High voltage electrical stimulation in the augmentation of muscle strength: effects of pulse frequency.

This study was designed to determine the effects of pulse frequency (20pps, 45pps, 80pps) on subjects' voltage tolerance, delayed muscle soreness, and muscle strength gained following 6 weeks of electrical stimulation. Thirty healthy men (mean age = 22 years) were randomly assigned to three groups. Subjects in group 1 (n = 10), group 2 (n = 10), and group 3 (n = 10) had their right quadriceps femoris muscles electrically stimulated with a high-voltage pulsed galvanic stimulator present at pulse frequencies of 20pps, 45pps, and 80pps, respectively. The left limb of each subject served as the control. For all the groups, the duty cycle of the stimulator was set at 10 seconds on and 50 seconds off during the stimulation. At each training session, the maximal tolerable voltage for each subject was monitored. Ten maximum contractions was allowed at each training session. Muscle soreness perception was evaluated 48 hours after stimulation using a 10-point visual analog scale. Electrical stimulation was administered three times a week for 6 weeks. For each subject, the average voltage output and muscle soreness rating were computed at the end of each week. With a cable tensiometer, the knee extension isometric force of both limbs was evaluated before training and at the end of the second, fourth, and sixth weeks of the study and 3 weeks after training. Repeated measure's analysis of variance was used to determine significant differences in the dependent variables. The results showed that the maximum voltage tolerance, muscle soreness ratings, and muscle strength gained by the three groups are not significantly (p > .05) different.(ABSTRACT TRUNCATED AT 250 WORDS)