The importance of vitamin D for bone health is now well-recognized, and the epidemic of vitamin D insufficiency and deficiency is thought to contribute to a wide range of medical conditions including cancers, mood disorders, autoimmune conditions, cardiovascular disease and more.1 As such, vitamin D sufficiency (25(OH)D greater than 30 ng/ml) is associated with a reduced risk of death from all causes.2,3
In addition to bone, vitamin D receptors are present in almost all cells of the body, including muscle cells. Vitamin D’s primary function is the regulation of calcium transport and metabolism – since calcium transport is an integral part of muscle contraction and relaxation, vitamin D is extremely important for proper muscle function. There is also evidence that achieving vitamin D sufficiency may help to increase muscle mass. In the early 20th century, observations led athletes and trainers to believe that sunlight exposure could enhance athletic performance. Athletic performance has been reported to vary seasonally, peaking in the summer; positive effects of UVB exposure on athletic performance were reported as early as the 1930s. There is speculation that improved vitamin D status is the reason for these findings.4,5
Previous studies have shown that vitamin D status correlates with muscle function in the elderly, and that vitamin D supplementation improves muscle strength in elderly and/or deficient populations.6-9 New research is beginning to extend these findings to physical performance in athletes. Since there is a high prevalence of vitamin D insufficiency overall, and vitamin d is crucial for bone and muscle function, does vitamin D status affect injury rates or performance in athletes? Two studies on professional ballet dancers suggest that it does.
Indoor athletes are likely to have insufficient vitamin D levels.5,10 The first study showed that this was true of ballet dancers in a UK company; on average, their vitamin D status was insufficient (<30 ng/ml) all year round and varied seasonally. In the winter, dancers averaged 14.9 ng/ml (deficient), and in the summer, 23.9 ng/ml (insufficient). The authors also observed a greater occurrence of injuries in the winter months.11 The follow-up study provided vitamin D3 supplements (2000 IU/day) to some of the dancers during the winter, and investigated muscle function and injury rates. In the vitamin D group, there were increases in isometric strength and vertical jump height, plus significantly fewer injuries compared to the control group.12
This is consistent with a previous study of UK athletes, which compared 5000 IU vitamin D for 8 weeks to placebo. The researchers saw increases in sprint times and vertical jump height in the vitamin D group, but not in the placebo group.13
These results suggest that vitamin D’s beneficial effects on bone and muscle physiology can translate into enhanced athletic performance. Achieving sufficient blood vitamin D levels (25(OH)D of 30-45 ng/ml) is crucial for the health of the entire body, not just for preventing osteoporosis.
Image credit: Flickr - TooFarNorth
1. Holick MF, Chen TC: Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr 2008;87:1080S-1086S.
2. Melamed ML, Michos ED, Post W, et al: 25-Hydroxyvitamin D Levels and the Risk of Mortality in the General Population. Arch Intern Med 2008;168:1629-1637.
3. Zittermann A, Iodice S, Pilz S, et al: Vitamin D deficiency and mortality risk in the general population: a meta-analysis of prospective cohort studies. Am J Clin Nutr 2012;95:91-100.
4. Hamilton B: Vitamin d and athletic performance: the potential role of muscle. Asian J Sports Med 2011;2:211-219.
5. Cannell JJ, Hollis BW, Sorenson MB, et al: Athletic performance and vitamin D. Med Sci Sports Exerc 2009;41:1102-1110.
6. Glerup H, Mikkelsen K, Poulsen L, et al: Hypovitaminosis D myopathy without biochemical signs of osteomalacic bone involvement. Calcif Tissue Int 2000;66:419-424.
7. Sato Y, Iwamoto J, Kanoko T, et al: Low-dose vitamin D prevents muscular atrophy and reduces falls and hip fractures in women after stroke: a randomized controlled trial. Cerebrovasc Dis 2005;20:187-192.
8. Bischoff HA, Stahelin HB, Urscheler N, et al: Muscle strength in the elderly: its relation to vitamin D metabolites. Arch Phys Med Rehabil 1999;80:54-58.
9. Bischoff-Ferrari HA, Dietrich T, Orav EJ, et al: Higher 25-hydroxyvitamin D concentrations are associated with better lower-extremity function in both active and inactive persons aged > or =60 y. Am J Clin Nutr 2004;80:752-758.
10. Peeling P, Fulton SK, Binnie M, et al: Training environment and Vitamin D status in athletes. Int J Sports Med 2013;34:248-252.
11. Wolman R, Wyon MA, Koutedakis Y, et al: Vitamin D status in professional ballet dancers: Winter vs. summer. J Sci Med Sport 2013.
12. Wyon MA, Koutedakis Y, Wolman R, et al: The influence of winter vitamin D supplementation on muscle function and injury occurrence in elite ballet dancers: A controlled study. J Sci Med Sport 2013.
13. Close GL, Russell J, Cobley JN, et al: Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function. J Sports Sci 2013;31:344-353.