(14) HAND RELEASE PUSH-UPS AND SPRINT-DRAG-CARRY PERFORMANCE MEDIATE MEMORY TASK RESPONSE TIME AT REST AND UNDER PHYSICAL STRESS IN ARMY ROTC CADETS.

BACKGROUND Military operations require soldiers to perform and keep track of complex tasks in high-pressure situations. Research shows that cognitive resources deplete faster as a function of external and internal stress. Additionally, high-intensity functional movements like lifts, presses, and sprints, have been shown to have stress-buffering benefits, which could improve cognitive functioning. The US Army’s move to a more robust, functional fitness test necessitates research identifying the relationship between fitness test performance and cognitive performance. 

PURPOSE To determine if Army combat fitness test (ACFT) events can predict choice response time (CRT) during a working memory task over repeated bouts of sprints and bodyweight exercises and during recovery. 

METHODS 40 cadets (5F, Mass:71.8±14.09kg, Height:172.8±8.4cm) participated during a physical training session. Phase 1:warmup and familiarization of the 2-back n-back working memory (WM) task. Each cadet had a practice and baseline trial. Phase 2: cadets completed a circuit of 4 rounds of 4 exercises followed by the n-back task. The exercise order was a plank, bodyweight reverses lunge, hand release pushups, and max effort 400m sprint. Immediately following the 400m sprint, cadets did the n-back task before restarting the circuit. Five minutes post-circuit, a final n-back task was performed. A mediation path analysis using R was conducted on the data collected combined with ACFT scores from one month prior. 

RESULTS Figure 1 shows the model between hand-release pushups (HRP), sprint-drag-carry (SDC), and the latent variable choice response time (LV-CRT). Results show that the model is a good fitting model with 𝜲²(16)=14.502, p=.561, RMSEA (classic)=0.0, SRMR=.10, and CFI=1.0. The model used an explicit mean structure, all paths were estimated, and the model was not fully saturated. The latent variable CFA of choice response time for repeated measures was significant all with p-values< .001. The individual paths were all significant below p< .05, path “a” (SDC~HRP), path “b” (LV-CRT ~ SDC), and path c’ (LV-CRT ~ HRP). SDC did not reach significance for resting CRT 5, p=.08. A Sobel test was conducted for indirect effect Sobel statistic=2.45, p=.01, which indicates that SDC has an indirect effect on choice response time and there is partial mediation. 

CONCLUSIONS Increasing anaerobic capacity (SDC) and muscular endurance (HRP) through high-intensity functional training (HIFT) may improve CRT on tasks that involve WM, which is a critical component in the dual tasks tactical athletes often perform. A potential mechanism could be that HIFT fosters increased stress tolerance, which in turn protects cognitive resource allocation when under physical strain.  
PRACTICAL APPLICATIONS This provides further evidence that a robust, functional training approach improving muscular endurance, anaerobic capacity, and cognitive training should continue for tactical athletes.

Acknowledgements: None