Surface EMG and motor control of the upper extremity in muscular dystrophy: a pilot study

The aims of this pilot study were to determine levels of EMG potentials generated in arm muscles and examine the kinematics of hand motion of subjects with muscular dystrophy. A series of tests were designed to record EMG during maximal isometric force application, and to study synergistic muscular activity during arm motion. A test-bed was constructed where the subjects were seated next to a table and were asked to apply maximum radial force with their elbow flexed at 30°. The force attitude was 30°, 60°, 90°, and 120° degrees relative to the lateral aspect. For the dynamic tests, targets were placed along the same attitudes and the subjects were asked to reach for the target with a special arm support provision that ensured frictionless sliding. The limited results obtained to date show that the onset/termination of muscle activation could be recognized and activity level could be identified. Synergistic muscle activity and coordination patterns were identifiable in the subjects tested from the residual muscle potentials. Kinematic characteristics identified for point-to-point hand movements resemble those of healthy subjects. These results support further inquiry into the use of electromyography and motion patterns as methods for determining motor control strategies in people with MD.