LCRG Research Brief | Protecting the Female Athlete: Concussions, ACL Injuries and Nutrition by Laurel School

CENTER FOR RESEARCH ON GIRLS

athletics A SERIES OF RESEARCH AND INFORMATIONAL PUBLICATIONS BY LCRG

“Putting the world’s best research to work for girls.”

by Tori S. Cordiano, Ph.D. and Lisa Damour, Ph.D.

PROTECTING THE FEMALE ATHLETE: RESEARCH ON CONCUSSIONS, ACL INJURIES AND NUTRITION Participation in athletics contributes to health but can, for girls, pose some special challenges. GIRLS AND CONCUSSIONS Girls show higher rates of concussion than boys participating in the same sports Research consistently indicates that girls experience more concussions than boys in similar sports, including soccer1 and basketball2, though the rates at which they differ vary. Researchers define concussion as a change in brain functioning following a force to the head3. Diagnosis and treatment of concussion is complicated by the fact that symptoms are often subtle and difficult to detect, can be non-specific to concussion and might not present immediately following the injury4. Though young children do not show significant sex differences in their rates of concussion, severity of symptoms or recovery time, sex differences in these areas begin to emerge around puberty5. In addition to longer general recovery time from concussion, female athletes also show poorer visual memory6 and greater declines in simple and complex reaction times following concussion and more subjective and objective concussion effects7. Research has begun to explore factors that may contribute to these differential effects of concussion.

athletics:

PROTECTING THE FEMALE ATHLETE: RESEARCH ON CONCUSSIONS, ACL INJURIES AND NUTRITION

What accounts for sex differences in concussion? While the research in this area is still developing, researchers have identified certain factors that likely contribute to sex differences in concussion. These include: • Anatomical differences, including structure of the neck and blood flow in the brain, may increase female athletes’ susceptibility to concussion and help explain differences in symptom severity and recovery time8. • Hormones likely play a role, though their impact is difficult to study due to fluctuations during females’ menstrual cycles. Research into the effect of hormones on concussion is in the preliminary stage9. GIRLS AND ACL INJURIES Girls are more likely than boys to rupture an ACL The ACL stabilizes the knee and connects the femur to the tibia. Devastating injuries to the anterior cruciate ligament (ACL) can occur while playing sports – such as soccer and basketball – that require cutting, rapid deceleration and jumping. Girls are at least three times as likely10 as boys to sustain non-contact ACL injuries.

Several factors contribute to girls’ vulnerability to ACL injuries Research11 suggests several factors may make girls more prone to ACL injuries than boys. First, girls generally show decreased neuromuscular control, such as relying on quadriceps muscles rather than hamstring muscles during movements like pivoting, landing and stopping12,13. Second, girls tend to show greater hamstring flexibility during and after puberty, while boys’ hamstring flexibility declines during that same developmental period14. Increased hamstring flexibility can lead to decreased dynamic control of the knee, and weaker hamstring muscles can affect the coactivation of hamstring and quadriceps muscles necessary for protecting the knee during movement. Finally, anatomical differences related to the angle at which the tibia meets the femur increase girls’ susceptibility15 to ACL injuries. Particularly during puberty, as growth spurts lead to a changing center of mass and challenged muscular control, anatomical differences become a factor in girls’ ACL injuries.

Preventing ACL injuries in female athletes Neuromuscular training programs that condition girls to use specific muscle groups to stabilize their knees have been found to reduce ACL injuries in female athletes16,17. These programs help to reduce strain on the ACL by improving girls’ balance and strength18 and by teaching girls the biomechanics19 of movements that will protect their knees. Research suggests that beginning these interventions during early adolescence may provide the most benefit for injury prevention20.

NUTRITION FOR FEMALE ATHLETES How much should young female athletes eat? Athletes need enough calories and nutrients to support critical biological processes, daily living activities and exercise training. Commonly, sports nutrition assesses an athlete’s energy availability (EA), which is the “amount of the individual’s energy intake that is available for other body processes and functions, once the energy cost of sporting activity has been subtracted21.” Chronic low EA can cause delayed puberty, menstrual irregularities, bone damage, shortness of stature and increased risk of injury22. Energy intake beyond the athlete’s need can result in weight gain and obesity and increase the risk of injury in young athletes23. The specific caloric demands needed to maintain adequate EA vary across young female athletes and depend on metabolic rate, training volume, training intensity and the shifting nutritional demands of pubertal development24.

What should young female athletes eat?25 Carbohydrates maintain energy during exercise and replace energy stores after exercise • Protein provides the basic elements that build and repair tissue • Dietary Fats provide energy and essential fatty acids and help the body absorb fat-soluble vitamins • Vitamins and Minerals support energy production, bone strength, immune function, cellular repair and muscle restoration and development. Key vitamins and minerals (listed below) may be low in the diets of female athletes, especially those who restrict energy intake or avoid meat, fish, poultry and dairy products. • B-vitamins aid energy production and cellular repair • Vitamin D supports bone health, muscle function and boosts the immune system • Calcium is essential to building and repairing bone tissue, maintaining bone mineral density and preventing stress fractures • Iron helps deliver oxygen throughout the body and is key to the enzymes involved in energy production • Zinc supports growth, muscle health and energy production. •

The Female Athlete Triad26 The Female Athlete Triad is a term used to refer to three interrelated health problems sometimes seen in female athletes: low energy availability, menstrual disturbances and impaired bone health. The loss of bone mass is especially concerning during girls’ peak bone-building years which begin during puberty. Low energy availability (EA) can result from restricting calories or from having a decreased appetite due to following a high fiber diet or engaging in high intensity exercise. In addition to being associated with abnormal menstruation, increased risk for stress fractures and poor bone health, low EA also links to hormonal disruptions and impaired immune functioning.

PROTECTING THE FEMALE ATHLETE: RESEARCH ON CONCUSSIONS, ACL INJURIES AND NUTRITION

Gessell, L.M., et al. (2007). Concussions among United States high school and collegiate athletes. Journal of Athletic Training, 42, 495-503.

Frommer, L.J., et al. (2011). Sex differences in concussion symptoms of high school athletes. Journal of Athletic Training, 46, 76-84.

Myer, G.D., Ford, K.R., Palumbo, J.P. & Hewett, T.E. (2005). Neuromuscular training improves performance and lower-extremity biomechanics in female athletes. Journal of Strength and Conditioning Research, 19, 51-60.

Carney, N., et al. (2014). Concussion guidelines step 1: Systematic review of prevalent indicators. Neurosurgery, 75, S3-S15.

[endnotes]

Griffin, L.Y. et al. (2006). Understanding and preventing noncontact anterior cruciate ligament injuries. The American Journal of Sports Medicine, 34, 1512-1532.

Mandelbaum, B.R. et al. (2005). Effectiveness of a neuromuscular and proprioceptive training program in preventing anterior cruciate ligament injuries in female athletes: 2-year follow-up. The American Journal of Sports Medicine, 33, 1003-1010.

National Collegiate Athletic Association (2014). Guideline 21: Sport-Related Concussion. In 2014-2015 NCAA Sports Medicine Handbook (pp. 56-64).

Myer, G.D., Sugimoto, D., Thomas, S. & Hewett, T.E. (2014). The influence of age on the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: A meta-analysis. The American Journal of Sports Medicine, 41, 203-215.

Roehr, B. (2016, March 9). Concussions affect women more adversely than men. Scientific American: Neurological Health.

Covassin, T., Elbin, R.J., Harris, W., Parker, T. & Kontos, A. (2012). The role of age and sex in symptoms, neurocognitive performance, and postural stability in athletes after concussion. American Journal of Sports Medicine, 40, 1303-1312.

Broshek, D.K., et al. (2005). Sex differences in outcome following sports-related concussion. Journal of Neurosurgery, 102, 856-863.

Roehr, B. (2016, March 9).

Wunderle, K., Hoeger, K.M., Wasserman, E. & Bazarian, J.J. (2014). Menstrual phase as a predictor of outcome after mild traumatic brain injury in women. Journal of Head Trauma Rehabilitation, 29, E1-E8.

Desbrow, B. et al. (2014). Sports dietitians Australia position statement: Sports nutrition for the adolescent athlete. International Journal of Sport Nutrition and Exercise Metabolism, 24, 570-584, p. 572.

Bass, S., & Inge, K. (2010). Nutrition for special populations: Children and young athletes. In L.M. Burke & V. Deakin (Eds.), Clinical sports nutrition (4th ed., pp. 508– 546). Sydney: McGraw Hill.

Prodromos, C.C., Han, Y., Rogowski, J., Joyce, B. & Shi, K. (2007). A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthroscopy, 23, 1320-1325.

McHugh, M. (2009). Oversized young athletes: A weighty concern. British Journal of Sports Medicine, 44, 45-49.

Petrie, H.J., Stover, E.A. & Horswill, C.A. (2004). Nutritional concerns for the child and adolescent competitor. Nutrition, 20, 620-631.

American College of Sports Medicine, American Dietetic Association & Dieticians of Canada (2000). Joint position statement: Nutrition and Athletic Performance. Medicine & Science in Sports & Exercise, 32, 2130-2145.

Silver, H.J. & Mandelbaum, B.R. (2007). Prevention of anterior cruciate ligament injury in the female athlete. British Journal of Sports Medicine, 41, i52-i59.

Nattiv, A. et al. (2007). The female athlete triad. Medicine & Science in Sports & Exercise, 39, 1867-1882.

Hewett, T.E. & Myer, G.D. (2005). Reducing knee and anterior cruciate ligament injuries among female athletes. The Journal of Knee Surgery, 18, 82-88.

Myer, G.D., Ford, K.R., McLean, S.G. & Hewett, T.E. (2006). The effects of plyometric versus dynamic stabilization and balance training on lower extremity biomechanics. The American Journal of Sports Medicine, 34, 445-455.

Hewett, T.E., Myer, G.D. & Ford, K.R. (2006). Anterior cruciate ligament injuries in female athletes: Part 1, mechanisms and risk factors. The American Journal of Sports Medicine, 34, 299-311.

Hewett et al. (2006).

Griffin, L.Y. et al. (2000). Noncontact Anterior Cruciate Ligament Injuries: Risk Factors and Prevention Strategies. Journal of the American Academy of Orthopaedic Surgeons, 8, 141-150.

American Academy of Pediatrics (September, 2016). State Advocacy Focus: Concussion Management: Return to Play. Retrieved from https://www.aap.org/en-us/advocacyand-policy/state-advocacy/Documents/Concussion.pdf Noyes, F.R. & Barber-Westin, S. (2012). ACL injuries in the female athlete: Causes, impacts, and conditioning programs. New York: Springer Heidelberg. LaBella, C.R., Hennrikus, W. & Hewett, T.E. (2014). Anterior cruciate ligament injuries: Diagnosis, treatment, and prevention. Pediatrics, 133, e1437-e1450.

Castle, J. (2015). Eat like a champion: Performance nutrition for your young athlete. New York: American Management Association.

CENTER FOR RESEARCH ON GIRLS Putting the world’s best research to work for girls.

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athletics: PROTECTING THE FEMALE ATHLETE: RESEARCH ON CONCUSSIONS, ACL INJURIES AND NUTRITION

RESOURCES FOR PARENTS, COACHES AND ATHLETES Resources

State Advocacy

CONCUSSION MANAGEMENT: RETURN TO PLAY27

Concussion Management: Return to Play

This fact sheet, produced by the American Academy of Pediatrics, provides information,

Sports-related concussions in youth athletes are underreported. Coaches, parents, and teachers often fail to recognize the signs of concussions in young athletes.

OVERVIEW

AAP guidelines and helpful links for additional guidance. https://www.aap.org/en-us/advocacy-and-policy/state-advocacy/Documents/Concussion.pdf

This book provides helpful information to guide training techniques toward reducing and preventing ACL injuries in female athletes.

AAP POSITION

ACL INJURIES IN THE FEMALE ATHLETE28

Proper management of concussions, including cognitive and physical rest, is imperative to ensure that the student athlete does not suffer long-lasting effects of injury. A coalition of physicians organizations including AAP chapters, athletic trainers, youth sports associations, and professional sports teams have led efforts to pass state laws requiring coaches, teachers, and athletic trainers to have training in the identification of concussion in youth athletes and athletes suspected of concussion to be cleared for play by the child or adolescent athlete's pediatrician and medical team prior to returning to the field.

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Coaches and athletic trainers should be trained in the identification of concussions, and refer any student athlete suspected of sustaining a concussion to a licensed physician, such as a pediatrician, neurologist, primary care sports medicine specialist, or neurosurgeon with expanded knowledge and experience in pediatric concussion management for evaluation.

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Pediatricians and other physicians can be an important resource in educating coaches, athletic trainers, and other adults that work with young athletes in recognizing the signs of concussion injuries and when to seek medical attention for their athletes.

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A team approach consisting of the child or adolescent athlete’s pediatrician and medical team, the school team, and the family team to assist the student in his or her return to learning is ideal.

ANTERIOR CRUCIATE LIGAMENT INJURIES: DIAGNOSIS, TREATMENT, AND PREVENTION29

Division of State Government Affairs | stgov@aap.org | www.aap.org/stateadvocacy

This clinical report, provided by the American Academy of Pediatrics, provides accessible, up-to-date information for parents regarding ACL injuries in children and teens. http://pediatrics.aappublications.org/content/133/5/e1437

EAT LIKE A CHAMPION: PERFORMANCE NUTRITION FOR YOUR YOUNG ATHLETE30 This research-driven, practical book addresses the nutritional needs of athletes aged eight through eighteen.

FIND A NUTRITIONIST The “Find an Expert” section of the Academy of Nutritionist and Dietetics website lists Registered Dietician Nutritionists by location and area of expertise. www.eatright.org

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