Assessing stroke-induced abnormal muscle coactivation in the upper limb using the surface EMG co-contraction Index: A systematic review

Electromyography (EMG) is increasingly used in stroke assessment research, with studies showing that EMG co- contraction (EMG-CC) of upper limb muscles can differentiate stroke patients from healthy individuals and correlates with clinical scales assessing motor function. This suggests that EMG-CC has potential for both assessing motor impairments and monitoring recovery in stroke patients. However, systematic reviews on EMGCC's effectiveness in stroke assessment are lacking. To address this, the present study aims to synthesize recent evidence on EMG-CC's use in evaluating stroke-induced muscle abnormality. Eighteen studies including a total of 308 stroke patients and 155 healthy controls were included. Fifteen out of Eighteen included studies used the EMG-CC to successfully differentiate abnormal muscle co-contraction performance of the affected upper limb, even in comparison to the unaffected side in static tasks (isometric maximal voluntary contractions) and dynamic tasks (movement-oriented or goal-oriented). The EMG-CC shows promise as a convenient and effective tool for evaluating the extent of abnormal muscle coactivation in the upper limbs of post-stroke patients with spasticity as well as assessing the effectiveness of rehabilitation interventions. Further research is needed to validate these findings and establish standardized protocols for EMG-CC's use in stroke assessment.