Lots of ideas for receiving the benefits of exercise without actually, you know, exercising have come and gone in the last 50 years. So it’s worth being a little skeptical about this one: mice, when given a certain molecule, could run 100 minutes longer without any training.

The usual caveats apply: this is a mouse study, and we haven’t tested the drug in humans. But scientists hope that this compound — called GW1516, or GW for short — can be turned into a medicine that provides benefits for people who have trouble exercising. (By this, they mean people who have heart conditions or other physical limitations, not just the lazy among us.)

What’s exciting here, though, is that GW comes from our knowledge of genetics. See, scientists already know that it’s possible to genetically engineer mice to run a lot longer than normal mice without getting tired. Activating this gene, called PPAR delta, has other benefits, too. It’s harder for these mice to gain weight, and they respond well to insulin — so they’re less likely to become diabetic. All of these are benefits of being fit, because normal exercise activates PPAR, too. But you can’t run around genetically engineering a hyper-fit population — so figuring out how to get the benefits from a drug is clutch. In a study published today in the journal Cell Metabolism, scientists injected mice with GW for eight weeks. The compound activated the PPAR gene, and the mice treated with it got benefits just like the genetically engineered ones did.

All of the mice used in the experiment were sedentary, and the scientists first gave them tests to see how long they could run without getting exhausted; they defined “exhaustion” as blood sugar dropping below a certain level. By the end, mice in the control group ran about 160 minutes before they became exhausted. But mice who took the drug could run for 270 minutes.

The team also took a look at other differences in the mice who got the molecule versus the ones who didn’t. Genes that break down fat for energy did more work in the mice with GW. At the same time, genes that beak down carbs for energy did less work. This makes sense, because it’s exactly what happens in real life: the bodies of really fit people typically burn fat for fuel instead of carbs.

All this said, the mice that took the molecule didn’t have any better muscles than the ones that didn’t, so it seems like the benefits come from changing how their body breaks down energy. It’s all early days for this research, but if this finding pans out in humans, it could be very good news for people who are sick and very bad news for gyms.

This story was originally published on May 2, 2017 and has been updated with video.