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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 the 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.


Dear Dr. Mirkin: Can changing my diet late in life lower cholesterol and prolong life?

Yes, a study from the University of Maryland shows that eating a healthful diet after age 70 increases your chances of reaching 80 by 24 percent (Journal of the American Dietetic Association, February, 2011).

The study followed 2,582 people ages 70 to 79 for 10 years. They were categorized as 1) those who ate a healthful diet of mostly fruits, vegetables, fish, poultry, whole grains, and nuts; 2) those who ate high-fat (dairy and meat); and 3) those who ate a lot of sugar and flour (doughnuts, cakes, cookies, etc.) Meat and cheese are rich sources of calories, saturated fat and cholesterol that increase risk for heart attacks and strokes. Sugared drinks and foods made with sugar or flour raise blood sugar and are also sources of excess calories that increase risk for diabetes and heart attacks. Compared to those who ate a healthful diet, the high-fat eaters were 40 percent more likely to die, and the high-sugar group was 37 percent more likely to die.


Reports from

Principles of training
Good and bad fats
CRP measures inflammation


Dear Dr. Mirkin: Can salt restriction increase risk for diabetes in exercisers?

Severe salt restriction can prevent cells from responding to insulin to cause diabetes, according to a study in Metabolism (Epub October 29, 2010). 152 healthy men and women were put on either a low or high-salt diet for a week. Those on the low-salt diet had much higher levels of aldosterone, renin and norepinephrine hormones (which raise blood pressure), and were less able to respond to insulin.

Many doctors recommended salt restriction even to those who do not have high blood pressure. This is probably good advice for people who do not exercise regularly, but athletes and serious exercisers know that they cannot recover from hard exercise without replacing the salt they lose in sweat. If you fail to replace salt, especially when exercising in hot weather, you will tire earlier and risk dehydration, muscle cramps and injuries. This study shows that you may also be increasing your risk for diabetes. More


Recipe of the Week:

Golden Lentil Soup

You'll find lots of recipes and helpful tips in The Good Food Book - it's FREE

February 13th, 2011
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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