Anthropometrics And Body Composition Predict Performance During A Direct-fire Engagement Simulation.

Abstract

Heavy load carriage is linked to lower performance in direct-fire engagements and higher physiological strain (higher O2 cost, lower cerebral blood flow); which have potential tactical consequences (impaired mobility, marksmanship, cognitive ability). However, performance may also deteriorate with other nonfunctional loads (i.e, excess body fat). PURPOSE: To determine the association between anthropometric and body composition measures and performance during a direct-fire engagement simulation. METHODS: Thirty three healthy male (n = 25) and female (n = 8) volunteers (age 25.7 ± 7.0 yr) underwent a direct-fire engagement simulation. Anthropometric and body composition measures were taken prior to the simulation using a stadiometer and bioelectrical impedance analysis. Marksmanship with cognitive workload and a fire and move drill (16 x 6 m sprints) were completed under combat load (25 kg) during the direct-fire engagement simulation. Marksmanship accuracy and reaction time were assessed as the number of target hits and the time between target callout and engagement, respectively. Cognitive performance was assessed as the number of correct arithmetic problems answered between target engagements. Susceptibility to enemy fire was modeled on sprint duration during the fire and move drill. Partial correlation and multiple linear regression were conducted to establish the relationship between anthropometric and body composition measures and performance outcomes, controlling for age and sex. RESULTS: Higher percent body fat and fat mass predicted greater susceptibility to enemy fire (r = 0.42, p = 0.03 and r = 0.38, p = 0.02, respectively), and worse cognitive performance (r = -0.49, p = 0.01 and r = -0.45, p = 0.01, respectively). Higher body mass index also predicted worse cognitive performance (r = -0.49, p = 0.01). Taller stature predicted worse marksmanship accuracy (r = -0.40, p = 0.02) and higher fat-free mass predicted slower marksmanship reaction times (r = 0.41, p = 0.02). CONCLUSIONS: Anthropometric and body composition measures were predictive of survivability (i.e., susceptibility to enemy fire) and lethality (i.e., marksmanship, cognitive performance) during the direct-fire engagement simulation. These data suggest anthropometrics and body composition modulate combat effectiveness.