Discussion
A Dance-Specific Questionnaire (DEAQ) investigating physical, physiological and psychological indicators and correlates showed that dancers are a specific group of high-level artistic performers displaying indicators of LEA and at risk of RED-S.
RED-S risk score from DEAQ
The DEAQ was derived from a questionnaire-based approach similar to that applied to sports. Negative RED-S risk scores, calculated from the DEAQ, indicated LEA in 57% of female and 29% of male dancers, suggesting that these dancers are at risk of developing the clinical consequences of RED-S, in common with athletes in certain sports.5 6 Yet only 29% of dancers had heard of RED-S. The DEAQ addresses the cultural gap between dance and sport by presenting an established screening questionnaire in a dance friendly format.
While there are fewer RED-S studies in male athletes,6 the identification of males dancers at risk is consistent with findings from a self-report survey of male athletes15 and a study of male cyclists where results from a questionnaire were linked with quantified clinical consequences of RED-S.12 Nevertheless, the average risk score for male dancers was not as marked as in females, although fewer males responded to the questionnaire than females. Males perform a different repertoire from females, reflected in a lower percentage of males being advised to lose weight and fewer seeing low weight as a factor in being cast. However, in common with females, the male dancers expressed a desire to be lighter and linked controlling what they ate to self-esteem.
Physical aspects of LEA in dancers
Ballet, the main dance form in this study, is practised worldwide and requires a slim physique to meet aesthetic, technical and repertoire demands. Ballet also forms part of the early training of dancers who go on to practise other genres. Literature review indicates that for female dancers of all skill levels, disordered eating, menstrual disruption and poor bone health are significant health issues.16 Early training specialisation, combined with a high training load, found in this study, is characteristic of dance.2 Intensive training during the teenage years increases the already considerable energy demands of physical development. This situation is recognised as an early risk factor for developing female athlete triad.3 17 Our study found BMI at the lower end of range (average for female dancers 19.7) and large variation in adult weight (15% for female dancers). In a study of retired female dancers, low BMI and duration of amenorrhoea during a dance career were found to be independent variables for low BMD in the long term.4
Physiological indicators of LEA in dancers
Endocrine function: Menstrual status in females and testosterone levels in males are sensitive, objective indicators of LEA, linked to the clinical outcome of impaired bone health and stress fracture of RED-S.18 Menstrual disruption, in particular functional hypothalamic amenorrhoea due to LEA, is characteristic of the clinical risk assessment of RED-S.13 The high incidence of menstrual disruption among dancers in this study, is far in excess of general population19: primary amenorrhoea 8% vs less than 0.01% and combined primary and secondary amenorrhoea 33% vs 4%. A history of amenorrhoea was reported 28% in dancers. Oligomenorrhoea associated with increase in training loads was reported in 17% of dancers. Overall, half of the female dancers reported disrupted menstrual function. Extensive literature demonstrates adverse health outcomes of the hypo-oestrogen state in terms of impaired bone, cardiovascular and neuromuscular function.20–22 Although 79% female dancers recognised that lack of menstrual cycles could have adverse consequences; 23% considered this ‘normal’ for dancers. This erroneous view might be perpetuated by a failure of staff to address amenorrhoea (43%) or enquire about menstruation on presentation of injury (35%), despite amenorrhoeic status being a well-documented risk factor for both soft tissue and bone stress injuries.[18].18
Gastrointestinal function: Disrupted gastrointestinal function is a well documented, validated indicator of LEA.9 Seventy-seven per cent dancers reported such digestive issues indicative of LEA. Misinterpretation of these symptoms can prompt further restrictive practices: half of female dancers and one-third of male dancers were excluding food groups. Furthermore, a third of dancers reported food intolerances, although very few had actually been formally tested.
Injuries: Incidence of injury was lower than might be expected, in view of the high percentage of dancers assessed as being in LEA, compared with high rate of stress fracture reported in male and female runners in LEA.18 However, the consequences of LEA occurring during peak bone mass accumulation manifest with an increased incidence of stress fractures during mid-20s.23 Furthermore, dancers in this study were not preselected by attending an sports injury clinic in a questionnaire-based study of female athletes.10
Psychological aspects as correlates for LEA in dancers
Psychological factors in athletes can both contribute to the cause and be the consequence of LEA.5 6 This study found a significant interplay between the psychological cluster of control of weight, eating and exercise dependence. Both male and female dancers indicated that controlling what they ate and what they weighed were important factors linked with self-esteem. Psychological drivers of competitiveness, perfectionism and self-control can render athletes susceptible to disordered eating behaviours.24 Development of attitudes regarding ‘ideal’ body type/weight and teammate modelling of eating behaviours can trigger disordered eating in junior athletes and pre-professional dancers.25 26 Vocational training and dance performance involve living away from home, often abroad, where dancers may use dance peers and social media as comparators. Eighty-three per cent of dancers cited social media as influential in feeling that weight loss was desirable.
Seventy-one per cent of dancers in this study reported feeling anxious about missing class. Exercise dependence is reported as a reliable indicator of eating psychopathology tendencies in female athletes27 and biochemical indicators of RED-S in male athletes.11
From this study, a statistically significant relationship was found between psychological factors and physical outcome of BMI min. The perceived performance advantage of weight loss can be a driver of disordered eating in aesthetic sports and dance.28 29 In our study, 73% of female dancers stated that being of low body weight would improve chances of being cast in significant roles. Forty-four per cent of female dancers and 33% of males reported being advised, at some point, to lose weight. Most commonly, dancers had been encouraged to exclude carbohydrates, contrary to research showing that low carbohydrate diets limit physical performance at high intensities.30
Our study found a significant relationship between the psychological factors of control and physiological outcome of menstrual function. Dancers expressed dissatisfaction with their current weight, wishing to be lighter, in keeping with the drive for thinness being an indicator of LEA, with increased menstrual disruption,31 reduced triiodothyronine and resting metabolic rate (RMR).32 Reduced RMR in male and female dancers is an indicator of LEA.33
‘Thinness-related learning’ for dancers, who already have perfectionist traits, is cited as increasing the risk for eating disorders.34 This study revealed a lifetime incidence of an eating disorder of 15% for female and 14% for male dancers, primarily anorexia nervosa. These findings are comparable to those previously reported in dancers and athletes and being higher than the non-athletic population.35 36 Exclusion of food groups by choice was reported by 50% female and 33% of male dancers.
A detrimental interplay of psychological factors for LEA can be perpetuated by the nature of dance training and performance, where selection strongly favours certain physical and psychological characteristics.
Limitations and further work
The aim of this study was to obtain a global picture of dance health and specifically trial a DEAQ. While there are different schools of ballet and companies vary in their approaches, dance training follows a very similar pattern worldwide. Nevertheless, this study was observational and cross-sectional, with potential for self-selection bias, particularly in case of male dancers, which could account for polarised scores.
Further current longitudinal research is investigating male and female dancers in the same company. This study includes use of DEAQ to validate in its entirety, with monitoring of biometrics, including training load, well-being, injury, menstrual tracking, hormone profiling and dance performance. The outcomes of educational intervention directed at behavioural change will be studied.