, the odds ratio was 5.04 [95% confidence interval (CI): 0.53-48.3]. However, no significant dif-
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Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball...
Figure 1. Flow of the 36 Baseball Pitchers Throughout the Four-Year Study.
ference was observed in the frequency of throwing-related shoulder injury between the pitchers with and without the presence of scapular dyskinesis (p = 0.16). Seven out of the 10 pitchers who did not have the presence of scapular dyskinesis on their throwing arm side developed throwing-related elbow injuries (Table 2). Thus, no relationship was considered between the presence of scapular dyskinesis on the throwing arm side and a throwing-related elbow injury.
DISCUSSION Forty-seven percent of the collegiate baseball pitchers showed the presence of scapular dyskinesis on their throwing arm side. Subsequently, five throwing-related shoulder injuries were observed over the four year-course of collegiate seasons while 10 throwing-related elbow injuries were observed. The ratio of throwing-related elbow to shoulder injuries observed in this study were similar to a previous study in which predraft baseball players incurred throwingrelated elbow injuries 3.5 times as many as shoulder injuries.1 The results of the current study prospectively indicated that collegiate baseball pitchers with the presence of scapular dyskinesis on their throwing side increased odds of suffering throwing-related shoulder injuries, compared to those without the presence of scapular dyskinesis during the course of a season, although the odds ratio did not reach a significant difference (p = 0.16). The findings of this study were not fully consistent with previous studies. Shitara et al20 demonstrated an odds ratio of 1.23 for high school baseball pitchers with the presence of scapular dyskinesis, compared to pitchers without scapular dyskinesis. The authors followed the protocol of the scapular dyskinesis test utilized by Uhl et al15 in which the subjects elevated arms in the sagittal and scapular plane without an external weight load. As a result, they identified the presence of scapular dyskinesis in 22 (28.2%) out of the 78 pitchers available for the assessment while they prospectively found 21 shoulder/elbow injuries during the course of season. It is plausible to speculate that no external weight application in their scapular dyskinesis tests decreased the ability of the test to identify scapular dyskinesis. Another previous research study using the protocol of the scapular dyskinesis test performed bilaterally with 2.3 kg weights in both sagittal and coronal plane arm movements7 identified the presence of scapular dyskinesis in 122 of the 246 (49.6%) high school baseball players on the dom-
Figure 2a. An example of a right-handed pitcher, who was classified with no scapular dyskinesis on the throwing side (right) whereas the presence of scapular dyskinesis was observed on the nonthrowing side (left).
inant side including both subtle and obvious scapular dyskinesis.9 The authors, however, did not find throwing-related upper extremity injuries to be related to the presence of scapular dyskinesis. One possible reason for the difference in the findings of this study might have been their inclusion of not only pitchers but also position players in their prospective study. High school pitchers are nearly two times more vulnerable to noncontact and overuse shoulder and elbow injuries than position players.21 Based on this injury prevalence finding, prospective studies should be exclusively implemented with baseball pitchers regarding the relationship between throwing-related shoulder injuries and scapular dyskinesis. Both previous studies suggested potential alterations of scapular dyskinesis during the course of the season while two of the studies did not re-examine scapular dyskinesis later in the season.9,20 The present study found that 81.0% of the scapular dyskinesis test results were not changed on the throwing side from the previous to the following year for those 18 pitchers who remained with the team for more than one year. This indicates that most, if not all, of the highly competitive collegiate baseball pitchers had likely developed their scapular adaptations related to long-term repeated throwing motions.
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Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball...
In addition to scapular dyskinesis on the throwing side, clinicians need to be aware of habitual throwing-related scapular adaptations, such as greater degrees of internal rotation and anterior tilt of the scapula on the dominant side, compared to the non-dominant side.22 This internal rotation of the scapula has been argued in a cadaveric study to predispose baseball pitchers to increase the area of internal impingement generated during maximal external rotation in the late cocking phase of the throwing motion.23 In addition, glenohumeral internal rotation deficit often seen in baseball pitchers along with posterior capsular thickening24,25 may increase the anterior tilt of the scapula to create what is known as “a wind-up effect” of the scapula.26 Factors implicated in the mechanism of UCL injury include peak and mean pitch velocity, body weight, height, and age.27 These predictive factors may yet explain 7% of variance in UCL reconstruction rates in MLB pitchers.27 With respect to scapular dyskinesis associated with UCL injury, a cadaveric study revealed that an increase in the internal rotation of the scapula significantly increased the valgus torque of the elbow in the position of maximum glenohumeral external rotation, compared to the resting scapular position.28 However, the results of the present study are not consistent with those of Itami et al,28 and found that no relationship was observed between the scapular dyskinesis test and throwing-related elbow injuries in collegiate baseball pitchers. LIMITATIONS
Figure 2b. An example of a right-handed pitcher, classified as having scapular dyskinesis on both the throwing side (right) and non-throwing side (left), who was diagnosed with subacromial impingement syndrome and was unable to play for 14 days during the course of a season.
Table 1. Injures diagnosed over the four year-course of seasons (n=38). Injuries
This study included collegiate baseball pitchers with asymptomatic shoulders at baseline. Thus, the implication of the findings to individuals of differing ages, levels of performance, and presence of shoulder symptoms should be limited. Also, the athletes in this study sustained only five throwing-related shoulder injuries over four seasons, which might be insufficient to conclude no statistical relationship in throwing-related injuries for the baseball pitcher with the presence of scapular dyskinesis. Additionally, the amount of weight load used in the scapular dyskinesis test was 3.2 kg which may indicate another limitation. However, the mean body weight of the subjects in this study was 88.8 kg, which was 20 kg more than that of the previous studies advocating the weight load of 2.3 kg for the scapular dyskinesis test.20,24 Those previous studies were also implemented with heterogeneous overhead athletes including female athletes and different NCAA divisions, such as water polo, swimming, volleyball, tennis, and softball, in addition to baseball. Consequently, the authors suggest that the amount of weight load used in a study of the scapular dyskinesis test should be discerned for the type of sport in which the athlete participates as well as the subject’s body weight. An additional limitation might include the athletes who were observed over the course of two to three seasons although none of the five throwing-related shoulder injuries diagnosed were in the same subjects.
CONCLUSION
#
Throwing Shoulder Injuries SLAP
1
Impingement syndrome
3
Thoracic outlet syndrome
1
Throwing Elbow Injuries Ulnar collateral ligament sprain
7
Muscle-tendon strain
2
Lateral epicondylitis
1
creased odds of suffering throwing-related shoulder injury, compared to those without the presence of scapular dyskinesis over the course of four seasons. However, no statistically significant difference in injury was observed between those with and without the presence of scapular dyskinesis on the throwing side, likely owing to insufficient throwingrelated shoulder injuries observed during the course of this study. Further studies are warranted to investigate the application of the currently advocated scapular dyskinesis test and its relationship to throwing-related injury prevention in baseball players.
CONFLICTS OF INTEREST
The authors report no conflicts of interest.
The results of this study indicate that collegiate baseball pitchers with the presence of scapular dyskinesis had in-
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Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball...
Table 2. Relationship between the Results of the Scapular Dyskinesis Testing and Shoulder and Elbow Injuries NOTE: SD= scapular dyskinesis
ACKNOWLEDGEMENT
Submitted: September 03, 2021 CDT, Accepted: February 28,
The authors thank Connor Lauffenburger, MA, ATC for his assistance with data collection during this study.
2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
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Can the Scapular Dyskinesis Test be Associated with Throwing Related Injuries During the Course of Collegiate Baseball...
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11. Tate AR, McClure P, Kareha S, Irwin D, Barbe MF. A clinical method for identifying scapular dyskinesis, part 2: validity. J Athl Train. 2009;44(2):165-173. doi:1 0.4085/1062-6050-44.2.165
15. Uhl TL, Kibler WB, Gecewich B, Tripp BL. Evaluation of clinical assessment methods for scapular dyskinesis. Arthroscopy. 2009;25(11):1240-1248. doi:10.1016/j.arthro.2009.0 6.007 16. Hickey D, Solvig V, Cavalheri V, Harrold M, Mckenna L. Scapular dyskinesis increases the risk of future shoulder pain by 43% in asymptomatic athletes: a systematic review and meta-analysis. Br J Sports Med. 2018;52(2):102-110. doi:10.1136/bjsport s-2017-097559
7. McClure P, Tate AR, Kareha S, Irwin D, Zlupko E. A clinical method for identifying scapular dyskinesis, part 1: reliability. J Athl Train. 2009;44(2):160-164. do i:10.4085/1062-6050-44.2.160
17. Hogan C, Corbett JA, Ashton S, Perraton L, Frame R, Dakic J. Scapular dyskinesis is not an isolated risk factor for shoulder injury in athletes: a systematic review and meta-analysis. Am J Sports Med. 2020;49(10):2843-2853. doi:10.1177/03635465209685 08
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27. Chalmers PN, Erickson BJ, Ball B, Romeo AA, Verma NN. Fastball pitch velocity helps predict ulnar collateral ligament reconstruction in major league baseball pitchers. Am J Sports Med. 2016;44(8):2130-2135. doi:10.1177/036354651663430 5
23. Mihata T, Jun BJ, Bui CNH, et al. Effect of scapular orientation on shoulder internal impingement in a cadaveric model of the cocking phase of throwing. J Bone Joint Surg Am. 2012;94(17):1576-1583. doi:10.21 06/jbjs.j.01972 24. Laudner KG, Moline MT, Meister K. The relationship between forward scapular posture and posterior shoulder tightness among baseball players. Am J Sports Med. 2010;38(10):2106-2112. doi:10.1177/ 0363546510370291
28. Itami Y, Mihata T, McGarry MH, et al. Effect of increased scapular internal rotation on glenohumeral external rotation and elbow valgus load in the late cocking phase of throwing motion. Am J Sports Med. 2018;46(13):3182-3188. doi:10.1177/03635465188002 67
International Journal of Sports Physical Therapy
Trunt A, Fisher BT, MacFadden LN. Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers. IJSPT. 2022;17(4):715-723.
Original Research
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers Aaron Trunt 1 1
a
, Brandon T. Fisher 2, Lisa N. MacFadden 1
Sports Science Institute, Sanford Health, 2 Orthopedics and Sports Medicine Research, Sanford Health
Keywords: baseball, assessment, isometric, rehabilitation, upper extremity https://doi.org/10.26603/001c.35722
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background There is a lack of valid and reliable tests that assess upper extremity strength and function for rehabilitation and injury prevention purposes in throwing athletes. The Athletic Shoulder (ASH) test has been proposed as a reliable measure of shoulder strength, but has not yet been studied in baseball pitchers.
Hypothesis/Purpose The purpose of this study was to establish values for healthy baseball pitchers performing the ASH test, compare those values with other common tests of shoulder strength and function, and compare ASH test performance bilaterally. It was hypothesized that the dominant arm would perform significantly better on the ASH test compared to the non-dominant arm. A secondary purpose of the study was to evaluate if ASH test performance was related to fastball velocity in baseball pitchers. It was hypothesized that ASH test performance would positively correlate with fastball velocity.
Study Design Cross-Sectional Study
Methods College and high school baseball pitchers were recruited to complete shoulder range of motion (ROM), isokinetic shoulder strength, and isometric shoulder strength testing using the ASH test. The ASH test was used to assess force production as a proxy for strength bilaterally at four levels of shoulder abduction (0°, 90°, 135°, and 180°), using a force plate. Approximately one-week later subjects returned for a bullpen session where fastball velocity was recorded with a radar gun. Bilateral differences in passive ROM, isokinetic, and isometric shoulder strength were examined using paired t-tests while linear relationships between isometric shoulder strength and fastball velocity were assessed using Pearson correlations.
Results Thirty-five healthy pitchers participated in the study (19.7 ± 1.8 years). Pitchers demonstrated significantly greater isometric shoulder strength at the 90° and 135° abduction positions with the throwing arm compared to the non-throwing arm. Pitchers also demonstrated commonly observed musculoskeletal adaptations in the throwing arm such as increased passive external rotation, decreased passive internal rotation, and
a
Corresponding author: Aaron Trunt Sanford Sports Science Institute, Sanford Health 2215 W Pentagon Place Sioux Falls, SD 57107 P: 218-256-6333 Aaron.Trunt@sanfordhealth.org
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers
greater internal and external rotator strength during isokinetic testing. Peak force production during the ASH test was not related to fastball velocity.
Conclusion The ASH test is capable of detecting bilateral shoulder strength adaptations commonly observed in other clinical tests in healthy pitchers. Pitchers demonstrated greater isometric peak force during the ASH test at levels of shoulder abduction similar to those observed in pitching. While these results may be intriguing for clinical use, peak force from the ASH test was not correlated to fastball velocity in pitchers, and therefore should be used with caution for predictions in this realm.
Level of Evidence 2
Clinical Relevance A need exists for objective measures of shoulder strength for rehabilitation and injury risk monitoring in throwing athletes that are easy to administer, have high reliability and validity, and provide minimal re-injury risk to athletes recovering from injury.
What is known about the subject Data from the ASH test has been published previously in non-throwing athletes and was shown to be valid and reliable in that group. However, the test has not been explored widely in throwing athletes who are known to have significant musculoskeletal adaptations to the throwing shoulder.
What this study adds to existing knowledge The results from this study confirm that the ASH test is sensitive enough to detect the adaptations that are present in the healthy throwing athlete’s shoulder. Due to the prior proven validity and reliability and these results, the test can be used to monitor throwing arm strength and function during rehabilitation or as a pre/intra-season screening tool to help describe arm health.
INTRODUCTION Overhead (OH) athletes such as baseball pitchers are subject to a variety of overuse injuries due to high and repetitive stresses placed on the shoulder. The glenohumeral articulation in particular is susceptible to injury secondary to a lack of inherent stability for the purpose of allowing large ranges of functional mobility.1 Overuse injuries to the glenohumeral joint and surrounding tissues are commonly first managed non-surgically. However, those that do require surgery typically involve a lengthy rehabilitation process and have potential for poor outcomes in athletes hoping to return to their prior level of competition.2,3 Reasons for poor outcomes observed in injured OH athletes include the instability of the shoulder, severity of the injuries suffered, the surgical interventions performed to repair the injuries, as well as many others. While there are multiple valid and reliable tests used to assess lower limb function and strength during the rehabilitation process, few exist for determining the strength and function of the upper extremity. For example, athletes that suffer an anterior cruciate ligament injury requiring surgery often undergo a rigorous and lengthy pre-operative and post-operative rehabilitation process that involves multiple tests of lower limb strength and function at various time points post-surgery. Among these are isometric and isokinetic tests at various joint angles or speeds often used to objectively measure muscle strength, determine agonist/antagonist relationships, and forecast rehabilitation
outcomes.4,5 Although isokinetic dynamometry is considered the gold-standard with regard to muscle strength testing in the clinical setting, it is not always an option for clinicians.6 Further, the same post-injury rehabilitation testing strategies observed in lower limb injuries are not utilized to the same degree in shoulder injuries due to the lack of validated and clinically relevant tests available to the clinician and patient.7 Therefore, there is need to identify additional tests for the upper extremity that can reliably determine strength and function of the shoulder such that clinicians can make informed decisions when preparing an OH athlete to return to competition or sport. The Athletic Shoulder (ASH) test has recently been proposed as an objective and reliable measure of isometric force production (as a proxy for strength) of the shoulder girdle musculature.8 The test involves measuring force production of the combined shoulder musculature at varying degrees of shoulder abduction with the athlete in the prone position using a force plate. The high validity of force plates and multiple test positions to target different combinations of musculature providing objective measures of upper extremity strength make the ASH test an intriguing option to aid the clinical care team in making decisions on return to play with OH athletes. While data has been published evaluating rugby and softball players with the ASH test, data does not yet exist for baseball pitchers performing the test.8,9 Baseball pitchers exhibit well-documented adaptations in shoulder strength and function (such as humeral and glenoid retroversion, posterior capsular tightness, increased
International Journal of Sports Physical Therapy
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers
labral forces, humeral head translation, capsular expansion, decreased internal rotation and increased external rotation ROM) in the dominant arm and core/hips when compared to the non-dominant side that other athletes do not.10–12 As such, any test measuring upper extremity strength should be sensitive to the adaptations that the OH athlete’s shoulder undergoes. Therefore, the purpose of this study was to establish values for healthy baseball pitchers performing the ASH test, compare those values with other common tests of shoulder strength and function, and compare ASH test performance bilaterally. It was hypothesized that the dominant arm would perform significantly better on the ASH test compared to the non-dominant arm. A secondary purpose of the study was to evaluate if ASH test performance was related to fastball velocity in baseball pitchers. It was hypothesized that ASH test performance would positively correlate with fastball velocity.
METHODS The study was cross-sectional in nature and examined healthy male baseball pitchers recruited from local collegiate and high school baseball programs including those that had made a successful return to competition following previous injury. Testing took place within three weeks of the anticipated start of the season, or following completion of a competitive baseball season such that subjects were acclimated to throwing regularly. Seven of the subjects were left hand dominant while the remaining were right hand dominant. Six of the subjects were high school players and the remaining were Division-II collegiate pitchers. Informed consent (or parental consent with subject assent for those younger than 18 years old) was obtained for all subjects prior to their participation in the study. The Sanford Health Institutional Review Board approved the study and the rights of all subjects were protected. Data collection consisted of two sessions. First, subjects arrived for a clinical assessment where anthropometrics, past injury history, shoulder strength, and shoulder range of motion (ROM) data were collected. Prior to ROM and strength testing, all subjects warmed up for five minutes on an upper body ergometer at a self-selected pace. Passive shoulder external and internal rotation ROM was then assessed bilaterally using the scapular stabilization method previously described in detail by Wilk et al.13 A trained researcher moved the subject’s shoulder through either internal or external rotation until the end range was determined and recorded by a second researcher using a goniometer. Two measurements were taken for each motion and the average of the two was used for analysis. If the two measurements differed by greater than 10%, a third measurement was taken and the average of the three was used for analysis. Next, isokinetic and isometric shoulder strength was measured. Isokinetic strength was assessed using an isokinetic dynamometer (Biodex, Mirion Technologies, Shirley, NY) with subjects seated upright with 90° of shoulder abduction and 90° of elbow flexion in the scapular plane as described previously.14 Internal and external rotation strength were measured concentrically at speeds of 90, 180,
and 270°/s and eccentrically at 90°/s for each arm with five reps per speed. The initial testing arm was chosen randomly and subjects were allowed a warmup set to familiarize themselves with the protocol (Figure 1). Peak torque normalized to bodyweight was collected for each test condition. Peak torque has been found to be reliable when isokinetically measured for shoulder internal and external rotation.15 The strength test battery (isokinetic or isometric) was assigned randomly with at least three minutes of rest between the two protocols. Isometric shoulder strength was measured bilaterally using the ASH test. Testing was performed as described by Ashworth et al.8 with subjects prone on the floor at a predetermined level of shoulder abduction and palm of the hand resting on a force plate. In addition to the three “I, Y, T” test positions used, a fourth position of 0° shoulder abduction was used where the subjects’ hand was resting by their side. For each test position, subjects were asked to push into a portable force plate (Bertec Inc., Columbus, OH) with as much force as possible for three seconds. This was repeated for three trials at each test position with 30 seconds of rest between each trial (Figure 2). Verbal encouragement was provided for each trial and force data was collected at 1000 Hz. Peak force was extracted for each trial, normalized to bodyweight, and averaged across the three trials for analysis. Approximately one week later, subjects returned for a bullpen session in a biomechanics laboratory. No subjects had played a game or been injured between testing sessions. The lab setup consisted of an artificial mound 13.7 meters (45 feet) from a simulated strike zone. The strike zone was positioned to account for the shortened throwing distance. Subjects were allowed to complete their own warmup process consisting of static and dynamic stretching, light throwing of baseballs and weighted balls, and pitches off a mound. Once subjects indicated they were ready to throw with maximum effort, ten fastballs were thrown at the strike zone. Pitch speed was recorded using a radar gun (Stalker Pro II, Stalker Sports Radar, Plano, TX) and the five fastest pitches thrown for strikes were averaged and used for analysis. All data analysis was performed in MATLAB (Version 2021a, Mathworks, Natick, MA). Shoulder strength and ROM results were compared for bilateral differences using paired t-tests. Additionally, the relationship between ASH test performance and fastball velocity was assessed using Pearson correlation (α = 0.05).
RESULTS Thirty-five male pitchers participated in this study. Ball velocity and subject anthropometrics can be found in Table 1. Means and standard deviations for passive shoulder ROM data can be found in Table 2. Subjects exhibited significantly greater external rotation (ER) ROM and significantly less internal rotation (IR) ROM on the dominant arm compared to the non-dominant arm (p < 0.001 for each). There was not a significant difference in total ROM bilaterally between arms (p = 0.16). Multiple significant differences were observed in isokinetic strength bilaterally (Table 3). Subjects produced sig-
International Journal of Sports Physical Therapy
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers
Table 1. Subject demographics (mean ± SD) Age (years)
19.7 ± 1.8
Height (cm)
187.0 ± 9.7
Mass (kg)
89.6 ± 15.3
Fastball Velocity (m/s | mph )
36.3 ± 3.3 | 81.1 ± 7.4
Dominant Arm
28 Right; 7 Left
Injury History* (n)
4
*Denotes subjects had a previous shoulder or elbow injury that required surgery.
Table 2. Shoulder passive range of motion, reported in degrees (mean ± SD) ROM (°) ER
D
ND
p-value
126.6 ± 11.5
116.7 ± 13.4
< 0.001
IR
44.9 ± 14.1
58.5 ± 15.5
< 0.001
Total
171.8 ± 15.2
175.2 ± 18.0
0.16
D; Dominant arm, ND; Non-Dominant arm, ER; External Rotation, IR; Internal Rotation.
Table 3. Isokinetic shoulder strength, reported as peak torque in N-m/kg (mean ± SD) Test Speed (°/s)
Concentric
Eccentric
External Rotation
Internal Rotation
External Rotation
Internal Rotation
D
ND
D
ND
D
ND
D
ND
90
0.43 ± 0.12
0.43 ± 0.11
0.72 ± 0.20
0.65 ± 0.17
0.46 ± 0.15
0.39 ± 0.12
0.90 ± 0.22
0.83 ± 0.21
180
0.37 ± 0.11
0.35 ± 0.11
0.61 ± 0.16
0.56 ± 0.17
-
-
-
-
270
0.31 ± 0.11
0.28 ± 0.11
0.55 ± 0.18
0.47 ± 0.16
-
-
-
-
D; Dominant arm, ND; Non-Dominant arm. Bolded values indicate respective D-ND pair showed statistically significant difference (p < 0.05).
Table 4. Isometric shoulder strength, reported force in % bodyweight (mean ± SD) Abduction Angle (°)
D
ND
p-value
0
13.0 ± 2.5
12.4 ± 2.9
0.06
90
12.0 ± 2.8
11.0 ± 2.4
<0.001
135
12.9 ± 3.0
11.9 ± 2.4
0.001
180
15.2 ± 3.6
14.6 ± 3.6
0.21
D; Dominant arm, ND; Non-Dominant arm. Bold values indicate respective D-ND pair showed statistically significant difference (p < 0.05).
nificantly greater peak torque when measuring both the external and internal rotators eccentrically in the dominant arm compared to the non-dominant arm (p = 0.002 and p = 0.004, respectively). The internal rotators of the dominant arm also produced significantly greater peak torque concentrically compared to the non-dominant arm at all three speeds tested (p < 0.05 for all). Additionally, the dominant arm external rotators produced significantly greater peak torque concentrically compared to the non-dominant arm at the 270°/s test speed (p < 0.05). Isometric peak force measured by the ASH test was not significantly different bilaterally for two of the four abduc-
tion positions (Table 4). Subjects produced significantly greater peak force at the “T” (90° abduction) and “Y” (135° abduction) test positions on the dominant arm compared to the non-dominant (p < 0.001 and p = 0.001, respectively). Peak force production during the ASH test for the throwing arm was not statistically significantly related to fastball velocity (Table 5).
DISCUSSION The purpose of this study was to collect data on healthy baseball pitchers performing the ASH test, in both the dom-
International Journal of Sports Physical Therapy
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers
Table 5. Linear relationships between ASH test and fastball velocity
Fastball Velocity
0°
90°
135°
180°
r
0.05
0.10
0.04
0.08
p-value
0.76
0.56
0.80
0.63
Results reported for dominant arm only.
Figure 1. Isokinetic testing protocol followed for each participant.
Figure 2. Athletic Shoulder test protocol followed for each participant.
inant and non-dominant arms. Other relevant and frequently used measures of shoulder strength and function are presented in addition to ASH test results to provide a comparison to commonly used clinical assessments. The results of this study support the initial hypothesis that pitchers would perform significantly better on the ASH test with the dominant arm compared to the non-dominant arm. The ASH test was not found to be a good predictor of fastball velocity for pitchers in this study, rejecting the secondary hypothesis. Many of the additional findings support those previously reported; with pitchers exhibiting greater external rotation and limited internal rotation on the throwing arm as well as increased concentric internal rotator strength and eccentric external rotator strength compared to the nondominant arm.14,16–19 Pitchers in this study exhibited significant differences bilaterally in passive shoulder ROM for internal and external rotation. This coincides with previous findings in baseball pitchers where the dominant arm undergoes an adaptation of increased external rotation and decreased internal rota-
tion.20–22 Pitchers in this study had an ER increase of 9.9° and an IR decrease of 13.5° on average in the throwing arm compared to the contralateral side, demonstrating lack of significant overall loss of ROM. These findings are comparable to previous studies where it has been found that the ER-IR increase-decrease relationship is near equal.20,21 In this study, ten of the players (28.6%) had differences of <5° for ER bilaterally. A prospective study by Wilk et al.23 found that professional pitchers without a difference in shoulder ER on the throwing arm of at least 5° greater than the non-throwing arm were at 2.2 times greater risk of upper extremity injury. While the athletes in this study were not of professional caliber, it is likely that the findings from Wilk et al. may translate to high school and collegiate players. Thus, the ten players with differences of <5° for ER bilaterally may be at higher risk of injury. Future prospective research in non-professional athletes assessing preseason and intra-season ROM is imperative for further clarification and appropriate risk-profiling.
International Journal of Sports Physical Therapy
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers
Multiple significant differences were observed bilaterally in isokinetic strength measurements. Specifically, pitchers demonstrated significantly greater eccentric external rotator peak torque as well as significantly greater concentric internal rotator peak torque at all three testing speeds on the dominant arm compared to the non-dominant (Table 3). Pitchers also exhibited significantly greater concentric external rotator strength at the fastest test speed. These findings support those previously reported that OH athletes develop significant rotator cuff strength differences bilaterally for both the internal and external rotators.14,17,24 Interestingly, the current findings contradict previous findings of reduced external rotator strength,14 as pitchers presented with an increase in eccentric and concentric ER strength. The differences in level of play of the athletes in this study may be a possible explanation for these findings. Adaptations to the glenohumeral joint complex are likely progressive as the throwing athlete ages and may be more pronounced in professional athletes compared to the population in this study. However, this study provides benchmark data for high school and collegiate athletes and could be easily expanded and repeated in the professional population to evaluate normative data in that population. Specific to the ASH test, pitchers demonstrated significantly greater isometric strength at 90° and 135° of shoulder abduction on the dominant arm compared to the nondominant. This could be a result of the angle of shoulder abduction at which pitchers commonly throw, between 80 and 110+ degrees.25 The throwing shoulder horizontal adductors are likely stronger in these positions through adaptations acquired by pitching. This novel outcome demonstrates that the ASH test is capable of detecting bilateral strength differences in baseball pitchers presenting with musculoskeletal adaptations common to overhead athletes. Only one other study has used the ASH test to examine shoulder strength in throwing athletes and found no significant differences bilaterally.9 Potential explanations for the conflicting results may lie in the positioning utilized for the modified version of the ASH test and from player types. Biaggi et al.9 examined subjects in supine positioning rather than prone as the ASH test is typically performed and included players from all fielding positions, rather than pitchers alone. This study utilized pitchers only and the prone position for the purpose of isolation of shoulder strength in dedicated OH throwing-specific athletes. The findings of the current study warrant future research using the ASH test and the prone position to examine shoulder strength in OH athletes from other sports such as tennis and handball to determine if similar trends exist in these populations. Mean peak force for both arms was ≥11% bodyweight for all positions tested in the ASH test. Only two participants (5.7%) in the 0° and 135° abduction positions and three participants (8.6%) in the 90° position produced less than 9% peak force normalized to bodyweight. While the sample size of this study is not large enough to establish normative ASH test values for baseball pitchers at all levels (e.g. professional and youth), the data presented here provides a good basis for assessing adolescent and college pitchers. These findings could be utilized by clinicians as a preseason screening tool to monitor shoulder health or as a rehabilitation guideline when determining progress in in-
jured baseball pitchers. The benefits of including this test as part of a battery of tests to determine shoulder function and strength include the high reliability, validity of force plates, and opportunities to explore additional isometric force-time variables such as impulse and rate of force development in an isolated, controlled setting with low risk for further injury or instability during testing. Future research should be done to determine the clinical relevance of the ASH test and its relationship with other tests of upper extremity function such that clinicians can be confident that the test adds value and clarity to the complex process that is rehabilitation of shoulder injuries, which currently lacks reliable and objective methods for determining return to play appropriateness. This study is not without limitations. First, the current ASH test protocol requires the use of a force plate, limiting the usability when one is not available. Future studies may investigate the feasibility of more cost-effective options such as a handheld dynamometer for administering the ASH test. The cohort tested for this study consisted of high school and collegiate athletes. This limits the generalizability of the findings to populations outside of the one studied such as youth and professional. Although significant differences were discovered in the ASH test bilaterally, there has been no study which has examined ASH test performance and outcomes in injured OH athletes. Therefore, the ASH test may be more useful as a pre-season and post-injury benchmark for recovery following injury, or as a baseline for healthy players to determine adequate rest between throwing outings, and the results should be taken into appropriate context. Examining the effects that rehabilitation has on ASH test performance at multiple time points during recovery from injury/surgery is also critical to understand the true relevance of the test. Furthermore, players with specific injuries and surgeries should be investigated, as anatomic and functional deficit varies with differing injury patterns which may be reflected in ASH test data. Nonetheless, the current study presents intriguing results regarding value and utility of the ASH test.
CONCLUSION This study presents the strength and ROM profile for a group of healthy collegiate and high school pitchers in which ASH data had not previously been reported. Pitchers in this study produced significantly greater peak force at the 90° and 135° abduction positions, which are similar to the position of the shoulder when throwing a baseball. These findings are in agreement with the adaptations commonly observed in pitchers in which shoulder ROM and strength are altered to favor the throwing motion. While these results may be intriguing for clinical use, caution should be taken when using peak force from the ASH test as a means of predicting fastball velocity in pitchers.
International Journal of Sports Physical Therapy
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers
ACKNOWLEDGMENTS
DISCLOSURES
The authors would like to thank Zadok Isaacs, Jason Thompson, and Cody Reed for their help in the data collection process.
The authors have no financial or conflicts of interest to disclose. This study was approved by the Sanford Health Institutional Review Board.
FUNDING
This research was internally funded by Sanford Health.
Submitted: December 01, 2021 CDT, Accepted: April 09, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers
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11. Sauers EL, Huxel Bliven KC, Johnson MP, Falsone S, Walters S. Hip and glenohumeral rotational range of motion in healthy professional baseball pitchers and position players. Am J Sports Med. 2014;42(2):430-436. doi:10.1177/0363546513508537 12. Borsa PA, Wilk KE, Jacobson JA, et al. Correlation of range of motion and glenohumeral translation in professional baseball pitchers. Am J Sports Med. 2005;33(9):1392-1399. doi:10.1177/036354650427349 0 13. Wilk KE, Reinold MM, Macrina LC, et al. Glenohumeral internal rotation measurements differ depending on stabilization techniques. Sports Health. 2009;1(2):131-136. doi:10.1177/1941738108331201 14. Wilk KE, Andrews JR, Arrigo CA, Keirns MA, Erber DJ. The strength characteristics of internal and external rotator muscles in professional baseball pitchers. Am J Sports Med. 1993;21(1):61-66. doi:10.1 177/036354659302100111 15. Perrin DH. Reliability of isokinetic measures. J Athl Train. 1986;21(4):319-321. 16. Ellenbecker TS, Davies GJ, Rowinski MJ. Concentric versus eccentric isokinetic strengthening of the rotator cuff: objective data versus functional test. Am J Sports Med. 1988;16(1):64-69. doi:10.1177/ 036354658801600112 17. Ellenbecker TS, Mattalino AJ. Concentric isokinetic shoulder internal and external rotation strength in professional baseball pitchers. J Orthop Sports Phys Ther. 1997;25(5):323-328. doi:10.2519/jos pt.1997.25.5.323 18. Alderink GJ, Kuck DJ. lsokinetic shoulder strength of high school and college-aged pitchers. J Orthop Sports Phys Ther. 1986;7(4):163-172. doi:10.2519/josp t.1986.7.4.163 19. Hurd WJ, Kaufman KR. Glenohumeral rotational motion and strength and baseball pitching biomechanics. J Athl Train. 2012;47(3):247-256. doi:1 0.4085/1062-6050-47.3.10 20. Crockett HC, Gross LB, Wilk KE, et al. Osseous adaptation and range of motion at the glenohumeral joint in professional baseball pitchers. Am J Sports Med. 2002;30(1):20-26. doi:10.1177/03635465020300 011701
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Athletic Shoulder Test Differences Exist Bilaterally in Healthy Pitchers
21. Meister K, Day T, Horodyski M, Kaminski TW, Wasik MP, Tillman S. Rotational motion changes in the glenohumeral joint of the adolescent/Little League baseball player. Am J Sports Med. 2005;33(5):693-698. doi:10.1177/0363546504269936
24. Noffal GJ. Isokinetic eccentric-to-concentric strength ratios of the shoulder rotator muscles in throwers and nonthrowers. Am J Sports Med. 2003;31(4):537-541. doi:10.1177/03635465030310041 001
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International Journal of Sports Physical Therapy
da Silva LG, Ferrer RM, de Souza JR, Gracitelli MEC, Secchi LLB. Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report. IJSPT. 2022;17(4):724-731.
Case Reports
Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report Lucas Gomes da Silva 1 , Rafael Marques Ferrer 2 , José Roberto de Souza Jr. 3 , Mauro E.C. Gracitelli 4 , a Leonardo Luiz Barretti Secchi 5 1
Physical Therapy Department, Centro Universitário Sudoeste Paulista (UNIFSP) – Campus Itapetininga – Itapetininga – Brazil;, 2 Brazilian National Society of Sports Physical Therapy (SONAFE-Brazil) – São Paulo – Brazil;, 3 Sciences and Technologies in Health Post-Graduation Program, University of Brasília (UNB), 4 Institute of Orthopedics and Traumatology, School of Medicine,, University of São Paulo – São Paulo – Brazil, 5 Physical Therapy Department, Federal University of São Carlos (UFSCar) – Post-Graduate Program in Physical Therapy – Laboratory of Analysis and Intervention of the Shoulder Complex – São Carlos - Brazil., Federal University of São Carlos (UFSCar) Keywords: Crossfit®, Pectoralis major rupture, Physical Therapy https://doi.org/10.26603/001c.35720
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
Background and Purpose The upper limbs are frequently injured during CrossFit® practice, and in some cases, surgical repair is recommended. The purpose of this case report was to describe the rehabilitation process performed after the surgical repair of a pectoralis major rupture in a CrossFit® practitioner.
Design Case report.
Case Description The subject was a 26-year-old man, with 1.75m and 69kg, who practiced CrossFit® for five years and sustained the injury during the execution of the ring dip. The rehabilitation protocol was of 16 weeks duration. Passive modalities and exercises focusing on range of motion, muscle strength, and CrossFit®-specific movements were performed. Shoulder range of motion was assessed through goniometry, and muscle strength was assessed through isometric dynamometry.
Outcomes At week seven the subject had full range of motion, and at week fourteen achieved limb symmetry (Limb Symmetry Index - 84.78 – Abduction; 97.58 – Adduction; 86.15 – Internal Rotation; 85.06 – External Rotation) in muscle strength. The subject returned to his previous level of athletic activities. Conclusions: A 16-week protocol performed with exercises focusing on range of motion, muscle strength, and CrossFit®-specific movements was abe to promote the return to sport at the pre-injury level in a CrossFit® practitioner.
INTRODUCTION CrossFit® is an activity with increasing numbers of participants that offers benefits in terms of VO2 max, body composition, strength, endurance, and mental health.1 The prevalence of musculoskeletal injuries in CrossFit® practitioners ranges from 12.8 – 73.5%, while the incidence rates reported in previous studies ranges between 0.2 and 18.9 in-
a
juries per 1000 hours of training.2 Despite the belief that CrossFit® is a sport that causes a high number of injuries due to the high-intensity exercise, it presents similar injury rates compared to other recreational activities.1 The shoulder (26%), spine (24%), and the knee (18%) are the most commonly injured sites.1,2 In general, most of the injured CrossFit® athletes return to sport in few weeks, however, in 8.7% of injured practitioners a surgical procedure was required, most commonly at the knee joint.2 Injuries occur
Corresponding author: Leonardo Luiz Barretti Secchi – Physical Therapy Department –Centro Universitário Sudoeste Paulista (UNIFSP) – Itapetininga Campus – José de Almeida Carvalho’s Street, 1695 – Leonor Village ZIP CODE: 18200-021 - Itapetininga - SP - Brazil – leobfisio@gmail.com - +5515981198265.
Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report
most commonly in novice athletes and are related to different weightlifting movements, such as deadlift, snatch, clean and jerk, squat, and overhead press.3–5 The shoulder was the most affected location for injury identified in a previous systematic review.2 Muscle injuries were frequent, and often related to a previous injury or inadequate technique.6,7 The most commonly involved muscles were the deltoid, trapezius, and scapular muscles.7 Despite the prevalence of muscle injuries in CrossFit®, no report regarding pectoralis major injury in CrossFit® practitioners was found in the literature. The pectoralis major is commonly injured in sports such as snowboarding,8 football, and weightlifting.9 Injury to the pectoralis major region is related to highintensity and external overload and occurs usually in men in sports involving abduction and external rotation of the glenohumeral joint.10 The treatment of choice is a surgical repair performed within eight weeks; the surgical technique chosen considers the physician’s proficiency and preference,11 and generally offers a good prognosis.12 After surgical repair of the pectoralis major, positive outcomes include significant pain relief and improved aesthetic appearance; the return to sport occurs in roughly six months.13 Information about the rehabilitation process after a pectoralis major injury and subsequent surgical repair in CrossFit® practitioners is potentially important considering the number of athletes participating in the sport, the complex nature of this injury, and the lack of information in the literature about the rehabilitation process. Therefore, the purpose of this case report was to describe the rehabilitation process performed after the surgical repair of a pectoralis major rupture in a CrossFit® practitioner.
STUDY DESIGN This case report was carried out according to the recommendations of CARE (Case Report Guidelines), which was developed to provide accuracy and transparency in the publication of case reports.14 CASE DESCRIPTION
The subject of this case report, E.P.G was a 26-year-old man, (1.75m and 69kg), who had participated in CrossFit® for five years. As part of his training, the athlete performed the ring dip with five series of six movements, the first without additional weight, and the later series with 10 kg, 20 kg, 30 kg, and 40kg respectively. The weights were added using two vests and two bags. (Figure 1). During the eccentric phase of the last series the patient reported feeling a “click”, as well as the feeling that the left pectoralis major was “tearing apart”. Subsequently he also reported stiffness and loss of movement in the left shoulder complex. A Magnetic Resonance Image (MRI) was performed and verified a complete rupture of the sternal portion of the left pectoralis major tendon (non-dominant arm), with retraction of 5 cm of the tendinous stump, signs of edema, as well as stretching of the clavicular portion (Figure 2). A surgical approach was chosen considering the potential benefits regarding the rate of return to sport when compared to conservative treatment.15
OUTCOMES SURGICAL TREATMENT
A direct repair of the tendon in the humerus using two unicortical buttons and two high-resistance tape wires was used via a deltopectoral approach.16 REHABILITATION PROGRAM
Recent systematic reviews have synthesized the literature regarding pectoralis major ruptures occurring during sports and with subsequent surgical repairs.9,13 Pectoralis major injuries are rare and the studies included in the systematic reviews present with low methodologic quality, lack of clear injury description, diversity of reported outcomes, and poorly described rehabilitation processes.9,13 Seven studies in these reviews recommended passive shoulder range of motion within four to six weeks after surgery, followed by isometric exercises, and progressive increases in resistance training after six months. In addition, full activity was allowed within six months.13 The rehabilitation protocol described in this case report was constructed considering the current literature available in relation to a pectoralis major rupture followed by surgical repair. The experience of the therapist regarding the sport was used to inform the rehabilitation process. No studies have been published that discuss pectoralis major tendon repair strain properties; the amount of stress this tissue can tolerate in the post-surgical is not fully understood.17 Therefore, exercise prescription is dependent on the tissue healing process and individual functional readiness in all stages; this process is based on clinical impression.17 CrossFit® is a sport that allows the adaptation of the exercises considering the three major usual gestures (gymnastic; LPO; catabolic). Thus, it was performed a weekly progression of the exercises following the recommendations to protect the surgery (Table 1). The subject used an arm sling for 30 days in medial rotation position for pain control and protection of the surgical intervention. The rehabilitation program began three weeks after surgery and was performed three times a week for two weeks, and two times a week until the end of rehabilitation at week 16. Each session lasted for 60 to 70 minutes. There were post-operative restrictions until week four regarding stretching and strengthening exercises, for that reason, the protocol focused initially on preventing deformities/contractures of the joint capsule and biceps brachialis, coracobrachialis and subscapular muscles. Also, one important goal was to improve mobility of the scar. Passive range of motion began in post-op weeks three and four, and muscle strength, proprioception, and return to sport was the focus of weeks five to sixteen. The full protocol is presented in Appendix 1.
OUTCOMES The subject achieved full active shoulder extension, internal rotation and external rotation on the affected side in week six, and full shoulder flexion and abduction in week seven (Table 1).
International Journal of Sports Physical Therapy
Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report
Table 1. Shoulder range of motion from week two to seven ROM (°) Flexion
Week 2
Week 4
Week 5
Week 6
Week 7
I
NI
I
NI
I
NI
I
NI
I
NI
80
180
138
180
145
180
155
180
180
180
Extension
8
35
25
35
28
35
35
35
35
35
Abduction
35
180
90
180
100
180
110
180
180
180
Internal R
40
55
50
55
50
55
55
55
55
55
External R
12
55
50
55
50
55
55
55
55
55
Legend: ROM= Range of Motion; I= Injured side; NI= Non-injured side; Internal R= Internal Rotation; External R= External Rotation; * Week 3 was not assessed.
Figure 1. Ring Dip movement – Sagital plane (A and B) Frontal Plane (C and D)
Figure 2. Magnetic Resonance Imaging (T2 frontal plane) showing the rupture (blue arrows) of the left pectoralis major tendon with substantial tendon retraction and an associated hematoma.
Muscle strength assessed using model microFET2; Hoggan Health Industries Inc, West Jordan, UT demonstrated asymmetry in week seven in the groups evaluated, however, this asymmetry was not present in week fourteen. At that
time, the subject presented with relative symmetry in shoulder abduction (LSI ≅ 84.78), adduction (LSI ≅ 97.58), internal (LSI ≅ 86.15), and external rotation (LSI ≅ 85.06)
International Journal of Sports Physical Therapy
Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report
Table 2. Shoulder muscle strength in week’s seven and fourteen Week 7
Week 14
I
NI
LSI
I
NI
LSI
Abduction
8.5
19.8
42.9
19.5
23.0
84.78
Adduction
7.9
11.8
66.9
12.1
12.4
97,58
Internal R
-
-
-
22.4
26.0
86,15
External R
9.1
11.4
79.82
18.8
22.1
85,06
Abduction/Adduction
0.92
0.59
-
0.62
0.53
-
External R/Internal R
-
-
-
0.83
0.85
-
Isometric strength (N/Kg)
Agonist/Antagonist Ratio (%)
Legend: I= Injured side; NI= Non-injured side; Internal R= Internal Rotation; External R= External Rotation; LSI= Limb Symmetry Index (injured/non-injured x 100); *Internal rotation was not assessed in week seven considering the safety of the surgical procedure
strength. Also, muscle balance was assessed using the agonist (abductors): antagonist (adductors) ratio (Table 2). After sixteen weeks of postoperative treatment the subject was able to return to all athletic activities related to CrossFit® without range of motion or strength deficits. The practitioner showed no limitation or fear to return to practicing any movement of the sport (including the ring dip) due to the progressive load applied and the safety adopted during the rehabilitation. The patient adhered to the protocol and followed the recommendations inside the box and at home.
DISCUSSION The subject of this case report was a 26-year-old male that had been performing daily and systematic CrossFit® training for five years. He did not use anabolic steroids. The subjects age is within the range of CrossFit® practitioners (20-40 years) described in previous studies.18 Also, males are more likely to sustain an injury than females.19 The success experienced by this athlete with the provided protocol is important considering that the pectoralis major is essential to strenuous activities.8 The results of this case report are similar to two previous case reports that described a post-op protocol for a pectoralis major rupture in a male snowboarding athlete and in a soldier of the US army.8,20 Those protocols had duration of sixteen8 and twenty-four weeks,20 and similar to the one used in the current case report, were performed to control pain, avoid adherence formation, gain range of motion, restore muscle power, and to return to daily activities/sport. In both cases, the participant had full active and passive range of motion, muscle power symmetry according to isometric dynamometry and returned to his previous level of athletic activities at the end of the treatment.8,20 Ninety percent of CrossFit® practitioners that have had an upper limb surgical procedure returned to sport,12 and several authors have shown the benefits of the surgical management for pectoralis major injuries.18,21,22 In fact, surgical treatment of a complete tendon tear has been consistently superior to non-surgical options, particularly in young individuals.8,17 Thus, the choice for the surgical treatment followed by the rehabilitation protocol executed
was chosen for the injury presented by the athlete. CrossFit® practitioners commonly present with a high degree of intrinsic motivation, enjoyment of the challenges associated with the sport, and athletic affiliation23 which together contribute to the adherence and maintenance of this activity. Together, these factors may be considered to have been associated with the success of the rehabilitation of the subject of this case report. Regarding injury mechanism, the subject of this case was injured during the eccentric phase of the Ring Dip that consists of elbow extension with shoulder adduction (with an external load of 40 kg). In prior case reports, the snowboarding athlete injured during a forced abduction with external rotation, and the soldier sustained the injury during the concentric portion of a bench press (external load of 143 kg).8,20 In all cases, an audible sound, pain, loss of movement, and weakness of the affected side was experienced. These results suggest that a pectoralis major injury likely occurs when the muscle is under maximum contraction on the demand of the specific exercises with external overload. . In addition, history of previous injuries, lack of coach supervision, the experience on CrossFit®, and the participation in competitions may be related to the etiology of injury.2 Isolated injuries in the proximal region of the upper limbs with indication for surgical treatment related to participation in CrossFit® may be increasingly seen in clinical practice, as the number of CrossFit® practitioners has grown substantially in the past several years. There are reports in the literature of latissimus dorsi injury, stress fracture of the humeral head, and isolated rhabdomyolysis of the infraspinatus muscle in CrossFit® athletes.24–26 To the authors knowledge, this is the first case report regarding a rehabilitation protocol after the pectoralis major rupture with subsequent surgical repair in a CrossFit practitioner. The main strength of this case report was the medical team as the surgeons and physiotherapists involved had experience in the treatment of CrossFit® injuries. Also, the short time between the surgery and the beginning of the rehabilitation protocol must be highlighted as a factor for good prognosis. Finally, the adherence of the subject to the intervention proposed by the medical team is a factor that
International Journal of Sports Physical Therapy
Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report
should be considered when evaluating the success of the protocol. The limitations must be highlighted. As is typical with case reports (without a comparison subject or group), the results herein can only be described for this subject and are not considered transferrable to other subjects. This case report assessed the program’s impact on the shoulder range of motion and muscle strength. However, the return to daily activities/sport was assessed only qualitatively and not through a patient-reported outcome or scale.
tioners, the results of this case report indicate that a protocol focused on range of motion, muscle strength, and sports-specific movements is effective to promote the return to athletic activities. Future studies are necessary to evaluate the effectiveness of this type of protocol in different high-level and recreational CrossFit®.
CONFLICTS OF INTEREST
The authors report no conflicts of interest.
CONCLUSION The results of this case report indicate that a Crossfit® practitioner can be successfully returned to sport after surgical repair of the pectoralis major. While isolated injuries of the pectoralis major have a rare occurrence in Crossfit® practi-
Submitted: October 19, 2021 CDT, Accepted: April 09, 2022 CDT
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International Journal of Sports Physical Therapy
Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report
REFERENCES 1. Meyer J, Morrison J, Zuniga J. The benefits and risks of CrossFit: A systematic review. Workplace Health Saf. 2017;65(12):612-618. doi:10.1177/216507991668 5568 2. Rodríguez MÁ, García-Calleja P, Terrados N, Crespo I, Del Valle M, Olmedillas H. Injury in CrossFit®: A Systematic Review of Epidemiology and Risk Factors. Phys Sportsmed; 2021. 3. Alekseyev K, John A, Malek A, et al. Identifying the most common CrossFit injuries in a variety of athletes. Rehabil Process Outcome. 2020;9:1179572719897069. doi:10.1177/11795727198 97069 4. Moran S, Booker H, Staines J, Williams S. Rates and risk factors of injury in CrossFitTM: A prospective cohort study. J Sports Med Phys Fitness. 2017;57(9):1147-1153. doi:10.23736/s0022-4707.16.0 6827-4 5. Elkin JL, Kammerman JS, Kunselman AR, Gallo RA. Likelihood of injury and medical care between CrossFit and traditional weightlifting participants. Orthop J Sports Med. 2019;7(5):232596711984334. do i:10.1177/2325967119843348 6. Aune KT, Powers JM. Injuries in an extreme conditioning program. Sports Health. 2017;9(1):52-58. doi:10.1177/1941738116674895 7. Toledo R, Dias MR, Souza D, et al. Joint and muscle injuries in men and women CrossFit® training participants. Phys Sportsmed. 2021;1-7. doi:10.1080/0 0913847.2021.1892468 8. Vasiliadis AV, Lampridis V, Georgiannos D, Bisbinas IG. Rehabilitation exercise program after surgical treatment of pectoralis major rupture. A case report. Phys Ther Sport. 2016;20:32-39. doi:10.1016/j.ptsp.20 16.05.001 9. Bodendorfer BM, Wang DX, McCormick BP, et al. Treatment of pectoralis major tendon tears: A systematic review and meta-analysis of repair timing and fixation methods. Am J Sports Med. 2020;48(13):3376-3385. doi:10.1177/03635465209044 02 10. Bak K, Cameron EA, Henderson IJ. Rupture of the pectoralis major: A meta-analysis of 112 cases. Knee Surg Sports Traumatol Arthrosc. 2000;8(2):113-119. do i:10.1007/s001670050197
11. Gupton M, Johnson JE. Surgical treatment of pectoralis major muscle ruptures: A systematic review and meta-analysis. Orthop J Sports Med. 2019;7(2):2325967118824551. doi:10.1177/232596711 8824551 12. Carbone S, Candela V, Gumina S. High rate of return to CrossFit training after arthroscopic management of rotator cuff tear. Orthop J Sports Med. 2020;8(4):232596712091103. doi:10.1177/2325967120 911039 13. Yu J, Zhang C, Horner N, et al. Outcomes and return to sport after pectoralis major tendon repair: A systematic review. Sports Health. 2019;11(2):134-141. doi:10.1177/1941738118818060 14. Gagnier JJ, Kienle G, Altman DG, et al. The CARE guidelines: Consensus-based clinical case report guideline development. J Diet Suppl. 2013;10(4):381-390. doi:10.3109/19390211.2013.8306 79 15. Cohen M, Abdalla R. Lesões nos Esportes. 1st ed. São Paulo: Revinter; 2003. 16. Sanchez A, Ferrari MB, Frangiamore SJ, Sanchez G, Kruckeberg BM, Provencher MT. Pectoralis major repair with unicortical button fixation and suture tape. Arthrosc Tech. 2017;6(3):e729-e735. doi:10.101 6/j.eats.2017.02.002 17. Manske RC, Prohaska D. Pectoralis major tendon repair post surgical rehabilitation. N Am J Sports Phys Ther. 2007;2(1):22-33. 18. He ZM, Ao YF, Wang JQ, Hu YL, Yin Y. Twelve cases of the pectoralis major muscle tendon rupture with surgical treatment-an average of 6.7-year followup. Chin Med J (Engl). 2010;123(1):57-60. 19. Weisenthal BM, Beck CA, Maloney MD, DeHaven KE, Giordano BD. Injury rate and patterns among CrossFit athletes. Orthop J Sports Med. 2014;2(4):2325967114531177. doi:10.1177/232596711 4531177 20. Hoppes CW, Ross MD, Moore JH. Undetected pectoralis major tendon rupture in a patient referred to a physical therapist in a combat environment: Acase report. Phys Ther. 2013;93(9):1225-1233. doi:1 0.2522/ptj.20120141 21. Provencher MT, Ryu R. Failed arthroscopic shoulder surgery. Sports Med Arthrosc Rev. 2010;18(3):129. doi:10.1097/jsa.0b013e3181eb6d02
International Journal of Sports Physical Therapy
Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report
22. Shepard NP, Westrick RB, Owens BD, Johnson MR. Bony avulsion injury of the pectoralis major in a 19 year-old male judo athlete: a case report. Int J Sports Phys Ther. 2013;8(6):862-870. 23. Dominski FH, Serafim TT, Siqueira TC, Andrade A. Psychological variables of CrossFit participants: a systematic review. Sport Sci Health. 2021;17(1):21-41. doi:10.1007/s11332-020-00685-9
25. Routman HD, Triplet JJ, Kurowicki J, Singh N. Isolated rhabdomyolysis of the infraspinatus muscle following the CrossFit “Sissy test”: A report of two cases. JBJS Case Connect. 2018;8(1):e2. doi:10.2106/jbj s.cc.17.00020 26. Godoy IRB, Malavolta EA, Lundberg JS, da Silva JJ, Skaf A. Humeral stress fracture in a female CrossFit athlete: A case report. BMC Musculoskelet Disord. 2019;20(1):150. doi:10.1186/s12891-019-2674-1
24. Friedman MV, Stensby JD, Hillen TJ, Demertzis JL, Keener JD. Traumatic tear of the latissimus dorsi myotendinous junction: Case report of a CrossFitrelated injury. Sports Health. 2015;7(6):548-552. doi:1 0.1177/1941738115595975
International Journal of Sports Physical Therapy
Rehabilitation After Surgical Treatment of Pectoralis Major Rupture in a CrossFit® Practitioner: A Case Report
SUPPLEMENTARY MATERIALS Appendix 1 Download: https://ijspt.scholasticahq.com/article/35720-rehabilitation-after-surgical-treatment-of-pectoralis-majorrupture-in-a-crossfit-practitioner-a-case-report/attachment/90307.docx?auth_token=GYytLOqgcMnYT7IYpNPN
International Journal of Sports Physical Therapy
Dietz Z, DeWeese D, Shaw N, et al. Stride Length and Torso Biomechanics As They Relate To Medial Elbow Injuries In Adolescent Aged Baseball pitchers: A Clinical Commentary. IJSPT. 2022;17(4):732-737.
Clinical Commentary/Current Concept Review
Stride Length and Torso Biomechanics As They Relate To Medial Elbow Injuries In Adolescent Aged Baseball pitchers: A Clinical Commentary a
Zachary Dietz 1, Dylan DeWeese 1, Neil Shaw 1, Cody Huth 1, Jacob Ball 1, Victoria Reeves 1, Ryan Monti 1 , Ryan Bitzel 1 1
Walsh University
Keywords: collateral ligaments, pitcher, injury, baseball, adolescent https://doi.org/10.26603/001c.35258
International Journal of Sports Physical Therapy Vol. 17, Issue 4, 2022
There is a limited amount of literature examining torso biomechanics and stride length while addressing their relationship to medial elbow injuries in the adolescent baseball pitcher. Anatomical changes, growth, early sport specialization, multiple team participation, mound distance, mound height, and high pitch counts place adolescent pitchers at an exceptionally higher risk for medial elbow injuries. Existing evidence indicates that decreased stride length and altered trunk rotation is correlated with increased medial elbow loading for the adolescent overhead athlete. Further research is required to quantify adequate parameters for torso kinematics, control, and their correlation to stride length, in order to positively affect the biomechanical transfer of energy and potentially prevent injuries during the overhead throwing motion. The purpose of this clinical commentary is to examine and summarize the role of torso biomechanics and stride length in relation to medial elbow injuries in adolescent baseball pitchers.
Level of Evidence 5
INTRODUCTION As competitiveness increases from youth to high school baseball, so do external pressures, expectations, and physical demands. Adolescent pitchers in particular experience a tremendous increase in volume of overhead throwing as age and level of play increase. Zaremski et al. suggest that adolescent pitchers throw an average of 119 pitches per game, including the warm-up, bullpen activity, and in-game pitches.1 Additionally, improving velocity and throwing a variety of different pitches normally become a higher priority in adolescence and beyond. These factors, along with anatomical changes, growth, early sport specialization, participation on multiple teams, mound distance, mound height, and high pitch counts place adolescent pitchers at an exceptionally higher risk for medial elbow injuries. Utilizing proper throwing mechanics, specifically torso rotation and stride length, is one way to minimize this risk without compromising performance. The purpose of this clinical
a
Corresponding author: Ryan Monti, PT, DPT, SCS Walsh University 2020 East Maple St North Canton, Ohio 44720 RyanMontiPT@gmail.com
commentary is to examine and summarize the role of torso biomechanics and stride length in relation to medial elbow injuries in adolescent baseball pitchers. Currently, there is a limited amount of literature connecting torso biomechanics and stride length while addressing their relationship to medial elbow injuries in the adolescent baseball pitcher population. ELBOW FORCES WITH OVERHEAD PITCHING
A valgus moment at the elbow consists of a medially directed load, which is greatest during the cocking phase of the pitching motion when the shoulder is abducted and externally rotated. This valgus moment is counteracted by the muscle-tendon units crossing the medial elbow, creating a varus moment during the late cocking phase. As the arm internally rotates through the late cocking phase, at velocities up to 7,500 degrees per second, torque is produced, which places tension on the ulnar collateral ligament and com-
Stride Length and Torso Biomechanics As They Relate To Medial Elbow Injuries In Adolescent Aged Baseball pitchers: A...
pression at the radiocapitellar joint.2 Pitchers with upper extremity range of motion deficits may compensate from other areas of the body, which could lead to injury. Current literature regarding biomechanical analysis of torso rotation also states that a decrease in synergistic control of torso musculature during the pitch leads to an increased varus moment on the elbow, placing higher torque upon the upper extremity.3–7 Therefore, prior literature has shown how optimizing torso biokinematic control through hip and shoulder separation can aid in increasing pitch velocity.8 In the author’s opinion, this information could be extrapolated to lower the probability of medial elbow injuries. OVERVIEW OF THE PITCH CYCLE
Table 1. Risk Factors and Likelihood of Upper Extremity Injury23 Risk Factors
Likelihood of Significant Upper Extremity Injury
Pitching faster than 85 mph
2.5x
Throwing >80 pitches/game
3.8x
Throwing >8 months/year
5x
Pitching fatigued
36x
Mph= miles per hour
To best describe and evaluate biomechanical control, the process of throwing a pitch needs to be broken down and defined. The baseball pitch utilizes all aspects of the kinetic chain where each segment receives elastic potential energy from the previous segment. The segments follow the summation principle, in which energy is transferred when the subsequent segment begins rotating as the prior segment has reached maximal angular velocity. Stability and neuromuscular control from the lower extremities, lumbopelvic structures, and core musculature are essential to optimize the effects of the summation principle.9 This stability establishes a platform for the upper extremities to receive energy and generate velocity.9 The overhead pitch is routinely broken down into sequential phases related to the generation and transfer of potential and kinetic energy. After initiation of the pitch cycle, the conversion of potential energy into kinetic energy occurs during the stride phase as the pitcher steps toward home plate.10 The completion of the stride phase is seen as the lead foot makes contact with the ground, the throwing arm reaches its initial point of cocking, and is followed by the initiation of pelvic rotation towards the batter.11–13 As the hips rotate towards home plate, the upper quarter continues into its cocking phase producing lower quarter and upper torso dissociation.3,14,15 This separation aids with achieving maximal shoulder external rotation during the later portion of the cocking phase and creating a pre-stretch to abdominal musculature to eventually aid with energy transfer. Improper timing, lack of segment separation, or loss of energy transfer into the acceleration phase could be a critical point for the necessity of compensatory upper extremity energy generation.10 The acceleration phase follows, as the summation of energy is transferred into shoulder internal rotation and to the point of ball release. As baseball players age, there are natural changes in pitching mechanics that occur due to a combination of experience, confidence, coaching, and growth. As pitchers mature, there are consistent adaptive changes that occur related to natural physical development as well as related to throwing. These changes include throwing shoulder internal and external rotation range of motion, increased segmental trunk separation, increased stride length, and a decrease in stride forefoot angle.8,15–17 Additionally, this natural physical development is accompanied by kinetic changes producing a resultant increase in velocity and el-
bow torque.8,12 All of these changes could pose a risk for elbow associated injuries for the developing athlete. INFLUENCE OF TRUNK ROTATION ON RISK OF INJURY
Chaudhari et al. have suggested that inappropriate trunk rotational timing when pitching has been associated with injury.9 Error in timing of trunk rotation correlates with increased demand on the upper extremity, which could lead to a medial elbow injury.10,18,19 The lack of synchronization between trunk rotational timing and stride limits the amount of energy transfer from the trunk to the upper extremity. Loss of rotational range of motion could be the main factor of injury. Previous authors indicate that fatigue and pitching velocity are the best predictive factors of medial elbow injury, which was the driving factor for USA Baseball and Little League Baseball, Inc to implement agebased guidelines for pitch-count maximums and required rest times.4,6,20–22 The question remains: Are pitch-count regulations enough to prevent throwing related injuries in the adolescent population? Other modifiable factors could further aid in reducing overuse injuries. Pitch-counts do not consider the individual kinematics of the pitcher, the transfer of energy through the kinetic chain, the volume a pitcher throws per year, or how fatigue influences the biomechanics of the pitch. Olsen et al. suggest the following modifiable risk factors and suggest that they are related to the predisposition of adolescent pitchers to medial elbow injury: inadequate pitch counts, pitch velocity greater than 85 miles per hour, throwing more than eight months in the year, and throwing through fatigue all exponentially increase risk of injury (Table 1).23 In addition, this clinical commentary presents considerations regarding the kinematic chain that predispose the baseball pitcher to medial elbow injury. Optimizing safe kinematics could ultimately aid with injury prevention and provide a positive effect towards an athlete’s baseball career. Although several factors change from adolescence to young adulthood, studies aiming to identify how pitching mechanics affect elbow loading and velocity are consistent across various ages. As one would expect, velocity, demands, and torque continue to increase with age, but these variables’ relationship with mechanics does not fluctuate.24 For this reason, the biomechanics regarding the pitch cycle are often applied across different age demographics. Previous research has displayed a link between trunk rotation
International Journal of Sports Physical Therapy
Stride Length and Torso Biomechanics As They Relate To Medial Elbow Injuries In Adolescent Aged Baseball pitchers: A...
and internal elbow varus moment in college-aged athletes.25 Cohen et al. have shown that increased trunk rotation away from the throwing hand correlates with a more significant increase in varus force than in velocity.25 Furthermore, early rotation of the trunk has been found to cause alterations in shoulder positioning for pitchers between the ages of 9 through 18.26 There is no evidence to support an ideal amount of rotation to balance the risk and benefit, but there is support for excess trunk rotation being harmful. INFLUENCES OF STRIDE LENGTH ON RISK OF INJURY
Previous authors have utilized a focused approach to pelvic and torso rotation as a power generator for the overhead athlete.25,27 Research falls short when comparing stride length abnormalities to upper extremity injuries in the adolescent population. Stride length, as defined by Ramsey et al. is the horizontal distance between the location of the drive-foot calcaneus at peak knee-height and the calcaneus of the contralateral foot at ground contact.28 This is a highly modifiable aspect of pitching mechanics that has been found to impact various body segments along the kinetic chain during the pitching motion, including forces experienced at the shoulder and elbow.29 Prior authors have reported a desired stride length (DSL) among highly skilled and proficient pitchers aged 17-21, ranging from 80-87% of body height, but DSL has been reported to be as low as 66% of body height in less experienced middle school and adolescent aged athletes. Pitchers that exhibit a shorter stride length decrease potential force development throughout the kinetic chain due to a reduced trunk rotation moment.19 Exceeding stride length norms can cause increased physiologic demands on the body; however, are associated with decreased stress to the upper extremity, potentially due to the increased total body momentum towards the plate that occurs with overstriding.28 Current evidence indicates that exceeding or failing to meet an optimal stride length can potentially lead to increased fatigue, kinematic compensations, and upper extremity injuries.28–30 Finally, it is important to note that Sgori et al. have determined that a 10% increase in stride length and its relationship to increased pitch velocity are a natural sign of physical growth and development.8 The pitch cycle is a sequence of events where multiple segments of the body are interconnected through the kinetic chain.18 Efficiency of movement is based on their interdependence to transfer momentum from the ground to the upper body.18 As stride length nears foot contact, highly efficient pitchers will demonstrate a closed foot angle. Closed foot angle is defined as the forefoot being angled toward the thrower’s arm (Figure 1). Overhead athletes who demonstrate excessive closed foot angle upon stride foot contact cause their arm to be ahead of the rotating shoulder during the late cocking phase, leading to a closed front hip, throwing across their body, and lack of efficient force transfer from the pelvis to the upper extremity.22 If the forefoot angle becomes more open toward the glove side, undesirable anterior translational stress can be produced at the shoulder.22 This could be due to early pelvic rotation or altered trunk separation from the upper extremity.10,24
Figure 1. Stride Leg Positioning C = stride foot offset, θ = forefoot angle, - - - = neutral/neither open nor closed
Figure 2. Internal Trunk Rotation Angle at Ball Release Adapted from Cohen et al25
Anterior translated force at the shoulder combined with maximal external rotation range of motion during the latecocking phase produces increased valgus loading at the elbow, increasing the risk for elbow injuries.22 In contrast, pitchers that demonstrated more of a closed angle at stride foot contact did not present with increased valgus loading at the elbow.22 Another aspect related to stride foot angle is stride foot offset, the horizontal distance between the center of the lead ankle and center of the trailing ankle (Figure 1). An excessive stride foot offset angle, known as “opening up” (Figure 1), can disrupt the timing and efficiency of torso rotation, transfer of energy up the kinetic chain, causing increased humeral internal rotation torque, and as a con-
International Journal of Sports Physical Therapy
Stride Length and Torso Biomechanics As They Relate To Medial Elbow Injuries In Adolescent Aged Baseball pitchers: A...
Table 2. Pitch Cycle Biomechanical Nodes for the Adolescent Baseball Pitcher Biomechanical Node
Normative Mechanical Values
Forefoot Position
Slightly closed 9 y/o 23 º (+3) as one ages to 15 y/o 14 º (+ 4) 15
Stride Length
66% of body height (SD 7.1%) pitchers 9-14 y/o 33 Each year of age associated with a 10% increase in stride length8
Stride Foot Offset
9 y/o 2 +2 cm open as one ages to 15 y/o 18 +3 cm closed 15
Trunk Separation (Axial rotation of upper trunk relative to the pelvis)
9 y/o 23 º (+2) as one ages to 15 y/o 42 º (+3) 15
Internal Trunk Rotation at BR (Throwing arm side towards home plate; Figure 2)
8-13.5 y/o 25 º (+9)13 (Compared to 18-24.8 y/o 23 º (+8); for every additional 10º increased elbow stress)25
Single-Limb Support (Dominant leg = same side as throwing arm)
10.2 sec (SD 5.9)33
y/o = years old, SD = standard deviation, BR = ball release, sec = seconds
sequence could lead to valgus load at the medial elbow.10,18,22,24 Stride foot offset, a component that has not been widely researched, plays a pivotal role in force generation for the overhead athlete. EXAMINATION AND EVALUATION OF THE PITCH CYCLE
Examination and evaluation can be used to quantify the range of motion, balance, and physical performance capabilities needed to complete the pitch cycle and provide further insight into clinical judgement for correction. This can be accomplished through standard anthropometric measurements and biomechanical analysis. A current concept being explored includes the impact of drive leg hip internal rotation range of motion and its impact on trunk rotation.31,32 Further research is needed to quantify the optimal range of hip internal rotation that is specifically needed for the adolescent baseball player. However, some evidence supports the examination of bilateral hip flexion and internal rotation range of motion due to its resultant influence on elbow injury.31 Prior authors have described a relationship between pitching skill level and lower extremity function as it is related to lower extremity power and singlelimb balance.33 Additional physical performance metrics for lower extremity power, such as the double-leg vertical jump, have shown a moderate correlation to stride length in the younger baseball athlete.33 To provide thorough analysis of the pitch cycle, it is advisable to utilize video analysis software that can reduce body motion velocity and capture segmental change.6,34 Additionally, various kinematic values based on age can be utilized to capture lower extremity and trunk positioning (Table 2). Correction of any deficits found can be addressed using therapeutic exercise and education, such as stretching and balance training.35 This could also include methods of motor learning, such as constraints
led approach or differential learning, to coordinate patterns of movement and explore solutions for movement error.36
CONCLUSION Existing evidence indicates that altered stride foot positioning and trunk rotation is correlated with increased demand on the upper extremity.8,10,18,24,33 Inefficiency throughout the kinetic chain leads to compensation from the upper extremity and increases the tensile forces at the medial elbow. The forces traveling through the kinetic chain lose momentum, leading to the increased demand of the upper extremity to maintain adequate force production. Over time, the increased forces placed upon the throwing arm may lead to overuse injuries in the medial elbow. Current evidence also indicates that optimal stride length changes according to the age and growth/maturation of the pitcher.8 Optimal torso rotation has not yet been quantified, but problems with early and late rotation have been identified. Both biomechanical components likely impede the transfer of energy throughout the kinetic chain, and compensatory motion transpires. Additional research should be conducted to specifically evaluate the correlation between torso biomechanics and stride length, quantify adequate torso kinematic parameters, as well as their collective effects on elbow injuries in the adolescent population
CONFLICT OF INTEREST
There are no conflicts of interest to disclose. Submitted: April 24, 2021 CDT, Accepted: February 18, 2022 CDT
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CCBY-NC-4.0). View this license’s legal deed at https://creativecommons.org/licenses/by-nc/4.0 and legal code at https://creativecommons.org/licenses/by-nc/4.0/legalcode for more information.
International Journal of Sports Physical Therapy
Stride Length and Torso Biomechanics As They Relate To Medial Elbow Injuries In Adolescent Aged Baseball pitchers: A...
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International Journal of Sports Physical Therapy
Stride Length and Torso Biomechanics As They Relate To Medial Elbow Injuries In Adolescent Aged Baseball pitchers: A...
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International Journal of Sports Physical Therapy
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