tDCS, CSE, and Grip Strength Performance
The present study aimed to extend the research of Pourmajidian et al. (2020) by investigating whether cathodal preconditioning enhances the effect of subsequent anodal tDCS on CSE and performance in a submaximal grip strength task. It was hypothesised that cathodal preconditioning would increase the effects of anodal tDCS on CSE when compared to conventional anodal tDCS and sham tDCS. Regarding exercise performance, it was hypothesised that cathodal preconditioning would increase the effect of subsequent anodal stimulation of the motor cortex on the time to exhaustion (TTE) in a submaximal isometric grip strength task beyond that seen after conventional anodal and sham tDCS. The current study implemented a within-subjects, single-blinded, sham-controlled, randomised block design. All experimental protocols were conducted in the same temperature controlled (~ 23 ℃, 33% humidity) laboratory. Participants were required to attend the laboratory on five separate occasions; a familiarisation session and four experimental sessions corresponding to four different experimental conditions (cathodal preconditioning, sham cathodal preconditioning, conventional, sham conventional). The study sample size, method and data analysies plan were pre-registered on Open Science Framework (OSF; https://osf.io/8vdma). The experimental protocol was approved by the local human research ethics committee (Project ID: 11882).