(23) SEX DIFFERENCES IN MARKERS OF PERFORMANCE FOLLOWING THE ARMY COMBAT FITNESS TEST AMONG ROTC CADETS

Purpose: This study assessed differences between sexes in their recovery from performing the Army Combat Fitness Test (ACFT) while consuming military-style meals-ready-to-eat (MRE) for 3 days. Methods: Twenty-three (n=23, 17 males and 6 females) Corps of Cadet members participated in the study. For baseline (BL) testing, day 1, participants reported to the lab in a fasted state and consumed an MRE meal (≈1,250 kcals, 145 g carbohydrate, 45 g protein, 60 g fat) for breakfast, waited four hours, then performed a standard ACFT. Participants returned to the lab on days 2 and 3, were fed an MRE for breakfast and sent home with two, for lunch and dinner. On day 4, participants returned to consume an MRE for breakfast, then repeated the ACFT four hours later. The ACFT performance variables included a 3-repetition maximum deadlift (MDL), standing power throw (SPT), hand-release push-ups (HRP), Sprint-Drag-Carry (SDC), plank (PLK), and a two-mile run (2MR) with the addition of a vertical jump. Relative load per each ACFT task was calculated by dividing the task metric by the participants' weight. Data were analyzed using a general linear model (GLM) with repeated measures and mean percent change from BL with 95% confidence intervals. Results: GLM analysis revealed no overall time (p=0.252, η_p²=0.457) nor time x sex (p=0.457, η_p²=0.365) effects for any ACFT performance variables. Univariate analysis revealed sex effects for the vertical jump (p< 0.001, η_p²=0.498), MDL (p< 0.001, η_p²=0.632), SPT (p< 0.001,η_p²=0.478), SCD (p< 0.001,η_p²=0.776), and 2MR (p=0.007, η_p²=0.303), wherein males performed better than females. Percent change from BL analysis (Figure 1) revealed males had a greater MDL load (4.3% [0.7, 7.8], p=0.019), a longer PLK (33.7% [17.2, 50.1], p< 0.001), and a better overall total ACFT score (6.7% [1.2, 12.2], p=0.020) compared to their BL values. Conversely, females did not display the same outcomes (Figure 1), even demonstrating a decrease in SPT (-12.1 % [-24.2, -0.1], p=0.049). Additionally, when accounting for the relative load, percent change from BL analysis revealed males had a greater relative MDL load (3.2 % [0.2, 6.3], p=0.034) and total ACFT score (5.0 % [1.1, 8.9], p=0.014), while the females had a shorter SPT (-26.7 % [-51.1, -2.2], p=0.034) compared to their BL values. Conclusions: These data show that males generally have greater ACFT performance scores than females, with males also demonstrating improved performance on the ACFT following 3 days (72h) of recovery. Practical Applications: These data provide insight into the sex difference in ACFT performance and highlight potential areas of focus (i.e., resistance training and conditioning) for females to improve their scores. Acknowledgements: The National Pork Board funded this study as part of a Department of Defense sub-award (M2401649).