4 Things You Didn’t Know About Rhabdomyolysis (aka Rhabdo)

Kristen Domonell Fact Checked
A photo of people during a spin class
© Santi Nuñez / Stocksy United

In recent years, a weird-sounding condition called rhabdomyolysis got a lot of attention as a scary — and possibly lethal — side effect of very intense workouts like CrossFit. If you were a consistent member of your intense-training gym, it might have rightfully caused some nervousness. If that’s not your scene, you probably moved on with your life. 

But recently, reports of rhabdo for people participating in less hardcore activities, like spin classes, are making a lot of fitness fanatics wondering: “Could rhabdo happen to me?”

What is Rhabdomyolysis?

Rhabdomyolysis, also known as rhabdo, is essentially muscle breakdown. When you exercise, some muscle breakdown is normal, and part of the process of getting stronger, explains Dr. Nayan Arora, a nephrologist at UW Medical Center – Montlake.

But when people overstress their muscles, they risk the muscle tissue breaking down so much that it releases the protein myoglobin into the bloodstream. Myoglobin is toxic to the kidneys, which is why rhabdo can lead to kidney damage or complete kidney failure if left untreated, Arora explains.

Rhabdomyolysis was first described by doctors treating people with severe crush injuries during the First and Second World War. They found that many patients who survived the crush injury often died several days later of kidney failure. Examination of their kidneys found the renal tubules were choked with myoglobin.

This finding led them to treat victims of crush injuries with fluids to prevent myoglobin and other toxins from accumulating in the kidneys. This remains the standard treatment today.

Symptoms of rhabdomyolysis include muscle pain, muscle weakness and darkened urine. And while rhabdo is serious — and seriously terrifying — Arora says it’s still pretty rare. That means you shouldn’t let it stop you from exercising, but having it on your radar is good. 

Here are four things to know about rhabdomyolysis:

1. It’s not just from hardcore workouts.

Arora says there has been a slight uptick in cases of exercise-related rhabdo, likely because of the rise in popularity of grueling workouts, from high-intensity interval training to spinning and ultrarunning. But muscle exertion isn’t the only cause.

Rhabdo can be caused by anything that results in muscle damage, including trauma and crush injuries, use of prescription drugs, such as statins, and illicit drugs, such as methamphetamine and cocaine, dehydration and heat stroke, viral infections, including COVID-19, and some inherited conditions.

2. Dehydration puts you at a higher risk.

Usually, doing a challenging workout alone won’t land you in the hospital, says Arora. Most people who get rhabdo from exercise were doing something really intense and didn’t drink enough water before and during whatever activity they were doing. 

“Going all the way back to 1940 with victims of crush injuries, it was people who didn’t have access to water who had the highest risk,” says Arora.

Exercising in hot, humid conditions or while taking creatine supplements, ephedra diet pills or energy drinks with high doses of caffeine also increases your risk. 

3. You’ll have darkened urine

Arora says one rhabdomyolysis symptom is red or brown urine, which patients often mistake for blood. What looks like blood is actually myoglobin, a toxin that can lead to kidney damage. When this happens, your condition has gotten serious, and it’s important to seek medical help right away, he says.

4. It can take three days to set in.

You might expect to know shortly after, or even during a workout, that something is wrong. But rhabdo usually peaks at 24 to 72 hours after a workout or injury, says Arora. Delayed-onset muscle soreness, or DOMS, is normal after a tough workout, and it can sometimes be hard to differentiate between DOMS and rhabdomyolysis, he says.

Arora says if you experience muscle pain or weakness in one muscle group that seems out of proportion to the workout, it could be rhabdo. Swelling or a cramp-like sensation that won’t go away, especially in one muscle group, are other possible signs. If you’re sore all over, you’re probably OK, but it’s always better to err on the side of caution if you’re concerned, he says.

Rhabdomyolysis Treatment and Prevention

If you think you may have rhabdomyolysis, get yourself to an emergency room right away. Rhabdo can be fatal if left untreated, says Arora. And unfortunately, even with treatment, some people are left with permanent damage or disability. That’s not to scare you, but it is a reminder to not only listen to your body during times of intense heat or physical stress, but to also do what you can to prevent it from happening in the first place.  

IV fluid is the No. 1 rhabdomyolysis treatment to prevent kidney damage, Arora adds. To protect yourself from getting rhabdo in the first place, make sure you hydrate, hydrate, hydrate.

How much water you should drink depends on a lot of factors, including your weight, fitness level and the foods you eat during the day, says Arora. But a good rule of thumb during exercise is to drink some water every time you take a break — and to give yourself those breaks even if you’re in a class that doesn’t encourage rest.

“Basically, the whole point of treatment is to prevent you from getting kidney damage, and the way to do it is with huge doses of fluids,” he says.

Depending on the severity of the injury, IV fluids are usually given for two to five days. At that point, most people will have recovered. The doctor will recommend an exercise break. This could be a couple of weeks to a couple of months but it will depend on many factors, including the severity of the condition and a person’s fitness level. Easing back in with a provider’s guidance is always recommended, Arora says.

The Takeaway 

At the end of the day, no workout is worth dying over. Arora says to listen to your body, ease into new workouts, pay attention to hydration, take regular breaks and seek help immediately if something feels wrong after a workout. 

This article was originally published on Oct. 11, 2017. It has been reviewed and updated with new info. Ari Cofer contributed to this article.