Researchers at the Salk Institute for Biological Studies in California, led by prominent researcher Dr. Ronald M. Evans, have found two drugs which mimic the effects of exercising on mice, and expected to work the same way on humans. The drugs trigger changes which are typically following physical exercise and ultimately lead to improved muscle functioning and energy-burning abilities of the body.

One drug, codenamed GW1516, increased the mice's running time by 68 percent and distance by 70 percent. The second drug, AICAR, increased running time by 23 percent and distance by 44 percent. The AICA ribonucleotide is an intermediate in the generation of inosine monophosphate.

Although the discovery seems too good to be true, Dr. Ronald M. Evans is a prominent and well-respected researcher who studied for a long time the effects of hormones on muscles. In 2004, Dr. Evans and his team announced that they tweaked a gene called PPAR-delta, a master regulator of many different genes, managing to produce mice which were capable of twice the endurance of normal mice.

Subsequently, they focused on tweaking the activity of the gene with drugs, which is exactly what they accomplished. They found out that several drugs already available influenced significantly the way the body tunes its muscles. Of these, AICAR has been around for many years and is thus relatively safe for humans. It is owned by drug maker Schering-Plough Corp., which is trying to use it as an intravenous infusion for the prevention of ischemia-reperfusion injury, a complication of bypass surgery.

The researchers rushed tests to the World Anti-Doping Agency, which prepares a list of forbidden substances for the International Olympic Committee. Allegedly, they are working on implementing tests before this year's Olympics.

The primary beneficiaries of the drugs could be people who are unable to exercise during long hospital stays, those who are bedridden and those who cannot exercise for other reasons. Also, diabetics and obese people are other potential targets.

There are other benefits to doing actual exercise, which are unlikely to be reproduced by the "exercise pills," if they ever get approved. Exercising reduces mental stress, strengthens bones and can help improve cholesterol levels and lower blood pressure. It is unclear how the most important muscle, the heart, reacts to these drugs which trick the body into changing muscle behavior.

Recently, researchers discovered that mice fed with a diet supplemented with resveratrol did not live longer than other mice but were far healthier in several important measures. Resveratrol, found in red wine (also found in the crust of peanuts and walnuts, in grapes, blueberries, peanut butter, pistachios and other foods) seemed to ward off the effects of age on heart, bones, eyes and muscle of mice, improving conditions that make the elderly very frail like cataracts, osteoporosis and poor motor coordination.