Bilateral effects of six-week unilateral electromyostimulation or voluntary isometric training on dorsiflexion strength and muscle activation
Yu, JH, Zhou, S & Huang, LP, 'Bilateral effects of six-week unilateral electromyostimulation or voluntary isometric training on dorsiflexion strength and muscle activation', Chinese Journal of Rehabilitation Medicine, vol. 23, no. 9, pp. 777-781.
Objective: To investigate the bilateral effect of unilateral electromyostimulation and voluntary isometric training on isometric dorsiflexion strength and capacity in muscle activation using twitch interpolation technique. Methods: Thirty healthy male volunteers, aged 18-30 years, were randomly assigned into three groups (n=10 each): electromyostimulation (EMS), voluntary isometric contraction (VIM), and control (CON). In EMS and VIM groups, the right leg was trained, three sessions per week for six weeks. Each EMS session inincluded percutaneous stimulation on the tibialis anterior muscle at 50 Hz, 50-100 mA, to induce contraction force that was equivalent to 60-70%MVC, with duties cycles of 5 s on, 10 s off, for 15-20 min. The VIM session contained static dorsiflexion at 60-70%MVC, 8 repetitions per set, for 3-5 sets, with 1 min resting intervals between sets. Results: Repeated measures ANOVA with Bonferroni adjustment detected significant (P＜0.05) increase in dorsiflexion MVC of both legs in both EMS (13.3% on the right side, 15.6% on the left) and VIM (15.3%, 14.8%), while CON showed no significant increase (2.5%, -2.7%, respectively). The muscle activation was significantly improved at both limbs in the EMS group (P＜0.05, right 9.0%, left 7.4%) but neither in the VIM (7.4%, 5.4%) and the CON (0.6%, -0.3%) (P>0.05), respectively. Conclusions: Unilateral electromyostimulation and voluntary isometric training significantly improved dorsiflexion strength not only at the exercised leg, but also at the contralateral limb. The increased capacity in muscle activation was responsible for much of the improved strength, particularly for the EMS training.