Comparison of the effects of electrical stimulation and exercise on abdominal musculature

The purpose of this study was to test the effect of electrical stimulation and volitional exercise on abdominal muscle strength and endurance. Changes of voltage, current, and tissue resistance were analyzed to determine tissue conditioning to stimulation. Subjects were randomly assigned to a control, stimulation (S), volitional exercise, or exercise combined with stimulation (ES) groups. Maximal voluntary isometric contraction and endurance data were recorded. In the three experimental groups, the number of repetitions and time of sustained contraction were increased by a predetermined amount during 4 weeks of training. The S and ES groups were stimulated using a biphasic, symmetrical pulse waveform having 200 microsec phase duration and 50 pulses per second. The ES group demonstrated the largest significant increases in abdominal strength, while the S group was the second best mode. No significant change in endurance occurred among the groups. Voltage and current increased significantly whereas tissue resistance decreased. It was concluded that combined exercise and stimulation may prove to be the most effective method of improving abdominal strength. J Orthop Sports Phys Ther 1987;8(12):567-573.