EMG Patterns in Robot Assisted Reaching Movements of Upper Arm.

Variations in muscle activation, underlying improvements in muscle strength and muscle function, in response to training of patients with congenital or acquired brain injuries, are still poorly understood. Much better results in sensorimotor and cognitive processes are promised by the emerging robot-mediated therapy. One of the most interesting features of a robot-mediated therapy is the ability to quantify the performance of the rehabilitation tasks proposed to the patient. Although the shoulder is the most complex joint in the body, both as to freedom range and for the muscular-tendon structure, not so many commercial or research devices have been proposed to study its movements and no study has proposed a standardized, quantitative electromyographic assessment during robot-assisted reaching movements of the upper arm. This study aimed to develop a quantitative assessment of the electromyographic pattern of the arm???s muscles involved in reaching movements robot-assisted by means of indices used to describe effectively the main features of the pattern in four normal subjects and to implement rehabilitation strategies patients oriented. Each subject underwent the proposed motor task and EMG recording, repeating the trial three times; for a total of twelve reaching movements for each sequence. Number of EMG activations and deactivations recorded for each of the eight studied muscles are gathered. The proposed method effectively described the main pattern???s features in normal subjects.