Cycling Does Not Weaken Bones

A recent article from France may explain why some top bicycle racers have low bone densities, indicating an increased risk for breaking their bones (The Physician and Sportsmedicine, October 2010). Nobody has ever shown that bicycling or any other type of exercise weakens bones. I discussed this in detail in my 9/12/10 eZine.

We may now have an explanation for the weak bones found in some elite bicycle racers: they could have taken glucocorticoids to help them ride faster. These drugs, taken for just a few days, take calcium out of bones to cause low bone density, osteoporosis and bone fractures. Examples of glucocorticoids include Cortisone, Dexamethasone, Hydrocortisone, Prednisolone and Prednisone.

Female athletes who were not competitive bicycle racers were given 50 mg of prednisone per day for one week and then tested to see how long they could continue cycling at 75 percent of their maximal output (VO2max). They were able to last 66.4 minutes after a course of prednisone, compared to only 47.9 minutes after placebo (European Journal of Applied Physiology, November 2009). That's an incredible 30 percent increase in endurance time.

The limiting factor in how fast you can ride a bicycle or run, ski or skate over long distances is the time it takes for oxygen to get into your muscles. Therefore anything that decreases your need for oxygen will help you to move faster over distance. Sugar requires less oxygen than fat or protein to be converted to energy by your muscles. So anything that causes your muscles to burn more sugar, and less fat, makes you faster. Corticosteroids markedly elevate blood sugar levels. For example, a normal blood sugar is below 100. After taking steroids, your blood sugar can rise over 300.

Glucocorticoids, taken in pills or injections, are banned by the World Anti-Doping Agency (WADA) during competition. Athletes get around the rule restricting corticosteroids by claiming that they have *asthma treated with steroid inhalers, *certain skin disorders treated with steroid creams, or *muscle or joint injuries, immune disorders or diseases treated with steroid creams, pills or injections.

People should take glucocorticoids only if they need them to treat a serious, usually life-threatening disease. Not only can glucocorticoids cause permanent osteoporosis, they also can increase risk for diabetes, high blood pressure, heart attacks and fat gain. They are very different from the anabolic steroids that some athletes take to grow larger and stronger muscles.


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