Abstract
Transcranial direct current stimulation (tDCS) has been used aiming to boost exercise performance and inconsistent findings have been reported. One possible explanation is related to the limitations of the so-called “conventional” tDCS, which uses large rectangular electrodes, resulting in a diffuse electric field. A new tDCS technique called high-definition tDCS (HD-tDCS) has been recently developed. HD-tDCS uses small ring electrodes and produces improved focality and greater magnitude of its aftereffects. This study tested whether HD-tDCS would improve exercise performance to a greater extent than conventional tDCS. Twelve endurance athletes (29.4 ± 7.3 years; 60.15 ± 5.09 ml kg−1 min−1) were enrolled in this single-center, randomized, crossover, and sham-controlled trial. To test reliability, participants performed two time to exhaustion (TTE) tests (control conditions) on a cycle simulator with 80% of peak power until volitional exhaustion. Next, they randomly received HD-tDCS (2.4 mA), conventional (2.0 mA), or active sham tDCS (2.0 mA) over the motor cortex for 20-min before performing the TTE test. TTE, heart rate (HR), associative thoughts, peripheral (lower limbs), and whole-body ratings of perceived exertion (RPE) were recorded every minute. Outcome measures were reliable. There was no difference in TTE between HD-tDCS (853.1 ± 288.6 s), simulated conventional (827.8 ± 278.7 s), sham (794.3 ± 271.2 s), or control conditions (TTE1 = 751.1 ± 261.6 s or TTE2 = 770.8 ± 250.6 s) [F(1.95; 21.4) = 1.537; P = 0.24; η2p = 0.123]. There was no effect on peripheral or whole-body RPE and associative thoughts (P > 0.05). No serious adverse effect was reported. A single session of neither HD-tDCS nor conventional tDCS changed exercise performance and psychophysiological responses in athletes, suggesting that a ceiling effect may exist.
Highlights
Daniel Gomes da Silva Machado 1,2, Marom Bikson 3, Abhishek Datta 3, Egas Caparelli‐Dáquer 4, Gozde Unal[3], Abrahão F
They showed that a-Transcranial direct current stimulation (tDCS) (2 mA for 20 min) applied over the temporal cortex (TC), targeting the left insular cortex, improved cycling performance by approximately 4% in professional cyclists and decreased heart rate (HR) and ratings of perceived exertion (RPE) in submaximal intensities[16]
A paired t-test showed no difference between the two tests in the reproducibility phase for time to exhaustion (TTE) (t = − 0.228; P = 0.82; r = 0.97; Fig. 3A), HRmax (t = 1.383; P = 0.19; Fig. 3B), and V O2max (t = − 0.047; P = 0.96; Fig. 3C) attained during TTE test
Summary
Daniel Gomes da Silva Machado 1,2, Marom Bikson 3, Abhishek Datta 3, Egas Caparelli‐Dáquer 4, Gozde Unal[3], Abrahão F. Participants performed two time to exhaustion (TTE) tests (control conditions) on a cycle simulator with 80% of peak power until volitional exhaustion They randomly received HD-tDCS (2.4 mA), conventional (2.0 mA), or active sham tDCS (2.0 mA) over the motor cortex for 20-min before performing the TTE test. Okano et al.[16] were one of the firsts to demonstrate the modulation of whole-body exercise performance and exercise-related perception by tDCS They showed that a-tDCS (2 mA for 20 min) applied over the temporal cortex (TC), targeting the left insular cortex, improved cycling performance by approximately 4% in professional cyclists and decreased heart rate (HR) and ratings of perceived exertion (RPE) in submaximal intensities[16]. Meta-analytical evidence has shown improvements in muscle strength and endurance during an exercise involving isometric and dynamic c ontractions[19]
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