Rhabdomyolysis is a potentially fatal condition that can be triggered by a variety of inciting events, including excessive muscular exertion. The purpose of this study was to investigate the causes of creatine kinase elevation (CK≥1,000U/L) to determine what percentage result from exRML, the aetiology and kinetics of CK levels, as well as the complications of exRML and comorbidities that may predispose an individual to this condition.We performed a cross-sectional analysis of the emergency department database for patients with CK≥1,000U/L between 2012 and 2017. In total, there were 1,957 cases of rhabdomyolysis diagnosed based on laboratory data and documentation. Trauma was the most common cause for rhabdomyolysis (n=726/1,957; 37.1% respectively).ExRML was identified in 2.1% (n=42/1,957) of the total cases. Patients with ExRML were significantly younger (30.1±10.6 years) with a significantly higher maximal level of CK compared to the non-exertional causes of rhabdomyolsis, (CK=16,884.4±41,645.6U/L; both p<0.005). The far majority of cases were sport or exercise related (n=35/42; 83.3%), with strength training at the gym making up the largest group of athletes (n=16/42; 38.1%). The main complication amongst the ExRML group was acute kidney insufficiency, which was observed in 42.9% of patients. The CK levels of the patients in the ExRML cohort steadily decreased after initiation of aggressive hydration.ExRML may be more prevalent than the current literature predicts, which is important to recognize as it has the potential to cause kidney failure, irregular heart rhythm, and death. Therefore, physicians and active individuals should be sensitized to the signs and symptoms that may lead to earlier recognition and proper treatment in exercising individuals.