What Runners Need to Know About Rhabdo

Jump to:What Is Rhabdo?Why Is It So Dangerous?How Running Could Lead to RhabdoWhat Else Could Lead to RhabdoThe Warning Signs All Runners Should KnowShortly after the New York City Marathon, tragic news broke: A 24-year-old runner, Rachel Apa, collapsed on the course and died in the hospital after doctors worked for six hours to save her life, according to the New York Times. Apa’s father told NYT the cause of death was rhabdomyolysis (a.k.a. rhabdo).The news is shocking and saddening—as well as unsettling. Questions are popping up from runners on social media as to how something like this could happen to a young woman who was reportedly a former Division I field hockey player at Bucknell University and had spent months training for the marathon.To help answer some of those questions, we talked to doctors to explain what runners need to know about rhabdo, and how to stay safe.What Is Rhabdo? First, know that rhabdo is relatively rare and dying from it is even rarer. Approximately 26,000 cases of rhabdomyolysis are reported annually in the United States, and the mortality rate starts at 10 percent but may go up to 50 percent in severe cases.In short, rhabdo is a breakdown of muscle that in and of itself is not life-threatening. In fact, Derek M. Fine, MD, a nephrologist at Johns Hopkins Medicine, says that if you were to test creatine kinase (a.k.a. CK, a blood marker of muscle breakdown) in marathon runners after the race, “most” of them would show elevated levels of the enzyme.The Centers for Disease Control and Prevention says that multiple CK tests are the only way to accurately identify rhabdo, though. Normal CK is between 20 and 200 U/L, but rhabdo is diagnosed when it reaches five times the upper limit.“There’s always a little bit of muscle breakdown and the reason is because, at least in [a] marathon, you’re using the muscles so much that at some point they can run out of an energy supply,” Fine says, adding that the mitochondria can't keep up and make enough of what’s called ATP (adenosine triphosphate), which is your primary source of energy.Why Is It So Dangerous? Rhabdo becomes dangerous when it becomes more severe. As muscle tissue breaks down, the body can release harmful substances into the bloodstream, including myoglobin, a protein that can damage the kidneys, and excessive amounts of potassium.As for myoglobin, the protein can get “stuck” in the kidney and cause kidney failure or injury at various levels, Fine says. “It can be quite severe, but that usually takes a little bit of time to manifest,” he explains.Fine says that high levels of potassium are probably a bigger risk than myoglobin. “When the muscle cells break up, you get a very large release of potassium into the bloodstream and that potassium then can cause cardiac arrhythmias,” he says. This can cause kidney failure (your kidneys are the organ tasked with getting rid of extra potassium) or potentially sudden cardiac arrest.“Under normal circumstances, if it’s happening slowly and you’ve got decent kidneys, you pee the potassium out and it never gets that high in the blood,” he says. “If there's severe rhabdo and you have a huge amount of muscles breaking down, you can release a ton of potassium and your body can't get rid of it fast enough.”In addition to the rapid release of these substances, rhabdo can sometimes lead to other issues that resemble sepsis or even multisystem organ failure, Fine says.Still, rhabdo is not a common underlying cause of cardiac arrest, says Lili Barouch, MD, director of sports cardiology at Johns Hopkins Medicine and an endurance athlete herself. However, it can lead to abnormal heart rhythms due to severe electrolyte problems, primarily high potassium. And as Fine also explains, kidney failure (as well as other organ failure) can result in cardiac problems, she says.How Running Could Lead to RhabdoIt’s not just running that can increase risk of rhabdo—any heavy exercise can do damage to muscles, Barouch says, particularly exertional rhabdomyolysis. In fact, Fine says that there have been incidents of rhabdo reported in CrossFit athletes for this reason. Whether it’s a marathon or weight lifting, it’s in high-effort situations that the muscle breakdown can accelerate rapidly and lead to problems.As for running, while training does induce microscopic damage to muscles that later repairs in a stronger way—a positive outcome—many people push harder in a marathon. “For a race, you’re usually going at a much higher level of effort and you’re really pushing yourself to your limit,” Barouch says.This can be true for athletes of any level, but people who aren’t as highly trained who push really hard on race day may be at higher risk, Fine says. “The most common reason [for getting rhabdo] is you’ve got someone who overdoes it and who wasn’t trained enough,” he says. (This was not necessarily the case with Apa, just a potential risk factor for runners in general.)Another risk factor is dehydration, Barouch says. “If someone’s dehydrated, the amount of those muscle breakdown products [your body produces] that can become toxic to the kidneys starts to really go up. You're unable to clear the toxins out of your body fast enough and that can cause more damage,” she says.On the flip side, good hydration can help flush the myoglobin from the kidneys, per Fine. But, he points out that there’s a delicate balance between being over- and underhydrated: “While you’re running a marathon, your kidneys are getting messages from your brain to hold on to water, so if you keep putting water in there, the water dilutes out the sodium in the blood and you can get hyponatremia,” he says. The key: Drink to thirst and take electrolytes during a long or hot race, Fine says.Carbohydrates could help as well. “Part of rhabdo could be if you’re not giving enough carbohydrates and energy [to your body], you can't make ATP [the energy currency you need to perform] and that’s where the muscle could break down,” Fine says.Another factor for marathon runners is environmental conditions. “If it’s a particularly hot day, for example, that seems to be a big risk factor,” Fine says. In fact, there was an unusually large incidence (24 cases) of exertional rhabdomyolysis at the 2022 NYC Marathon, per a study in Nephron Clinical Practice, likely associated with the “unseasonably high heat and humidity” on race day, per the authors.Younger runners may actually be at higher risk of rhabdo, likely because they’re more inclined to take risks and push harder than the older population, Fine says, potentially ignoring signs of rhabdo.What Else Could Lead to RhabdoThere’s also a genetic component to rhabdo, Fine says. So, if you have had rhabdo before, or have a family member who has had rhabdo, it could be worth looking into your own risk more closely.It’s not super common, but genetic tests look at certain markers that might suggest someone is more susceptible to rhabdo. “It’s not like you're going to say, ‘Okay, I’m going to run a marathon, I’m going to go do prescreening genetic testing,’” Fine says. “But in someone who may have had this before, even if they said, ‘Well, I did CrossFit and I got rhabdo and I'm now going to try to run a marathon,’ that sort of person may be worth checking.”Finally, certain medications (including statins and certain antidepressants) and underlying conditions (like McArdle disease and Duchenne muscular dystrophy) might predispose someone to rhabdo, Barouch says.The Warning Signs All Runners Should KnowThe experts agree that signs of rhabdo can be hard to identify because aches are pretty much unavoidable when running a marathon. Still, severe pain in the working muscles (e.g., the legs) is a red flag, Fine says, as are muscle weakness and swelling.“Of course during a marathon, people tend to have muscle pain, but if it’s much more severe than usual or much more severe than expected,” that’s what to watch for, per Barouch. Severe muscle soreness after the race is also something to keep an eye on, she adds.Another thing to look out for is urine color. “What one might see early on is very sort of dark orange, rust-colored urine, and that’s the myoglobin coming out,” Fine says. “If someone’s got muscle pain and their urine’s orange, they probably want to go and get checked out and maybe get hydrated and get a CK level checked in an emergency room.”Per the CDC, the earlier you get treated, the more likely you’ll recover without long-lasting or permanent health effects, so don’t wait if you suspect you have rhabdo.At the end of the day, it comes down to listening to your body. “As endurance athletes especially, we tend to push ourselves really hard for a race because we have personal goals, time goals, things like that, but you still have to listen to your body,” Barouch says.If something feels off, don’t ignore it. “Marathons are not comfortable to run for anybody, but if your muscles seem extremely painful or if you start to have other symptoms, if you’re having breathing problems, chest problems, things like that, that seem out of the ordinary, [do] not ignore those warning signs either for rhabdo or another medical condition that might be building up,” Barouch says.