The Cross-Education Effect of Unilateral Arm Training on Contralateral Muscle Strength and EMG Activity: The Modulatory Roles of tDCS and Practical BFR
Keywords:
Cross-education, Blood flow restriction, tDCS, Strength, Neural adaptationAbstract
Cross-education refers to strength gains in the untrained limb following unilateral training. Blood flow restriction (BFR) and transcranial direct current stimulation (tDCS) are known to induce peripheral and neural adaptations, respectively. This study investigated whether combining unilateral BFR and tDCS enhances cross-education effects in the untrained arm. Thirty-eight healthy young men were randomly assigned to four groups: tDCS-pBFR, Sham-pBFR, tDCS, and Control. Over four weeks, participants performed unilateral dumbbell curl training (30% 1RM, 3 sessions/week). The primary outcomes for the untrained arm were one-repetition maximum (1RM), arm muscle circumference (AMC), and electromyography (EMG) activity. ANCOVA with pre-test as covariate was used for statistical analysis. Strength of the untrained arm (1RM) increased significantly in tDCS-pBFR and Sham-pBFR groups compared with control (p < 0.05), while AMC changes were significant only in Sham-pBFR. EMG activity did not differ significantly among groups. No significant difference was observed between tDCS-pBFR and Sham-pBFR groups. Unilateral BFR training, with or without tDCS, produces cross-education effects in the contralateral untrained arm. Strength improvements appear to be primarily mediated by neural adaptations, with limited changes in muscle size or EMG activity. These findings support the use of BFR and neuromodulatory interventions to enhance contralateral strength, particularly in rehabilitation settings.
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Copyright (c) 2025 Behzad Taheri, Fatemeh Nikseresht (Author); Khadijeh Irandoust (Corresponding Author); Ziya Fallah Mohammadi, Somayeh Namdar Tajari (Author)
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