Anodal Motor-Cortex Transcranial Direct Current Stimulation and Explosive Lower-Limb Power in Healthy Active Adults: A Sham-Controlled Systematic Review and Meta-Analysis

Abstract

Anodal transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) has been proposed as an ergogenic aid. Prior reviews pooled heterogeneous outcomes, and none isolated explosive lower-limb power or separated jump output from force–time kinetics. We asked whether anodal M1 tDCS versus sham improves explosive lower-limb power in healthy active adults, analysing these two outcome categories separately. Following PRISMA 2020 (PROSPERO CRD420261438841), four databases were searched up to 3 July 2026 for randomised and crossover trials. Random-effects meta-analyses (REML with Hartung–Knapp) pooled Hedges’ g by category; risk of bias (RoB 2) and certainty (GRADE) were assessed. Seven trials were included. tDCS did not significantly improve jump output (k = 6; g = 0.44, 95% CI −0.05 to 0.92; p = 0.069; I2 = 19%). The kinetics estimate was moderate (k = 3; g = 0.67, 95% CI 0.53 to 0.81; I2 = 0%) but did not survive a conservative small-sample correction (95% CI −0.23 to 1.57; p = 0.086). Certainty was very low throughout. Including a further trial whose comparator was a no-intervention control made both estimates significant, indicating a fragile evidence base. Current evidence does not establish an ergogenic benefit; adequately powered, pre-registered trials are needed.