Ballet dancers are a unique population of athletes in that, unlike other sports, their success strictly depends on both physical capabilities and aesthetic factors. While the physical demands of the performing sport are strenuous, ballet dancers are often required to exhibit a thin physique, frequently resulting in weights 10-12% below the ideal. These low weights are commonly achieved by low energy intakes which increase dancers' susceptibility to the development of various health conditions. Research investigating the health of dancers, however, is limited and hampered by methodological limitations. To address these issues, we tested the hypothesis that dancers would report a low habitual energy intake and, therefore, be subject to conditions comprising the Female Athlete Triad, including low energy availability, suboptimal bone density and menstrual irregularities. In addition, we hypothesized that elite female dancers would have lower than expected resting metabolic rate (RMR) based upon their fat-free mass, and thus greater energetic efficiency as a result of chronic energy deficiency. As hypothesized, dancers reported a significantly lower energy intake and exhibited a lower RMR as compared to lean, pair-matched controls. Because treatment of these metabolic abnormalities is challenging, prevention of adverse health outcomes among adolescent pre-professional dancers is key in promoting overall health and optimal performance. Through our subsequent 'formative work', we determined that the current availability of nutrition education offered to both professional and pre-professional dancers is minimal and of questionable quality. Thus, we developed, implemented, and evaluated a DVD-based educational program, entitled "Nutrition for Optimal Performance", aimed at improving health knowledge and behaviors of pre-professional adolescent ballet dancers. Our findings indicate that participants increased their knowledge of basic nutrition principles and self-efficacy for adopting healthier dietary habits, as compared to pre-program and control group scores, and that knowledge gains were sustained at a six-week follow-up assessment. Collectively, these studies provide the field of dance medicine with novel findings related to the characteristics and health conditions of professional ballet dancers, and the effectiveness of a low-resource, disseminable nutrition education program which promotes the health and optimal performance of pre-professional adolescent ballet dancers. / Ph. D.

Bakgrund: Återhämtning och nutrition är viktiga aspekter för att minimera risken för skador hos idrottare. Ett för lågt energiintag kan leda till flera negativa fysiologiska effekter då kroppens energibehov inte tillgodoses. Hos kvinnor är menstruationsdysfunktion (MD) ett vanligt symptom på långvarig låg energitillgänglighet och hög förekomst har främst rapporterats hos kvinnliga idrottare inom viktkänsliga idrotter såsom uthållighetsidrott. Syfte: Syftet med denna studie var därför att beskriva skadebilden hos svenska och danska kvinnliga landslagsidrottare på seniornivå samt undersöka eventuella samband mellan förekomst av skador och menstruation. Metod: Alla danska och svenska kvinnliga landslagsidrottare blev kontaktade per mejl och tillfrågade om deltagande via online-enkät där frågor om skador det senaste året och menstruation ingick. Deltagare blev klassificerade att ha MD om de uppgav att de aldrig haft menstruation, ingen menstruation de senaste tre månaderna, menstruationscykler med längre intervall än 35 dagar eller <9 menstruationscykler de senaste 12 månaderna. Alla deltagare blev klassificerade som antingen icke-viktkänsliga (t.ex. bollsport) eller viktkänslig idrottare (t.ex. uthålligsidrott). Resultat: Totalt svarade 634 (25%) idrottare på enkäten. Den rapporterade skadeprevalensen under de senaste 12 månaderna för samtliga inkluderade deltagare var 57%. 30% av deltagarna blev klassificerade att ha MD med en högre förekomst i viktkänsliga idrotter (39% vs 24%; P = <0,001). Deltagare med MD rapporterade fler skador under de senaste 12 månaderna (P = 0,004) och hade en högre risk för skada (OR = 1,52; 95% CI = 1,06–2,19; P = 0,024) samt högre risk för att ha varit långvarigt skadad (>22 dagar) (OR = 1,87; 95% CI = 1,23–2,55; P = 0,003) jämfört med deltagare med regelbunden menstruation. Deltagare från viktkänsliga idrotter hade en högre risk för skada (OR = 1,50; 95% CI = 1,02–2,21; P = 0,039) och högre risk för att ha varit långvarigt skadad (OR = 2,11; 95% CI = 1,38–3,24; P = <0,001) jämfört med deltagare från icke-viktkänsliga idrotter. Konklusion: Resultaten indikerar att kvinnliga landslagsidrottare med självrapporterad MD har en ökad skaderisk, speciellt inom viktkänsliga idrotter som uthållighetsidrott. Menstruationsdysfunktion bör därför tas i beaktning då det har negativ inverkan på idrottares hälsa och prestation. Vidare finns det ett stort behov av mer kunskap för att implementera effektiva kön- och idrottsspecifika preventionsåtgärder. / Background: Recovery and nutrition are important aspects in order to minimize injury risk in athletes. Multiple negative physiological impairments have been recognized in athletes due to low energy intake. One common symptom of prolonged low energy availability in females is menstrual dysfunction (MD) and high prevalence has been reported mostly in female athletes in weight-sensitive sports like endurance sports. Aim: The aim of the present study was to describe injuries among Swedish and Danish female national team athletes and to investigate potential connections between injury prevalence and menstruation. Method: All Swedish and Danish national team athletes were invited via e-mail to complete an anonymous online survey, which held questions about injuries the past year and menstruation. Participants were classified with MD if they stated that they never had menstruation, no menstruation the last three months, menstruation cycles with longer intervals than 35 days or <9 menstruation cycles the last 12 months. The participants were also divided in groups of non-weight sensitive athletes (e.g. ball game) or weight sensitive athletes (e.g. endurance sport). Results: A total of 634 (25%) athletes completed the survey. Among all participants an injury prevalence of 57% was observed and 30% were classified with MD. Higher prevalence of MD was reported in weight-sensitive sports (39% vs. 24%; P = <0,001). Athletes with MD sustained more injuries (P = 0,004), reported higher risk of injury (OR = 1,52; 95% CI = 1,06–2,19; P = 0,024) and to be long-term injured (>22 days) (OR = 1,87; 95% CI = 1,23–2,55; P = 0,003) compared to athletes with regular menstruation. In athletes from weight-sensitive sports a higher risk of injury was observed (OR = 1,50; 95% CI = 1,02–2,21; P = 0,039) and also to be long-term injured (OR = 2,11; 95% CI = 1,38–3,24; P = <0,001) compared to athletes from non weight-sensitive sports. Conclusion: The result indicates that female national team athletes with self-reported MD have increased injury risk, especially in weight-sensitive sports like endurance sports. Menstrual dysfunction has a negative impact on both health and performance, and therefore athletes and coaches need to pay attention to menstrual function. More research is needed to implement effective sex and sport-specific preventive measures.

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