Lactate consumption mediates repeated high-intensity interval exercise-enhanced executive function in adult males

[PURPOSE]: Lactate is a principal energy substrate for the brain during exercise. A single bout of high-intensity interval exercise (HIIE) can increase the blood lactate level, brain lactate uptake, and executive function (EF). However, repeated HIIE can attenuate exercise-induced increases in lactate level and EF. The lactate levels in the brain and blood are reported to be correlated with exercise-enhanced EF. However, research is yet to explain the cause-and-effect relationship between lactate and EF. This study examined whether lactate consumption improves the attenuated exerciseenhanced EF caused by repeated HIIE. [METHODS]: Eleven healthy men performed two sets of HIIE, and after each set, 30 min were given for rest and examination. In the 2(nd) set, the subjects consumed experimental beverages containing (n = 6) and not containing (n = 5) lactate. Blood, cardiovascular, and psychological variables were measured, and EF was evaluated by the computerized color–word Stroop test. [RESULTS]: The lactate group had a higher EF (P < 0.05) and tended to have a higher blood lactate level (P = 0.082) than the control group in the 2(nd) set of HIIE. Moreover, blood lactate concentration was correlated with the interference score (i.e., reverse score of EF) (r = -0.394; P < 0.05). [CONCLUSION]: Our results suggest that the attenuated exercise-enhanced EF after repeated HIIE can be improved through lactate consumption. However, the role of lactate needs to be elucidated in future studies, as it can be used for improving athletes’ performance and also in cognitive decline-related clinical studies.