Undesired coactivation in upper limb muscles may depend on severity of impairments in stroke survivors

In this case study, we sought to determine whether undesired muscle coactivation limits the upper limb workspace, and whether the coactivation varies with stroke severity. During a voluntary reaching task with different supporting forces on upper limb, changes in muscle activation levels were recorded and then compared with healthy subjects. A chronic hemispheric stroke survivor did not show the undesired coactivation between shoulder abductor and elbow flexor during elbow extension to reach targets, which implies that the occurrence of undesired activation might vary in stroke survivors, and depend on the severity of their brain lesions.