The influence of winter vitamin D supplementation on muscle function and injury occurrence in elite ballet dancers: A controlled study

Objectives: Athletes who train indoors during the winter months exhibit low serum 25.rhydroxyvitamin D [25(OH)D] concentrations due to a lack of sunlight exposure. This has been linked to impaired exercise performance. The purpose of this study was to assess the effects of oral vitamin D-3 supplementation on selected physical fitness and injury parameters in elite ballet dancers. Design: Controlled prospective study. Methods: 24 elite classical ballet dancers (intervention n = 17; control n = 7) participated in a controlled 4-month oral supplementation of vitamin D-3 (2000 IU per day). Isometric muscular strength and vertical jump height were measured pre and post intervention. Injury occurrence during the intervention period was also recorded by the in-house medical team. Repeated measures ANOVA and Mann-Whitney-U statistical tests were used and significance was set at p <= 0.05. Results: Significant increases were noted for the intervention group for isometric strength (18.7%, p <0.01) and vertical jump (7.1%, p < 0.01). The intervention group also sustained significantly less injuries than the controls during the study period (p < 0.01). Conclusions: Oral supplementation of vitamin D-3 during the winter months has beneficial effects on muscular performance and injury occurrence in elite ballet dancers. (C) 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.