Overcoming limitations in elbow movement in the presence of antagonist hyperactivity

A traditional perspective on rehabilitation of patients with abnormal muscular hyperactivity presumes that relaxation should be facilitated prior to recruitment of antagonists, if effective movement about a joint is to occur. The purpose of the study was to determine the effect of training weak triceps brachii muscles, with hyperactivity present in the opposing biceps brachii muscles, on elbow function in individuals at least 1 year poststroke.

Sixteen patients with chronic stroke were randomly assigned to receive electromyographic biofeedback to retrain the triceps muscle (n = 8) or to receive conventional movement training (n = 8).

Both groups participated in 5 baseline and 10 training sessions involving tasks requiring elbow extension. Preintervention and postintervention measurements included elbow extension range of motion, triceps and biceps muscle electromyographic activity during performance of elbow extension, resisted elbow extension, and a reaching task.

Two-sample t-test results of between-group comparisons for each variable were not significant. One-sample t-test results of within-group comparisons showed significant increases in triceps muscle mean electromyographic activity during two of the three tasks for the feedback group, but not for the nonfeedback group. Passive and active range of motion in both groups increased significantly, although biceps muscle co-contraction persisted.

These results suggest that functional improvements at the elbow may have been due to biomechanical (peripheral) rather than neuromuscular (central) changes about the joint. Furthermore, these preliminary data indicate that patients with stroke may be trained to increase movement without first being trained to specifically inhibit hyperactivity in muscles.