Many previous studies on near-infrared spectroscopy (NIRS) based evaluation of muscle oxygenation, have assessed the association of muscle oxygenation with muscle fatigue and exercise tolerance. To examine the changes in oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) levels, some studies performed occlusion of arterial blood flow in the upper arm and measured the biarticular forearm muscle oxygenation; however, these muscles are subject to contractions based on the position of the arm, which could have led to discrepancies in the findings. Therefore, this study aimed to assess the association between muscle oxygenation and vascular occlusion in the tibialis anterior muscle during isometric exercise using NIRS. Twenty-nine women of mean age of 20.00 ± 1.56 years were included. Maximum isometric contraction performed for successive 30 sec and 60 sec was assessed under occlusive and non-occlusive conditions of the unilateral femoral artery, with and without the use of a tourniquet, at the same time. The O2Hb level was reduced in both conditions, with a significant decrease observed earlier during an initial quarter of the exercise (p < 0.05). This significant decrease in the O2Hb level may be due to decreased oxygenation in the muscle associated with muscle contraction, primarily during aerobic exercise. Under the occlusive condition, the total rate of increase in the HHb levels was smaller than the total rate of decrease in the O2Hb levels. Therefore, adequate oxygen supply to meet the increased demand for the O2Hb cannot be achieved and the increase in the HHb level is suppressed during muscle contractions.
