Transcranial direct current stimulation (tDCS) over the left prefrontal cortex does not affect time-trial self-paced cycling performance: Evidence from oscillatory brain activity and power output

Abstract

ObjectivesTo test the hypothesis that transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) influences performance in a 20-min time-trial self-paced exercise and electroencephalographic (EEG) oscillatory brain activity in a group of trained male cyclists.DesignThe study consisted of a pre-registered (https://osf.io/rf95j/), randomised, sham-controlled, single-blind, within-subject design experiment.Methods36 trained male cyclists, age 27 (6.8) years, weight 70.1 (9.5) Kg; VO2max: 54 (6.13) ml.min-1.kg-1, Maximal Power output: 4.77 (0.6) W/kg completed a 20-min time-trial self-paced exercise in three separate sessions, corresponding to three stimulation conditions: anodal, cathodal and sham. tDCS was administered before each test during 20-min at a current intensity of 2.0 mA. The anode electrode was placed over the DLPFC and the cathode in the contralateral shoulder. In each session, power output, heart rate, sRPE and EEG (at baseline and during exercise) was measured.ResultsThere were no differences (F = 0.31, p > 0.05) in power output between the stimulation conditions: anodal (235 W [95%CI 222–249 W]; cathodal (235 W [95%CI 222–248 W] and sham (234 W [95%CI 220–248 W]. Neither heart rate, sRPE nor EEG activity were affected by tDCS (all Ps > 0.05).ConclusiontDCS over the left DLFC did not affect self-paced exercise performance in trained cyclists. Moreover, tDCS did not elicit any change on oscillatory brain activity either at baseline or during exercise. Our data suggest that the effects of tDCS on endurance performance should be taken with caution.

Does self-paced exercise depend on executive processing? A narrative review of the current evidence

“…Moreover, stimulating the prefrontal cortex for 20 min did not elicit any change in oscillatory brain activity either at baseline or during exercise (Holgado, Zandonai, et al, 2019). Hence, the current evidence available does not support the claim that tDCS is able to improve self-paced performance.…”

Is tDCS an Adjunct Ergogenic Resource for Improving Muscular Strength and Endurance Performance? A Systematic Review

“…Eight studies (Angius et al, 2015, 2018; Okano et al, 2015; Vitor-Costa et al, 2015; Barwood et al, 2016; Sasada et al, 2017; Lattari et al, 2018a; Holgado et al, 2019) evaluated the efficiency of tDCS for improving the endurance (see Tables 3, 4). Relevant side effects were not described.…”

“…The mean age of the participants from studies varied between 21 (Sasada et al, 2017) and 33(±9) (Okano et al, 2015) years. Regarding tDCS conditions, a-tDCS condition had sample sizes between 6 (Barwood et al, 2016) and 36 (Holgado et al, 2019), with a total of 133 participants among studies, while control condition had sample sizes between 6 (Barwood et al, 2016) and 36 (Holgado et al, 2019), with a total of 147 individuals among studies. There was no dropout.…”

“…In addition, only two studies (Okano et al, 2015; Sasada et al, 2017) reported experience in ET, which could be an influencer factor in a-tDCS response. Regarding mode of tDCS application, all studies using offline mode (Angius et al, 2015, 2018; Okano et al, 2015; Vitor-Costa et al, 2015; Barwood et al, 2016; Sasada et al, 2017; Lattari et al, 2018a; Holgado et al, 2019). In addition, all studies used crossover study design (Angius et al, 2015, 2018; Okano et al, 2015; Vitor-Costa et al, 2015; Barwood et al, 2016; Sasada et al, 2017; Lattari et al, 2018a; Holgado et al, 2019), with only a single session of tDCS for all of them.…”

“Brain-Doping,” Is It a Real Threat?

“…Regarding stimulation intensity, recent studies have proposed that due to the high inter-individual variability in participants' electric fields, it seems that the most efficient approach to induce constable cortical changes would be to apply an individualized current intensity for each person (Esmaeilpour et al, 2018; Laakso et al, 2019). Indeed, the usual stimulation intensity does not seem to induce oscillatory brain electrical changes at rest or during exercise (e.g., Holgado et al, 2019; cf. Vöröslakos et al, 2018).…”