of r = .88 and a standard error of measurement of 3.15 percent body fat; for women the correlation coefficient was r = .89 and the standard error of measurement was 3.12 percent body fat. It should be noted that the most important predictors are abdomen circumference in men and waist circumference in women. More recently, Leu and Friedl (2002) examined the relationship between the DoD equations and the Army equations. The correlation between the two equations for men was r = .99, for women r=.86. For women, the DoD equation reduced the percentage of Service members classified as overweight or overfat from 17 percent (using the Army equation) to 12 percent. This result is in line with the prevalence for men of 11 percent.
It is reasonable to consider that body composition may influence military performance. Studies by Pate and colleagues have examined the relationship between fitness and body composition. In one study, correlations were found between cardiorespiratory fitness and body composition (measured by skinfold) on the order of .32 in boys ages 15 and 16 and .26 in girls in the same age group (Pate and Shepard, 1989); in a second large-scale study, an inverse relationship was demonstrated between running speed and body composition in children ages 6 to 18 ranging from −.179 to −.253 for boys and .156 to −.273 for girls (Pate, Slentz, and Katz, 1989).
Higher weight (and fatness) negatively impact endurance performance in two ways: (1) weight appears in the denominator of the VO2 expression—greater weight is associated with lower weight-relative VO2max; and (2) greater weight increases the energy cost (and required VO2) associated with any level of activity. Therefore, the percentage of VO2max required by any level of activity is higher in heavier (and fatter) individuals because energy cost is increased and weight-relative VO2max is reduced. Since a measure of endurance fitness is reflective of both physiological fitness and weight status, BMI adds little to a model for predicting injury that includes fitness.
According to studies conducted at Fort Jackson and Fort Leonard Wood in the 1980s and 1990s (Jones et al., 1993b; Jones, 1992), there are no systematic relationships between injury and BMI or injury and body fat in military recruits. In one study, the highest percentage of injuries was found in the low and high BMI quartiles; in another study there was only slight variability across quartiles; and in a third study the injury rates in the top three quartiles were not significantly different from one another (38 to 42 percent). These patterns were similar for men and women, although the injury rates for women were double the rates for men.