Neuromuscular fatigue thresholds of the vastus lateralis, vastus medialis and rectus femoris muscles.

The purpose of this study was to compare the power outputs associated with the onset of neuromuscular fatigue in the superficial muscles of the quadriceps femoris group by simultaneously monitoring the EMG activity from the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles during a Physical Working Capacity at the Fatigue Threshold (PWCFT) test. Eleven adult males (mean +/- SD = 24 +/- 3y) served as subjects. There were no significant (p > 0.05) differences among the mean PWCFT values for the VL (226 +/- 58 W), VM (223 +/- 58 W) and RF (203 +/- 54 W) muscles. These findings indicates that the superficial muscles of the quadriceps femoris group generally responded as a unit with respect to the onset (threshold) of neuromuscular fatigue as measured by the PWCFT test.