Dance exposure, individual characteristics, and injury risk over five seasons in a professional ballet company

Abstract

Purpose: To describe the relationships between dance exposure, dancer characteristics, and injury risk across five seasons in a professional ballet company. Methods: Dance exposure time and clinician-reported time-loss and medical attention injury data were prospectively collected from 118 professional dancers of The Royal Ballet between 2015/16 and 2019/20. Cox proportional hazards and shared frailty models were fitted to overuse and traumatic injuries; individualized robust Z-scores for 7-day and 28-day accumulated exposure, and week-to-week change in exposure, age, sex, company rank, and injury history were included as time-varying covariates. Results: Across 381,710 h of exposure, 1332 medical attention and 427 time-loss injuries were observed. Positive relationships were observed between week-to-week change in exposure and overuse time-loss (+1 Z-score hazard ratio (HR): 1.27, 95% confidence interval (CI): 1.06-1.53) and medical attention injury risk (+1 Z-score HR: 1.17, 95% CI: 1.06-1.28). A negative relationship was observed between 7-day accumulated exposure and overuse medical-attention injury risk (+1 Z-score HR: 0.74, 95% CI: 0.66-0.84). Overuse time-loss injury risk was greater in soloists compared to the corps de ballet (HR: 1.47, 95% CI: 1.01-2.15), and in dancers with a higher previous injury rate (+1 injury·1000 h-1 HR: 1.06, 95% CI: 1.02–1.10). Only age was associated with traumatic time-loss (+1-year HR: 1.05, 95% CI: 1.01-1.09) or medical attention injury risk (+1-year HR: 1.04, 95% CI: 1.01-1.07). Conclusion: Professional ballet companies should implement training principles such as periodization and progression, particularly in the case of senior-ranking dancers, older dancers, and dancers with high rates of previous injury. These findings provide a basis for future prospective investigations into specific causal injury pathways.