Effect of task context on reaching performance in children with spastic hemiparesis

Objective: To investigate the effect of task context on the quality of reaching movements in children with spastic hemiparesis. Design: Randomized controlled experimental trial. Setting: Institute for the Study of Education and Human Development (ISED). Subjects: Twelve children (8-14 years of age) with spastic hemiplegic cerebral palsy. Interventions: Subjects made fast reaching movements with the affected or nonaffected arm on a digitizer in three context conditions: (a) reach to press a light switch to turn on a red light (functional), (b) reach to press the light switch; no light (semi-functional), and (c) reach to a marker (nonfunctional). Main outcome measures: Kinematics of reaching movements of affected and nonaffected arms: movement time (MT), peak velocity (PV), time to PV, percentage of MT where peak velocity occurred (PPV), and smoothness (i.e. number of movement units (MU)). Results: The functional condition elicited better quality of reaching for the nonaffected, but particularly the affected arm. Reaching of the affected arm was faster (larger MT; F = 10.21, p < 0.01), smoother (fewer MU; F = 19.95, p < 0.001), and better-controlled (right shift of PPV; F = 16.03, p < 0.001) compared with the semi- and nonfunctional condition. Reaching of the nonaffected arm was also faster (longer MT, F = 4.81, p < 0.05), and more smooth (fewer MU, F = 7.23, p < 0.05). Conclusions: These findings suggest that providing a functional context to perform a task may enhance the quality of reaching movements of the affected arm in children with spastic hemiparesis.