Efeito de um protocolo curto de aclimatação ao calor na recuperação após 10 km de corrida em intensidade autorregulada em ambiente quente

Abstract

Heat acclimation protocols, characterized by physical exercise sessions under environmental heat stress, are effective strategies for inducing physiological and perceptual adaptations and improving prolonged (aerobic) performance in hot environments. The first study of the thesis investigated the effects of environmental heat stress on physiological and perceptual variables during prolonged self-paced treadmill running and on lower limb neuromuscular performance after the run. The thirteen recreational runners who participated in the study maintained a lower average speed to complete the 10 km and showed higher ratings of perceived exertion during the run at 35°C compared to 25°C. Countermovement jump (CMJ) height was also reduced by 7% one hour after exercise, indicating neuromuscular fatigue; there was no difference in this reduction between the two environmental temperatures investigated. The second study analyzed physiological, perceptual, and physical performance responses after a 10 km self-paced run at 35°C. Data from the 16 volunteers indicated increased fatigue, muscle soreness, and urine specific gravity, as well as decreased vigor, perceived recovery, and cardiac parasympathetic activity after the 10 km run. The data also confirmed the reduction in CMJ height one hour after the run. Most of these changes were transient and returned to baseline after 24 hours, except for perceived recovery, which remained reduced. Neuromuscular performance changes were not associated with perceptual changes. The third study assessed the effects of short-term (5-day) heat acclimation on recovery after running in a hot environment. Sixteen participants were randomly allocated into one of the following two groups: control or acclimation. Heat acclimation resulted in better running performance without compromising recovery, which was similar between groups. The exceptions were the impaired cardiac parasympathetic reactivation during the first hour after the 10 km run and the beneficial effects mediated by heat acclimation on urine specific gravity and perceived fatigue values. In conclusion, a hot environment impairs aerobic performance and intensifies perceptual strain compared to a temperate environment. After running in the heat, changes are observed in lower limb neuromuscular performance, perceptual variables, and variables related to cardiac autonomic control and fluid-electrolyte balance. Finally, a short-term heat acclimation protocol improves performance and has minimal impact on recovery, even though acclimated individuals exercise at a higher external load than the controls.