title: Fitness, obesity and risk of heat illness among army trainees.
abstract: BACKGROUND
  Exertional heat illness (EHI) affects military personnel, athletes and occupational groups such as agricultural workers, despite knowledge of preventive measures.
  
  
  OBJECTIVE
  To evaluate EHI diagnoses during US Army basic training and its associations with fitness and body fat on entering military service.
  
  
  METHODS
  From February 2005 to September 2006, US Army recruits at six different military entrance stations took a pre-accession fitness test, including a 5-min step test scored as pass or fail. Subsequent EHI incidence and incidence rate ratios were analysed with reference to subjects' fitness (step test performance) and whether they met (weight qualified [WQ]) or exceeded body fat (EBF) standards.
  
  
  RESULTS
  Among the 8621 WQ and 834 EBF male subjects, there were 67 incidents of EHI within 180 days of entering military service. Among WQ subjects, step test failure was significantly associated with EHI (odds ratio [OR] 2.00, 95% confidence interval [CI] 1.13, 3.53). For those passing the step test, the risk of EHI was significantly higher in EBF than in WQ subjects (OR 3.98, 95% CI 2.17, 7.29). Expected ORs for the joint effects of step test failure and EBF classification under additive and multiplicative models were 4.98 and 7.96, respectively. There were too few women to evaluate their data in detail.
  
  
  CONCLUSIONS
  This study demonstrated that fitness and body fat are independently associated with incident EHI, and the effect of both was substantially higher. Those with low fitness levels and/or obesity should be evaluated further before engaging in intense physical activity, especially in warmer months.
authors.affiliation: Department of Clinical Investigation, William Beaumont Army Medical Center, El Paso, TX 79920, USA, sheryl.a.bedno.mil@mail.mil.
authors.forename: S A
authors.initials: SA
authors.lastname: Bedno
authors.affiliation: Preventive Medicine Program, Walter Reed Army Institute of Research, Silver Spring, MD 20901, USA, Mission Solutions & Services, ManTech International Corporation, Herndon, VA 22033, USA.
authors.forename: N
authors.initials: N
authors.lastname: Urban
authors.affiliation: Preventive Medicine Program, Walter Reed Army Institute of Research, Silver Spring, MD 20901, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Boivin
authors.affiliation: Preventive Medicine Program, Walter Reed Army Institute of Research, Silver Spring, MD 20901, USA, Mission Solutions & Services, ManTech International Corporation, Herndon, VA 22033, USA.
authors.forename: D N
authors.initials: DN
authors.lastname: Cowan
mesh_terms: D000328:Adult; D015992:Body Mass Index; D018882:Heat Stress Disorders / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data; D016017:Odds Ratio; D050177:Overweight / Q000453:epidemiology*; D010809:Physical Fitness; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
keywords: Body fat; fitness test; heat illness; military; obesity.