Continuous moderate-intensity aerobic exercise improves cognitive function including working memory (WM). We aimed to determine the differences in the effects of exercise on WM based on pre-exercise WM function and oxyhemoglobin (O2Hb) changes. We enrolled 12 healthy adult males who, after a 4-min rest and warm-up, performed a 20-min exercise regime at a workload corresponding to 50% of maximal oxygen consumption. They performed a pre- and postexercise two-back test, and the reaction times were recorded. Near-infrared spectroscopy was used to monitor the O2Hb concentration in the left prefrontal cortex during the exercise. Based on the pre-exercise reaction time, the subjects were allocated into either a fast group (FG) or a slow group (SG). The pre- and postexercise changes in the reaction time and time-to-peak O2Hb were compared. Further, we determined the relationship between the change in the reaction time and time-to-peak O2Hb. There was no significant change in the reaction time of the FG; however, that in the SG decreased significantly. The time-to-peak O2Hb in the FG was significantly less than that in the SG. These results showed differences in the changes of reaction time and O2Hb changes between the FG and SG.
Keywords: Moderate-intensity exercise; Near-infrared spectroscopy; Oxyhemoglobin; Prefrontal cortex; Two-back test; Working memory.