earticle

영어

Purpose: This study aimed to investigate the effect of transcranial direct current stimulation (tDCS) on the onset of upper extremity muscle activities during forward reaching performance. Methods: Fifteen healthy men (age, 24.2±1.55y) participated in this randomized double-blind crossover study. Each participant received both a sham and 2-mA stimulation over M1 bilaterally for 20 min, with a minimum washout period of 4 days. Muscle activation was evaluated for all the participants during the task of reaching out for a marked target as fast as possible, using electromyography (EMG) before and immediately after tDCS application. Results: For the within arm-length reaching performance in the 2-mA stimulation session, the muscle activities of the anterior deltoid (AD), posterior deltoid (PD), biceps brachii (BB), and inferior spinatus (IS) were decreased significantly during, immediately after, and 20 min after the tDCS period compared with the baseline values (p for all values ＜0.05). The pectoralis major (Pec) muscle showed a significant decrease only in the 20-min period after tDCS compared with the baseline values (p=0.001). For the beyond arm-length reaching performance, the 2-mA application on the AD, PD, BB, and IS showed significant decreases in onset time in all the periods after tDCS as compared with the baseline (p for all values ＜0.05). The onset of the triceps brachii muscle activity significantly decreased immediately and 20 min after the tDCS periods. For the Pec muscle, the onset time of muscle activation significantly changed only in the 20 min after the tDCS period compared with the baseline values. Conclusion: The present study demonstrated that bilateral tDCS over M1 facilitates muscle activation rapidly during the reaching performance, regardless of the reaching target distance.