The Influence of Dual Sources Cerebellar Transcranial Direct Current Stimulation on Muscle Fatigue

Transcranial direct current stimulation (tDCS) applied unilaterally to the cerebellum (ctDCS) can improve several aspects of human motor performance. The purpose of the study was to examine the influence of dual source tDCS delivered bilaterally over the cerebellar cortices (dsc-tDCS) on the time to task failure (TTF) of a fatiguing contraction. The study utilized a double-blind, randomized, SHAM-controlled, within-subjects, crossover design and participants were given either dsc-tDCS or SHAM stimulation in two different experiments held 7 days apart. Every aspect of the two experiments was the same except the type of stimulation (dsc-tDCS or SHAM) delivered during the fatiguing contraction. The fatiguing contraction was executed with a precision grip at 15% of the maximum voluntary contraction (MVC) force and participants were instructed to maintain the contraction for as long of time as possible (TTF). The TTF and fatigue index were both similar for the dsc-tDCS and SHAM stimulation conditions. In addition, the electromyographic (EMG) activity, force error, and standard deviation (SD) of force measured during the fatiguing contraction were also not statistically different between the dsctDCS and SHAM stimulation conditions. The findings suggest that dsc-tDCS does not decrease the rate of progression of muscle fatigue.