Pilot Study of Bone Turnover Biomarkers, Diet, and Exercise in Elite Female Ballet Dancers.

Introduction: Elite ballet is one of the most demanding physical activities for the skeleton, making dancers susceptible to bone stress injuries. This pilot study compared bone remodeling in professional female ballet dancers from the Royal Ballet Company with controls from Imperial College London. Methods: The study included dancers (n = 5, median age 29 ± 16 years) and controls (n = 6, median age 24 ± 8.5 years). The main outcome measure was bone turnover, assessed by measuring the ratio of resorption (NTX) and formation (P1NP) markers in urine and serum. Estrogen metabolism was evaluated through 2OH/16OH metabolite ratios. Both markers were measured using ELISA kits. Diet was tracked using 72-hour diaries, and weekly exercise hours were recorded through 2-week diaries and cross referenced with training logs. Results: Results showed significantly higher bone resorption to formation ratio (NTX/P1NP) in dancers versus controls (P < .050), and elevated estrogen metabolite ratios (2OH/16OH) (P < .010). These findings occurred despite similar dietary profiles between groups including fat (P = .874) carbohydrate (P = .501) and protein (P = .099). Dancers showed significantly higher weekly exercise hours (46.50 ± 38.75 vs 14.75 ± 11.75 hours/week, P < .001) and lower BMI (18.36 ± 1.35 vs 20.77 ± 3.66, P = .020). Conclusions: The pilot data suggest elite ballet dancers may exhibit an imbalance in bone remodeling with high resorption and low formation relative to controls. This imbalance in bone turnover markers could serve as a screening tool for identifying dancers at increased risk of bone stress injuries. The NTX/P1NP ratio could potentially offer a low-cost, non-invasive approach to identify at-risk dancers early and implement preventative measures. Further research and longitudinal trials are needed to test whether these markers can predict bone stress injury risk.