Bilateral effects of unilateral electromyostimulation training on strength and surface myoelectric signal

Objective: To investigate the bilateral effects of unilateral electromyostimulation(EMS)training on muscle strength and surface myoelectric signal by surface electro myogram(sEMG)technique. Method: Thirty healthy male volunteers, aged 18—30 years, were randomly assigned into three groups (n=10 each): EMS group, voluntary isometric contraction (VIM) group, and control (CON) group. The patients of EMS and VIM groups were trained the right legs, 3 sessions per week for 6 weeks. All groups were tested for muscle strength and sEMG pre-and post-training period. Result: Repeated measures ANOVA with Bonferroni adjustment revealed significant increase (P0.05) in dorsiflexion maximal voluntary contraction(MVC) of both legs in both EMS group(33.6% on the right leg, 27.8% on the left) and VIM group(37.4%, 28.5%), while CON group showed no significant increase (1.3%, 0.8%, respectively). The average amplitude of electromyogram(AEMG) improved significantly in both limbs of EMS group (P0.05; right 68.1%, left 57.7%) and in VIM group(100.4%, 59.4%), CON group(5.04%, -4.07%) (P0.05), respectively.There was non-linear relationship between muscle strength and amplitude of surface myoelectric signal during iso-metric contraction, y=43.762(9.584) t . Conclusion:The results indicated that unilateral EMS and voluntary isometric training could significantly improve muscular strength not only in the exercised legs,but also in the contralateral limbs. The results also indicated that the increased AEMG was responsible for much of the improved strength.A non-linear relationship between muscle strength and sEMG amplitude, could probably use to assess subjects' exertion test for clinical rehabilitation.