The Effects of 11+ Dance on Physiological Parameters in Adolescent Ballet Dancers: A Randomized Controlled Equivalence Trial.

Introduction: The use of neuromuscular interventions in sports induce meaningful motor performance in strength, sprint and power. The aim of this study was to investigate the effectiveness of the "11+ Dance" exercise program versus normal training (control) on possible adaptations in power, lower-body strength, and inter-limb asymmetry in adolescent ballet dancers. Study Design: Prospective randomized controlled trial. Methods: Dancers (n = 76) from a pre-professional ballet school volunteered for this study. Data from the two trials (pilot and main trials) were combined to protect the results from possible learning effect of the intervention. Participants were randomly assigned to either the 11+ Dance intervention (n = 38) or Control (n = 38). Participants completed at least 21 sessions over 7-9 weeks. The 11+ Dance intervention consisted of neuromuscular-based exercises, whereas the Control group carried out their normal routine. Baseline and post intervention outcome measures included countermovement jump (CMJ), reactive strength index (RSI), isometric mid-thigh pull (IMTP), and inter-limb asymmetry (ASYM). Results: Non-statistically significant improvements were noted for both 11+ Dance and control groups across outcome measures; CMJ F(1, 66) = 3.52, P = .065, ${\eta }_p^2$ = .051 (14% vs 8%), RSI F(1, 65) = 1.02, P = .316, ${\eta }_p^2$ = .015 (6% vs 13%), and IMTP F(1, 67) = 1.7, P = .197, ${\eta }_p^2$ = .025 (23% vs 18%). ASYM (F[1, 63] = .109, P = .743, ${\eta }_p^2$ = .002) (24% vs 15%). No statistically significant interaction for adherence was revealed for all the parameters. Conclusion: The 11+ Dance intervention elicited similar physiological adaptations as the Control group. Larger longitudinal studies are needed to investigate the efficacy of the 11+ Dance on injury incidence and severity as current evidence suggests prophylactic programs such as the 11+ Dance have an effect on injury prevention.