Transcranial direct current stimulation (tDCS) is widely studied for its potential to enhance exercise performance by modulating corticospinal excitability (CSE). However, the inconsistency in the effects of tDCS on CSE and exercise performance highlights the need for continued investigations. There are two avenues of investigation that are explored in this thesis: optimising tDCS application to manipulate CSE for performance enhancement and exploring alternative psychophysiological mechanisms of tDCS that may be implicated in exercise performance outcomes. This thesis aims to better understand and optimise tDCS for improving exercise performance in healthy individuals. This thesis is comprised of seven chapters: an introduction (Chapter 1), two literature reviews (Chapters 2 and 4), three research papers (Chapters 3, 5, and 6), and a discussion (Chapter 7). Chapter 2 reviews methods for optimising tDCS in exercise performance, comparing various parameters including timing, intensity, and montage. Chapter 3 presents a single-blind sham-controlled study using a novel tDCS application method to enhance CSE and grip strength TTE, reporting no significant effect on either exercise performance or CSE. Chapter 4 critically analyses physiological mechanisms of tDCS, covering both immediate and enduring effects, as well as neuronal and non-neuronal effects. Chapter 5 presents a double-blind crossover experiment assessing the impact of tDCS and exercise on blood-brain barrier (BBB) permeability, finding no impact on BBB or cycling time to exhaustion. Chapter 6 reports a single-blind sham-controlled study on tDCS effects on exercise-related pain sensitivity, showing no additional hypoalgesic effect. Overall, this thesis partially supports the potential of tDCS of the motor cortex to improve exercise performance, though the exact mechanisms of this effect and potential optimised applications remain unclear. Future research on optimisation and understanding of tDCS will contribute to more consistent and robust results.
Understanding and optimising the effects of transcranial direct current stimulation on endurance exercise performance
Lewis, A. (Author). 2024
Student thesis: Doctoral Thesis