Observations of improvement of reaching in five subjects with left hemiparesis

Kinematic analysis and surface electromyography were used to study reaching by five subjects with left hemiparesis as they attempted to touch each of three targets. The targets were placed to require movement within and out of extensor synergy. Each subject was tested five times over a nine week period. Over this time, amplitude of peak velocity and sense of limb position significantly improved in the paretic arms. The increase of amplitude of peak velocity was more strongly related to a decrease in the discontinuity of movement (r = -0.48) than to maximal level of contraction of the prime movers (anterior deltoid: r = 0.25; biceps: r = 0.39). This finding may be a sign of learning or increased maturity of reach. These results, if replicated in a larger sample, would support therapy designed to improve learning of new sensorimotor relationships in the hemiparetic limb.