Women athletes can manipulate menstrual cycle


Q. My roommate claims women athletes can improve their endurance by taking drugs that will change their menstrual cycles. Just how does that work?

A. Female athletes may have greater endurance in the last part rTC of their menstrual cycle than in the first. Using that information, a gynecologist can manipulate the periods of a woman who normally has regular cycles by prescribing pills containing progesterone, a female hormone, for 10 days -- 35 days before her athletic event.

This procedure will cause the athlete to menstruate a few days after she stops taking the pills. The athletic event will then take place around 20 days after she starts to menstruate -- just when her endurance should be at its highest.

Muscles need fuel for energy which they get from fat and sugar, which is both stored in muscles and circulating in the bloodstream. The most important fuel for exercise is a sugar called glycogen, stored in muscle fibers. When your muscles run out of their stored glycogen, they hurt and become hard to coordinate. Increasing your storage of muscle glycogen increases endurance.

Women have the most glycogen in their muscles after one of their ovaries releases an egg. So, world-class female athletes who want to ensure they possess the greatest amount of endurance for an important competitive event should compete on the 20th to 25th day of their menstrual cycle, after the egg is released and before they start their next period.Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine and associate dean for faculty affairs at the school.

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