Cognitive Assessment During Heat Tolerance Test (HTT)

Abstract

According to the Israel Defense Forces (IDF) regulations every soldier who had suffered an exertional heat injury (EHI) while exercising during military training, in varying degrees of severity, from heat exhaustion to heatstroke had to take the heat tolerance test (HTT) as part of clearance for back to duty. The criteria to determine the tolerance to heat are based solely on physiological parameters, while no cognitive evaluation is considered in the HTT. PURPOSE: To evaluate the correlation and the role of cognitive assessment and mood state with the physiological parameters monitored during the HTT. METHODS: Eighty five post EHI subjects, performed the IDF HTT (treadmill: 5km/h 2% elevation at 40C 40%). Subjects were continuously monitored for body core and skin temperatures, heart rate and sweat rate. Before, during (60 min.) and at the end of the HTT (120 min.) all participants took voluntarily a psychomotor vigilance test (PVT), which consisted of visual reaction time test using a laptop (cognitive assessment), and filled the profile of mood states (POMS) questionnaire (mood state assessment). RESULTS: According to the physiological criteria 66 subjects were diagnosed as heat tolerant (HT) and 19 as heat intolerant (HI). Analysis of the POMS revealed, in the different criteria, a lower mood for the HI individuals (p<0.01). PVT resulted with longer reaction time in the HI group (p<0.01). CONCLUSION: The adverse effects of heat stress on cognitive performance and mood state during HTT was lower for HT than HI subjects. Cognitive assessment during HTT can be used as an auxiliary tool in the HTT.