One force: limited sex differences in retrospective assessment of physiological and psychological attributes of elite warfighters.

A physical performance gap between sexes exists with females generally performing worse than men. However, physical performance has improved over time across sex, with the rate of improvement greater for females. Given recent efforts by the US military to facilitate sex-integration, this study examined the extent to which sex differences are present in elite military personnel. Graduates of the US Army Ranger Course (70 M; 12 F) were compared across measures of body composition (anthropometry and dual-energy X-ray absorptiometry), aerobic capacity, biomarkers of health, and survey assessments of nutritional supplement intake, psychological and lifestyle factors. Graduates had similar time in service, military experience, grit, resilience, sport participation, and outdoor hobbies. Females attained a higher level of education (P = 0.015) and rank (P = 0.023) than males. Females had lower bone mineral content (P = 0.049) and fat-free mass (P = 0.014) than males with similar fat mass (P = 0.487). Absolute and relative aerobic capacity differed by sex (P = 0.001). There were no differences overall in nutritional supplement use, but females reported greater vitamin and mineral supplement-use than males (P = 0.004). Females had lower albumin, ferritin, glucose, and higher hemoglobin A1C, potassium, and sodium than males (P < 0.05). Sport participation, psychological attributes (i.e., grit and resilience), biomarkers of health, and nutritional supplement use were similar between male and female elite military schools graduates, though fat-free mass and aerobic capacity differed by sex as expected. This study suggests that when elite, high performing male and female soldiers are compared, their mental state and physical performance are more similar than same sex civilian counterparts.NEW & NOTEWORTHY A physical performance gap exists between sex, however over time the rate of improvement has been greater for females. Unlike trends in civilian sport, comparative analysis among elite warfighters revealed fewer sex differences in body composition, psychological outcomes, and self-directed lifestyle choices, including history of sport participation, military experience, and nutritional supplement use. This initial comparison indicates males and females are similar individuals with many common defining traits and characteristics of elite warfighters.