Accelerometry and salivary cortisol response during air force special tactics Officer selection

Background: Special Tactics Officer (STO) selection is conducted to select officers to enter the combat controller training pipeline. The aims were to determine physical activity patterns, estimate energy expenditure, and identify whether return and/or unsuccessful candidates demonstrated differences in cortisol responses compared to non-selected and/or first-time attendees. Methods: Participants completed the STO selection, consisting of 5 days of physical and mental challenges. Participants were equipped with ActiCals®, and saliva samples were collected throughout the STO selection. Results: Average activity counts were 684 ± 200 counts{bullet operator}min^-1, with no group differences. Estimated energy expenditure was 4,105 ± 451 kcal{bullet operator}day^-1. Cortisol was elevated following extended physical training but returned to baseline during rest. Return candidates had significantly lower cortisol responses compared to first-timers, 0.43 ± 0.06 μg{bullet operator}dl^-1 versus 0.76 ± 0.18 μg{bullet operator}dl^-1, respectively, p < 0.05. Conclusions: An individual's salivary cortisol response to the stresses incurred during the STO selection has the potential to be incorporated into the entire picture of a candidate's performance and ability to handle stress.