Cardiorespiratory fitness (CRF) is a crucial performance requirement of specialized military occupations. Age and physical activity (PA) are established predictors of CRF, but it is not clear how these predictors combine with each other and/or with genetic predisposition.
PURPOSE: To derive inclusive explanatory models of CRF in U.S. Navy Explosive Ordnance Disposal (EOD) operators, synthesizing conventional (e.g., age, body composition, and PA) and novel influences (e.g., genetic variance), was performed.
METHODS: Forty male, active duty EOD operators completed a graded exercise test to assess maximal oxygen consumption and ventilatory threshold (VT) using the Bruce protocol. Aerobic performance was further quantified via time of test termination and time at which VT was achieved. Body composition was determined via dual-energy x-ray absorptiometry, and PA was assessed by self-report. Genetic variants underlying human stress systems (5HTTLPR, BclI, −2C/G, and COMT) were assayed.
RESULTS: In univariate regression models, age, body composition, PA, and 5HTTLPR consistently predicted CRF and/or aerobic performance (R2 range .07-.55). Multivariate regression models routinely outperformed the univariate models, explaining 36%-62% of variance.
CONCLUSIONS: This study signifies a shift toward inclusive explanatory models of CRF and aerobic performance, accounting for combined roles of genetic, physiologic, and behavioral influences. These findings have implications for assessment, selection, and training of specialized military members, and may also impact mission success and survivability.