Chris Thornham had his training dialed in. He was working with a pro cycling coach and squeezing in 15 hours a week as he prepped for a 100-mile mountain bike race—nothing out of the ordinary for him. But mid-race, things started to go sideways. “I would reach for food and my bicep would cramp. My jaw, hands, my quads, basically every muscle in my body was cramping,” he says. As an endurance athlete, he was no stranger to pain, so he kept on pedaling. But after he crossed the finish line, he sat in the medical tent, shaking uncontrollably. Thornham suspected he might have rhabdomyolysis, a dangerous condition caused by muscle damage, but he wasn’t peeing brown (a tell-tale sign), so he went home. Two days later, still foggy and unable to think clearly, he told his wife, “I think you should take me to the hospital.” He was admitted for four days and pumped full of IV fluids to flush out his system.
What is Rhabdo?
Rhabdomyolysis, or rhabdo for short, is a medical condition that occurs when your muscles take too much damage, too fast. “This breakdown of muscle causes the intracellular contents of the muscles to leak into the bloodstream,” explains Tedd Girouard, director of the athletic training program at University of Nevada Las Vegas. These proteins and electrolytes, when released in large amounts, can overwhelm the kidneys, which “is made up of all these little tubes that filter blood and help us produce urine,” says Girouard, “If the tubes get blocked, the kidney can’t do its job anymore.” This can lead to swelling, increased body weight from water retention, and kidney failure.
The spectrum of rhabdo ranges from mild (think next-level soreness) to life-threatening. Girouard mentions that some athletes likely experience minor cases and recover with rest and hydration, while others develop flu-like symptoms or intense swelling post-working, indicating the condition is worsening. In extreme cases, rhabdo can be fatal. If you’re concerned, the only way to know for sure is to get a blood test for creatine kinase, a muscle protein. Girouard’s advice? if you’re seeing concerning signs, don’t take your chances—seek medical help immediately.
The Warning Signs
The first warning sign of rhabdo is pain that goes way beyond your normal workout soreness, says Alex Rothstein, program coordinator of exercise science at New York Institute of Technology. (In Thornham’s case, it was extreme cramping during his ride.) Another sign? A steep drop in performance. If a usually manageable workout suddenly feels impossible, it’s time to call it. Marathoners or endurance athletes, especially, should pay attention to this: “If you should be moving fast based on your training but now you’re walking and it’s very painful, that would be an early indicator,” says Girouard.
While urine is the hallmark symptom of rhabdo, it’s not always a good gauge. “By the time that you’re starting to experience this with urine—whether you’re having little or very dark urine—it’s a sign you’ve already gone too far,” says Rothstein. In Thornham’s case, he never experienced dark urine, which shows that rhabdo can present differently depending on the person.
Who’s at Risk?
While the condition is quite rare, rhabdo often makes headlines after grueling college sports practices or military training—like an incident at Tufts College that left 9 lacrosse players hospitalized. This is more likely when athletes jump into heavy training at the beginning of the season without enough preparation.
It is also commonly associated with high intensity interval training (HIIT) and group settings, like CrossFit, spin classes, or Navy SEAL training. “With the group mentality, there’s a lot of peer pressure to exercise harder and harder,” says Girouard. So the very thing that makes group classes great—the motivation to push yourself—can also make them risky. This is something that both individuals and coaches should be mindful of: Just because the goal is to complete “as many reps as possible” (AMRAP, a popular CrossFit format) doesn’t mean you should push to the point of collapse.
