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.