Exercise in a Pill?

Scientists have discovered what could be the ultimate workout for couch potatoes: exercise in a pill.

In experiments on mice that did no exercise, the chemical compound, known as AICAR, allowed them to run 44 percent farther on a treadmill than those that did not receive the drug.

The drug, according to the researchers, changed the physical composition of muscle, essentially transforming the tissue from sugar-burning fast-twitch fibers to fat-burning slow-twitch ones—the same change that occurs in distance runners and cyclists through training.

According to the study, published Thursday in the journal Cell, the researchers said the drug's fat-burning ability could also help reduce weight, ward off diabetes and prevent heart disease—the benefits of daily aerobic activity without the perspiration.

It is unknown if the drug has any benefit for athletes who actually work out—or any human for that matter, because the research has so far only involved mice.

Lead researcher Ronald Evans, a molecular physiologist at the Salk Institute for Biological Studies in La Jolla, Calif., said he already has been contacted by dozens of athletes and overweight people who have heard about his research from lectures he has given on the subject.

Evans said he has notified world anti-doping officials, who are scrambling to implement a test for it before the Beijing Olympics start next week.

The compound, which is naturally produced in tiny amounts in human muscle cells and has been studied for decades, is readily available through Web sites that cater to researchers. One site was offering it for $120 a gram.