Abstract
The purpose of this inquiry was to examine how children with (M = 10.5 years) and without Developmental Coordination Disorder (M = 10.9 years) recruited the relevant degrees of freedom needed for an interceptive task such as ball catching. Ten balls were projected, at the speed of 7m/s, to the dominant side of the participant. Two digital cameras (60 Hz) were used for the purpose of 3D reconstruction, and APAS system was used to extract the angular displacement of the shoulders and trunk. Significant differences were found between the groups in trunk (Mnodcd = 31 deg vs. Mdcd = 16 deg) (t (18) = 4.69, p < .001), but not in shoulder actions (Mnodcd = 66 deg vs. Mdcd = 64 deg). Also, typically developing children exhibited tight coupling between the angular displacement of the two elements, as compared to children with DCD who decoupled the actions of the shoulder and trunk (rnodcd = .84 vs. rdcd = .58) (t (18) = 4.84, p <. 001). Children with DCD were also more variable in the magnitude of the resulting correlations (rnodcd = .15 vs. rdcd = .28). From these results we suggest that inter-segmental coordination is jeopardized in children with DCD, and that this may be due to the less than optimal recruitment of degrees of freedom associated with trunk action.%
