Fig. 1.

Spectra acquired from a healthy human subject at extremes of muscle oxygenation. The solid spectrum was acquired after 3 min of 100% O₂ breathing. The dashed spectrum was acquired after 15 min of arm ischemia. Oxymyoglobin and oxyhemoglobin absorb near 580 nm in the visible region; deoxymyoglobin and deoxyhemoglobin absorb near 760 nm in the near infrared region. The visible and NIR bands that were used to estimate Mox are indicated by the sets of vertical dashed lines. In the wavelength region between 610 nm and 730 nm, the detector was saturated. These spectral values do not represent measurements of tissue absorbance and were not used in the spectral analysis.