You’ve most likely heard of CrossFit, the popular and, yes, way hard workout program that promises to get you into super great shape in a short amount of time by focusing on high-intensity interval training. But even though it’s such a crowd favorite these days, there actually haven’t been any scientific studies to see if the program works…until now.

Researchers at the University of Wisconsin-La Crosse’s exercise physiology program tracked 16 healthy volunteers who did two CrossFit workouts, Donkey Kong and Fran (side note: obsessed with those names). The results? The women burned just over 12 calories per minute, and maintained an “elevated heart rate throughout the entire workout,” which is basically a fancy fitness way of saying that they passed the test—that is, they satisfied fitness industry guidelines for cardio workouts.

But here’s the thing: Even though it’s now scientifically proven that CrossFit boosts endurance, we wouldn’t be able to sleep at night if we told you to jump blindly on the CrossFit bandwagon if you’ve never done it before. Why? CrossFit is hard—like, really hard.

For one thing, it was recently linked to rhabdomyolysis, a scary medical condition resulting from pushing yourself too hard. And the lead researcher of the CrossFit study, John Porcari, head of the University of Wisconsin’s Clinical Exercise Physiology Program, even said that its intensity is “off the charts.”

That said, we’re obviously in favor of a good workout, so if you choose to go down the CrossFit road, 1) props, and 2) be sure to take care of yourself in the process. Oh, and 3! Check out our fun on-the-road CrossFit workout so you can exercise wherever you are!