Effects of electrical stimulation, isokinetic exercise and concurrent isokinetic exercise with electrical stimulation on acquisition and retention of strength, endurance and bilateral transfer in females

Abstract

The purpose of this study was to examine the effects of four different training methods (isokinetic exercise, electrical muscle stimulation, concurrent electrical muscle stimulation with isokinetic exercise, and no training) on the acquisition and retention of strength, endurance and bilateral transfer in females. Subjects consisted of 30 female volunteers aged 17-25. Subjects were randomly assigned to one of the four treatment groups. Those subjects performing exercise trained only their right leg. Following an explanation as to the premise of the study, subjects were pretested on the four dependent variables of static extension (0°/sec), dynamic extension (60°/sec), dynamic extension (180°/sec), and dynamic muscular endurance (180°/sec). Groups were trained Monday, Wednesday and Friday each week for a six week duration. Every training session required subjects to warm up with 6-8 repetitions followed by a training phase consisting of 3 sets of 10 repetitions. Subjects trained isokinetically were exercised at a speed of 60°/sec. Electrical stimulation was delivered by way of a 10 second contraction, followed by a 20 second recovery phase. Maximum current was delivered at 50 pulses/sec with a corresponding wave width of 200 microseconds. The protocol utilized for the concurrent treatment was identical to the other two methods. Surge and rest times, however, were altered to allow for a two second contraction followed by a one second recovery phase. Subjects were assessed for strength and endurance at the beginning of the 6 week training program, at the conclusion of training and after a 4 week detraining period. Data were analyzed with a MANOVA in a 4 x 2 x 3 design. Percentage differences between tests and among groups on variables were presented. An alpha level of .05 was accepted for all statistical procedures. Results showed: (a) the strength training methods employed did not significantly improve either static or dynamic strength; (b) no significant increase in endurance was noted with any of the training procedures; (c) there was a wide variation of training responses among all the subjects; (d) none of the training groups were found to be superior for improving strength and endurance; (e) none of the training procedures resulted in a significant transfer of strength; and (f) following 4 weeks detraining, none of the training procedures resulted in a significant loss of strength.