Effect of increase in body temperature on cognitive function during prolonged exercise / 体力科学

This study examined the effect of prolonged exercise with and without hyperthermia on cognitive function. In this study, 9 male subjects cycled at 50% watt max for 60 min in a room maintained at 23°C. Water-perfused suits with water at 7°C (COOL) and 47°C (HOT) were randomly used during the 2 cycling periods. Rectal temperature, skin temperatures, heart rate, ratings of perceived exertion (RPE), and thermal sensation were evaluated during exercise. The Stroop color-word test (SCWT) and executive processing test (EPT) were conducted every 15min during exercise to evaluate cognitive function. In the COOL trial, the core temperature stabilized at 37.5 ± 0.1°C (mean ± SE), whereas in the HOT trial, the core temperature increased to 39.1 ± 0.1°C, with a concomitant increase in RPE and thermal sensation. Although the reaction time for the simple task of the SCWT improved when the body temperature increased slightly during the COOL trial, the conflict task of the SCWT was impaired during the latter stages of exercise during the HOT trial. The reaction time for the HOT trial was significantly longer than that for the COOL trial. Compared to the bigining of exercise the reaction time for the EPT was impaired at 60 min during the HOT trial, and this reaction time was longer than that for the COOL trial. The present findings indicate that exercise-induced hyperthermia during the latter stages of exercise impairs cognitive as well as physiological functions.

THE GENDER DIFFERENCES IN THERMOREGULATORY RESPONSES DURING EXERCISE RECOVERY / 体力科学

The purpose of this study was to investigate the gender differences in thermoregulatory responses during the recovery from prolonged exercise. Fourteen (7 males and 7 females) subjects cycled for 45 minutes at 55%VO₂max and then rested for 105 minutes in the hot and humid environment (30℃, 80% relative humidity) or cool environment (20℃, 60% relative humidity). Both males and females showed same variations in rectal temperature (Tre) during exercise and recovery periods. Total sweat volume and water intake were significantly larger in males than in females during recovery in the both environments. In the heat condition, mean skin temperature (Tsk) decreased immediately after the cessation of exercise in females but not in males (the recovery period (R) 5–15 min : <i>p</i><0.01, R15–20 min : <i>p</i><0.05). These results suggested there are gender-related differences in the mechanisms and also the process maintaining the balance of heat production and heat loss response during recovery from prolonged exercise. Moreover the heat might modify gender differences of heat loss response during recovery as an important factor.