Update: Exertional rhabdomyolysis, active component, U.S. Armed Forces, 2017-2021.

Among active component service members in 2021, there were 513 incident cases of exertional rhabdomyolysis, for an unadjusted incidence rate of 38.6 cases per 100,000 person-years (p-yrs). Subgroup-specific rates in 2021 were highest among males, those less than 20 years old, non-Hispanic Black service members, Marine Corps or Army members, recruits, and those in “other” and combat-specific occupations. During 2017–2021, crude rates of exertional rhabdomyolysis reached a peak of 43.1 per 100,000 p-yrs in 2018 after which the rate decreased to 38.4 and 38.6 per 100,000 p-yrs in 2020 and 2021, respectively. Compared to those in other race/ethnicity groups, non-Hispanic Black service members had the highest overall rate of exertional rhabdomyolysis in every year of the period. Overall and annual rates were highest among Marine Corps members, intermediate among those in the Army, and lowest among those in the Air Force and Navy. Most cases of exertional rhabdomyolysis were diagnosed at installations that support basic combat/recruit training or major ground combat units of the Army or the Marine Corps. Medical care providers should consider exertional rhabdomyolysis in the differential diagnosis when service members (particularly recruits) present with muscular pain or swelling, limited range of motion, or the excretion of darkened urine after strenuous physical activity, especially in hot, humid weather.