Rhabdomyolysis: prevention, diagnosis, and when to see a doctor

Rhabdomyolysis is far easier to prevent than to treat. Most cases in athletes are related to predictable mistakes: too abrupt a start of a new program, training in the heat, dehydration, and ignoring early symptoms. Our editors have gathered practical principles of prevention, explained how doctors confirm the diagnosis, and listed the signs that must not be delayed.

Early symptoms that must not be ignored

The classic triad of rhabdomyolysis is muscle pain, weakness, and dark urine. In practice, however, the full triad is far from always present. Many athletes present only with pain and swelling, and the urine may remain a normal color, especially in the early stages.

The main difference from ordinary soreness is disproportion. The pain is much more pronounced than usual after a similar workout; the muscles are swollen, firm, painful to the touch; movement in the joint is limited by pain; weakness appears that does not go away within a day or two.

• urine the color of tea, cola, or dark beer;
• pronounced muscle swelling (for example, 'pumped-up' biceps after pull-ups);
• pain that grows rather than decreases over time;
• a decrease in the amount of urine, nausea, vomiting;
• general weakness, fever, rapid heartbeat.

A typical trap is deciding that you 'just overdid it' and training again the next day or taking a painkiller from the NSAID group. Both decisions can worsen the situation: repeated exercise deepens the damage, and NSAIDs reduce blood flow in the kidneys.

If symptoms appeared after an unusual workout, you should first stop, drink water in moderate amounts, and see a doctor for a blood and urine test rather than wait.

Prevention: how to build up the load

The main principle is gradualness. A new program, a return after a break, a switch to a new sport or a new type of exercise require several weeks of adaptation. Interestingly, even a single moderate eccentric workout substantially protects the muscle from damage during the next one (the so-called repeated-bout effect).

In group classes and 'challenges,' peer pressure often forces people to work far beyond their capabilities. Coaches should give newcomers separate, lighter exercise variants and not encourage training 'to the point of vomiting.' Athletes themselves should remember that a first session is not a competition.

The temperature regime is the second pillar of prevention. Training in the heat should include acclimatization over several days, sufficient fluid, and rest. At signs of overheating — headache, dizziness, cessation of sweating — training must be stopped.

Finally, take pharmacology into account. People taking statins or other drugs with known myotoxicity should discuss a training plan with their doctor. Stimulants, diuretics, alcohol, and especially DNP substantially increase the risk; the editors do not recommend their non-medical use.

Diagnosis: tests and their interpretation

The basis of diagnosis is the level of creatine kinase (CK) in the blood. The CK peak usually occurs 1–3 days after the damage and then gradually decreases. Therefore a single measurement may not show the full picture; the doctor often orders repeated tests over time.

There is no rigid CK threshold that 'automatically' means rhabdomyolysis in an athlete. Clinical sources often use a level exceeding the upper limit of normal by at least five times, yet in trained people after a hard session much higher values can be asymptomatic. Therefore the doctor evaluates the numbers together with the symptoms and kidney function.

Other important tests: creatinine and urea (kidney function), potassium, calcium and phosphorus, a general urine test. A characteristic sign of myoglobinuria is that a test strip shows 'blood' in the urine, while under the microscope there are almost no red blood cells. Sometimes blood or urine myoglobin is measured, although it is quickly excreted and can normalize earlier than CK.

If rhabdomyolysis recurs or occurs after moderate exercise, the doctor may refer the patient to a neurologist to look for metabolic myopathies: genetic tests, muscle biopsy, special exercise tests. If compartment syndrome is suspected, the pressure in the fascial compartment is measured.

Treatment and return to training

Treatment of rhabdomyolysis is carried out by doctors, and its basis is intravenous fluid therapy, which maintains adequate urine output and protects the kidneys. In parallel, electrolytes are monitored, especially potassium, and kidney function. Mild cases are sometimes managed on an outpatient basis, but the decision on this is made by a doctor.

During treatment it is important to give up training, alcohol, stimulants, and NSAIDs without the doctor's agreement. All supplements should be temporarily stopped and reported to the medical staff.

Return to sport should be step by step. Military and sports guidelines (in particular the Uniformed Services University guideline on exertional rhabdomyolysis) recommend starting with light activity only after symptoms and laboratory values have normalized, and then gradually increasing the load under supervision. Athletes with a severe course, kidney injury, or repeated episodes need an individual assessment.

During the return it is useful to keep a symptom diary and not to be shy about stopping if pain or swelling returns. The first 'full' training week is not the time for personal records.

When to see a doctor

Call for help or go to the emergency department immediately if, after training, dark urine appeared, the amount of urine sharply decreased, there is pronounced swelling and muscle pain, nausea and vomiting, palpitations, or confusion.

Immediate evaluation is also needed when pain in the muscles of the lower leg or forearm becomes very severe, the skin is taut, and passive movement of the fingers sharply intensifies the pain: this may be compartment syndrome.

You should make a routine appointment with a doctor if you have had an episode of rhabdomyolysis before, take statins and feel unusual muscle pain, notice a disproportionately strong reaction to moderate exercise, or have relatives with metabolic myopathies or complications under anesthesia.

During the visit, tell the doctor about the nature of the training, the conditions (heat, humidity), and all medications, supplements, alcohol, and stimulants. This information often helps to find the cause faster and prevent a recurrence.

Editorial conclusions

Rhabdomyolysis in athletes can mostly be prevented: gradual loading, acclimatization, adequate hydration, and avoidance of risky substances work better than any supplements.

The diagnosis is based on a combination of symptoms and laboratory data; the creatine kinase level should be interpreted over time and together with kidney function.

Dark urine, severe pain, and muscle swelling are a reason for immediate medical attention, not for painkillers and a new workout.

For a deeper understanding of the topic, we recommend our materials on the causes of rhabdomyolysis and its link to pharmacology, on cramps in athletes, and on training in hot conditions.

References

1. Bosch X, Poch E, Grau JM. Rhabdomyolysis and acute kidney injury. N Engl J Med. 2009;361(1):62–72.
2. Nance JR, Mammen AL. Diagnostic evaluation of rhabdomyolysis. Muscle Nerve. 2015;51(6):793–810.
3. Kim J, Lee J, Kim S, et al. Exercise-induced rhabdomyolysis mechanisms and prevention: a literature review. J Sport Health Sci. 2016;5(3):324–333.
4. Chavez LO, Leon M, Einav S, Varon J. Beyond muscle destruction: a systematic review of rhabdomyolysis for clinical practice. Crit Care. 2016;20(1):135.
5. Clarkson PM, Hubal MJ. Exercise-induced muscle damage in humans. Am J Phys Med Rehabil. 2002;81(11 Suppl):S52–S69.
6. Uniformed Services University, Consortium for Health and Military Performance. Clinical Practice Guideline for the Management of Exertional Rhabdomyolysis in Warfighters. 2020.