Epidemiology of Exertional Heat Illness Among U.S. High School Athletes

BackgroundIt is estimated that more than 9000 high school athletes are treated for exertional heat illness annually. Risk factors include being obese and beginning practice during hot and humid weather, when athletes are not yet acclimated to physical exertion in heat.PurposeTo describe the epidemiology of exertional heat illness in high school athletes.MethodsNational High School Sports–Related Injury Surveillance System data (2005/2006–2010/2011) were analyzed in 2012 to calculate rates and describe circumstances of exertional heat illness.ResultsExertional heat illness occurred at a rate of 1.20 per 100,000 athlete exposures (95% CI=1.12, 1.28). Exertional heat illnesses were widely distributed geographically, and most occurred in August (60.3%). Of the exertional heat illnesses reported during practice, almost one third (32.0%) occurred more than 2 hours into the practice session. The exertional heat illness rate in football (4.42 per 100,000 athlete exposures) was 11.4 times that in all other sports combined (95% CI=8.3, 15.5, p<0.001). In addition, approximately one third (33.6%) of exertional heat illnesses occurred when a medical professional was not onsite at the time of onset.ConclusionsAlthough most exertional heat illnesses occurred in football, athletes in all sports and all geographic areas are at risk. Because exertional heat illness frequently occurs when medical professionals are not present, it is imperative that high school athletes, coaches, administrators, and parents are trained to identify and respond to it. Implementing effective preventive measures depends on increasing awareness of exertional heat illness and relevant preventive and therapeutic countermeasures.