Transcranial direct current stimulation (tDCS) over primary motor cortex leg area promotes dynamic balance task performance

The aim of the study was to investigate the effects of facilitatory anodal tDCS (a-tDCS) applied over the leg area of the primary motor cortex on learning a complex whole-body dynamic balancing task (DBT). We hypothesized that a-tDCS during DBT enhances learning performance compared to sham tDCS (s-tDCS). In a randomized, parallel design, we applied either a-tDCS (n = 13) or s-tDCS (n = 13) in a total of 26 young subjects while they perform the DBT. Task performance and error rates were compared between groups. Additionally, we investigated the effect of tDCS on the relationship between performance and kinematic variables capturing different aspects of task execution. A-tDCS over M1 leg area promotes balance performance in a DBT relative to s-tDCS, indicated by higher performance and smaller error scores. Furthermore, a-tDCS seems to mediate the relationship between DBT performance and the kinematic variable velocity. Our findings provide novel evidence for the ability of tDCS to improve dynamic balance learning, a fact, particularly important in the context of treating balance and gait disorders. TDCS facilitates dynamic balance performance by strengthening the inverse relationship of performance and velocity, thus making tDCS one potential technique to improve walking ability or help to prevent falls in patients in the future.