USEMS SIXTH EDITION - DANCE MEDICINE
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Motion and stability in the dancer’s hip - How much is too much? An article by Joshua D. Harris,
Injury rates in dance and the relationship between load and injury in professional ballet dancers An article by Nick Allen
What is the place of Profiling at the Royal Ballet School? An article by Karen Sheriff
Editors’ Note I was a medical student when I first encountered the subspecialty of Dance Medicine. Former England Men’s football team physician, Dr Ian Beasley, spoke with great enthusiasm about the clinical challenges of working with professional dancers in his role as Medical Advisor to the Royal Ballet. He explored key issues around managing overuse injuries, vitamin D deficiency and relative energy deficiency in sport. More recently, I’ve heard Darren Burgess, Director of High Performance at Arsenal, describe with wonder and amazement the athleticism of Cirque Du Soleil performers. To paraphrase Burgess; “We have this impression that to be strong you have to go to the gym all the time… spending time with the members of Cirque Du Soleil gave me a completely different perspective”. Seeing how animated two practitioners, who are more accustomed to working with some of the planet’s best footballers, become when discussing the impressive athleticism of those in the performing arts is very telling. With that in mind, I am delighted to dedicate the 6th edition of the USEMS eMagazine to furthering the specialty of Dance Medicine. This wouldn’t have been possible without the leadership of Dr Amal Hassan, Guest Editor for this edition, who has helped to bring together a number of experts to write about pertinent issues within the specialty. We hope that the topics covered are interesting and inspiring, and we’d appreciate if you could share this edition far and wide. Finally, this will be Fadi, Steff and I’s last contribution to the USEMS eMagazine. The first specks of grey have appeared in my hair and the slow recede to baldness has accelerated, making it increasingly difficult to justify my association with a student-led magazine. When we started this resource back in 2015, we never expected to receive such positive feedback – it has been one of the most rewarding aspects of my journey in sports medicine to date. We look forward to seeing the eMagazine go from strength to strength under new leadership.
Dr Sean Carmody (Co-Editor) Dr Fadi Hassan (Co-Editor) Dr Steffan Griffin (Co-Editor) Dr Amal Hassan (Guest Editor, 6th Edition)
MOTION AND STABILITY IN THE DANCER’S HIP – HOW MUCH IS TOO MUCH? JOSHUA D. HARRIS, MD HOUSTON METHODIST ORTHOPEDICS & SPORTS MEDICINE, OUTPATIENT CENTER, 6445 MAIN STREET, SUITE 2500, HOUSTON, TX 77030; JOSHUAHARRISMD@GMAIL.COM; 713-441-8393 (OFFICE PHONE); 713-790-5134 (OFFICE FAX). The global impact of dance and dance medicine has bridged the worlds of art, sport, and science. Ballet dancers are artistic athletes that require a high degree of technical skill, strength, balance, and stability – all while making it look effortless, beautiful, elegant, and graceful. The demands on the body of the ballet dancer are very real – with both acute and chronic injuries being highly prevalent. Our group in Houston has taken a keen interest in the health of the dancer, in an attempt to not only treat injuries when they occur, but also prevent them from occurring in the first place. Ballet poses a unique set of challenges in a perspective of injury evaluation and management. In a large study of over 2,000 amateur and professional dancers, we recently showed that the vast majority of injuries in ballet dancers involve the lower extremity (frequently the hip and groin) and/or spine (66% to 91%).1 In addition, nearly threequarters (64% to 75%) are due to overuse. Within the realm of dance, ballet requires significant flexibility without causing pain. Higher degrees of range of motion are advantageous, unless they cause symptoms. This is the delicate balance between laxity (excessive motion without symptoms) and instability (excessive motion with symptoms). Across the spectrum of hip stability, a new concept has emerged over the past decade, “microinstability”. The hip is a deep, constrained, spherical
round ball-and-socket joint that was previously considered highly stable. So, hip instability was limited to dislocations: rare events that occurred from high-energy trauma such as that in motor vehicle collisions, falls from great heights, among other dramatic injury mechanisms. When we investigated the bony and soft tissue structures that could account for hip instability (or microinstability), there are several dozen reported, and a few previously unreported, reasons that play a role.2 In a round ball-and-socket joint like the hip, the ball should mostly rotate around a fixed centre of rotation. When that centre of rotation moves (biomechanically defined as translation, not rotation), the ball “slides” around in the socket – this is instability. When the ball (femoral head) comes completely out of the socket (acetabulum), that is a dislocation. Microinstability occurs on a much smaller scale of the latter. Dancers with microinstability typically complain of pain with dancing, and symptoms of instability – apprehension, fear of the hip “popping”, “giving out”, “snapping”, “giving way”, “buckling”, “shifting”, or “feeling loose” or “unstable”. Previous work in the dancers’ hip has shown that translations do frequently occur in ballet, where the femoral head slides in the acetabulum, potentially giving rise to microinstability.3-5 Our group identified similar magnitude and frequency of translation in both male and female hips.6 Interestingly, and contrary to our experience in 3
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USEMS - DANCE MEDICINE
Houston, the previous studies showed that the hips were normally shaped – in other words, round ball-and-socket without evidence of femoroacetabular impingement (FAI) and/or dysplasia. In looking exclusively at plain radiographs (“x-rays”) in our dancers, 32% had evidence of the cam type of FAI (aspherical femur), with a higher rate of cam shape in males (57%) than females (12%).7 Further, the prevalence of dysplasia (a three-dimensionally complex acetabular socket-side “shallowness” that may lead to hip instability) was quite high – 89% of dancers had at least one hip with at least mild dysplasia. In Houston, and across the world, clinicians that care for dancers “treat the patient, and not the x-ray”. Thus, despite the high prevalence of radiographic abnormalities does not necessarily equate to symptoms. In fact, dysplasia may be helpful as motion may be increased with greater degrees of hip flexion, abduction, and external rotation, a combination absolutely necessary for adequate turnout. FAI is, simply put, mechanically speaking, a premature conflict between femur and acetabulum. In the presence of symptoms due to this mechanical conflict (cam for the femur, pincer for the acetabulum), the term “FAI Syndrome” has been recently coined by the Warwick Agreement. 8 Thus, not all dancers identified with cam and/or pincer shape have symptoms (FAI Syndrome). This was true in our Houston cohort. However, this brings up the most salient point in the investigation of any person, patient, dancer, athlete with hip and/or groin pain. The primary symptom of FAI Syndrome is motion-related or position-related hip, groin, back, buttock, and/or thigh pain. By nature of the participation in ballet (or any activity that involves high degrees of hip motion – gymnastics, yoga, figure skating, mixed martial arts, pilates, certain high-intensity interval training, among others), many dancers demonstrate obligatory impingement in order to achieve the motion necessary to perform certain positions, poses, holds, maneuvers, jumps, etc. The typical clinical signs of patients with FAI Syndrome include physical exam maneuvers that involve deep flexion and rotation that reproduce the patient’s symptoms. Thus, in the setting of abnormal (like those in the Houston cohort) or normal (like those in the Swiss cohort) radiographs, if a dancer complains of symptoms with variable combinations of flexion and rotation, then FAI Syndrome (defined as the
triad of symptoms, clinical signs, and radiographs) (and/or dysplasia) is high on the differential diagnosis. Several investigations have shown that FAI may cause instability.9-11 The mechanical conflict in the ball-andsocket (“square peg in a round hole”) may lead to a levering effect in the hip joint that causes instability on the side opposite the impingement. If impinging in the front of the hip (anterior), then instability may occur in the back (posterior). If impinging on the top outside (superolateral), then instability may occur on the bottom (inferior). If impinging in the back of the hip (posterior), then instability may occur in the front (anterior). Although not 100% definitively known at the current time, it is now well recognised that cam FAI is a primary cause of osteoarthritis of the hip. The mechanism involves the abnormal shape that causes joint articular cartilage and labral cartilage damage which is the sine qua non of the early end of the osteoarthritis spectrum. The cam morphology likely occurs during the adolescent growth spurt (between the ages of 10 and 16 years of age) due to weight-bearing sports participation.12 Is it preventable? No one definitively knows.13 Can it be successfully treated without surgical correction of the shape and joint damage? Yes. 14 This includes a combination of conservative care (education, activity modification that learns to avoid provocative activities) and physical-therapy led rehabilitation (strength, stability, and motion). Surgical treatment may be indicated when non-surgical measures are unable to satisfactorily relieve symptoms that are unacceptable to the patient. Surgery involves fixing the joint damage by repairing the labral tear and correcting the FAI morphology (making the ball and socket round again). So which one is better – surgical or non-surgical treatment? We currently don’t know. There are several randomized studies across the world that are trying to answer that exact question. The next decade of study will reveal the answer – stay tuned!!!
* References available upon request
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LIFE AS A TEAM PHYSICIAN
In Germany and Switzerland there is no dedicated training program In SEM like in the United Kingdom. The program here is called “additional designation of sports medicine”. Pre-requirement for it, is a medical license and a board certification in a different area of patient care e.g. orthopaedic and trauma surgery. In Germany the candidate then additionally has to undertake 240 hours of sports medicine instructions as well as duty in a sports club for 120 hours, or 12 months training in a designated sports medicine centre. For this reason as well as training in orthopaedics and trauma, for the past 2 years I have been team physician of the American football club, Lucerne Lions in Switzerland.
Dr. med. Dr (hu) Henrik Bäcker Dr Henrik Bäcker is a member of the ECOSEP Junior Doctors Committee I am a junior doctor currently enrolled in the specialization program to become an orthopaedic and trauma surgeon at the university hospital Berne. I have a strong interest in Sports and Exercise Medicine and am on the European College of Sports and Exercise Medicine (ECOSEP) Junior Doctors Committee. Having worked in American football, Football, Karate and at marathons outside the UK I thought it might be interesting to tell you more about my experience as a team physician and about the training programme in other parts of Europe!
Before moving to Berne I worked in Lucerne at the department of general surgery where one of our senior consultants asked me to become a team physician. At the beginning I thought this would be great idea and opportunity; however I subsequently came to realise this it is also a great responsibility. My task is to care for all emergency scenarios and try to prevent injuries which may occur during a match or competition. There is always some support from a paramedic, sometimes a physiotherapist or even an on-site ambulance (for marathon or football match).
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On match day, I start my checks well before kick-off. All equipment has to be checked including ambu-bag, emergency medication (cardiac drugs, analgesia and sedatives), spinal immobilisation equipment and surgical emergency kit for small injuries like lacerations. For big events like marathon or football matches a defibrillator is required as well. Luckily, the most commonly needed pieces of equipment are ice packs and cool sprays! The medical team are located along the long side of the pitch and are responsible for both side – Lucerne Lions and the guest team. In American football the most common injuries are joint dislocations (shoulder, fingers and elbows), concussions, ankle/acromioclavicular sprains and rarely fractures (metacarpal bones, ankle, ribs or vertebral bodies). Injuries are indicated by the referee waving his white cap which gives permission for medical staff to enter the pitch. For each injured player we run the emergency trauma protocol of primary survey airway with cervical spine, breathing, circulation, disability and exposure, followed by the secondary survey.
things are common! One of the challenges of pitch side medicine is that diagnostic tools are limited. No ultrasound or x-ray can be performed – so fractures or intraabdominal bleeding cannot be excluded via imaging. Classical assessments like palpation, percussion, auscultation are the most reliable tools. In the two years I have been there only four patients have been admitted to hospital directly – due to concussion and shoulder or elbow dislocation. I work as a team physician in my free time when I am not on duty in the hospital. It is a great responsibility but I really enjoy and love the work. It is completely different from duties in hospital where a whole range of equipment especially diagnostic and treatment tools is available. I encourage everyone who is interested in sports medicine to experience a match as a team physician! In the meantime don’t forget to follow us on Facebook (ECOSEP Junior Doctors Committee)/Twitter (ECOSEP_JDC) and check out our new website for some g re a t t r a i n e e s p e c i fi c co n t e n t + fo r u m www.ecosepjdc.eu
For patients with dyspnoea it is essential to carefully remove the helmet whilst at the same time stabilizing the cervical spine to enable a free airway. Afterwards the Canadian spine and head rule is applied and in cases where there is high suspicion of fracture a stiff neck is utilised and the player is admitted to hospital. As American football is a high traumatic sports we must be aware of severe injuries such as intra-cranial bleeding, vertebral injuries or intraabdominal traumas. Luckily we have not seen anything like this yet however in case of any suspicion we directly admit the individual to the nearest hospital by ambulance. For cases of concussion, the SCAT (sport concussion assessment) tool is used. This test helps monitor each individual player by assessing them at the beginning and end of the American football season and after an incident during a match. This allows individual monitoring of player cognitive state and simplifies the return to sports following concussion. After every match/competition the medical and organising staff meet for a debrief session to discuss recent injuries and treatment plan, helping us to learn from errors and improve care. Being team physician requires a lot of theory and knowledge of common conditions, remember common 6
Can Vitamin D be a panacea or flash in the pan? Dr Julian Widdowson Consultant specialist in Sports and Exercise Medicine Long before the known benefits of sunlight in the synthesis of Vitamin D3 and the prevention of Rickets, the ancient Greeks proposed the benefits of sunlight to improve health. Herodotus was said to have recommended ‘solaria’ as a cure for ‘weak and flabby muscles’ and the Greek Olympians were told to train and then rest in the sun to aid recovery [1].
calcium channels, combine to exert a profound effect on muscle regeneration and strength [4]. Herein, perhaps, lies the reason behind Herodotus’ cure for the ‘weak and flabby muscles’. Vitamin D3 has also been shown to have a multitude of beneficial effects in other systems:
The role of Vitamin D3 in bone health is well documented. It is synthesised in the skin under the influence of UVB forming pre-vitamin D3, which is then quickly converted to vitamin D3 before its hydroxylation in the liver and then kidney to form the active form 1,25-hydroxycholecalciferol. Further recent research has identified the presence of vitamin D receptors (VDR) in many tissues through which the active 1,25-hydroxycholecalciferol exerts its action. VDR have been found not only in bone but also skeletal muscle [2].
• • • • • • •
Action
Innate and acquired immunity [6] Bone health [7] Cardiovascular health [8] Biological processes within skeletal muscle [9] Neuromuscular function [10] Peak performance [11] Soft tissue injury repair [12]
Vitamin D3 deficiency, therefore, has the potential to significantly increase injury risk and delay healing. Vitamin D3 deficiency has been described as a worldwide epidemic with the most common cause being inadequate sunlight, as shown in low levels found in Northern Europeans [3]. However, this is not restricted to cooler climates, deficiency has also been noted in inner city young adults in
The effect of Vitamin D3 on calcium homeostasis is well recognised however, there is also evidence for the genomic and non-geonomic roles of vitamin D3. The genomic effect exhibited by the direct action on muscle regeneration, and the non-genomic response of rapid action on membrane
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the USA, elite gymnasts in Australia and ballet dancers in the UK [16]. Skin colour has also been shown to be a significant variable in ability to absorb UVB. Fairer skin can only be exposed to UVB for a short time before it burns and darker skin require longer exposure to achieve the beneficial absorption [18]. Dietary intake of Vitamin D3 is another factor in determining potential deficiency. Vitamin D3 rich foods include fish oils, cereals, eggs and powdered milk. However, it is unlikely that diet alone will match the vitamin synthesised form sunlight, as highlighted by the Department of Health’s National Diet and Nutrition Survey in 2011, which showed the intake of these foods to be poor in developed countries. In many studies it is accepted that levels of the major circulating form of Vitamin D3 - 25(OH)D - between 50–75 nmol/L represent insufficiency, while levels below 50 and 25 nmol/L represent deficiency and severe deficiency, respectively [5]. Nevertheless, the US Institute of Medicine (IoM) guidelines are:
• • • •
<12 nmol./L severely deficient, 12–<30 nmol./L deficient, 30–50 nmol./L inadequate, >50 nmol/L adequate.
How can levels be improved and what is the optimum level to be beneficial? Many studies have investigated optimum Vitamin D levels. Heaney et al, 2013 found that at serum 25[OH]D concentrations >75 nmol.L patients were healthier [13]. Close et al, 2013 found that serum levels of 80 nmol/L were associated with better calcium absorption efficiency than levels of 50 nmol/L, and that levels of 74 nmol/L were better than 52 nmol/L at lowering risk of fracture [14]. Other authors suggest that serum concentrations needed for other health benefits are > 100 nmol/L [15]. The benefits of Vitamin D supplementation are well recognised in the elderly [17], however there is a paucity of level four studies in young athletes. A non-randomised study of 24 elite classical ballet dancers showed that oral supplementation of Vitamin D3 during winter months significantly improved muscular performance and reduced 8
injury rates over a four month period compared to a control group [16]. The dosage given in this study was 2000IU per day. No serum Vitamin D3 levels were recorded in this study. Other studies have shown the beneficial effects of higher doses of Vitamin D3 supplement. Close et al, 2013 in a small RCT of professional football players showed a significant increase in vitamin D3 levels after an eight-week course of 5000Iu per day compared with controls, with 60% achieving higher levels than 100nmol/L [14]. This study also showed an increase in muscular performance in the treated group compared with controls. Garland et al, 2011 found that in order to achieve the health benefits of preventing cancer, serum levels of over 100nmol/L were required, via a daily dose of 9,600IU [15]. It is therefore possible that optimal Vitamin D intake/ concentration may not be the same for all outcomes and that absorption/metabolism of Vitamin D is likely to differ among individuals. Also individual characteristics (BMI or disease) may further modify circulating levels of Vitamin D. Current recommendations on daily supplementation of vitamin D are largely expert driven, rather than evidence based Is toxicity a risk? In 2011, the US IoM suggested a tolerable upper intake of 4000 IU/day [19], which is in accordance with recent guidance published by the European Food Safety Authority (EFSA, 2012) suggesting a maximum daily dosage <10,000IU [20]. Current recommendations on daily supplementation of Vitamin D are largely expert driven, rather than evidence based. Toxicity is rare potentially occurring at levels > 200nmol/L, however athletes should be discouraged from unmonitored large dose supplements Limitations with studies There are a number of limitations in the research into Vitamin D levels in athletes. There are large differences in baseline plasma concentrations of 25(OH)D in different populations, which could interfere with the effect of supplementation. Contamination with private use of Vitamin D might also further dilute any definite association. It is difficult to account for the effect of sunlight on the results and all the studies are small study populations. There are also logistical issues in performing longitudinal studies as athletes and dancers move on.
Potential dose regime
Next 2 Plasma
B a s e d o n t h e l i t e r a t u re , a p ro g r a m m e o f supplementation was recently implemented in a group of 46 professional rugby players (awaiting publication) to move 25OHD levels to above 100nmol/L and maintain this level through the winter. The regime is shown in the table below.
level IU
Dose over 5 First month days IU
daily IU
months winter daily IU
0-50
10,000
2500
next 3 months daily IU
5000
2500
5000
2500
next 7 days 51-80
The desired levels were achieved over winter in over 90% of the players using this regime.
10,000
free then 2500 daily
Conclusion Dancers are artistic elite athletes pushing their bodies to the extreme to perform a range of complex manoeuvres, requiring high levels of fitness and agility, and injury rates are high (21). Dancers of all genres are at high risk of Vitamin D insufficiency or even deficiency, leading to a high risk of injury. They spend six to eight hours a day training in-doors throughout the year, and along with the rest of the young athletic population, their dietary intake of Vitamin D3 rich foods is likely to be low.
81-110
5000
5000
2500
>110
2500
2500
2500
*References available upon request
Due to the lack of high quality research in this specific athletic cohort, supplementation advice on how to manage dancers with Vitamin D deficiency is not straightforward. There is evidence demonstrating that treatment of Vitamin D3 deficiency is beneficial to the health of individuals [6-10] and there is some evidence to suggest that correcting deficiency may well improve muscle function and therefor reduce injury rates [10,16]. Current research is not able to identify an ideal serum level of Vitamin D3, however there is some evidence to suggest that levels >75nmol/L improve muscle repair following injury [22] and also enhance immunological function (23). In line with current guidance from the US IoM and the EFSA it seems reasonable to suggest that daily dosing of 5000IU per day through the winter would benefit the dancer and is well within the safety levels (<10,000IU) of the IoM (19) Further research with high level large population studies are required with a view to potentially identifying appropriate dosage regimes to achieve optimum Vitamin D3 levels to improve performance and reduce injury rates in athletes and dancers.
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Do fitter dancers dance “better” and “longer”? Dr Manuela Angioi iBSc Sports and Exercise Medicine course lead and Dance Medicine lead at QMUL.
Within dance medicine and science research there is an everincreasing interest towards the benefits of increased physical fitness levels in relation to both performance and injury status. Relatively recent studies have detected significant statistical associations between specific physical fitness components, such as muscular power, endurance and aerobic capacity and qualitative aspects of performance in contemporary and ballet dancers (1, 2). Moreover, studies have investigated the relationship between selected physical fitness levels and injury occurrence and severity (3,4). Angioi and colleagues detected significant negative correlations between the total number of days off due to injuries and standing vertical jump height (r = –0.66; p = 0.014), ; by using regression analysis they reported that days off due to injuries was best predicted from standing vertical jump performance (p = 0.014) (3). In ballet dancers, low levels of aerobic fitness were significantly associated with many of the injuries sustained over a 15-week period (r = .590, p = 0.034), and body fat percentage was significantly associated with the length of time a dancer had to modify activity as a result of a diagnosed injury (r = -.614, p = 0.026) (4). Nevertheless, these observed “associations” do not imply causality, meaning that 11
only carefully designed intervention studies ensure that the observed “effects” (i.e. dancing better or suffering less injury) are consequences of the increased levels of muscular fitness. The investigation of the cause-effect relationship has to be suppor ted by robust methodological approaches including the use of appropriate inferential analysis to detect “true changes” in the sample studied, or in other words avoiding type 1 error.
Physical fitness and dance Physical fitness components include cardiorespiratory fitness, anaerobic capacity, muscular strength/power, joint mobility and muscle flexibility, and body composition. Poor levels of physical fitness have been generally associated with injuries. Inadequate aerobic capacity, for instance, is linked to fatigue, which in turn may lead to musculoskeletal damage (5). In dance, common exploits of upper body muscular endurance occur during partner work, when repeatedly lifting and supporting other dancers, as well as during transitory movements from floor to standing and vice versa (6). Lower body muscular power, on the other hand, is necessary in the development of elevation during the take off phase of any type of jump. Nevertheless, Wyon and colleagues (7) have previously reported significant differences between ballet and contemporary style dance for exercise intensity (p < 0.001), changes in direction (p < 0.001) and discrete skills (p < 0.05) with gender differences noted in the latter (p < 0.05). By using match analysis systems Wyon et al. were also able to characterise the exercise intensity for the two styles and they noted that Ballet was characterised by longer periods at rest (38 s.min − 1) and high to very high exercise intensities (9 s.min − 1), whilst contemporary dance featured more continuous moderate exercise intensities (27 s.min − 1). Therefore, data for contemporary dance and ballet should be studied separately.
Supplementar y training and dance performance In 2012, a combined circuit and vibration-training programme were implemented to ascertain if increased physical fitness levels were reflected in the aesthetic 12
competence of 24 female contemporary dancers (professionals and students). Each dancer either undertook the combined circuit - vibration training (in addition to usual dance training) for six weeks (intervention group) or simply carried on with their usual dance training (control group). The procedure used to recruit and allocate dancers to either group was performed according to scientific guidelines for research design, hence ensuring the minimal effects of other variables on results and/or the reduction in bias (8). All 24 dancers were tested for baseline levels of lower body muscular power, upper body muscular endurance and aerobic capacity via reliable, field-based tests including standing vertical jump, number of press-ups performed in one minute and a dance-specific aerobic fitness test (9). The dancers also undertook an “aesthetic competence” test (1), which was previously developed to objectively score (from one to ten) seven aspects of contemporary performance, including control of movement; spatial skills; accuracy of movement; technique; dynamics, timing, and rhythmical accuracy; performance qualities; overall performance (overall ICC for inter reliability: r=0.96; p<.01). 12 dancers undertook the supervised fitness training; this was organized twice a week and each training session lasted 60 minutes, comprising of circuit training (CT), 10 minutes rest and whole-body vibration training (WBV). CT consisted of lower and upper body exercises, organized in 10 stations. The 10 exercises included: jumps with feet in parallel position (using a jumping rope), press-ups, bicep curls, triceps extension (with free weights of 0.5 kg each), single leg squat, squats-jumps, relevés in first position, grand-plié in second position, chest press exercises (with free weights of 0.5 kg each), and plank. Dancers had to exercise for 30 seconds at each station, with 10 seconds of transitory time between one station and the other, making the total time for each circuit of 6 min 50 sec (including the rest between each station). Dancers had to complete four circuits per session. The WBV training protocol used six dance-specific static positions on a vibration platform (frequency set at 35 Hz and amplitude at 2.5 mm) including: 1) plié with feet in first position; 2) plank (elbow flexed on the floor and feet on platform); 3) lunge (right and left leg); 4) press up, 90° bend at the elbows; 5) feet in relevé; 6) hamstring position, bent over
at waist, with knees slightly bent and hamstrings tensed. tailored to the choreographic demands, if these are The training consisted of three sets, lasting 40 seconds known in advance; the use of WBV training in particular has been shown to provide adaptation of the muscular with two minutes rest between each set. system with minimal time cost, which is a vital advantage While results of the baseline tests revealed that all 24 when the daily work time in dance is controlled by unions dancers had similar levels of muscular power, endurance, and the majority of time is focused on artistic training. aerobic capacity as well as all scoring similarly in the aesthetic competence test, we observed differences Dance Medicine Education following the six weeks of supplementary fitness training. More specifically, Repeated measures ANOVA A recent collaboration between the Royal Ballet School revealed and Sports and Exercise Medicine, Queen Mary University of London, has led to a partial redesign of the annual significant increases for the conditioning group in lower screening process of dancers. One of the aims is to body muscular power (11%), upper body muscular investigate the physiological adaptions to training, endurance (22%), aerobic fitness (11%), and aesthetic particularly in relation to aerobic capacity, and competence (12%) (p < 0.05). The observed increased investigate possible associations between overall aerobic aerobic levels were attributed to the circuit training, capacity and injury profile using a combination of while the increases in muscular power and endurance retrospective and prospective design. These projects will were a result of the combined CT and WBV training. WBV form part of the final thesis that iBSc and MSc students training in particular has been proven to stimulate both have to submit as part of the degree requirement. concentric and eccentric contractions; hence, the enhancement of muscular power occurs via potentiating For more information about the MSc in Sports and the neuromuscular system of the subject (10). The fact Exercise Medicine (and Dance Medicine module, est. 2012 that dancers who did not undertake the fitness training and open to external students) please follow this link: did not improve in the studied fitness components https://youtu.be/zOaa1PluZ0o suggests that dance training is not sufficient enough to overload the aerobic/anaerobic and musculoskeletal systems and thus, to produce physiological adaptations This article has been adapted from Angioi M et al (2012). Effects of that will enhance each individual fitness component. Supplemental Training on Fitness and Aesthetic Competence Parameters in Contemporary Dance: A Randomised Controlled Trial.
What are the implications of such findings for Med Probl Perform Ar; p:3-8 the Sports Medicine community?
Firstly, the present study contributes to the open debate *References available upon request whether dancers would further benefit from enhanced physical fitness levels equal to other athletes. Secondly, available evidence suggest that incorporating supplementary training will help bridge the observed fitness gap between performance preparation (class and rehearsals) and performance periods. Nevertheless, the incorporation of supplemental training into the dancersâ&#x20AC;&#x2122; schedule must take into account present workload, which can already involve six to eight hours/day of exercise at varying intensities. Training sessions need to be timetabled to prevent fatigue interfering with the high skill elements of dance. The selection of exercises can be
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One Dance UK – Healthier Dancer Programme , Founding partner of the National Institute of Dance Medicine and Science, UK One Dance UK’s Healthier Dancer Programme began research into dancers’ health and injury prevalence in 1996 with the publication of Fit to Dance; a nationwide self-report survey of injury and perceived causes.2 This report highlighted the need for more support for dancers who sustained injuries, and for more preventative treatment and support. In 2005, the second national enquiry into dancers’ health and injury in the UK was published.1 Results demonstrated that injury was perceived to have occurred as a result of fatigue and overwork, insufficient warming-up or cooling-down, recurring injury or not being able to respond to the early warning signs of injury.2 Whilst it was clear there had been progress since 1996, the report highlighted that there was more work to be done in educating dancers with regards to the importance of warming-up, cooling down and the risk of overtraining and fatigue.
Around 80% of all dancers will suffer an injury each year through training, rehearsal of performance.1 Dancers are athletes as well as artists, and they train extensively throughout the year to reach peak physical performance, whilst also maintaining the aesthetic qualities required of the many different dance styles they are required to perform. The overarching aims of dance medicine and science have always been to optimise a dancer’s potential and reduce their risk of injury. The first Healthier Dancer Programme conference hosted by Dance UK (now One Dance UK) and the inaugural year of the International Association for Dance Medicine and Science both occurred in 1990. 3 Since then dance medicine and science has been a rapidly growing field, supporting dancers from training through professional careers and beyond.
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Information garnered from these two national inquiries highlighted the urgent need for a UK based organisation championing dance medicine and science research, whilst ensuring dancers had access to free or affordable specialist clinical services. In 2012, with the support of founding partners – One Dance UK, Trinity Laban Conservatoire of Music and Dance, University of Wolverhampton, Birmingham Royal Ballet, Royal National Orthopaedic Hospital and University of Birmingham - the National Institute of Dance Medicine and Science (NIDMS) was established. Through shared expertise, the NIDMS partners strive to improve access to specialist clinical care for dancers, to progress dance medicine and science research and provide educational resources and workshops for dancers, dance students, teachers and dance managers. In February 2017, NIDMS welcomed the Royal Ballet as a partner, bringing further expertise to the organisation. Since NIDMS’ inception, the partners have established three NHS dance injury clinics in London (Royal National Orthopaedic Hospital), Birmingham (Queen Elizabeth Hospital) and Bath (Royal United Hospital), providing free, dance specialist healthcare through an interdisciplinary team. The London clinic, led by Dr Roger Wolman has seen over 800 dancers across 12 different dance genres since opening in 2012, many of whom would not be able to access dance specialist healthcare privately due to financial restrictions. The support of clinicians who understand the specific needs of dancers in training and those with professional careers is invaluable for those experiencing injury; “Any injury is stressful for a dance student, but not knowing what the injury is increases that stress enormously. Without an appropriate diagnosis, effective treatment is delayed. We are now able to refer these students, via their GP, directly to the dance specialist teams at the NIDMS clinics, who have the expertise and understanding to deal swiftly, sympathetically and
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appropriately with any dance related injury issue.” - NIDMS NHS Dance Injury Clinic User The NHS dance injury clinic teams also work in conjunction with schools and companies who have existing in-house provision who choose to work with the NHS dance injury clinics for more complex cases;
“I decided to use the NIDMS NHS clinic because from time to time my dance students sustain complex injuries that require specialist knowledge from a variety of disciplines. The clinics complement my in house provisions as the practitioners and consultants are constantly supportive and helpful and work with me collaboratively to reach the best possible outcome for each dancer.” - Kim Hutt, injury specialist and Lecturer in Physical Support at London Contemporary Dance School
One Dance UK’s Healthier Dancer Programme (HDP) operates under the umbrella education programme of NIDMS, providing HDP talks to dance schools, companies, universities and conferences across the UK and internationally. The HDP benefits from the expertise of the Dance Medicine and Science Expert Panel4, offering the most up-to-date advice, informed by current practice and research, to One Dance UK members and the wider industry. The Healthier Dancer Programme also manages a nationwide Healthcare Practitioners Directory, a free searchable online database listing details of medical, p s y c h o l o g i c a l , a n d co m p l e m e nt a r y h e a l t h practitioners throughout the UK.5 One Dance UK and NIDMS continues to advocate for further epidemiological research and are currently fundraising for a large-scale, three-year, prospective study across multiple dance companies and schools to establish the common causes of injury and to implement training programmes which will reduce the risk of injury.
NIDMS is keen to support practitioners with gaining more experience working with dancers to improve the overall healthcare support dancers receive. Therefore, the NIDMS partners are pleased to offer a limited number of placements or oberserverships in both an NHS and private setting. If you wish to receive more information about placements or observerships please email manager@nidms.co.uk Although much progress has been made since 1990, there is still much more to do, and One Dance UK and NIDMS continue to advocate for dancersâ&#x20AC;&#x2122; health, the continued education of dancers, teachers and company managers, and remain at the forefront of dance medicine and science research. For further information on NIDMS please visit www.nidms.co.uk or contact manager@nidms.co.uk
To learn more about the Healthier Dancer Programme please visit http://www.onedanceuk.org/programme/ healthier-dancer-programme/ or email hdp@onedanceuk.org
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A place for Dance Medicine within Sports Medicine, injury rates in dance and the relationship between load and injury in professional ballet dancers By Nick Allen Healthcare director at the Birmingham Royal Ballet
When I was asked to contribute a piece for the USEM magazine for BASEM I quietly reflected on how far dance has come in the awareness of the sports medicine fraternity over the last decade. Sport can be defined as an activity that involves physical exertion and skill. Many definitions of sport go on to include that sport is governed by various sets of rules, is competitive and can involve a contest or game between two opponents. Given these definitions dance may fail to fully fulfil these criteria, but as an athletic pursuit, the numerous studies into the physiological demands of dance [1-5] reinforce the sports medicine communityâ&#x20AC;&#x2122;s growing interest in what dancers are undertaking. The role of sports medicine is clearly articulated in the aims of the British Association of Sport and Exercise Medicine, in promoting and studying methods for the protection and improvement of public health and fitness. Amongst the public there is a growth in dance participation (Arts Council, 2009). One Dance UK (previously Dance UK) suggests that there is a growing trend to dance among the UK population, quoting an 17
83% increase in the number of school pupils choosing dance. Research undertaken by the ‘PE and School Sport Club links scheme’ shows dance second only to football as the most popular activity of school children (Dance UK, 2010). The number of students taking GCSE Dance has increased from 7,003 in 2001, 15,730 in 2005 to 18,866 in 2007 according to the Assessment and Qualifications Alliance (aqa.org 2009), and 1220 students graduated with degrees in dance in 2007/08 (HESA, 2009). Within the amateur and voluntary sectors there are over 3,000 dance groups, engaging 140,000 people (Arts Council, 2009). The total workforce of dancers within the UK is estimated at around 40,000 people, with teachers comprising the greatest proportion (Arts Council, 2009). Among the professional or elite ranks, One Dance UK report that there are 3000 dancers registered in the UK (Dance UK, 2010). While these figures still fall short of some of the more popular sporting pursuits, they highlight a growing area of physical activity, notably in younger females where there is evidence of reduced levels of participation in sports. From a public health perspective, therefore, providing appropriate support for dancers may enhance our overall public health agenda.
Our original work reported combined incidence rates of 4.4 injuries per 1000 hours of dance. Table 1. Allen et al, 2012 [6] Female dancers
Male dancers
Injury
Injury
Number of
incidence/
Number of
incidence/
injuries (% of
1,000 hrs
injuries (% of
1,000 hrs
all injuries)
dancing
all injuries)
dancing
(95%CI) Restricted dance ac,vity
(95%CI)
150 (87)
3.6 (3.1-4.2)
147 (80)
3.8 (3.3-4.5)
22 (13)
0.53 (0.35-0.81)
36 (20)
0.94 (0.68-1.30)
172 (100)
4.1 (3.6-4.8)
183 (100)
4.8 (4.1-5.5)
Complete withdrawal from dance related ac,vity* ALL INJURIES
* injuries that required the full withdrawal of dance related ac,vity as part of the overall severity
This was at the upper level of the findings previously reported in the literature, when we conducted a systematic review on incidence rates, but as you can see in Table 2, there is large variation of reporting of injury incidence in dance.
As in sport, the physical and psychological demands of dance are changing. Birmingham Royal Ballet is recognised as one of the top ballet companies in the world, and as such, they tour all over the world, performing around 150 shows a year; a repertoire that consists of around 18 different ballets. This variation in choreography alone requires the dancers to be truly versatile, “multi-sport” athletes and with this increase in physical demand, potentially, comes an increased risk for injury.
Most notable from our research were the high exposure rates noted. A typical week saw dancers clocking up to 35 hours of dance related activity alone, not including any additional training e.g. core stability, strength or fitness training. Unsurprisingly we noted a greater proportion of overuse injuries.
My journey in dance stared over 10 years ago with me trying to understand the incidence of injury and its impact on performance. Thanks go to Professor Colin Fuller and Dr John Brooks and their seminal work with England rugby, which provided the foundation to build a robust injury audit tool for dance. Additional thanks to Dr Brooks and Professor Matthew Wyon who were instrumental in my undertaking a comprehensive injury audit and prospective epidemiological study at the Birmingham Royal Ballet. Now in its 12th year we can reflect on incidence rates and patterns of injury in a cohort of elite professional dancers.
With the global awareness of the need to optimise loading in our athletic populations, Tim 18
Gabbett eloquently presents data that reflects the importance of acute/chronic workloads and how these may affect injury rates seen. Those who delve into Gabbett’s work further see the importance of appreciating the impact of: career loading; previous seasons loading; alongside the typical appreciation of chronic training load from the last four weeks. This leads to a pattern of younger athletes possibly being at an increased risk of injury through a lack of suitable chronic training load and older athletes being more at risk due to either excessive accumulative chronic loading or previous injury affecting training load.
No of studies (design) Limitations
Overall injury incidence 29 (observational)
serious limitations
Inconsistency
serious inconsistency
Indirectness
no serious indirectness detected
Imprecision
no imprecision
*based on 12 studies
Table 2. Reproduced from Allen et al, 2014 [7]
Having reflected on the injury rates from the start of our injury audit, we have noted an increased incidence of injury occurring amongst the younger, corps dancers. These dancers may not have had the suitable level of chronic loading to provide resilience to injury when exposed to spikes in their acute workload, resulting in increased injury risk, including more frequent bone stress injuries - another area Dr Gabbett’s work has explored. The lower injury incidence seen among principal dancers at the Birmingham Royal Ballet may relate to cumulative chronic loading, and these are largely limited to joints. So, how do you solve a problem like training load in dance? An obvious place to start would be to examine a typical dance’s schedule, which may include two performances a day; up to eight shows a week and potentially around 150 shows a year. Football talks about fixture congestion players having less than three days to recover between matches - but I think that would fulfil the definition of fixture congestion in dance terms. Further, the increased overall activity-based exposure through daily classes and rehearsal may also influence the frequency and nature of injuries that are seen in dance. Our original research used estimated-exposure as a measure to calculate load, which based on contractual schedules. We 19
are currently working closely with Greg Retter, Clinical Director at the Royal Ballet Company, to develop our electronic medical notes software system to allow us to document both accurate exposure data capture, alongside session intensity measures to start to appreciate training load as part of our move to understanding optimal training load in elite ballet dancers. This training load needs to respect both the physical demands of performance as well as the stage of a dancer’s career. * References available upon request
Publication bias
undetected
Average incidence/ 1000hrs (Range of incidence/1000hrs) (95%CIs) 1.33injuries/1000hrs (0.18-4.7injuries/ 1000hrs) (0.20-4.35)*
Actual no. of injuries/no of participants/year (range) (95%CIs) 1.93 injuries/dancer/ year (0.05-6.83) (0.29-4.5)
Quality
very low
What is the place of Profiling at the Royal Ballet School? Karen Sheriff
The Royal Ballet School (RBS) trains elite young classical ballet dancers from the ages of 11-16 (at White Lodge, Richmond) and from 15-19 (at the Upper School, Covent Garden). Since 2015, we have seen an increase in the School's commitment to growing its medical team. As of September 2017 we have full multidisciplinary teams mirrored across the two sites comprising 18 members of staff including counsellors, sports physicians, Pilates instructors, sports scientists, physiotherapists, school nurses and a nutritionist. As with any other elite sporting institution, the School aims for excellence, and our healthcare team is in the early stages of at the ‘beginning’ of a journey to reflect such excellence through our application of dance science to ballet performance. In-line with the school’s mission to ‘Set the Standard’ in all areas, we have taken on this challenge by committing to look at both the physical and psychological well-being of our dancers and translate our findings to an open, but traditional, world of aesthetic art. Screening or profiling is historically seen as an essential part of injury prevention programmes in any elite sport. The 20
theory being that there are inherent intrinsic, measurable characteristics that contribute to a dancer’s injury [1]. However, the relative importance of profiling and how it enhances our understanding of injury prevention is often debated in sport [1-3]. Non-standardisation of the demographic [4], the tests chosen, the testing procedures themselves, or the timing of athlete screening is partly accountable for this [1,5].
conclusions [2,5] and will help us in our aim to enhance the long-term health and careers of our dancers.
At the RBS we as the healthcare team take dancers’ past medical/injury histories and take into account both physical and psychological aspects of objective health. We feel that there is cause for profiling our dancers on a termly basis, not just in-line with common sport/dance practice (ref[1,5]) but to enable us to understand how screening is important in the context of injury, and (more so to the dancers), their changing dance conditions throughout the year [3] and performance. We are therefore prompted to ask “how does this add to our picture of their resilience?” to keep it focused, functional and useful.
As such, our department has two main research questions for this academic year:
What we Include & why… When we design physical profiling for our dancers, we encompass a range of capacity measures including: single seated single-leg press; overhead capacity; calf capacity (based on unpublished injury prevention work by the Australian Ballet Company) and anterior and posterior trunk capacity. Anthropometric measures, range of motion (ROM) measures (hip, thoracic and first ray), aerobic fitness (as of September 2017) and countermovement jumps in parallel (double and single leg) on force plates. Force plate information helps us gain an understanding of the unique ‘movement signature’ of our dancers and particularly the way force is produced when they jump. Our emphasis here is on kinetic variables such as peak take-off and landing force and peak rate of force development, where we mainly look for any limb asymmetries or high forces in either the landing, but particularly the take-off phase of their jump. This in order to help us identify any injury risk factors that may be related to excessive tendon/bone healing. We also include a ‘RED-S’ (Relative Energy Deficiency in Sport) questionnaire, particularly to highlight any students who may be more at risk of stress fractures [5] and who may require additional multidisciplinary support [6]. To record this information, we use an on-line athlete management system, which accurately collects and records all injury and profiling data. It allows for precise longitudinal tracking to enable more accurate clinical
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Projects for this academic year… We know that we are understanding more and more about optimal loading in sport and for example, how the influence of acutre:chronic workloads that may affect injury [5,76].
1. What is the Loading Picture of an elite pre-professional classical ballet dancer? 2. What does the Profiling Picture of an elite pre-professional classical ballet dancer look like? To allow us to quantify and answer these questions we have teamed up with two universities who will be covering in-house research projects at the Upper School. Through St Mary’s University, Twickenham we have an MRes in Sports Science who will be investigating ‘load’ in our students: both measuring the internal load and possibly external loads with indoor GPS and accelerometry [7,8]. This work is especially important in the pre-professional ballet dance cohort as we know they are at increased injury risk when exposed to increased training intensity [1]. However, unlike other professional sports, the loads that dancers are exposed to are not yet not quantified. From initial trial data we can suggest that the jump load exposure in ballet dance is likely to be higher than in any other sport, and from our profiling data, we can begin to understand, for example, what a ‘good’ landing force is, and how these variables in the dancer’s movement signature may change over a season. We are under no illusions that monitoring load in itself will reduce injuries, however, once quantified, controlling this load could help us in our aim of reducing the bony and tendon injury burden common in this cohort of athletes [7] We are also collaborating with Queen Mary University of London to undertake a further four projects: 1.
MSK injury Profile – one year cohort observation
Previous research has shown that screening does not identify “…robust physical factors predictive of injuries in elite pre-professional adolescent ballet dancers” [1]. However, we believe our data to be useful in the role it plays in both preventing injury, and guiding return to baseline (performance
ready) in our dancers. It is also useful to replicate previous research to ensure its relevance for the screening tests we use on our students, as our department grows. This project will be undertaken using our on-line notes system, which will allow us to highlight any correlations between our injury and profiling data, in order to identify potential injury risk factors [9]. We will aim to record numbers of injuries per 1000 hours of dance [1]. 2. Aerobic changes during one year of training using the classical ballet dance aerobic fitness test (DAFT test) We know that fatigue can increase the chances of injury in the dance cohort [10]. At the RBS, we feel that the aerobic demands placed on our dancers via the intensive (and repetitive) classes, assessments, rehearsals and performances, are highly challenging. However, traditionally, we have been unable to quantify a dancer’s readiness for this physical challenge. To measure this, we employed the use of the valid and reliable, submaximal, ballet-specific fitness test, in the DAFT [11]. Thanks to its specificity (replicating a class/rehearsal/performance environment) we have been successful in achieving full ‘buy-in’ from both staff and students to ensure their competency in performing the test properly. All students will be tested at three points throughout this academic year. 3. Kinematic differences between neutral and first position jumping We know that parallel countermovement jumps are able to track meaningful physiological changes [12] and are also able to give data relating to consistency speeds and their comparison to other sports. However, where sport aims to screen athletes in a way that reflects what the athletes do [13-14], we must do the same in dance. The classical ballet ‘turnout’ position is used by the dancers in all of their ballet training and it has already been shown that there are differences in the forces and jump height produced between parallel jumps and jumps performed in ‘turnout’ [15]. It is for this reason that we will be comparing key force data between these jumps in our dancers, aiming to implement a ballet-specific jump movement profile for next year to ensure the ongoing specificity of our screening protocol. We hope this will help us understand the loading rates within our dancers in a turnount position, and specifically to compare peak forces relative to the dancer’s body weight. We feel this may identify trends between variables such as high take-off rate of force development and our loading 22
injuries, and importantly give us specific return to dance performance measures. 4.
Self-efficacy & injury, with REST Q questionnaire
Research suggests that dancers [3] and aesthetic athletes [16] commonly perceive themselves to lack the ability to cope with injury [3] and we know that psychological load is recognised as a relevant stressor [5]. Further sport is acknowledged to be cognitively demanding, with coping capacity and wellness being known to have the same negative relationship with performance as load and recovery [17]. We will therefore be using the REST-Q questionnaire to measure stress and recovery in our dancers at different points throughout this academic year. In Summary/So what does this mean?… We feel this is an exciting year for the healthcare team and dancers at the RBS. We need to understand the complexities of our specific subject group, and how best to support them. Enhancing our understanding of our dancers’ internal & external workloads and matching them to their physical profiles and injury data will allow us to look at their capacity to handle the loads they are exposed to, adding invaluable insight to the needs of young pre-professional ballet dancers. Understanding the prevalence and patterns of injury in our unique group of athletes will potentially lead to targeted injury prevention and management [4]. We are looking at the science that underpins the art and seeing how this relationship affects performance. We hope that by improving dancers’ performance we will, in-turn, reduce injury/re-injury and, importantly by optimally managing their load [18], maximise the long term health and professional longevity of our dancers.
* References available upon request
Recovery amongst pre-professional ballet dancers: a cross-sectional questionnaire-based study using the RESTQ-Sport tool Fabian Roberts BSc (Hons)
Background Dancers are tasked with the formidable goal of achieving critical acclaim through performance. Success requires combining technically sound artistic prowess with rigorous physical activity [1]. As such, Ballet is physically demanding [2, 3]. Early specialisation and intense preprofessional training prepare dancers for the complex artistic and athletic ability required of professionals [4-6]. Rigorous training, limited restbreaks, and regular performances incur significant demands that predispose to a variety of complex injuries [7]. Because the livelihood of dancers depends on their ability to perform, many perform through pain, inhibiting effective recovery and potentially increasing injury risk [8]. Ballet dancers are very susceptible to injury [9], with an incidence in professionals reported between 0.62 and 4.4 per 1000 dancing hours [5, 10]. The commonest injuries occur at the ankle, foot and lumbar spine [5, 10, 11]. Similar patterns are seen in pre-professionals, but with lower reported incidences (1.09-1.90 per 1000 dancing hours) [4, 12, 13]. Research has linked stress to injury in athletes. The Kenttä and Hassmén model explains the ‘athletic balance’ in which optimum health is maintained through equilibrium between physical and psychosocial stresses [14]. Imbalances in either direction may increase injury risk, though heightened stressors incur a greater risk. Andersen and Williams have described a proportional relationship between high stress levels and increased risk of traumatic injury [15]. This knowledge helps us understand the dangers that stress pose to athletes.
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Dancer burnout is attributed to the demand for performance perfection. Year-round training often leads to fatigue and regular injuries [16], yet the exact role that stress plays in burnout is poorly understood and largely anecdotal [17, 18]. New evidence could help develop injury prevention strategies and identify dancers at highest risk [19].
Injury incidence was calculated as values per 1000 dance exposures [23]. Descriptive statistics were applied to anthropometric and dance measures. A Shapiro Wilk test for normality was performed, with 95% confidence intervals applied to injury rate and risk. RESTQ-sport 76 data was analysed using the RESTQ-Sport Database Program Version-1 (RESTQ-SDP) [22]. Mann Whitney U was used to detect significant differences in overall RESTQ-Sport 76 scores between the male and female groups. Significant differences between the groups was assessed using an independent t-test. Associations between injury rates and RESTQSport 76 scores were investigated using multiple regression analysis. The value was set at p < 0.05.
Stress in other sports has been investigated using the RESTQSport questionnaire [19, 20]. Investigating stress-recovery states has highlighted that stress and recovery affect injury rates. To date, no studies using this questionnaire have been conducted to assess the relationship in dancers. Dancers may have more risk of injury than other athletes due to higher physical and psychological stressors [7]. Finding an effective method of anticipating and preventing injuries could protect athletes at highest risk. Considering this, and the current knowledge gap, this study has two aims: (1) to investigate how monitoring and analysing stress-recovery balance informs the prediction and prevention of injuries in pre-professional dancers; and (2) to investigate injury rate and its association with stress and recovery. Hypothesis: stress has a proportional relationship with injury. Null hypothesis: there is no significant association between
stress and injury. Methodology A cross-sectional, non-experimental design was used to assess pre-professional dancers recruited from the Royal Ballet School (RBS), comprising 61 participants selected per the inclusion/ exclusion criteria (appendix 1). Sample size calculations demonstrated 21 participants were needed for significant outcomes to be observed with 95% confidence [20, 21]. Anthropometric and performance data were obtained. Data was collected during pre-participation screening in April 2017. Ethics approval was obtained from Queen Mary University, London (QMREC2014/24/119). Participants provided informed, written consent. Records were anonymised and held on a passwordprotected computer.
Results Shapiro-Wilk tests demonstrated that male height and weight and female weight were normally distributed (> 0.05). Mean age was 18.5 ± 0.5 years. Significant differences in height, weight, and BMI (p < 0.001) were found between the groups, but there was no significant difference in years trained (p = 0.140) or training sessions per week (p = 0.145). The overall scores for each sub-category of the questionnaire by gender are given in figure 1. No significant difference was observed between the overall scores of males and females (U = 173.5, p = 0.838) or individual sub-categories (p = 0.317).
Injury data was collected using the Healthier Dancer Questionnaire (HDQ) [22] (appendix 3), which groups injury types by musculoskeletal area, then body part. Participants were asked to recount injuries in the previous 12-months, perceived cause of injuries and injury-related days absent from dancing.
There were 106 reported injuries; 59 female and 47 male (figure 2). “Muscular” injuries were the commonest (45.3%) (figure 3). Lower limb was the commonest injury site (55.7 %) (figure 2). The commonest duration of absence was “1-3 days” (28.3%) (figure 3). The commonest perceived cause of injury was “fatigue/ overwork” [39.2%] [figure 4]. Confidence intervals for both injury rate and injury risk demonstrated no difference between the groups (table 1).
The RESTQ-Sport 76 questionnaire was used to determine the stress and recovery states of each participant [23] (appendix 4,5), scored on a Likert-type scale from zero (never) to six (always), depending on how regularly events occurred in the previous three days. Sub-scales have good internal consistency (0.67 – 0.89) and high test re-rest reliability (>0.79) [23].
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Table 1 – Participant injury rate by gender, and injury risk by gender [24] Gender Female Male All participants
Injury Rate (per 1000 dance exposures)
Percentage Injury risk (%)
2.67 (95% CI: 1.99 – 3.35)
80.6 (95% CI: 66.7 - 94.5)
2.42 (95% CI: 1.73 – 3.11)
80.0 (95% CI: 65.7 - 94.3)
2.69 (95% CI: 2.18 – 3.20)
80.3 (95% CI: 70.4 – 90.3)
Discussion This study found significant associations between the sportspecific stress sub-category “disturbed breaks” and injury rate in males, and the general stress sub-category “social stress” and injury rate in females. Rate of injury for was 2.69 per 1000 dance exposures (males = 2.42; females = 2.67) and risk of injury over 12-months was 80.3% (males = 80.0%; females = 80.6%).
Other than “disturbed breaks” in males and “social stress” in females, no clear association between injury rate and stressrecovery balance was found. Overall scores for stress-specific subscales were low in both groups, indicating low levels of stress in participants. The overall injury rate was higher than previously demonstrated [12, 26]. This is unexpected given the Andersen and Williams model [27].
Multiple regression analysis was run to predict injury rate from the 19 RESTQSport 76 sub-categories. In males, “disturbed breaks” predicted injury rate with statistical significance (F [1, 23] = 4.514; p = 0.045; R = 0.405) and in females, this was predicted by “social stress” (F [1, 23] = 6.112; p = 0.021; R = 0.458). No other sub-category demonstrated significant predictability.
The RESTQ-Sport tool’s implementation may explain this. It only considers the three-days prior to application, meaning that a relaxed schedule could be a confounder. However, this is difficult to qualify because individual participants’ schedules were not obtained. Without in-depth knowledge of schedules only limited parallels can be drawn. Testing the assumption that busier schedules incur higher stress levels, and therefore injury risk, would add significant weight to the discussion regarding injury prevention. Given the differing requirements in performance by gender, it is reasonable to assume that females would exhibit different stressrecovery scores [28-31]. However, no significant difference between overall group RESTQ-Sport scores was observed. Homogeneity of participants may account for this. Training is aimed at perfecting choreography for flawless performance [32] and this drive develops homogeneity within and between dance groups. No observed significant difference between the groups in respect of “training years” and “training sessions per week” supports this [table 2]. More diverse populations might reveal significantly varied profiles of RESTQ-Sport scores due to differences in teaching styles, schedules, and attitudes, which might predispose to different stress-levels. Among the many movements undertaken when performing, being “en pointe”, and performing “en dehors” are significantly involved in knee and ankle-joint injury through overload and repetitive ligament micro-trauma [33]. Data regarding injury distribution in this study is consistent with that published literature [11, 34, 35]. The annual risk of injury to the dancers is also consistent with the literature, and is attributable to the high number of dance exposures per participant [12].
Figure 4 –days lost to injury by gender for all participants
A final finding was that “overwork/fatigue” was a major perceived cause of injury. This echoes anecdotal evidence that stress and overwork are contributing factors to injuries in dance. However, definite associations cannot be drawn because data was analysed independent of dancer schedules. Without comparing RESTQSport and injury data to schedules, this link remains anecdotal.
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This study is limited by its cross-sectional design. A single stress-recovery assessment may inaccurately represent the stress-recovery relationship in this population. HDQ is prone to recall bias, as the recall period is long. Injury rates and risks may be affected by this. Participants all came from one elite ballet school. Limited population diversity may have negatively influenced RESTQ-Sport scores due to sample homogeneity. Repeat analysis of stress-recovery states of pre-professional dancers with prospective cohort design is proposed to allow for serial RESTQ-Sport measurements to be observed. This will enhance the importance of frequent monitoring of stress and recovery in preventing injuries in dance.
Conclusion Injury risk prediction based on the stress-recovery relationship has significant implications in injury prevention strategies in dance. These results suggest that stress influences injury development. Further research is required to explore the complex relationship between injury, stress and recovery. *References and appendices available upon request
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