Sex differences in the physical performance, physiological, and psycho‐cognitive responses to military operational stress

Abstract

Combat roles are physically demanding and expose service personnel to operational stressors such as high levels of physical activity, restricted nutrient intake, sleep loss, psychological stress, and environmental extremes. Women have recently integrated into combat roles, but our knowledge of the physical, physiological, and psycho-cognitive responses to these operational stressors in women is limited. The aim of this narrative review was to evaluate the evidence for sex-specific physical, physiological, and psycho-cognitive responses to real, and simulated, military operational stress. Studies examining physical and cognitive performance, body composition, metabolism, hypothalamic-pituitary-gonadal axis, and psychological health outcomes were evaluated. These studies report that women expend less energy and lose less body mass and fat-free mass, but not fat mass, than men. Despite having similar physical performance decrements as men during operational stress, women experience greater physiological strain than men completing the same physical tasks, but this may be attributed to differences in fitness. From limited data, military operational stress suppresses hypothalamicpituitary-gonadal, but not hypothalamic-pituitary-adrenal, axis function in both sexes. Men and women demonstrate different psychological and cognitive responses to operational stress, including disturbances in mood, with women having a higher risk of post-traumatic stress symptoms compared with men. Based on current evidence, separate strategies to maximize selection and combat training are not warranted until further data directly comparing men and women are available. However, targeted exercise training programmes may be advisable to offset the physical performance gap between sexes and optimize performance prior to inevitable declines caused by intense military operations.

Military tactical adaptive decision making during simulated military operational stress is influenced by personality, resilience, aerobic fitness, and neurocognitive function

“…Data presented herein are part of a larger study (U.S. Department of Defense award #W81XWH-17-2-0070; Beckner et al, 2021a ; Conkright et al, 2021a , b ). This prospective cohort study was designed to characterize the impact of 48 h of SMOS, involving sleep and caloric restriction and physical work, on military tactical adaptive decision making.…”

Occupational and Environmental Challenges for Women

“…Gender-comparison studies examining the physical, cognitive, metabolic, hormonal, and psychological health outcomes in military operational environments report that women have similar physical performance decrements under operational stress as men, yet greater physiological strain when completing the same physical tasks (58). Overall, women expend less energy and lose less body mass and fat-free mass, but not fat mass, compared with men when working in military operational environments (58). Military operational stress suppresses hypothalamic-pituitary-gonadal, but not hypothalamic-pituitary-adrenal, axis function in both sexes.…”

“…Men and women also demonstrate different psychological and cognitive responses to operational stress, including disturbances in mood, with women having a higher risk of posttraumatic stress (PTS) symptoms than men (58). The female stress response, characterized as the "tend and befriend" response, in comparison to the more commonly recognized "fight or flight" response typical of men, suggests a role for social support in times of operational stress (59).…”

The effect of sex and protein supplementation on bone metabolism during a 36-h military field exercise in energy deficit

“…There is emerging evidence that male athletes experience similar endocrine and bone metabolic responses to low energy availability, although men may be more resistant to these metabolic effects than women ( 14 ); to our knowledge, only one study has compared the bone metabolic response to energy deficits in men and women ( 12 ). Women have recently been allowed to enter combat roles alongside men in the UK Armed Forces and other nations, but there is a lack of data on women examining the bone metabolic responses to the physiological stressors—high levels of physical activity, energy deficiency, and sleep deprivation—associated with combat training ( 1 , 15 ). Alongside energy deficiency, sleep deprivation can also increase circulating markers of bone resorption and decrease circulating markers of bone formation ( 16 ), whereas exercise can increase markers of bone resorption and formation ( 17 ).…”