Abstract
The purpose of this study was to examine muscle performance output as effected by electrical stimulation with and without eledromyographic (EMG) biofeedback in conjunction with quadriceps femoris muscle (QFM) strengthening exercises. Six males and six females aged from 20 to 36 participated in this study. Subjects were assigned to one of three independent groups. One group (n = 4) performed maximal volitional isometric contractions (MVICs) of the QFM and served as the control; the second group (n = 4) underwent strength training augmentation concurrent with electrical stimulation; the third group (n = 4) received EMG biofeedback-triggered electrical stimulation (BTES), i.e., electrical stimulation based on EMG biofeedback from volitional isometric contractions. Each group underwent pretesting and posttesting to record MVICs. The groups trained 3 days a week for 6 weeks. All groups had an increase in peak torque production over the 6-week training period, with the EMG-BTES group showing the greatest increase from pretest to posttest. Results of this study give preliminary evidence of the usefulness of electrical stimulation, especially when triggered by an EMG biofeedback signal, in strength training.