The Effects of Low Frequency Electrical Stimulation on Muscular Strength and Endurance in Individuals with Multiple Sclerosis

The purpose of this study was to investigate the results of a practical application of a low frequency electrical stimulation (LFES) program of 8 pps to individuals with multiple sclerosis. Previous research has shown that such a program induces a conversion of fast twitch muscle properties to those of slow twitch. Electrical stimulation was applied for 3 hours per day, 6 days a week, for 6 weeks, to the quadriceps femoris muscle of nine subjects with multiple sclerosis. Pre and post measurements of average peak torque, mean force, and fatigue slope were taken as indices of the muscle's strength and endurance. Contralateral quadriceps muscles were used as control. A two-tailed analysis of variance with two within subject factors was used to analyze the data. Statistical significance (p < .11) and mean force (p < .10) was exhibited for the stimulated quadriceps muscle above that of the unstimulated control muscle. In view of the clinical nature of the research design, further investigation of these trends should be considered. Fatigability decreased in both the experimental and control legs suggesting a possible cross-training effect. Subjective responses were favorable and functional improvements were reported by all subjects. The study does establish LFES as a safe and comfortable option for inducing endurance exercise training on a muscle weakened due to MS. However, more research is needed to determine the extent of its usefulness and to ascertain the optimum protocol parameters.