Departmental Bulletin Paper 高強度自転車運動時の筋酸素化レベルと 肺胞レベルの酸素摂取量の動態
Kinetics of Muscle Deoxygenation and Pulmonary O2 Uptake during Heavy-Intensity Cycle Exercise

右田, 孝志

The near-infrared spectroscopy (NIRS) signal (deoxyhemoglobin concentration;[HHb]) reflects the dynamic balance between oxygen consumption and delivery during microcirculation. The aim of the present study was to estimate the kinetics of [HHb] during exercise and compare it with the kinetics of pulmonary oxygen uptake ( ・VO2p). Seven male distance runners performed a heavy-intensity, constant work rate cycle exercise. [HHb] and ・VO2p were measured during exercise, and the kinetics of both the variables was analyzed using a mono- or double-nonlinear regression model.[HHb] derived from NIRS remained at resting levels for a period of 11.0 ± 3.2 s afteran increase in the work rate. After the time delay, [HHb] rapidly increased with a timeconstant of 10.9 ± 3.2 s for the primary component; the increase was significantly faster than that of ・VO2p (23.8 ± 7.6 s, P < 0.05). The kinetic of [HHb] during the later phase of exercise (slow component phase) was different from that of ・VO2p and showed various patterns between individuals. These results suggest that local muscle O2 delivery and utilization were balanced during microcirculation for the first period after the onset of exercise (approximately 10 s), however, the rate of adjustment of O2 delivery and utilization did not match during subsequent phases (primary and slow component phases).

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