Thermal Stress-manipulated Lactate Response To High-intensity Exercise Is Not Associated With The Impaired P3 Amplitude

Short-duration high-intensity exercise (HIESD) enhances lactate (La) production, and cerebral La metabolism of circulating La due to HIESD contributes to exercise-induced improvements in cognitive performance, such as inhibitory control. Nevertheless, HIESD decreases neuroelectrical activity related to cognitive function (i.e., electroencephalographic event-related potentials; ERPs) such as the amplitude of P3 component. Given that hyperthermia during exercise reduces the amplitude of P3 component, an increased body temperature may alter the relationship between HIESD and ERPs. Or, given that prolonged exercise in a hot environment diminishes La production due to muscle glycogen depletion, we hypothesized that a diminished La response to HIESD following exercise in the hot environment would further impair the amplitude of P3 component. PURPOSE: To examine the impact of decrease in blood La level during HIESD following exercise intervention in the hot environment on the P3 components. METHODS: Twelve young males completed both hot and control trials in a crossover design. Initially, participants performed a 16-min HIESD protocol, starting at 20% VO2peak for 4 mins, with the intensity increased by 20% every 4 mins (i.e., 40%, 60%, and 80% VO2peak). Subsequently, a 45-min exercise intervention at 60% VO2peak in either the hot (36 °C) or control temperature (20 °C) was carried out. One hour after the exercise intervention, participants repeated the 16-min HIESD protocol. Blood La and the P3 amplitude/latency to a Go/No-go task were assessed before and after each HIESD protocol. RESULTS: The blood La response to the 2nd bout of HIESD was lower in the hot than control trial (P < 0.05). HIESD decreased the P3 amplitude (P < 0.05), but neither the exercise ‘bout’ nor the hot trial affected the P3 amplitude or latency (P > 0.05). CONCLUSION: When HIESD following prolonged exercise in the hot environment diminished blood La elevation, HIESD did not further impair the P3 amplitude.Supported by: JSPS KAKENHI