The effect of transcranial direct current stimulation on rating of perceived exertion: A systematic review of the literature

Abstract

The rating of perceived exertion (RPE) is a widely used method for monitoring the load during training, as it provides insight into the subjective intensity of effort experienced during exercises. Considering the role of brain in monitoring and perception of the effort, several studies explored the effect of transcranial direct current stimulation (tDCS) on RPE in different populations. The aim of current study is to review the studies that investigated the effect of tDCS on RPE in three groups including healthy untrained people, physically active persons, and athletes. Nine databases were searched for papers assessing the effect of tDCS on RPE. The data from the included studies were extracted and methodological quality was examined using the risk of bias 2 (ROB2) tool. Thirty-three studies met the inclusion criteria. According to the meta-analysis, active a-tDCS significantly decreased the RPE compared to the sham stimulation. The a-tDCS could decrease the RPE when it was applied over M1 or DLPF. Regarding the measurement tool, Borg's scale 6-20 and OMNI scale could show an improvement in RPE scale. A-tDCS is a promising technique that can decrease the RPE. M1 and DLPFC are suggested as the target area of stimulation. From the tools that measure the RPE, Borg's RPE 6-20 and OMNI scale could better show the effect of a-tDCS. This study demonstrates the impact of tDCS (transcranial direct current stimulation) on RPE (rating of perceived exertion) and addresses the effect of population, tDCS protocol, and measurement tools on the intervention. The most promising outcomes were the use of M1 (primary motor cortex) and DLPFC (dorsolateral prefrontal cortex) tDCS in athletics. In addition, Borg's scale 6-20 and OMNI (overall monitoring of the neuromuscular intensity) were the most effective measuring tools.