Rhabdomyolysis after spin class?
Two case reports involving the increasingly popular activity of “spinning” underscore the need for proper conditioning and adequate hydration before exercising strenuously.
Military trainees and casual athletes comprise many of the cases of exercise- induced rhabdomyolysis.4-6 People who exercise regularly are less likely to develop the condition than their more sedentary counterparts. As with our cases, a sudden increase in the intensity and duration of vigorous exercise, without proper training, may increase the likelihood of rhabdomyolysis.6
Other potential underlying causes. In addition to exercise and dehydration as depicted in our cases, rhabdomyolysis can result from burns, shock, acidosis, infections, crush trauma, immobility, malignancy, medications, toxins, abuse of drugs, or pre-existing illness such as sickle cell trait or other metabolic conditions.7,8
Clinical presentation varies. Regardless of the cause, patients typically present with muscle pain, weakness and cramping, and discolored urine.4,8 However, many patients will have dark urine associated with other symptoms, such as general malaise, visceral pain, swelling, muscle stiffness and tightness, fever, tachycardia, nausea, and vomiting.2,3 A careful history may help elucidate the cause.
Laboratory clues. Diagnostic guidelines commonly specify a serum CPK level 5 times the upper limit of normal as an indication of rhabdomyolysis, specifically in the exertional variety.9 Typically the level of this is around 1000 U/L.3 However, there is no agreement on what CPK level is diagnostic of rhabdomyolysis. Suggestions range from 1000 to 20,000 U/L.3,8 A CPK level in excess of 5000 U/L increases the risk for acute renal failure and renal cell death.3,10 In athletes, an elevated CPK after working out is not uncommon and may be much higher than in other individuals.6,8 Endurance exercises such as marathon running or cycling have been noted to elevate CPK for up to 2 hours postexercise.8
Myoglobin becomes detectable in urine when it exceeds 1.5 mg/dL.10 Urine becomes tea-colored or reddish-brown when myoglobin is >100 mg/dL.10
Complications from rhabdomyolysis include compartment syndrome, hyperkalemia, disseminated intravascular coagulation, coagulopathies, and acute renal failure.
Treatment for rhabdomyolysis consists of aggressive IV hydration with normal saline (with variable rate) or crystalloids to maintain a UOP of 200 to 300 mL/h.2,3,11 Avoid fluid overload in the elderly and those with renal or cardiac disease.2 As CPK and myoglobin continue to trend down, it’s important to adjust IV fluids and electrolyte replacement.2,11 Using bicarbonate to alkalinize the urine is controversial, with no studies showing any benefit.3,10 In severe situations, consider a nephrology consult for hemodialysis to bring down CPK, which may be secondary to renal failure and hyperkalemia.2,10 However, renal failure is less likely to occur in physically active, healthy athletes.
Advice after recovery. After an episode of acute rhabdomyolysis, conditioned athletes can return to physical training with resolution of their symptoms or a CPK level from 1000 to 5000 U/L, usually within a week.6 A more judicious approach may be needed for less fit individuals. Regardless of their fitness level, advise patients to avoid diuretics and alcohol before exercise, remain hydrated during and after exercise, and avoid overheating to decrease the likelihood of developing rhabdomyolysis.4 However, in patients with sickle cell trait, exertional sickling can occur with intensity of exercise without overheating.7
In the case of our male patient, poor physical conditioning and intensive, prolonged exercise followed by poor hydration and the diuretic effect of alcohol created the perfect storm for the development of rhabdomyolysis. On the other hand, our female patient routinely exercised, but still pushed herself beyond her limit and went too far too fast. Although BMI may play a role in the development of rhabdomyolysis, it does not appear to be as significant a factor as hydration status and overall physical conditioning.
Our patients’ prompt attention to the need for medical help and the recognition of the problem by their clinicians contributed to good outcomes in both cases.
CORRESPONDENCE Jacqueline DuBose, MD, Department of Family Medicine, Georgia Health Sciences University, 1120 15th Street, Augusta, GA 30912; jdubose@georgiahealth.edu
