Comparing Body Composition Methods for Air Force Reserve Officers' Training Corps Cadets

In special populations, such as Reserve Officers' Training Corps (ROTC) cadets, body composition is used not only as a predictor of fitness but for additional purposes such as qualification for enlistment, load carriage, and duty fulfillment. Body mass index (BMI) is the initial measurement recorded and is considered a representation of health and physical performance capabilities. Personnel exceeding threshold values of body weight based upon their height measurement are typically further evaluated using a circumference-based method that predicts the cadets' percent body fat. Military personnel who fail to meet these body composition standards may be penalized by being denied specific positions or promotions or risk being relieved from all military duties. In order to differentiate and accurately assess the components that constitute body composition, other methods of measuring body composition that provide greater accuracy should be explored. The purpose of this study was to compare multiple body composition methods, including the military's method of circumference-based measurement, in order to identify a suitable method for Air Force ROTC programs.

Participants were recruited from an Air Force ROTC Detachment at a large university in the Midwest United States. Anthropometric (height and weight) and body composition measurements (air displacement plethysmography [ADP], bioelectrical impedance analysis, skinfolds, and circumferences) were collected for each participant. A repeated-measure analysis of variance was used to compare body composition measurement methods. A Bonferroni adjustment was utilized for multiple comparisons. BMI and circumference results were displayed as a percentage of compliance according to Air Force Instruction guidelines. The university institutional review board approval was established to ensure that the design of this study protected the rights of the participants.

Twenty-four (21 males and 3 females) participants completed the study. A significant difference between skinfolds and bioelectrical impedance analysis occurred (P = .025). There were no other significant differences identified between other methods of body composition. Using the BMI and circumference compliant/non-compliant scale listed in the Air Force Instruction guidelines, a greater number of cadets fell into the non-compliant category according to BMI (n = 7) versus circumferences (n = 1). The circumference-based method underestimated body fat compared to the "gold standard" ADP.

The findings from this investigation suggest that the circumference-based method can appropriately provide accurate body composition results among Air Force ROTC cadets. Results also determined that the military's circumference-based method underestimated body fat compared to the "gold standard" ADP. Although circumference-based measurements might be efficient for use in larger populations, Air Force ROTC programs should evaluate other methods of measuring body composition to best fit the needs of individual cadets. Further research should be conducted to identify body composition methods that are easy to implement and provide accurate results at the individual level.