Decreased Percent Body Fat but Not Body Mass is Associated with Better Performance on Combat Fitness Test in Male and Female Marines

The military uses a variety of physical fitness tests to assess physical readiness. The Marine Corps designed the Combat Fitness Test (CFT) to emphasize functional fitness related to operational demands. The purpose of this study was to investigate the association between body mass (BM), fat free mass (FFM), and percent body fat (BF%) measured via air displacement plethysmography with CFT performance in male and female marines. Two-hundred 10 male (22.4 +/- 2.6 years) and 84 female (22.6 +/- 2.8 years) marines were grouped into quintiles according to BM (in kilograms), FFM (in kilograms), and BF%. Kruskal-Wallis test or 1-way analysis of variance were used to determine if significant differences in CFT total and component scores existed between the groups of subjects classified into quintiles of BM, FFM, and BF%. No significant differences in CFT scores were observed between BM quintile in either men or women. No significant differences in CFT scores were observed between FFM quintiles in men. Total CFT score (rho = 0.002), movement to contact (MTC; rho = 0.014), maneuver under fire (MANUF; rho = 0.008), and ammunition lift (AL; rho = 0.014) were all significantly different among FFM quintiles in women. Total CFT score (rho = 0.007), MTC (rho = 0.001), and MANUF (rho = 0.022) were significantly different among BF% quintiles in men. Total CFT score (rho = 0.008), MTC (rho = 0.033), and AL (rho = 0.016) were significantly different among BF% quintiles in women. Male and female marines in the quintile with lowest BF% had better CFT scores than those in higher quintiles. Targeted physical training and nutrition considerations to optimize BF% may help improve military task performance.