The effect of variable type of practice on one handed catching in children with developmental disorders

Abstract

Children with developmental disorders, such as DCD, struggle with interceptive tasks like ball catching. These problems may be due to less than optimal abilities to coordinate and control actions at intra- and inter-limb levels of organization. Although the kinematic characteristics exhibited by these children while catching are well documented, little has been done to enhance their skills to accomplish this seemingly simple task. One possible avenue to explore is the utilization of variable type of practice (Schmidt, 1975), which has been widely implemented as an intervention approach across many populations and skills (Van Rossum, 1990). From the conceptual standpoint, performance of a particular skill under varying task demands leads to improvements in parameterization of spatial and temporal aspects of organization, thus affording more flexible and adaptable movement patterns. It is plausible that this type of practice may positively affect the movement organization of children with developmental difficulties, however this issue has not been investigated thus far. Therefore, the purpose of this study was to examine the effects of variable type of practice on coordination and control of one-handed catching in children with symptoms of DCD and their typically functioning peers. Three boys and one girl (mean age = 10.5 years, SD = 1.29 years) with symptoms of DCD, and four typically functioning boys (mean age = 9 years, SD = 0 years) were recruited. Both groups participated in 12 variable practice sessions over a 6-week period. Three-dimensional kinematic analysis occurred at pre-, mid-, and post-intervention. Following a one-week delay, retention and transfer tests were administered to assess permanency and generalizability of the acquired patterns, respectively. The nature (mean and variability) of intra-limb coordination was inferred from intra-class correlations, which captured the degree of association between angular displacement of shoulder-elbow and elbow-wrist joint pairs.