EMG-Guided Human-Machine Interaction Training Develops New Intermuscular Coordination Patterns in Stroke: A Pilot Study

Background Stroke survivors often experience impaired upper extremity motor function due to abnormal muscle synergies. This pilot study evaluated the feasibility and preliminary effectiveness of electromyography-guided human-machine interaction training designed to expand the repertoire of intermuscular coordination patterns and improve upper extremity motor function in chronic stroke survivors. Methods Four chronic stroke survivors with mild-to-moderate upper extremity motor impairment and three age-matched healthy controls participated in a six-week electromyography-guided training intervention. Participants practiced selectively activating one elbow flexor muscle while suppressing another (brachioradialis or biceps brachii). Throughout the course of the intervention, the effect of the training on intermuscular coordination, task performance, and motor function and impairment level of stroke-affected upper extremity were assessed. Results Participants in both the control and stroke groups successfully learned to selectively activate targeted muscles, expanding their repertoire of habitual intermuscular coordination patterns. Stroke survivors demonstrated improvements in force generation, reaching ability, wrist rotation, and clinical measures of upper extremity motor function and spasticity. Participants also reported improved ease in performing daily activities. Conclusions This pilot study demonstrated the feasibility of using electromyography-guided human-machine interaction training to expand the repertoire of habitual intermuscular coordination patterns and improve upper extremity motor function in chronic stroke survivors. These findings highlight the potential of electromyography-guided human-machine interaction training as a neurorehabilitation approach to address motor deficits associated with abnormal intermuscular coordination following stroke. Trial registration: The study was registered at the Clinical Research Information Service of Korea National Institute of Health (KCT0005803).