Effects of Transcranial Direct Current Stimulation on Muscle Fatigue in Recreational Runners: Randomized, Sham-Controlled, Triple-Blind, Crossover Study-Protocol Study.

OBJECTIVES:The aim of this study is to evaluate the effects of transcranial direct current stimulation (tDCS) on central and peripheral fatigue in recreational runners. DESIGN:This is a clinical randomized, sham-controlled, triple-blind, crossover study. Twenty adult runners will be randomized on the first day of the intervention to receive active or sham tDCS before fatigue protocol. After 1 wk, the participants will receive the opposite therapy to the one that they received on the first day. The tDCS, 2 mA, will be applied for 20 mins over the motor cortex. The fatigue protocol will be performed after tDCS, in which the participant should perform concentric knee flexion/extension contractions until reaching three contractions at only 50% of maximum voluntary contraction. Central fatigue will be evaluated with the motor evoked potential of the quadriceps muscle; peripheral fatigue with the peak torque (N.m) using an isokinetic dynamometer; the electrical activity of the quadriceps muscle using surface electromyography (Hz); blood lactate level (mmol/L); and the subjective perception of effort (Borg scale). All evaluations will be repeated before and after the interventions. CONCLUSION:This study will evaluate the effect of tDCS on fatigue in runners, possibly determining an application protocol for this population.