Not familiar with rhabdomyolysis, or rhabdo for short? Physician and clinical exercise specialist Dr. Charlie Seltzer tells Livestrong.com that it's "the rapid breakdown of muscle tissue, which results in the release of the protein myoglobin into the bloodstream."
It's the same condition that can affect people whose muscles are severely injured in a car crash or even an earthquake. In mild cases, rhabdo may go unnoticed — your body filters out the myoglobin and your muscles heal. But in more extreme cases, your kidneys simply can't handle the myoglobin overload. The protein ends up getting caught in your kidney's filtering system, which can lead to renal failure if left untreated.
And it's not just your kidneys you have to worry about. The condition may also "significantly elevate potassium levels, which can cause irregular heart rhythms," says Dr. Seltzer. Left unchecked, having an irregular heartbeat can be deadly.
As scary as that all sounds, before you retire your indoor cycling shoes for good, here's something to keep in mind: "Any intense exercise can put somebody at risk for rhabdo," points out Dr. Seltzer.
When it comes to spinning, it's less the exercise than the environment that makes it risky. "It's a class setting where people generally push themselves very, very hard," he says. "If somebody is not used to that kind of exercise and does not build up to it, they can get into serious trouble."
Spinning newbies might want to be particularly cautious. According to a study in the _American Journal of Medicine_, of the 46 people documented with rhabdomyolysis in medical literature, 42 developed it after their first spin class. In three of those cases, the condition led to acute kidney injury.
While some people experience muscle weakness, pain and even nausea and vomiting immediately after (or during) a workout, it may take a others couple days to recognize the symptoms. If you notice that you're urine is dark and concentrated (also described as "tea-colored"), in addition to suffering from post-workout pain, you'll want to see a doctor immediately.
So how can you stay fit without putting yourself at risk for rhabdo? Research suggests that drinking alcohol (like, say, the night before a spin class), working out in overheated spaces, being malnourished (which can cause electrolyte imbalances), and taking creatine supplements may all make you more susceptible to rhabdo.
But according to Dr. Seltzer, "The best way to not get rhabdo is to make sure you're hydrated and not pushing yourself harder than you should be."
So even if you're in tip-top shape, you'll want to start slow any time you're trying out a new fitness class, which could be targeting muscles you don't normally use. You've got this!
What Do YOU Think?
How will this news affect your workouts? Will you think twice before pushing yourself to exercise harder in the future? Tell us in the comments!