Electromyographic analysis of the quadriceps femoris during isokinetic eccentric activation

The purpose of this study was to describe the activity of the quadriceps femoris during isokinetic eccentric activation. The subjects were 25 volunteer students (20–30 yr of age) in which both legs were analyzed (n = 50). Electromyographic (EMG) activity of the vastus medialis obliquus (VMO), rectus femoris (RF), and vastus lateralis (VL) was recorded with surface electrodes as subjects exerted a maximal eccentric activation at 30 deg/sec over three trials. There were no significant differences between the VMO, RF, and VL regarding onset, cessation, or duration of activity. Significant differences were found pertaining to EMG activity, rise time, and peak amplitude (p <.05). These results are clinically important in that the VMO is significantly more active than the RF and VL during an eccentric action; therefore, consideration to the VMO may be beneficial when rehabilitating the patient to return to functional activities.