A Functional Muscle Synergy for Forward Reaching

Abstract

There is increasing interest in the development of devices to assist rehabilitation. Functional electrical stimulation has the capacity to enhance muscle activation and timing during functional tasks. Identifying principal muscles may assist developers in designing operating parameters of these devices. In this study electromyography (EMG) and kinematic measures were taken from the affected and unaffected arms of stroke patients and both arms of healthy age-matched control participants. Three muscles (anterior deltoid, biceps and wrist extensors) were identified as forming a functional muscle synergy and are nominated as principal muscles for forward reaching. In control participants the three principal muscles were active prior to the start of movement in all trials. Activation was delayed in the affected arm of the participants with stroke. Facilitating appropriate activation of the principal muscles for reaching may enhance outcomes for people following stroke.