Exertional heat illness among overweight U.S. Army recruits in basic training.

INTRODUCTION Heat illness has not declined in the U.S. military despite preventive measures. The increase in overweight recruits entering the U.S. military may lead to an increase in heat-related events. This study compares the risk of heat illness among U.S. Army recruits who exceeded body fat standards at accession to those who met standards. METHODS Recruits with excess body fat and qualified applicants to the Army were required to take a preaccession fitness test during the study period (February 2005 through September 2006). The test included a 5-min step test and 1-min push-up challenge, scored as pass or fail. Incidence and outpatient usage for heat illness (any heat illness, heat stroke, heat exhaustion, and other heat illness) at 90 d of service were compared in 9667 male recruits of whom 826 had excess body fat and 8841 were qualified. There were too few heat events among women for analysis. RESULTS The incidence odds ratio among male recruits with excess body fat compared to qualified male recruits was 3.63 (95% CI: 1.92, 6.85). Men with excess body fat had an increased incidence of heat illness with a rate ratio of 7.25 (95% CI: 4.17, 12.61). DISCUSSION Although there were few heat illness events, the results indicate a significantly increased risk of heat illness and outpatient utilization among male recruits with excess body fat. It was estimated that approximately 70% of the relative risk for heat illnesses in men with excess body fat during basic training was associated with exceeding body fat standards. These findings may have implications for military accession and training.