Changes in Oxyhemoglobin Concentration in the Prefrontal Cortex and Primary Motor Cortex During Low- and Moderate-Intensity Exercise on a Cycle Ergometer.

The present study investigated whether changes in oxyhemoglobin (O2Hb) concentration over time differed across brain regions according to differences in gross movement intensity. Thirteen healthy adults (21.2 ± 1.0 years, 8 women) participated in this study. After 180 s of rest, the participants performed 600 s of exercise on a cycle ergometer. Exercise intensity was set at 30%VO2peak and 50%VO2peak. The prefrontal cortex (PFC) and primary motor cortex (M1) were chosen as regions of interest. In addition, mean arterial pressure (MAP) and scalp blood flow (SBF) were measured simultaneously. O2Hb concentration in PFC and M1 was significantly decreased in initial phase of the exercise, while it was significantly increased from the mid to final phase for both intensities compared with resting state values (p < 0.01). The O2Hb concentrations in the PFC and M1 were significantly decreased in the initial exercise phase. However, the MAP and SBF values did not exhibit a similar pattern. The main findings of our study were the follows: (1) During cycle ergometer exercise at the 30% and 50% O2Hb peak, the after O2Hb concentrations were transiently decreased in the initial exercise phase, and the concentrations then steadily increased in both the PFC and M1; and (2) the duration of the transient decreases in the O2Hb concentrations varied according to the brain region and exercise intensity.