Pop a Pill and Get Fit?

Author: Drucilla Dyess

Can you receive the benefits of exercise without working up a sweat? Maybe you can! According to a group of scientists, a pill that captures the endurance-boosting effects of exercise may be in your future.

Ronald M. Evans, Ph.D., of the Salk Institute for Biological Studies and the Howard Hughes Medical Institute in La Jolla, California and colleagues have test two compounds in lab mice with some surprising results. One compound, known as GW1516, boosted the endurance of mice that exercised but did nothing in sedentary mice. Too bad for you couch potatoes! But wait, the other compound called AICAR actually improved the endurance of mice that didn't exercise at all! Now, don't get too excited yet, because these compounds haven't been tested in people and aren't available on the market. However, if researchers are working on a drug test to look for traces of the compounds in the blood and urine of athletes to prevent any future cheating on their part, it could be available sooner than you think.

The research group was first able to create genetically engineered "marathon mice" in 2004 by making a modification to a mouse gene that increased the activity of a protein called PPAR-delta and boosted their endurance. Then the team worked to achieve the same goal without genetic engineering using GW1516, one of a family of compounds that researchers are looking at as obesity and diabetes drugs.

The mice were given GW1516 orally every day for a month to boost PPAR-delta. By the end of the month, mice who had been running daily on their exercise wheels were running 68 percent longer and 70 percent farther but there were no improvements seen in mice that weren't already exercising regularly. This prompted the researchers to focus on a different protein called activate protein kinase (AMPK), a master regulator of cellular and organismal metabolism. They used a drug called AICAR that mimics AMPK, "so muscle thinks it's burning fat," Evans said. AICAR was injected into inactive mice daily for a month to boost AMPK. Once again, at the end of the month, even the lazy mice ran 23 percent longer and 44 percent farther than before getting the injections. Therefore, they got the benefit of improved endurance without working out. Evans explained, "We think AMPK activity is the secret to allowing PPAR-delta drugs to work."

According to the researchers, these results show that the proteins AMPK and PPAR-delta "can be targeted by orally active drugs to enhance training or even to increase endurance without exercise." In a statement, Evans explained that as almost no one gets the recommended 40 minutes to an hour per day of exercise, that for this group of people, if there was a way to mimic exercise, it would make the quality of exercise that they do much more efficient.

Evans noted that prior studies suggest that AICAR might protect against weight gain while on a high-fat diet, which could make it useful in treating obesity, yet it would need to proven safe as it would have to be taken for a long time. Other researchers have studied both drugs for other uses. In fact, the drug that requires no exercise is now in advanced human testing to for it's possible prevention of a complication of heart bypass surgery.

Some experts agree that a drug like AICAR could someday be useful in treating obesity and diabetes, especially since it has been found that AICAR stimulates muscles to remove sugar from the blood in animals. In addition, people who can't exercise due to a medical condition might also benefit from such a drug.

It must be noted that these tests focused only on skeletal muscles and endurance with no concentration on the safety of the drugs or their ability to provide other benefits gained by exercising such as improving cardiovascular health.