Transcranial Direct Current Stimulation Improves Bilateral Ankle-Dorsiflexion Force Control in Healthy Young Adults

This study examined transient effects of transcranial direct current stimulation (tDCS) on bilateral force control in lower extremities. We recruited 14 healthy young adults and administered bilateral ankle-dorsiflexion force control tasks at 10% of maximal voluntary contraction. Participants were able to use real-time visual information on a targeted force level and forces produced by both feet. While performing bilateral force control, we provided active- and sham-tDCS in a random order. Bilateral tDCS protocol used for this study included anodal and cathodal stimulation targeting left and right leg areas of the primary motor cortex between hemispheres. Bilateral force control capabilities were estimated by calculating force accuracy, variability and regularity. In addition, we determined whether force control patterns differed between feet across active- and sham-tDCS conditions. The findings revealed that force accuracy and variability were significantly improved after applying active-tDCS protocol as compared with those for sham-tDCS condition. However, no differences in force control between feet were observed. These findings suggest that bilateral tDCS protocols may be a viable option for improving motor functions of lower limbs.