Muscle oxygenation, muscle force and electromyographic activity during isometric contraction

Abstract

The purpose of this study was to investigate the relationships of muscle oxygenation determined by using near-infrared spectroscopy with muscle force and electromyography during isometric contraction in ten healthy males. The subjects performed sustained isometric extension at 30%, 50% and 70% of the maximal voluntary contraction (MVC) for 10 seconds, respectively. Near-infrared spectroscopy and surface electromyography were simultaneously recorded from the right vastus medialis muscle. The rate of decrease in muscle oxygenation levels at the three intensities were significantly different (p < 0.01). A significant different was also found between the rate of decrease in total hemoglobin and myoglobin at 30% of MVC and that at 70% of MVC (p < 0.01). Integrated electromyography was positively correlated with muscle oxygenation level (r = -0.641, p < 0.0001). These results suggested that muscle oxygenation level during isometric contraction reflects muscle force and muscle activity.