Cognitive and Physiological Performance of Soldiers While They Carry Loads Over Various Terrains

This study examined the cognitive and physiological performance of soldiers as they carried loads over various terrains. Twelve soldiers each carried a light load (total weight, including clothing, 22.77 kg 50.19 LB) and a heavy load (total weight, including clothing, 36.94 kg 81.43 LB) over three terrains: blacktop road, sand, and mud. The cognitive tasks performed by the soldiers included arithmetical, memory, and monitoring tasks. The physiological variables were oxygen uptake, ventilation rate, heart rate, and rating of perceived exertion. Test participants also rated their overall workload after each trial. The results showed a significant (p = .018) Load x Block interaction for the monitoring task. In Block 2, the error rate for the light load condition was significantly lower than the error rate for the heavy load condition. There were significant main effects of load, terrain, and time for all the physiological variables. in this study, the energy expenditure (oxygen uptake) for walking on mud or loose sand was the same, and it was approximately 40% higher than the energy expenditure for walking on the blacktop road. Subjective ratings of workload showed significant differences as a function of load (p = .006) but not terrain.