Exercise In A Pill

That's how researchers are describing two drugs that apparently mimic the effects of physical exercise on the body, raising prospects of new treatments against diseases, new ways to cheat at sports, and new rationalizations for couch potatoes to stuff themselves at brunch.

In a series of startling experiments in mice, the drugs improved the ability of cells to burn fat and retain muscle mass, and they substantially prolonged endurance during exercise. Using one of the compounds for just a month, even sedentary, couch-potato mice improved their endurance running by a staggering 44%. Some mice that combined a month of exercise with the other drug bolstered their long-distance running by about 70% over untreated mice.

One of the drugs is already in late-stage human trials for other purposes, and the mouse experiments raise hopes for new strategies to protect people against obesity, diabetes and muscle-wasting diseases such as muscular dystrophy.

But underscoring the risks, one of the compounds has been withdrawn from human trials because of toxic side effects, and researchers said that the drugs could easily be abused by competitive athletes to enhance their performance. Researchers have already devised a test to detect them in blood and urine.