Athletes who participate in indoor sports such as ice hockey, basketball, volleyball, squash, and swimming are at obvious risk of being vitamin D deficient because they are inside so much. But is participating in an outdoor sport any better?

Do indoor sports cause bone deformity?

Let’s start with the obvious. A 1987 German study measuring the vitamin D levels of gymnasts confirmed what we would expect. Indoor athletes are very likely to be vitamin D deficient.

In fact, 33% of the athletes had vitamin D levels so low that they were at risk for developing rickets, a severe form of vitamin D deficiency that affects the body’s ability to absorb calcium and causes horribly deformed bones.

The authors X-rayed the gymnasts and found 19 or the 85 athletes studies had visible signs of bone deformity consistent with adult rickets.

Outdoor athletes fare no better.

A similar Finnish study compared the Vitamin D levels of female gymnasts to female long distance runners. You would think that the athletes who are outside all the time would be protected from low levels of vitamin D. They were not. Strangely enough, the outdoor athletes were as deficient as the indoor athletes. To make matters worse, 67% of the young women had dangerously low levels of vitamin D.

Bone damage does not sideline competitive women

You would think as the vitamin D levels became low affecting bone formation that these athletes would not be able to compete, but they soldier on. Unfortunately, the authors were not concerned about athletic performance. So we don’t know if the girls with low levels of vitamin D performed better as their levels of vitamin D levels were raised.

Being in a sunny climate doesn’t seem to help much

It’s easy to dismiss these studies by thinking you are protected by living in a sunnier climate than Finland or Germany, or that you are an outdoor athlete. Think again.

A study of indoor and outdoor athletes in the Middle Eastern country of Qatar showed that 91% of the athletes studied had blood levels of 25 Hydroxy Vitamin D below 20 ng/ml. Close to 60% of these athletes also had lowered bone density putting them at risk for stress fractures and other injuries.

Vitamin D is the repair hormone

There is some thinking that vitamin D is the “repair hormone” and athletes need more vitamin D because of the extreme wear and tear caused by training and competing. While this hypothesis has not been proven, it makes some sense in light of the consistently low levels of vitamin D found in athletes.

TAKE ACTION! Get your 25 Hydroxy Vitamin D level checked by your doctor. If you are away at school already, you can order a home test kit from ZRT labs. You should get tested twice a year, once in late August, when you levels will be at their highest, the other in early March when your natural stores will be depleted and at their lowest.

Optimal range for an athlete is between 50-100 ng/ml with the sweet spot between 60-70. This is much higher than most doctors feel is necessary, but with the extreme stress a DIII woman athlete is under, it’s better safe than sorry. There is not much benefit shown above 80. Vitamin toxicity only begins to show up when blood levels are above 200 for an extended period of time.