Skeletal Muscle Oxygenation During Incremental Exercise

The purpose of this study was to investigate the relationship between muscle oxygenation level at exhaustion and maximal oxygen uptake (V˙O2max) in an incremental cycling exercise. Nine male subjects took part in an incremental exhaustive cycling exercise, and then cuff occlusion was performed. Changes in oxy-(ΔHbO2) and deoxy-(ΔHb) hemoglobin concentrations in the vastus lateralis muscle were measured with a near infrared spectroscopy (NIRS). Muscle oxygenation during incremental exercise was expressed as a percentage (%Moxy) of the maximal range observed during an arterial occlusion as the lower reference point. A systematic decrease was observed in %Moxy with increasing intensity. A significant relationship was observed between %Moxy at exhaustion and V˙O2max (p < 0.01). We concluded that the one of the limiting factor of V˙O2max is the muscle oxygen diffusion capacity, and %Moxy during exercise could be one of the indexes of muscle oxygen diffusion capacity.