The effect of mode of ventilation on cerebral oxygenation during static exercise

The purpose of the present study was to determine the effect of the mode of ventilation on the cerebral oxygenation during heavy static exercise. Eight subjects performed static arm flexion exercise (70~80% of the maximal voluntary contraction force) with the following three different ventilation mode ; exercise with continued ventilation (CONT), exercise with concomitant breath holding (EX+BH), and exercise with pre-exercise hyperventilation (HV+EX). The levels of oxy-hemoglobin (HbO2), deoxy-hemoglobin (HHb), and total hemoglobin (THb) in the left prefrontal cortex were continuously monitored by the Nearinfrared spectoroscopy (NIRS). The main findings in the present study are as follows : 1) In EX+BH, prefrontal cortex O2Hb and THb during exercise show sharper and more marked increase than in CONT ; and 2) In HV+EX, prefrontal cortex O2Hb and THb responses during exercise were significantly smaller than those in CONT. These results show that the respiration mode before and during exercise affects prefrontal cortex oxygenation and blood volume during heavy static exercise.