Cognitive and Motor Skill Performance Are Improved By Active Cooling Following Passive Hyperthermia

Abstract

Hyperthermia causes a number of deleterious effects including decreased exercise performance and mental acuity. Neck cooling and hand and forearm cooling are both effective in attenuating heat strain during exercise in hot environments. However, only limited research exists on the effectiveness of either cooling methods on cognitive and motor skill performance following whole-body hyperthermia. PURPOSE: To investigate the effect of two active cooling modalities on cognitive and motor skill performance following passive hyperthermia. METHODS: Eleven healthy participants (6 females and 5 males; 22±5 y; 173±10 cm; 71.8±15.1 kg) were passively heated to 39°C rectal temperature (Tre) by 40°C whole-body immersion. They were then removed from the water and sat quietly in a room (24.6±0.8°C and 49.8±6.3% rh) and used either a 2.6 m2 commercially available cooling towel wrapped against the surface of their neck (NT), hand and forearm immersion in 10.5±1.3°C water (H), or cooled passively (C) until Tre reached 38°C. Simple reaction time, Stroop word color, time to complete a trail-making task (TMT), and time to screw three nuts on three bolts (N&B) were measured pre and post whole-body immersion and every 15 min during the cooling phase. One and two-way repeated measures ANOVA were used to determine differences across time and between conditions. RESULTS: Reaction time was faster (p<0.05) with H (349±41 ms) compared to both NT (364±60 ms) and C (380±65 ms). Success in the Stroop word color test was improved (p<0.05) when using NT (31±3) but not H (31±4) compared to C (29±4). Neither hand and forearm cooling nor neck cooling improved TMT ability. Time to complete the N&B task trended towards an improvement (p=0.06) with H (39.4±11.4 s) but not NT (43.1±12.0 s) compared to C (45.5±12.4 s). CONCLUSION: Reaction time and color-word interference ability were found to improve with hand and forearm cooling and neck cooling, respectively.