Impact of body size on women's military obstacle course performance

The United States Military Academy uses an Indoor Obstacle Course Test (IOCT) to assess military-relevant physical fitness. There are both anaerobic and aerobic fitness components to this test. Recent attention has been focused on the apparent difficulty of heavier female cadets to succeed on the IOCT. The purpose of this study was to use allometric scaling to examine the effects of body weight (BW), fat-free mass (FFM), percent body fat (%BF), and fat mass (FM) on IOCT performance for female cadets. The sample included 38 female cadets who successfully completed the IOCT. Performance was defined by the time, T, to complete the entire course. FFM was determined via a three-site skinfold test. Allometric modeling was used to determine the exponent in the following index: T*BW2 such that the independent contributions of body size are partialled out. This analysis was used for all four independent variables simply by substituting BW with the other independent variables. The following exponents were found to be significant (p < 0.05): 0.45 +/- 0.13 for %BF and 0.24 +/- 0.12 for FM indicating that these independent variables play a significant role in female performance on the IOCT. For example, if a female cadet could decrease her %BF from 20% to 18%, which would be decrement of ten percent, then her estimated decrease in IOCT time is 4%. In addition, a trend (p = 0.06) was found for FFM meaning that as FFM increases, T decreases. We conclude that, among USMA female cadets, small decreases in %BF may be significantly advantageous to IOCT performance.