Visual tracking behaviour of two-handed catching in boys with developmental coordination disorder.

BACKGROUND: Developmental coordination disorder (DCD) is a motor learning disability that affects coordination resulting in an inability to perform movement skills at an age appropriate level. One area suspected to contribute to the movement difficulties experienced are deficits in visuomotor control. AIMS: This study investigated visual tracking behaviour during catching in children with DCD. METHODS AND PROCEDURES: Twenty-four boys completed the study: 11 with DCD (9.43 years ±0.73) and 13 controls (9.16 years ± 0.68). Participants performed 10 central catching trials, with the best five used to evaluate tracking behaviour and motor responses. OUTCOMES AND RESULTS: Prior to ball release, the DCD group exhibited more fixations (p = 0.043) of lesser duration (p = 0.045). During flight, the DCD group took longer to initiate smooth pursuit (p = 0.003) however, once initiated, both groups were effectively able to maintain smooth pursuit. Despite initial delays, these had no impact on movement initiation time (p = 0.173), however, movement time was significantly slower in the DCD group (p = 0.031). CONCLUSIONS AND IMPLICATIONS: The results of this study demonstrate that catching performance in children with DCD likely reflect a combination of errors in attending to visual information and movement organisation.

Catch! Movement kinematics of two-handed catching in boys with Developmental Coordination Disorder.

PURPOSE: To quantify two-handed catching in boys with Developmental Coordination Disorder (DCD) by examining sequencing of the upper limb and trunk segments, and degree of symmetry. METHOD: Thirteen boys with DCD( ̅x=9.36 years ± 0.68) and 13 Controls ( ̅x=9.16 years ± 0.68) participated. Children performed 10 two-handed central catching trials, with the best five trials selected for analysis. RESULTS: The DCD group displayed greater variability in range of motion across all joint rotations in the catch phase. Specifically, increased shoulder flexion, thorax extension and elbow extension. Although the initiation of segmental movement occurred in the same order for the two groups, the DCD group initiated wrist extension considerably earlier. The DCD group also exhibited significant asymmetry in elbow flexion-extension. CONCLUSION: Despite success in performing this simple catching task (88% successful), the DCD group displayed an inefficient, variable and less symmetrical catching technique.