Faster speed at the expense of arm-trunk coordination during reaching in chronic spastic stroke patients
Abstract
Background. The velocity of reaching movements is often reduced in patients with stroke-related hemiparesis; however,
they are able to voluntarily increase paretic hand velocity. Previous studies have proposed that faster speed improves
movement quality. Objective. To investigate the combined effects of reaching distance and speed instruction on trunk and
paretic upper-limb coordination. The hypothesis was that increased speed would reduce elbow extension and increase
compensatory trunk movement. Methods. A single session study in which reaching kinematics were recorded in a group
of 14 patients with spastic hemiparesis. A 3-dimensional motion analysis system was used to track the trajectories of 5
reflective markers fixed on the finger, wrist, elbow, acromion, and sternum. The reaching movements were performed
to 2 targets at 60% and 90% arm length, respectively, at preferred and maximum velocity. The experiment was repeated
with the trunk restrained by a strap. Results. All the patients were able to voluntarily increase reaching velocity. In the
trunk free, faster speed condition, elbow extension velocity increased but elbow extension amplitude decreased and trunk
movement increased. In the trunk restraint condition, elbow extension amplitude did not decrease with faster speed.
Seven patients scaled elbow extension and elbow extension velocity as a function of reach distance, the other 7 mainly
increased trunk compensation with increased task constraints. There were no clear clinical characteristics that could
explain this difference. Conclusions. Faster speed may encourage some patients to use compensation. Individual indications
for therapy could be based on a quantitative analysis of reaching coordination.
Domains
Neuroscience
Origin : Files produced by the author(s)