Exercise in a Pill?

By Anastacia Mott Austin

If you could take a pill that makes your body think you’ve exercised – toning muscle, synthesizing fat, improving metabolism – would you take the pill instead of exercising?

"Hoo, yeah!" I can hear you shouting from here.

It’s what lazy couch potato people have been sitting on the couch waiting for.

Ronald Evans, a professor at the Salk Institute’s Gene Expression Laboratory, and a researcher with the Howard Hughes Medical Institute, led a team of scientists in studying not one but two drugs that could potentially alter the human response to exercise dramatically.

The study, done on lab mice, was published in this week’s edition of the journal Cell.

"We have exercise in a pill," said Evans to reporters. "With no exercise, you can take a drug and chemically mimic it."

The process to get to this point was fairly involved.

Evans and his team first worked with gene-altered mice, performing an experiment in which they genetically altered muscle fibers in developing mice to contract repeatedly without fatiguing.

Then they tried to mimic the effect by synthesizing a drug that could be used on adult mice whose muscles had already developed.

The drug, called GW1516, seemed disappointing at first, because when tested it had no effect on muscle performance in sedentary mice. There was no difference between mice taking GW1516 and regular mice.

The researchers then used GW1516 on mice who exercised. They compared two groups, both of whom were exercised regularly but only one of whom received the drug. The GW1516 group dramatically outperformed the regular mice, improving on speed and endurance by about 70% each.

But you’re waiting to find out about the part where you don’t have to exercise, right?

After the GW1516 experiment, the researchers continued, trying to find a compound that would mimic these great effects without the exercise.

They tried a compound called AICAR, which proved to be the magic bullet.

With AICAR, mice who had been sedentary were put on a treadmill and compared to mice who had been regularly exercised. The drug-dosed group outperformed the exercise-trained mice, as though they had been training regularly.

This drug works by mimicking energy metabolism, in essence tricking a muscle fiber into thinking it has burned its fuel sources and must burn more.

Said Evans, "It’s a little bit like a free lunch without the calories."

At a time when stats about rising obesity rates assail us in the news every day, and with the depressing news that we need to exercise for an hour a day to keep weight off, a miracle muscle-building, fat-burning pill seems too good to be true. So is it?

Dr. Evans seems to think the drug and its effects can be easily transferred to humans. But other scientists aren’t so sure.

"This is a well-done study with important implications if the same effects hold true in humans," said Dr. Mark Miller, a sports medicine professor at the University of Virginia. "[But it’s] a big if." Sometimes drug effects and lab experiments that work on mice don’t have the same effects on humans.

Still, if it does, the implications could be enormous. People with muscle-wasting diseases or those who are bedridden could benefit and save precious muscle strength. Our rates of obesity could finally start declining, and people could be healthier all around.

But some health experts say that there is no way to replace exercise. "The real issue here is that medication can help condition muscle," said Dr. David Katz, the director of the Prevention Research Center at Yale University School of Medicine, to reporters. "It is a wild and unjustified extrapolation to go from there to the notion that a pill could provide all of the benefits of exercise."

People also need the cardiovascular benefits of exercise, says Katz, to maintain health, and the possible side effects are unknown at this point.

Katz and others also expressed concern about the potential abuse of these drugs by athletes wanting a boost. Evans and his team have already developed a highly sensitive test that can detect either drug in urine, and can use it to test athletes in the upcoming Olympic Games – and Evans says that the drugs are easy to synthesize and may already be in use in some athletes.

While a drug that promises to deliver the benefits of working out without actually having to go through the sweaty pain of actually exercising sounds good, history has taught us that especially in the scientific world, there really is no such thing as something for nothing. Experts urge caution in the further development of either of these drugs.

Says Dr. Katz, "There are inevitably costs, and usually unanticipated toxicities," adding, "What's wrong with getting the benefits of exercise from exercise?"