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 EMG-CC'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.