Bilateral effect of unilateral electroacupuncture on muscle strength.

OBJECTIVES This study aimed to examine the bilateral effect of 4 weeks of unilateral electroacupuncture on leg muscle strength. DESIGN The effect of unilateral electroacupuncture at two selected acupoints, Zusanli (ST-36) and Xiajuxu (ST-39), which are located on the anterior tibialis muscle, on dorsiflexion strength was evaluated by statistical analyses of the interactions between the muscle strength pre and post 4 weeks of intervention, between the two legs, and between an experimental and a control group. SETTINGS/LOCATION The trial was carried out in the exercise rehabilitation laboratory at Tianjin University of Sport. SUBJECTS Thirty (30) healthy men with an average age of 20.9 +/- 2.98 (SD) years were randomly allocated into an electroacupuncture group (EG) and a control group (CG). They were physically active, but without specific strength training or previous experience of acupuncture. INTERVENTIONS Participants in the EG were given 3 sessions of electroacupuncture per week. In each session, the electroacupuncture was applied to the right leg at the acupoints with 8 duty cycles of 1 minute on and 1 minute off, pulse width of 1 millisecond, frequency of 40 Hz, and intensity of 30-40 V. Participants in the CG group kept their normal daily activities without additional intervention. OUTCOME MEASURES The maximum strength in dorsiflexion of each leg was examined by having participants lift weights in the range of motion of approximately 20 degrees at the ankle joint. RESULTS Repeated-measures analysis of variance with Bonferroni adjustment detected significant increase in strength of both legs (right 21.3%, left 15.2%) in the EG (p<0.05) and the increase was significantly higher than that of the CG (p<0.05). The CG showed no significant change (right 3.0%, left 4.8%), post-treatment. CONCLUSIONS Unilateral electroacupuncture at the selected acupoints improved muscle strength of both limbs. These findings may have implications in physical therapy and rehabilitation settings.