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

Background and/or Objectives: Transcranial direct current stimulation (tDCS) delivered to the dorsolateral prefrontal cortex (DLPFC) has been shown to enhance endurance in lower body cycling tasks, suggesting a role in modulating motor function. DLPFC-tDCS may offer a novel therapeutic approach to improve motor function for people with neuromuscular disorders. The purpose of this study was to examine the effect of DLPFC-tDCS on the time to task failure (TTF) of a fatiguing contraction performed by hand muscles.

Design: 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.

Setting : Laboratory settings using standardized equipment and protocols for exploring effects of transcranial direct current stimulation on hand muscle fatigue.

Participants : 13 healthy young adults

Interventions: DLPFC-tDCS

Main Outcome Measures: Time to failure (TTF) and fatigue index

Results: The main findings were that TTF and fatigue index did not differ between the DLPFC-tDCS and SHAM conditions. Furthermore, there were no significant differences during the fatiguing contractions in the rates of increase of electromyographic (EMG) activity, force error, or standard deviation (SD) of force between the DLPFC-tDCS and SHAM conditions.

Conclusions: Overall, the results indicate that application of DLPFC-tDCS does not reduce the rate of muscle fatigue development in the current task conditions.