Relationship between maximal oxygen uptake and oxygenation level in inactive muscle at exhaustion in incremental exercise in humans.

The aim of the present study was to determine whether the oxygenation level in an inactive muscle during an incremental exercise test, determined by near-infrared spectroscopy, influences the maximal oxygen uptake (Vo2max). The oxygenation level at the onset of incremental exercise was higher than that at rest and started to decrease at a high power output. A minimal level was observed at exhaustion during incremental exercise. Vo2 increased linearly after some delay, and the rate of increase in Vo2 was greater at a higher power output. Heart rate increased linearly after the time delay, and the rate of increase in heart rate did not change. There was a significant correlation between Vo2max and oxygenation level in inactive muscle at exhaustion (r=-0.89). We therefore concluded that the oxygenation level in inactive muscle at exhaustion during incremental exercise is associated with an individual difference in Vo2max.