IMPROVEMENT IN KINEMATIC CHARACTERISTICS AND COORDINATION FOLLOWING STROKE QUANTIFIED BY LINEAR-SYSTEMS ANALYSIS

The kinematic characteristics of standing up were studied during recovery following stroke. Patients with a diagnosis of hemiplegia were videotaped on two occasions: when they could first stand up independently and again when they could stand up and sit down three times in 10 seconds with no observable asymmetry. Peak angular velocity of the affected hip and knee joints increased, movement time decreased and the spectrum of the movement shifted towards higher frequencies. The velocity signals became smooth and bell-shaped, whereas initially they had multiple peaks. The hip and knee joints became almost perfectly coupled, whereas previously there was significant independent activity at each joint. However, the coordinative relation between the joints was a simple algebraic one with no significant dynamics and this did not change as the ability to stand up improved. The kinematic changes observed in the stroke patients mirrored those of normal motor skill acquisition.