She went to the ER where doctors diagnosed her with rhabdomyolysis, a serious and potentially fatal condition in which a person’s muscle breaks down quickly, releasing a damaging protein in the blood. It’s rare but it can cause severe kidney damage or even kidney failure, according to the U.S. National Library of Medicine.
Lauren’s story ended up in a case report published in the American Journal of Medicine, along with two other women who developed rhabdomyolysis after taking a spin class. Each time the condition occurred, it happened after a woman took her first spin class—and one woman’s kidneys were so damaged, she had to go on dialysis for a month
High-intensity exercise puts people at risk for rhabdomyolysis because the condition occurs after the body’s muscles are injured, as can happen when you’re going all-in at the gym. “The muscle fibers get injured, die, and enter the bloodstream,” explains women’s health expert Jennifer Wider, M.D. As a result, a person typically feels intense muscle pain, usually in the shoulders, thighs, or lower back, difficulty moving their arms or legs, and decreased or dark-colored urine. However, Wider says the symptoms can vary depending on the type of injury and the area that’s injured—some people have no muscle-related symptoms at all.
Wider calls rhabdomyolysis “dangerous,” adding, “the muscles are actually injured, broken down, and release the enzyme myoglobulin and creatinine kinase into the bloodstream, which can injure the kidney.”
While that’s a scary concept, you shouldn’t avoid taking up spinning for fear you’re going to damage your kidneys. Wider says it’s “unlikely” rhabdomyolysis will happen to you, but points out that it’s becoming more common with hardcore exercise programs. That’s why she recommends easing into new workouts, giving yourself time to recover between exercises, and exercising in a healthy and safe way. Basically, don’t try to become the queen of SoulCycle overnight if walking has been your go-to exercise. Follow that advice and you should be fine.