Effect of electrical stimulation of high and low frequency on maximum isometric force and some morphological...

The effects of two methods of electrical stimulation on maximum isometric force, calf girth, and skinfold thickness of stimulated and nonstimulated (contralateral) legs were studied. Thirty-six male volunteers, divided into three groups, participated in the experiment. Groups I and II were subjected to the procedure of electrical stimulation of m. triceps surae daily for a period of 21 days. Group I was stimulated by an alternating current of low frequency (50 Hz); group II was also stimulated by an alternating current but of higher frequency (2000 Hz). Group III served as control group. In groups I and II significant increases of the maximum isometric force (as measured on an electronic dynamometer) of the stimulated (50.3% and 58.8%) and also of the nonstimulated (contralateral) muscles (39.7% and 32.2%) were found. In group III no significant increase of the maximum isometric force was registered. After the period of stimulation, the skinfold thickness was notably reduced by 21.6% in group II, and calf girth was enlarged in both experimental groups. Relatively large changes were realized in the calf girth and the skin-fold thickness of the nonstimulated legs. The changes in group III were insignificant. It is concluded that electrical stimulation with low as well as high frequencies exerts great effects on muscle force.