Metabolic energy expenditure and fatigue limits in dismounted female warfighters while rucking in various multi-stressor environments

Principal Investigator:  J. Luke Pryor, PhD, ATC, CSCS

Funding Agency: US Army / Advanced Technology International

Abstract: Existing biomedical models that predict metabolic energy expenditure and exhaustion limits (e.g., fatigue) in dismounted Warfighters were developed almost exclusively for males. Differences in physical performance capabilities, body composition, thermoregulation at absolute work rates, and basal metabolism undermine the validity of these decision aids in female Warfighters, who are serving in combat roles in greater numbers than ever before. Sex differences in the energy costs of Warfighter tasks are additional complications that must be addressed. Even less is known about metabolic and fatigue effects of modern military loads on female Warfighters. Consequences of erroneous energy expenditure predictions are particularly detrimental given the importance of metabolic inputs to thermal modeling accuracy and fatigue prediction. Furthermore, females in the armed forces are at greater risk of exertional heat illness and more likely to be heat intolerant at similar absolute work rates than their male counterparts. Given the plethora of sex specific disparities current models that were developed primarily in males are not capable of accurately estimating metabolic energy expenditure and fatigue limits in females. Thus, empirical data are needed to modify existing or generate stand-alone equations to accommodate females and enhance accuracy of metabolic energy expenditure and exhaustion limit estimates in female Warfighters.