Vitamin D has until recently, played second fiddle to calcium – meaning, that vitamin D was best known for its ability to affect calcium levels throughout the body.

Newer research is revealing more of a direct supportive role of vitamin D in muscle strength, function, recovery and even physical and athletic performance.

Interestingly, the hormonally active form of vitamin D (calcitriol) is more representative of an anabolic hormone, than a vitamin when we look at its molecular structure.

Muscle Strength

Vitamin D has been shown to interact with several muscle proteins, suggesting that it promotes muscle cell growth in size and number. One interesting study found a positive association between vitamin D and strength; those people with higher vitamin D blood levels had improved marks on short performance activities and greater muscle strength.

Sports Performance

In regard to sports performance, there are a few additional studies showing how vitamin D can boost sports performance. 

In one study, a group of athletes were given a 5,000-unit dose per day of vitamin D, while another group was given a placebo. The vitamin D group had ‘substantially’ increased vertical jump heights compared to those taking the placebo.

In women of childbearing age, vitamin D supplementation led to improved agility and jump speed in a separate study.

And, another study looked at the relationship between vitamin D levels and the ability to obtain a contract in the National Football league. Researchers noted a significant correlation between players with lower vitamin D levels and release from the team due to poor performance or injury, before the regular season!

Fracture Risk

In a study of young male military recruits, those with lower vitamin D levels (under 20ng/ml) had a much greater incidence of stress fractures than those recruits with higher vitamin D levels. This isn’t the only study that links lower vitamin D levels and stress fractures.

These are just a few of the recent studies showing how adequate blood levels of vitamin D can give athletes a competitive edge, as well as avoiding stress fractures (which can take a long time to heal!)

How to Take Vitamin D

Vitamin D will be more beneficial if taken daily, rather than in weekly or monthly doses. This is important because oftentimes when a deficiency is found, doctors usually prescribe very large doses to be taken at weekly or monthly intervals. Instead of going this rout, opt for a daily dose.

Dosing can be determined after you get a blood test – amounts will of course depend on test results. We usually have people on 5,000 units daily.

You also have to take your location into consideration, although most of us in the continental U.S. could probably benefit from vitamin D supplementation for most of the winter. (But this is why you should get tested at least once a year so you can know – excess vitamin D can certainly cause problems.)

Lastly, I mention these dosing recommendations because it’s tough to maintain adequate vitamin D levels through diet alone. And, if you live in a place that experiences cold and cloud cover in the winter, you’re almost sure to be deficient unless you supplement.