Variable Practice May Enhance Ball Catching Skills in Some but Not All Children With DCD

Abstract

Children with DCD exhibit many motor issues including ball catching, which have not been addressed clinically. The purpose of this study was to examine if variable practice can improve one-handed catching performance of five boys with DCD with severe (M = 11.1 years, SD = .7) and moderate movement problems (M = 11. 7 years, SD = .9). Both groups attended 12 sessions, with 8 blocks of 10 attempts, across four different ball velocities. Children with moderate issues caught more balls at post- and transfer test, as compared to pre-test. Kinematic profiles showed that both groups exhibited stable configuration of the catching arm; however, only children with moderate issues increased (peak) velocity, degree of spatial adaptations, and extended the pre-programmed ballistic phase of the action. Thus, variable practice appeared to be effective for children with moderate issues but not those with severe problems. In line with VPH hypothesis, these improvements were due to strengthening of the schema responsible for spatial and temporal adaptations of the end effector.