Rhabdomyolysis results from excessive skeletal (striated) muscle breakdown, releasing intracellular contents into the bloodstream.1,2 Excessive serum levels of creatine kinase, potassium, free radicals, and myoglobin increase physiological stress on the internal organs to maintain life.1,2 In non-athletic endeavors, rhabdomyolysis results from injuries to large portions of skeletal muscle (eg, motor vehicle accidents or crush injuries), systemic infections, metabolic myopathies, and drug abuse.1 Exertional rhabdomyolysis develops from physical effort without traumatic or systemic injury, carrying a prevalence of approximately 26,000 cases annually within the United States.1 Up to 47% of rhabdomyolysis cases result from exertion.1,2 This Pearl of Practice presents recently published resources so athletic trainers can improve their knowledge of the prevention and treatment continuum for exertional rhabdomyolysis.
Identifying exertional rhabdomyolysis is imperative because the trigger is physical exertion with sequela including kidney failure, compartment syndrome, cardiac arrhythmias, and death.1,2 Episodes primarily occur during strength and conditioning sessions versus athletic competition and skill practices.1,3,4 Athletes will present 24 to 48 hours after exercise,1,5 typically describing the session as intensive multi-joint movements of disproportionate duration with minimal rest.2
Exertional rhabdomyolysis severity increases in athletes exerting the most effort or those physically incapable of performing the activity.3 Whenever athletes present with excessive localized soreness and weakness specific to muscles used during the workout (upper or lower body), particularly early in the season or after detraining, exertional rhabdomyolysis should be considered.1,2,5 This reported muscular discomfort is more pronounced compared to after work-out or delayed onset muscle soreness and occurs with or without muscular swelling, tenderness, malaise, nausea, and vomiting.1,2,5
Urine color (pigmentation) descriptors of reddish, cola, or tea raise suspicion for exertional rhabdomyolysis because myoglobin levels are potentially elevated.1,2,5 Visible myoglobinuria corresponds to 100 grams of muscle destruction.2 However, patients seldom describe myoglobinuria, making it an inappropriate clinical diagnostic indicator of exertional rhabdomyolysis.5 A urine dip-stick analysis has a sensitivity of 80% for rhabdomyolysis.1
Myoglobin concentrations were primarily used as diagnostic indicators for exertional rhabdomyolysis, but are now considered unreliable because filtration of serum myoglobin occurs more rapidly compared to creatine kinase.2 Serum myoglobin levels peak 12 hours after exertion and normalize within 24 hours,2 creating a low negative predictive value for ruling in exertional rhabdomyolysis.5 Conversely, creatine kinase levels peak 24 to 36 hours after exertion, potentially remain elevated for 5 days, and decrease approximately 40% per day.2 Creatine kinase measurements are the most reliable marker of exertional rhabdomyolysis diagnosis and recovery.2
After exertional rhabdomyolysis is suspected or confirmed, clinicians should consider clustering (team rhabdomyolysis): when group conditioning sessions create multiple exertional rhabdomyolysis cases from the same activity. Clusters are observed within a recent systematic review of exertional rhabdomyolysis in athletics because 79% (42 of 53) of the cases evaluated resulted from three specific conditioning sessions.1 Within organized athletics, once exertional rhabdomyolysis is diagnosed or suspected, all individuals who performed the activity should be evaluated while the conditioning protocol is reviewed.
Once hospitalized, administration of normal saline intravenous fluid is the standard treatment.1 However, incorporating sodium bicarbonate or mannitol can potentially aid recovery.1 Sodium bicarbonate alkalizes the urine, decreasing myoglobin toxicity, whereas mannitol increases renal blood flow and urine output until myoglobinuria ceases.1,2 A recent systematic review determined no difference between intravenous fluid treatment with or without sodium bicarbonate on hospitalization duration, but no articles describing mannitol use met their inclusion criteria.1 Although patients can be released without overnight hospitalization, the observed range was 1 to 8 days, with 4.5 days being average.1
The athlete should be comprehensively evaluated to determine whether his or her individual risk of exertional rhabdomyolysis recurrence is elevated (Table 1).6 Following evaluation, the athlete can begin individualized…