Physical performance, demographic, psychological, and physiological predictors of success in the U.S. Army Special Forces Assessment and Selection course

This study assessed predictors of successful selection in the very challenging and stressful United States Army Special Forces Assessment and Selection (SFAS) course among 800 Soldiers. A battery of measures were collected during the course and their ability to predict selection were assessed using logistic regression and chi-square tests. Physical performance measures were most predictive, including road march times, land navigation coordinates found, run times, fitness test score, obstacle course score, and pull-ups (p < .05). Soldiers that were officers or 18× enlisted (fast-tracked to SFAS), had <1 year of active duty, ≥ bachelor degree, no children, were not married, and were Ranger school graduates were more likely to be selected (p < .05). Several psychological measures were predictive, including intelligence quotient, grade level equivalents, resilience score, military aptitude score, and grit (p < .05). Basal serum physiological markers weakly predicted selection and were weakly associated with behavioral assessments. Lower C-reactive protein (< 9.5 nmol/L) and higher cortisol and sex-hormone binding globulin (SHBG) predicted selection (p < .05). Higher C-reactive protein (≥ 9.5 nmol/L) was associated with lower fitness test scores and slower road march time (p < .05). Cortisol was correlated with higher grit and resilience scores (p < .05). SHBG correlated with higher grade level equivalents and better performance on pull-ups, land navigation, obstacle course, and the fitness test (p < .05). Testosterone was correlated with faster run and road march times (p < .05). Dehydroepiandrosterone-sulfate (DHEA-S) correlated with lower resilience scores, and DHEA-S, epinephrine, and norepinephrine correlated with worse performance on several physical events (p < .05). These findings suggest measures that could be targeted in interventions to monitor and enhance performance and resilience.