Three years ago, Christina D'Ambrosio went to her first spin class, pedaling fast on a stationary bike to the rhythms of popular music as an instructor shouted motivation.
But D'Ambrosio, who exercises regularly, found the hourlong class was harder than she anticipated. By the end her legs were sore and wobbly.
"I thought my body just wasn't used to that kind of muscle ache because it was my first class," said D'Ambrosio, a kindergarten teacher from Pleasantville, N.Y.
Over the next two days, her legs throbbed with excruciating pain, her urine turned a dark shade of brown, and she felt nauseated. Eventually she went to a hospital, where she was told she had rhabdomyolysis, a rare but life-threatening condition often caused by extreme exercise. It occurs when overworked muscles begin to die and leak their contents into the bloodstream, straining the kidneys and causing severe pain.
After a two-week hospital stay, D'Ambrosio was released and has since recovered. Her case was highlighted in April in the American Journal of Medicine along with two other cases of spinning-induced rhabdomyolysis treated by the same doctors.
The report noted that at least 46 other cases of people developing the condition after a spin class were documented in the medical literature, 42 of them in people taking their first class. The report cautioned that the condition was very rare, and not a reason to avoid high-intensity exercise. But the authors said their goal was to raise public awareness so that people who begin a tough new workout program will ease into it to lower their risk of injury.
"I would never discourage exercise, ever," said Alan Coffino, the chairman of medicine at Northern Westchester Hospital and a co-author of the new study. "Spin class is a great exercise. But it's not an activity where you start off at full speed. And it's important for the public to realize this and for trainers to realize this."
Rhabdo, as many experts call it, has long been documented among soldiers, firefighters and others whose professions can be physically demanding. An Army study in 2012 estimated that about 400 cases of the condition are diagnosed among active-duty soldiers each year. On occasion there have also been large clusters of college athletes hospitalized with it after particularly grueling workouts.
But doctors say they are now seeing more of it among weekend warriors driven in part by the popularity of high-intensity workouts. Studies show that high-intensity exercise offers myriad health benefits, but for a small subset of people, many of them beginners, rhabdo can crop up and quickly turn ugly.
Two things can help you avoid rhabdo, said Joe Cannon, an exercise physiologist. Before starting a new program, do a less intense version of it first. That means riding a stationary bike at a moderate pace before starting a spin class, or doing just one set of a weightlifting exercise rather than multiple sets and repetitions.
But the most important advice is to know your limits: Don't be afraid to leave a class or to say no to a trainer if you are struggling.
