A kinematic study of contextual effects on reaching performance in personswith and without stroke: Influences of object availability

Objective: To examine the effects of context on reaching performance in neu rologically impaired and intact populations. Context was varied by the pres ence or absence of objects used to complete a task. Design: A counterbalanced repeated-measures design. Setting: A motor control laboratory in a university setting. Participants: Fourteen persons with stroke and 25 neurologically intact adu lts. Interventions: Each participant was tested under two conditions: the presen ce of the object, in which the participant reached forward with the impaire d arm (or corresponding arm) to scoop coins off the table into the other ha nd; and the absence of the object, in which the participant reached forward to the place where the coins would be placed in the condition of object pr esent. Main Outcome Measures: Kinematic variables of movement time, total displace ment, peak velocity, percentage of reach where peak velocity occurs, and mo vement units (derived from acceleration data) for reaching tasks. Results: The condition of using real objects elicited kinematically better performance of reaching movements than the condition of performing movement s without relevant objects present. Better performance was reflected by sho rter movement time, less total displacement, higher peak velocity, greater percentage of reach where peak velocity occurs, and fewer movement units. Conclusion: The results of this study showed that the condition of object p resent elicited better performance of movements represented by kinematic va riables than the condition of object absent. The clinical implication is th at the use of real and functional objects might be an effective way of faci litating efficient, smooth, and coordinated movement with the impaired arm in persons with stroke. This study, however, should be replicated and exten ded to confirm the validity of its findings and to allow for generalization in various functional activities.