Transcranial Direct Current Stimulation Before Intermittent Exercise Does Not Improve Physical Performance.

Abstract

Fatigue in physical exercise is not only a physical event but also emotional, regulated by rating of perceived exertion (RPE). Currently the transcranial direct current stimulation (tDCS) has been used in research on physical exercise to check responses in neuromodulation of the central nervous system, reducing fatigue and improving physical performance. The application of anodal tDCS on insular cortex, one of the areas responsible for awareness of the subjective feelings of the body, has shown decreased RPE and increased aerobic performance. PURPOSE: To determine whether brain neuromodulation with tDCS is able to improve physical performance of individuals in an intermittent supramaximal stimulus. METHODS: Ten physically active men participated in this study (26.4±4.6 years). In cross-over mode, randomized (counter-balanced), double-blind, subjects performed two tests in cycle ergometer on two separate days, thus they received anodal tDCS of 2 mA applied over the left insular cortex or sham tDCS, for 20 minutes before the beginning of the exercise, at rest, sitting. After the tDCS, the subjects performed a previous warm and after 4 minutes of rest the subjects performed four sprints maximum of 30 seconds (Wingate test) with four minutes of rest between each sprint. The physical performance, RPE, heart rate variability and electromyographic were analyzed. RESULTS: The average power relative (Watts/Kg) was not different between the treatments, anodal tDCS and sham tDCS respectively (1° sprint 6.9±0.4 vs 7.0±0.5; 2° sprint 6.5±0.5 vs 6.5±0.4; 3° sprint 5.7±0.7 vs 5.9±0.5; 4°sprint 5.3±0.9 vs 5.4±0.6). The results of the RPE, heart rate variability and electromyographic were not affected by tDCS (P≤ 0.05). CONCLUSION: The brain neuromodulation imposed by anodal tDCS on insular cortex does not have the potential to delay fatigue and enhance physical performance in intermittent supramaximal effort.