Instructions emphasizing speed improves hemiparetic arm kinematics during reaching in stroke

Stroke severely compromises the capacity for skilled motor control including the ability to reach with the stroke-affected upper-extremity. Research incorporating intensive motor therapies has broadly demonstrated the ability to improve hemiparetic reaching post-stroke, yet the role of specific task parameters has received less attention. These task parameters, such as speed-of-performance, may be important to the structure and delivery of motor rehabilitation. The objective of the study was to determine the influence of task pacing demands on hemiparetic reaching strategies in survivors of stroke.

Kinematic motion analysis was used to examine upper-extremity reaching patterns in 11 survivors of stroke. Participants were instructed to reach between two targets at a self-selected pace and as fast as possible. Outcome measures included maximal movement speed, accuracy, movement smoothness, and reaching strategies (anterior trunk flexion, elbow extension, and shoulder flexion).

Participants reached significantly faster and smoother during the task that emphasized speed while maintaining target accuracy. Participants used significantly less anterior trunk displacement during the fast condition, yet no change in shoulder flexion.

Task parameters that emphasize speed positively influence reaching strategies with the more-affected upper-extremity. Survivors of stroke were able to respond to changes in pacing demands while significantly reducing reliance on compensatory trunk movement. This outcome highlights the need to further understand the impact of task parameters during intensive motor therapies.