When Exercise Can Kill — The Rare Risk of Rhabdomyolysis

rhabdomyolysis causes

Story at-a-glance -

  • Muscle trauma due to overexercise can lead to rhabdomyolysis (rhabdo), a serious condition that can lead to kidney damage, renal failure and death
  • When muscle is damaged, it dumps myoglobin, an iron- and oxygen-binding muscle protein, into your bloodstream. Excessive myoglobin obstructs your kidney’s filtration system, which can lead to acute renal damage
  • Classic symptoms of rhabdo include muscle swelling, pain, muscle weakness and dark, scant urine output. Other possible symptoms include nausea, vomiting, fever, intense shivering, confusion and possibly fainting
  • Aside from overexercise, other circumstances that can trigger rhabdo include accidents and blunt trauma, prolonged immobilization, drug side effects and metabolic and genetic disorders
  • Rhabdo can happen with any intense, repetitive motion exercise. Spin classes have produced dozens of cases, typically among newcomers who work above capacity. But even professional athletes and military personnel are affected

By Dr. Mercola

A recent WebMD article1 addresses a rare but potentially fatal muscle disorder called rhabdomyolysis, or rhabdo for short. Estimates suggest it may affect 22 people out of 100,000, and muscle trauma due to overexertion is a common cause. Your skeletal muscles are under your volitional control, which is why they’re also known as voluntary muscles.

You engage them when walking and moving. When skeletal muscle is damaged through overexertion injury, the muscle starts dumping myoglobin, an iron- and oxygen-binding muscle protein, into your bloodstream. Excessive myoglobin obstructs your kidney’s filtration system, which can lead to acute renal damage.

Rhabdo causes kidney failure in up to 40 percent of cases, so early diagnosis and rapid medical intervention is crucial. Liberated potassium leading to hyperkalemia (high potassium in your blood), which can occur within hours after muscle injury, can also be life-threatening.

Signs and Symptoms of Rhabdo

The following symptoms are considered “classic” rhabdo symptoms, although all may not necessarily be present in all cases:

  • Muscle swelling
  • Pain in the affected muscle group
  • Muscle weakness or trouble moving your limbs
  • Dark and scant urine output

Other possible symptoms include nausea, vomiting, fever, intense shivering, confusion, dehydration and possibly fainting. While it is clear that rhabdomyolysis occurs due to the breakdown of damaged muscle tissue, there are many situations or circumstances that can trigger it. Some of the most prominent examples include:2


Pushing yourself while exercising, such as running too far or lifting weights beyond your limit, can damage your muscles. While muscle soreness is normal following a workout, suspect rhabdo if the pain is extreme and seems disproportionate to your exertion. Another tipoff is if symptoms trend toward getting worse rather than better over the next couple of days. Untreated, rhabdo will progressively get worse.

Accidents and blunt trauma

Patients who survive major accidents typically develop extensive muscular damage. Nonaccidental injury can also cause muscle trauma that can lead to rhabdo.

Prolonged immobilization

Being bedridden for long periods of time, such as when you suffer a stroke, can put pressure on the muscles pressing against the bed, cutting off blood flow and causing tissue death.

Drug side effects

Cholesterol-lowering medications such as statins or fibrates usually produce muscle weakness as a side effect. Abuse of illicit drugs such as cocaine and heroin can cause weakness as well.

Metabolic disorders

Certain metabolic disorders can raise your risk of rhabdo. This includes problems with metabolism of lipids (fats), carbohydrates or purines, hypothyroidism, diabetic ketoacidosis and electrolyte imbalances.

Genetic disorders

Genetic conditions that can raise your risk includes carnitine deficiency, McArdle’s disease, lactate dehydrogenase deficiency and Duchenne muscular dystrophy.

High-Intensity Repetitive Movement Is a Major Risk Factor

According to Dr. Maureen Brogan, associate professor of medicine at New York Medical College and author of a 2017 paper3 on the condition, rhabdo can happen with any intense, repetitive motion exercise. Spin classes (high-intensity cycling), for example, have produced dozens of cases, typically among newbies who are just starting out and are working above capacity.

One New York City hospital reports seeing 29 rhabdo cases within a four-year span, 14 of which were related to high-intensity cycling.4 According to Brogan, “The high-intensity exercise associated with spin class comes with significant risks to newcomers.” She even goes so far as to call spinning-induced rhabo a “public health concern.” WebMD reports:5

“She says she came to see it as that after six patients came to her hospital’s ER, and all involved people trying a cycling class for the first time … When she searched medical literature, 42 of the 46 cases she found also involved people going to cycling class for the first time.

‘Those are the patients that were most at risk because they may not be conditioned and are using and engaging new muscle groups for the first time at an intense rate,’ she says. ‘So even if you were a different type of athlete like a runner, and then you switch to biking and use quadriceps and gluteus maximus muscles at an intense rate — that first time, you may be at risk of getting rhabdo’ …

[P]eople who stop cycling for some time and then go back at the same rate are at risk, too. ‘[Cycling] is great exercise if you are conditioned for it,’ she says. ‘But you burn 600 to 900 calories in one class. You wouldn’t go out and run 6 to 9 miles on your first day of running. If you did that, you wouldn’t be able to walk either.’”

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Dehydration and Extreme Temperatures Raises Your Risk

Inadequate physical conditioning in combination with severe dehydration and/or extreme body temperatures raise your risk of rhabdo, regardless of the exercise you’re doing. Always make sure to stay well-hydrated before, during and after exercise, and take a break if you start feeling excessively hot. If you’re not conditioned to exercise in hot conditions, avoid starting a new type of exercise in a heated exercise room.

When starting a new exercise, even if you’re fit, listen to your body, start slow, take breaks and work your way up to greater intensity over time. It’s important to recognize that you don’t have to be in poor physical condition for rhabdo to occur, or that you have to work out for an extended period of time. One of Brogan’s patients developed rhabdo after just 15 minutes of cycling.

In fact, many rhabdo patients exercise regularly and express surprise when getting their diagnosis. The key to remember is that there’s a fine line between exercising to capacity and overexerting yourself. Approximately 7 to 8 out of 100,000 military recruits, for example, are affected each year, and even professional athletes — especially marathoners and ultramarathoners — have suffered its consequences.

No One Is Immune to Rhabdo

Professional snowboarder Amy Purdy was hospitalized in 2016 after participating in a CrossFit class for the first time. While generally well-conditioned, she had not done pullups for a few months and the high-intensity, repetitive pullups done during class did her in. She told WebMD:

“It wasn’t until 72 hours later, I was back in my hometown with friends at a restaurant around 11 at night. I told them I worked out too hard a few days ago, and my arms wouldn’t straighten all the way. I then took my jacket off and instantly noticed swelling around my elbows on both arms. The doctors were convinced I didn’t have it because my arms were only slightly swollen. They decided to test me anyway.

That whole experience was one of that [sic] hardest experiences of my life! If you push your body to failure and keep going, you are at risk. Listen to your body. It knows best. And if you find yourself going on days with overly stiff and sore muscles and you notice swelling, get to the hospital ASAP. It may not be rhabdo, but a simple blood test can tell.”

Diagnosis and Treatment  

Diagnosis usually begins with a review of your medical history and the events that led up to your medical visit. A variety of blood and urine tests can help diagnose rhabdo. The following tests are typically recommended:6

  • Complete blood count, including hemoglobin, hematocrit and platelets
  • Serum chemistries, including blood urea nitrogen, creatinine, glucose, calcium, potassium, phosphate, uric acid and liver function tests
  • Prothrombin time and activated partial thromboplastin time
  • Serum aldolase
  • Lactate dehydrogenase

In mild cases of rhabdo, simple lifestyle changes are typically sufficient for a full recovery. This includes:  

Hydration: Keeping your body properly hydrated helps flush out toxins and ease the workload of your kidneys. Drink clean, filtered water until your urine turns to a light-colored yellow.

Reduce exercise: Cut back on your workout until your muscles recover and your urine normalizes. This can help lower the amount of toxins entering your kidneys until you get better.

Increase circulation: Improving blood circulation is vital to helping your muscles heal and lowering your risk of tissue death. Gentle full-body massages and gentle movements can be helpful. Certain foods can also help improve blood circulation. This includes oranges, goji berries, dark chocolate, sunflower seeds, garlic, ginger and cayenne pepper.

Eat a nutritious diet: Optimizing your diet will also increase your chances of a full recovery. By focusing on eating organic, whole foods that are rich in nutrients, you are nourishing your muscles to recover better and improve your overall well-being.

While protein is important for muscle recovery, avoid protein loading as excessive protein consumption can stimulate your mTOR (mammalian target of rapamycin) for growth rather than regeneration, which is not what you need. To avoid this, limit your intake to 0.5 gram of protein per pound of lean body mass, and focus instead on eating the highest-quality protein you can get. This includes grass fed meats, raw seeds and nuts and pasture-raised eggs.

For more serious cases of rhabdo, additional measures may be required. An intravenous solution of special minerals may be used to counteract the potential harms caused by severe muscle damage. Electrolyte imbalances will need to be monitored and promptly treated as well, and in severe cases you may need hemofiltration to address kidney damage.

Rehabbing and Long-Term Prognosis

Overall, the prognosis of rhabdo is good as long as your blood, electrolytes and urine are closely monitored following muscle failure. The mortality rate for rhabdo is only 5 percent, but your risk can significantly increase if kidney failure occurs. If you take good care of yourself by moderating exercise, drinking enough water and getting enough rest, you will be on your way to a successful recovery. It can take time though. Purdy spent months in rehab before being able to lift even the lightest of weights.

While rhabdo is a serious condition, and can happen to anyone, you shouldn’t be scared away from exercise. The take-home message is to always listen to your body. Go easy when you first start something new or different from your regular fitness routine. Give your body some time to adapt and don’t go all-out during the initial sessions.

Also, if you just don’t feel right following a strenuous exercise, keep close watch on your symptoms. Check the color of your urine and pay attention to pain, swelling and weakness. If you’re trending downward when you know you should be recovering, seek medical attention. Blood tests can help diagnose the problem and with proper treatment, kidney damage can be avoided.