The Effect of Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex on Muscle Fatigue Resistance

Transcranial direct current stimulation (tDCS) delivered to the dorsolateral prefrontal cortex (DLPFC) can increase endurance time in lower body cycling tasks. The purpose was to examine the effect of DLPFC-tDCS on the time to task failure (TTF) of a fatiguing contraction performed by hand muscles. The study used a double-blind, randomized, SHAM-controlled, crossover design. Participants completed two experimental sessions on separate days with a washout between sessions. All facets of the experiments were identical except the stimulation condition (DLPFC-tDCS or SHAM) that was given concurrent with the fatiguing contraction. The fatiguing contraction involved gripping a manipulandum with the index finger and thumb using a precision grip and matching an isometric target equal to 15% of the maximum voluntary contraction (MVC) for as long as possible until task failure. The main findings were that TTF and fatigue index did not differ between the DLPFC-tDCS and SHAM conditions. Furthermore, there was no significant differences during the fatiguing contractions in the rates of increase of electromyographic (EMG), force error, or standard deviation (SD) of force between the DLPFC-tDCS and SHAM conditions. Overall, the results indicate that application of DLPFC-tDCS does not reduce the rate of muscle fatigue development in the current task conditions.