Changes in the Laterality of Oxygenation in the Prefrontal Cortex and Premotor Area During a 20-Min Moderate-Intensity Cycling Exercise.

A recent study based on near-infrared spectrometry (NIRS) showed that a single session of moderate-intensity exercise increases the cortical oxyhemoglobin (O2Hb) level. However, changes in the laterality of O2Hb throughout such exercises remain unknown. In the present study, we evaluated changes in the laterality of O2Hb in the prefrontal cortex (PFC) and premotor area (PMA) during moderate-intensity cycling for 20 min. Twelve healthy volunteers performed the exercise at 50% of the maximal oxygen consumption after a 3-min rest period. O2Hb levels in the right (R-) and left (L-) PFC and PMA were measured using multichannel NIRS and averaged every 5 min during the exercise period, and the laterality index (LI) for each 5-min period was calculated. LI for PFC showed significant changes in each period (first, second, third, and fourth periods: -0.40 ± 0.21, -0.03 ± 0.12, 0.14 ± 0.15, and 0.16 ± 0.10, respectively; p < 0.05), whereas that for PMA showed no significant changes (-0.07 ± 0.09, 0.23 ± 0.08, 0.17 ± 0.12, and 0.19 ± 0.09, respectively; p = 0.12). These findings suggest that the laterality of cortical oxygenation in PFC of healthy, young individuals changes during moderate-intensity exercise for 20 min, thus providing an insight into the mechanisms underlying exercise-induced improvements in brain function.