Physiological Parameters Of Bone Health In Elite Ballet Dancers

Abstract

Stress fractures are common among elite ballet dancers whereby musculoskeletal health may be affected by energy balance and overtraining. PURPOSE: To characterize bone health in relation to stress fracture history, body composition, and eating disorder risk in professional male and female ballet dancers. METHODS: A single cohort of 59 professional ballet dancers (M=30, 24±6yr; F=29, 23±5yr) was recruited. All participants underwent bone and body composition measures using dual-energy-xray-absorptiometry (DXA). A nutritional screen and stress fracture history was also collected. Aged-matched Z-scores were calculated for bone mineral density (BMD) and body composition. A 1x3 ANOVA and Chi-Square test was used to compare BMD and frequency for history of stress fractures for those scoring 0-1, 2-6, and 7+ using the EAT26 questionnaire for eating disorder risk. Regression was used to predict BMD from body composition and demographic information. RESULTS (Table): Female dancers demonstrated reduced spinal (42nd percentile, 10%Z<-1) and pelvic (16th percentile, 72%Z<-1) BMD. Several anthropometric and demographic measures were predictive of BMD (p<0.05, r2=0.66-0.90, SEE=0.08-0.10g/cm2). Those with a 7+ EAT26 score were observed to have a higher frequency for history of stress fracture (p<0.05). Higher EAT26 scores were also associated with lower total and spine BMD. CONCLUSIONS: Professional female ballet dancers exhibit reduced BMD (particularly in the pelvis) and body mass compared to the general population whereby low BMD and stress fractures tend to be more prevalent in those with a higher risk of disordered eating. When considering only total BMD, regions of high BMD (legs) were found, in some cases, to mask areas of low BMD (spine, arms, pelvis). Lastly, anthropometric and demographic variables are predictive of BMD in this population and may be used as a field proxy in the absence of DXA.