‘Couch potato’ exercise pill

“Scientists have invented a drug that keeps you as fit as an athlete without having to flex a muscle,” the Daily Express reported. Mice that had never exercised could run for 44% longer when given the drug, while another drug enabled them to run 76% further when they also exercised. In addition to being a “couch potato’s dream” (Daily Mail ), The Independent called it “a new threat to the Beijing Olympics” as the drugs could “potentially boost the performance of endurance athletes”.

It is important to point out that these chemicals have only been tested on mice, and their effects in humans may not be the same, and may have serious side effects. The chemicals are not readily available to the public. If athletes do manage to get hold of them, they should realise that they are risking not just their reputation, but also their health. It is also misleading to suggest that couch potatoes can take a pill that gives them the full benefits of exercise. Although the chemicals enhanced athletic ability in mice, they have not been shown to have the other beneficial effects of exercise, such as weight loss and reduction of the risk of various diseases.

Where did the story come from?

Dr Vihang Narkar and colleagues from the Salk Institute and other research institutes in the US and South Korea carried out the research. The study was funded by the Howard Hughes Medical Institute, Hilblom Foundation, and National Institutes of Health. The study was published in the peer-reviewed scientific journalCell.

What kind of scientific study was this?

This was an experimental laboratory study looking at the effects of two different chemicals, AICAR and GW1516, on exercise endurance in mice. Both these compounds target related chemical pathways in cells, and the researchers wanted to know if these pathways were involved in exercise endurance.

The researchers first took a group of 36 male mice and randomly divided them into four groups. The first group was not exercised (was sedentary) and was not given any drugs. The second group was also sedentary, but was given GW1516 by mouth. The third group was exercised (on a treadmill) and not given any drugs, and the fourth group was exercised and given GW1516.

Before treatment started and after four weeks of these treatments, six mice from each group had a treadmill test to see how far they could run, and for how long. The muscles in the remaining mice in each group were examined for changes in which genes were expressed or for changes in muscle structure.

The researchers carried out a similar experiment, where they injected sedentary mice with the chemical AICAR or a control substance and tested their performance before and after four weeks of treatment. They also carried out experiments where they gave mice GW1516, AICAR or both for six days, and then looked at which genes were switched on in the mice’s muscles.

What were the results of the study?

The researchers found that treating sedentary mice with GW1516 switched on genes which are involved in metabolism, but that it did not alter their muscle fibres or improve their endurance in the treadmill test. However, when the mice received both GW1516 and exercise training, it caused changes in gene expression, as well as in their muscle fibres, and increased their treadmill running time by 68% and running distance by 70% compared with mice who had exercise training but no GW1516.

Treating sedentary mice with AICAR switched on similar genes to those activated with GW1516 and exercise, and reduced the mice’s body fat without changing their weight. In addition, AICAR-treated sedentary mice ran 23% longer and 44% further than untreated sedentary mice on the treadmill test.

What interpretations did the researchers draw from these results?

The researchers conclude that they have identified chemical pathways that can be targeted by drugs taken orally. The drugs can improve the effects of exercise and can increase endurance without exercise. They say that drugs which mimic the effects of exercise have potential for use in treating muscle diseases and obesity.

What does the NHS Knowledge Service make of this study?

These complex experiments further the understanding of the biochemical pathways involved in developing endurance. Developing drugs that target these pathways may well provide treatments for human diseases in the future, but this is still a long way off. This study did not assess the safety of the compounds tested, and they may not prove to be safe for testing in humans, or to have the same effects on endurance.

Although these drugs improved endurance, they may not have the other benefits of exercise, such as weight loss and reduction in risk of various diseases. In particular, the authors specifically noted that the drugs did not affect the mice’s weight. Therefore, it is premature to suggest that these drugs could be the antidote to a couch potato lifestyle.

Sir Muir Gray adds...

Who needs a pill when there is a pavement outside?