Variation of muscle co-activation patterns in chronic stroke during robot-assisted elbow training

Hu X, Tong KY, Song R, Tsang VS, Leung PO, Li L

The aim of the study was to investigate the variation of muscle co-activation patterns during the course of robot-assisted rehabilitation on elbow flexion and extension for chronic stroke. A detailed electromyographic analysis was conducted on muscle activation levels and muscle co-activation patterns, represented by a co-contraction index of a muscle pair, for the muscles of biceps brachii, triceps brachii, anterior deltoid, and posterior deltoid, during training of elbow extension and flexion, actively assisted by a robot, from 0 degrees to 90 degrees by tracking a target moving at a speed of 10 degrees /s on the screen. Seven hemiplegic chronic stroke patients participated and received elbow training.

Each subject received 20 sessions (1.5 hours per session) of the elbow training on his/her paretic side at an intensity of 3 to 5 times a week for a training period of 7 consecutive weeks. The results showed that the electromyographic activation levels of the biceps brachii, triceps brachii, and anterior deltoid of each subject decreased during the training. The authors concluded that in the 20-session robot-assisted training, the excessive muscle activations reduced mainly in the first half of the training course, which could have been related to the learning process of the tracking skill and also to the reduction in muscle spasticity. The muscle coordination for achieving elbow tracking improved significantly in the latter sessions of the training, represented as decreased co-contraction indexes between the muscle pairs.

Archives of Physical Medicine & Rehabilitation, 2007, 88(8), 1022-9

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