Effects of tDCS on EMG parameters
CORTEX
The results of the repeated-measures ANOVAs showed a significant main effect of stimulation on the EMG parameters of all muscles, including the left deltoid muscle (FPost hoc comparisons revealed that bilateral anodal premotor tDCS significantly increased MVIC of the left deltoid muscle as compared to sham tDCS (p = 0.004). For the right deltoid muscle, both premotor (p = 0.009) and cerebellar (p = 0.020) tDCS significantly increased MVIC compared to sham tDCS. No significant difference was observed between the two active stimulation protocols (p > 0.998).For the left biceps muscle, again both, premotor cortex (p < 0.001) and cerebellar cortex (p < 0.001) stimulation significantly increased MVIC compared to sham tDCS. No significant difference was found between the active stimulation protocols (p = 0.239). For the right biceps muscle, bilateral anodal stimulation of the premotor cortex significantly increased MVIC compared to cerebellar stimulation (p = 0.011) and sham tDCS (p = 0.007). For the left triceps muscle, stimulation of the premotor cortex increased MVIC as compared to sham tDCS (p = 0.003). For the right triceps muscle, stimulation of the premotor cortex significantly increased MVIC compared to cerebellar cortex stimulation (p < 0.001) and sham tDCS (p < 0.001). Premotor cortex stimulation significantly increased MVIC of the left trapezius muscle compared to sham tDCS (p = 0.016), and for the right trapezius muscle, both premotor (p < 0.001), and cerebellar (p = 0.007) stimulation significantly increased MVIC compared to sham tDCS. Finally, for the left pectoralis muscle, both, premotor (p = 0.011) and cerebellar (p = 0.031) stimulation significantly increased the MVIC index compared to sham tDCS, and for the right pectoralis muscle, premotor tDCS significantly increased MVIC compared to cerebellar cortex stimulation (p < 0.001) and sham tDCS (p = 0.006).