Near-infrared spectroscopy (NIRS) has been a useful method for the detection of changes in in vivo muscle oxygenation and oxidative metabolism in healthy subjects as well as in patients with various diseases. The advantage of using NIRS over other invasive techniques is that the device itself is more portable and the procedure can be performed more simply. So far, commercially available single-distance continuous wave NIRS (NIRS_SDCW) device provide only the relative values of tissue oxygenation mainly due to the unknown path of NIR light through biological tissues. In particular, subcutaneous adipose tissue thickness greatly influences the light pathlength and makes it difficult to quantify tissue oxygenation. Alternatively, the arterial occlusion and sensitivity correction approach using NIRS_SDCW and the pathlength determination using sophisticated time-resolved or phase-modulated spectroscopy could estimate the absolute value of tissue oxygenation. This paper aims at reviewing primarily NIRS_SDCW studies for evaluating skeletal muscle oxygenation and oxidative metabolism, specifically in physiological and medical research area.