Athletes need to know about the importance of vitamin D and performance. Vitamin D acts more like a hormone in the body than a vitamin. Because of this, researchers think it plays a role in athletic performance; there are handfuls of studies showing an interesting relationship between vitamin D and athletic performance.
Most of us know that vitamin D is manufactured in the body as result of exposure to sunlight. Thus, levels tend to rise in the summer and decline in the fall and winter. A fascinating group of older studies from the 1950’s showed that exposing athletes to ultraviolet light improves athletic performance. An extension of these studies showed that performance is seasonal and reflects blood levels of vitamin D. Performance improves in the summer with higher levels and declines in the winter with lower levels.
In the muscles, vitamin D increases the size and number of fast twitch (Type II) muscle fibers; other studies show that vitamin D levels are directly associated with musculoskeletal function in older individuals. Another reason that we like vitamin D so much is that it can boost immune function. Of course, no one likes getting sick and its even worse when getting ill interferes with training and competition.
Athletes who exercise over 10-15 hours a week are more susceptible to getting ill with respiratory and gastrointestinal illnesses. I have all of my patients on a vitamin D regimen to keep them healthy through the winter.
Optimal levels of vitamin D are considered to be above 50 ng/ml. Maintaining adequate levels may also protect the athlete from several other medical conditions. It is especially important for women to maintain good levels of vitamin D as it protects against reproductive organ cancers as well.
This doesn't mean that you should start supplementing with large amounts of vitamin D. What you should do is get a blood test from your doctor; your goal is a vitamin D level above 50 ng/ml. It’s also important to know that sunscreen, while preventing skin damage, will also block the skin’s ability to manufacture the vitamin. This is why supplementation is so important.
If your doctor hasn't tested your vitamin D levels, ask them to. Its a simple blood test. Remember, you want levels at 50 and above.
Reference: Cannell JJ, Hollis BW, Sorenson MB, Taft TN, Anderson JJ. Athletic performance and vitamin D. Med Sci Sports Exerc. 2009 May;41(5):1102-10.