A pill that can replace exercise? Sounds too good to be true, right? For the time being, it is — unless you’re a lab mouse. (Stupid mice, they get all the cool drugs before we do.) But according to Scientific American, promising test results mean it might not be long before an “exercise pill” is in the works for humans.

So how does it work? “It tricks the muscle into ‘believing’ it’s been exercised daily,” says Ronald Evans, a developmental biologist at the Salk Institute for Biological Studies, in La Jolla, Calif., and co-author of a study published in Cell. “It proves you can have a pharmacologic equivalent to exercise.” (That’s pretty definitive language; usually scientists mumble about the results “suggesting” that something “might” work in humans … but this study proves it? We’re impressed … and maybe a little skeptical, too.) What it does it “reprogram” muscle cells, switching them from being sugar-burning, fast-twitching machines that are built for power and sudden bursts of speed but tire quickly — not so necessary if you’re a desk jockey/couch potato — to fat-burning, slow-twitching muscles that enjoy increased endurance and stamina.

You read right: not only would the pill help you lose weight, it also increases your endurance, meaning that if you do decide to work out (even while taking the pill), like lab mice, you may find you can rock the Stairmaster 40-50% longer without becoming exhausted. (I have a feeling this is going to be a hit with middle-aged men; kill that gut and cancel your Viagra presecription as well.)

The key to this transformation is a protein called PPARdelta, which the team previously showed could create so-called high-endurance “marathon mice” when the animals were genetically engineered to make a lot of it. But, a drug that targeted only PPARdelta—although having metabolic benefits like lowering fatty acids and blood sugar—had no effect on endurance unless the mice were running regularly.

Enter AICAR, which targets a protein called adenosine monophosphate-activated protein kinase (AMPK). AMPK is produced when cells need more energy, as they do when we’re exercising. It also interacts with PPARdelta, effectively turbo-boosting that protein’s activity. So, by using AICAR, the scientists thought they might be able to trick the body into thinking it was exercising.

After four weeks of treatment with AICAR alone, the mice that took it could run on treadmills nearly 1.5 times as long as untreated animals—and without any training.

That does sound too good to be true, doesn’t it? Naturally, some contrarian scientists agree, maintaining that there’s no way a pill can replace the multitude of benefits that actual sweat-through-your-shirt exercise provides your body (not to mention your mental health). Here’s hoping the naysayers are wrong!