Exercise-Heat Stress, Hyperthermia, Dehydration and Fatigue Effects on Cognitive Performance among Semi-Professional Male Athletes

Background: Evidence regarding heat stress, dehydration, hypohydration and fluid balance effects on semi-professional athletes’ cognitive function is still limited. This study aimed to examine the effects of exercise heat-stress, hyperthermia, dehydration and fatigue on cognitive performances in semi-professional athletes. Methods: Eighteen healthy male athletes from individual and team sports participated. Participants completed a cognitive and mood test battery prior, immediately after and post 120 min of treadmill exercise. A soccer-specific intermittent treadmill exercise protocol was completed in four experimental trials in temperate (normothermic) and hot (hyperthermic) conditions. Participants were hydrated and dehydrated in both conditions. Trial conditions were; normothermic 16.4 ± 0.02°C and 52 ± 1% RH, while hyperthermic 33.9 ± 0.3°C and 61 ± 1% RH. Results: Response times; the Stroop effect and Visual search tasks were quicker (584 to 690 ms, p= 0.001; 1978 to 2213 ms, p= 0.003) in the heat. Cognitive tasks showed that reaction time, visual process, motor speed and mood were similar in normothermic (p=0.001). Accuracy improved in hydrated hyperthermic by 1.2% (p=0.002) in Visual search. Total Mood Disturbance was significant in heat (p<0.001). Hydration status had no major effect in some cognition performance markers except for mood. Conclusion: The response times and accuracy improved following the cognitive testing in semi-professional athletes exercising in relatively humid, hot conditions. However, semi-professional athletes’ cognitive performances were relatively affected by hypohydration and their hydration status needs to be closely monitored during exercise.