In the British Army, ground close combat roles have opened to women, however, they must pass the newly developed, gender-neutral Role Fitness Tests for Soldiers (RFT(S)). Due to physiological differences between sexes, training that optimally prepares both sexes for military occupational demands and the RFT(S) is needed. The purpose of this study was to determine the efficacy of a 12-week periodized strength and power programme with concurrent interval training on RFT(S) performance and determine if performance adaptations differed between sexes. 39 recruit-aged (18-35 yrs) participants, including 21 men (29 ± 1 yrs) and 18 women (27 ± 1 yrs), completed the study. Participants performed 3 training sessions per week that included strength and power resistance training followed by interval training. Pre-to post-training, improvements were observed for seated medicine ball throw (4.5%, p < 0.001), casualty drag (29.8%, p < 0.001), single lift (8.9%, p < 0.001), water can carry (13.8%, p = 0.012), repeated lift and carry (6.5%, p < 0.001), 2-km load carriage (7.2%, p < 0.001) and 2-km run (3.2%, p = 0.021). Pre-to post-training improvements were also observed for maximal squat (27.0%, p < 0.001), bench press (8.9%, p < 0.001) and deadlift (24.6%, p < 0.001) maximal strength, but not upper body power or aerobic capacity. No differences in RFT(S) improvements were observed between sexes, however men performed better than women in all RFT(S) and physical performance measures. Concurrent resistance and interval training improves military occupational performance in men and women; however, women may need more training than men to pass the gender-neutral RFT(S). KEYWORDSExercise; fitness; gender; resistance; training Highlights . Twelve weeks of concurrent resistance and interval training improved seated medicine ball throw, casualty drag, single lift, water can carry, repeated lift and carry, 2-km load carriage and 2-km run performance, military occupational performance measures that comprise the British Army Role Fitness Test for Soldiers (RFT(S)). . Men and women demonstrated similar military occupational performance improvements from pre-to post-training, however, men performed better than women in all measures. . Simple linear regression analyses between improvements in RFT(S) tasks and measures of physical fitness (one-repetition maximal strength, upper body power, lower body power, aerobic capacity) demonstrated limited significant associations suggesting that military occupational performance improvement relies on simultaneous development of multiple fitness domains.

METHODS: Sixty U.S. Army infantry recruits (97% male) provided fasted blood and saliva samples at the beginning (PRE; week 0) and end (POST; week 22) of IMT. Peripheral leukocyte distribution was measured by flow cytometry, and T-cell and innate cell reactivity were measured by mitogen (anti-CD3/CD28 or lipopolysaccharide (LPS))-stimulated cytokine profiles in 48hr whole blood culture. Latent reactivation of Epstein-Barr virus (EBV), varicella-zoster virus (VZV), and herpes simplex virus 1 (HSV1) was measured in saliva by qPCR. RESULTS: Lymphocyte percentage increased (+28%) while granulocytes (-15%) and monocytes (-13%) decreased PRE to POST (all P < 0.01). This lymphocytosis was driven by an increase in natural killer cells (+19%), and accompanied by decreases in B-cells (-9%) and T-cells (-5%; all P < 0.01). Within T-cell subsets, terminally differentiated CD4+ (+22%) and CD8+ (+30%) cells increased while those of effector memory CD4+ cells (-11%), effector memory CD8+ cells (-54%) and central memory CD8+ cells (-15%) decreased (all P ≤ 0.02). T-cell production of most measured cytokines following anti-CD3/CD28 stimulation increased from PRE to POST (P < 0.05). Conversely, stimulation with LPS resulted in reduced production of most measured cytokines (P < 0.05). Prevalence of EBV reactivation was higher POST (n=30) relative to PRE (n=19; P = 0.01), but neither VZV nor HSV1 reactivation was observed at either time point. CONCLUSION: Lymphocytosis, maturation of CD4+/CD8+ T-cell subsets, and heightened T-cell reactivity at POST collectively suggests an appropriate immune response to pathogen challenges during IMT. Though EBV reactivation was increased at POST, no evidence of VZV or HSV1 reactivation, which are more common during severe stress, was observed. Findings suggest that EBV reactivation during IMT was likely appropriately controlled in recruits and that immune-competence was relatively uncompromised at the end of IMT.