Dynamic electrical muscle stimulation (EMS) training of the quadriceps femoris

Abstract

Previous research on muscle strengthening using electrical stimulation has mainly focused on isometric training. Thus, the aim of the study was to investigate the effect of isokinetic and isotonic electrical muscle stimulation training on the strength of the quadriceps femoris muscle group. A quantitative, experimental, comparative, research design, making use of a pre-test, treatment period, and post-test, was used. Subjects were divided into two experimental groups and one control group: Group A (isokinetic NMES group), Group B (isotonic NMES group) and Group C (control group). The non-dominant knee extensors of 24 subjects were assessed for peak torque by means of a Cybex 340 isokinetic dynamometer at angular velocities of 0°/s (at 60° of knee flexion), 60, 180, and 240°/s, before and after the experimental treatment period of 10 sessions. An ENDOMED CV-405 electrical muscle stimulator was used to administer the NMES training in Groups A and B. Dependent t-tests and Duncan's Multiple Range Test for Variance revealed that both isotonic and isokinetic electrical stimulation training resulted in significant knee extension torque improvements. Group A showed significant (p < 0.05) improvements of 13 to 21% at the angular velocities tested, while Group B showed significant (p < 0.05) improvements of 11.5, 7.5, and 19.5% at angular velocities of 0, 60, and 180°/s, respectively. Group C also showed a significant (p < 0.05) improvement of 6%, but only at 0°/s. Thus, isokinetic and isotonic electrical muscle stimulation training was shown to be effective in improving the muscle strength of the quadriceps femoris. Key words: Electrical muscle stimulation, strength training, isokinetic, isometric, peak torque, muscle strength, quadriceps femoris. (Af. J. Physical, Health Education, Recreation and Dance: 2003 Special Edition: 173-182)