Cerebral oxygenation in the frontal lobe cortex during incremental exercise tests: the regional changes influenced by volitional exhaustion.

ABSTRACT

The present study examined the regional differences of cortical oxygenation in the frontal lobe by near-infrared spectroscopy (NIRS) during incremental exercise tests and the precise location of NIRS was examined by brain magnetic resonance imaging (MRI). Pulmonary gas exchange and NIRS measurement during incremental cycling ergometry tests were investigated in 14 men. In 7 of these subjects, the right middle cerebral artery mean velocity (MCA Vmean) was simultaneously measured by transcranial Doppler (TCD). In the right medial of the frontal lobe cortex, Tissue Oxygenation Index (TOI) increased by 8.8% with its peak value at respiratory compensation threshold (RCT) and Normalized Tissue Hemoglobin Index (nTHI) increased until endpoint by 16.2%. During incremental exercise tests, the changing pattern of TOI was different according to the distribution of the probes. Volitional exhaustion by exercise induced the deteriorated TOI and MCA Vmean, whereas nTHI increased.