Studies show that if you want to live a long and healthy life, you need to start exercising. But what if the exercise is hurting you?

A recent study examined three new cases of rhabdomyolysis, or rhabdo for short, that developed as a result of intense physical exercise. Rhabdo is a condition that occurs when the muscles in the body break down and release proteins and enzymes into the bloodstream.

"Many cases of exertional rhabdomyolysis can be mild," says Dr. David Geier, an orthopedic surgeon and sports medicine specialist in Charleston, South Carolina. "Severe cases can lead to kidney failure, heart arrhythmias, blood clotting problems, high potassium levels and compartment syndrome."

Rhabdo is an extremely rare condition — a 2012 study on Army recruits undergoing basic training cited a incidence rate around 0.2 percent. But it can be serious. So when the condition spread into the spinning and CrossFit communities, people began to take notice.

When muscles affected by rhabdo release enzymes and the protein myoglobin into the bloodstream, and as these waste products circulate throughout the body, they can cause swelling, dizziness, fatigue, shortness of breath, chest pain, kidney failure and even cardiac arrest.

Causes and symptoms

CrossFit class Intense exercise that includes very large bursts of energy, like what you might find in a CrossFit class, can cause rhabdo. (Photo: Daxiao Productions/Shutterstock)

A number of factors can cause this kind of muscle breakdown: trauma, drug use and seizures among them. In the cases reported, the subjects were participating in intense exercise that included extreme bursts of energy like what might commonly be found in a spin class or CrossFit workout. In addition, researchers think dehydration might play a role in the development of the condition.

More often than not, people who develop exertional rhabdo are trying to get fit quickly by pushing too hard or too fast in a workout. That's easy to do when the guy next to you is pedaling like a mad man and the instructor up front is pushing you to dig deeper and pedal harder. But it's not just newbie exercisers that fall victim to rhabdo. Case in point: This extremely fit woman developed rhabdo after a particularly intense pull-up workout.

How to keep rhabdomyolysis at bay

The most important thing to know about exertional rhabdo is that it can be prevented by using common sense and good judgment. It's good to feel motivated and to push yourself out of your comfort zone. But you have to know your limits, and when you feel yourself approaching them, it's time to back off.

"Base your workouts on your own fitness level," says Geier. If you're new to spinning or any other type of group fitness class, work out in the beginner's group until you get the feel for the exercise and build up your conditioning. Also, be sure you're drinking plenty of fluids before, during and after your workout, and give yourself a day or two to recover as your body adjusts to the new routine."

Worried you might have pushed it too far? Keep an eye out for these symptoms and if they develop, call your doc ASAP:

  • Extreme muscle soreness. There's a difference between "Ouch, my legs hurt from leg day," and "I'm in too much pain to get out of bed." Be especially wary if those sore muscles are accompanied by swelling or joint pain.
  • Muscle weakness. Can't open the filing cabinet at work? That workout may have been too intense.
  • Cola-colored urine. Workout or not, this is sign something is amiss and you should get checked out immediately.

Remember: Exercise is a good thing. It's supposed to make you feel strong and healthy, not weak and broken. So feel free to put in a good sweat. Just be sure to listen to your body.