Fig. 2From: Review of early development of near-infrared spectroscopy and recent advancement of studies on muscle oxygenation and oxidative metabolismSchematic illustration of main types of near-infrared (NIR) spectroscopy instrumentation. a NIR continuous wave spectroscopy with single-distance (NIRSDCWS) or multi-distance (NIRMDCWS). b NIR time-resolved spectroscopy (NIRTRS). c NIR phase modulation spectroscopy (NIRPMS)Back to article page