It's no secret that sitting for long stretches isn't great for your body. Research has linked it to heart disease, obesity, diabetes, even cancer. But there's another health risk from sitting all day that most people don't know about: gluteal amnesia, or dead butt syndrome. It almost sounds like a joke, but it's not uncommon, says Andrew Bang, a chiropractor at the Cleveland Clinic's Wellness Institute: "I see the injury all the time in varying degrees." Dead butt syndrome develops when the gluteus medius—one of the three main muscles in the booty—stops firing correctly. That can happen if you spend too much time parked in a chair, explains Kristen Schuyten, a physical therapist at Michigan Medicine. "But it can also occur in very active individuals who just don't engage the glute muscles enough," she adds.