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

Objective: To examine the effects of context on reaching performance in neurologically impaired and intact populations. Context was varied by the presence 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 adults. Interventions: Each participant was tested under two conditions: the presence of the object, in which the participant reached forward with the impaired arm (or corresponding arm) to scoop coins off the table into the other hand; 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 present. Main Outcome Measures: Kinematic variables of movement time, total displacement, peak velocity, percentage of reach where peak velocity occurs, and movement 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 movements without relevant objects present. Better performance was reflected by shorter 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 present elicited better performance of movements represented by kinematic variables than the condition of object absent. The clinical implication is that the use of real and functional objects might be an effective way of facilitating efficient, smooth, and coordinated movement with the impaired arm in persons with stroke. This study, however, should be replicated and extended to confirm the validity of its findings and to allow for generalization in various functional activities.