Effects of repeated tDCS on lower limb muscle explosive strength and executive function in male collegiate volleyball players: a randomized controlled trial

Objective Volleyball requires superior lower limb explosive strength and rapid executive function for optimal performance and injury risk reduction, yet the efficacy of repeated transcranial direct current stimulation (tDCS) in enhancing these volleyball-specific physical and cognitive capacities remains unclear. This study aimed to investigate the effects of five consecutive days of tDCS on lower limb explosive strength and executive function in male collegiate volleyball players. Methods Thirty-two participants were randomized to receive real tDCS (anodal stimulation over M1, 2 mA for 20 min/day, n = 17) or sham stimulation (n = 15) for five consecutive days. Running jump height, countermovement jump (CMJ) height, isokinetic knee strength at 60°/s and 180°/s (extension/flexion, dominant/non-dominant leg), and event-related potential (ERP) indices (No-Go P3 amplitude/latency) during a Go/No-Go task, as well as reaction time (RT) in the task were assessed before and after the intervention. Results A significant Time × Group interaction was observed for running jump height ( P < 0.01) and No-Go P3 amplitude ( P < 0.01), with the tDCS group showing greater improvements than the sham group. For CMJ, isokinetic knee extensor strength (60°/s) and RT, no significant Time × Group interaction was observed, while a significant main effect of Time was detected (all P s < 0.05) without significant interaction. No-Go P3 latency showed no significant effects. Conclusion Five consecutive days of tDCS on the M1 area specifically enhances volleyball-related explosive jumping performance (running jump) and inhibitory control (increased Nogo-P3 amplitude) in male collegiate volleyball athletes.