Ball catching in children with developmental coordination disorder: control of degrees of freedom

Abstract

This study investigated two-handed catching in eight children (four males, four females) aged 7 to 8 years (mean 7y 4mo [SD 3mo]) with developmental coordination disorder (DCD) and their age-matched controls (AMCs). Kinematic data were collected to examine Bernstein's (1967) notion of freezing and releasing degrees of freedom (DF). Participants were asked to catch a ball 30 times, delivered in three blocks of 10 trials. Video analysis showed that children with DCD caught significantly fewer balls than their AMCs (p≤0.001) counterparts. Kinematic analyses showed that children with DCD exhibited smaller ranges of motion and less variable angular excursions of the elbow joints than their AMCs, and that their elbows are more rigidly coupled (p≤0.001). These data suggest that children with DCD rigidly fix and couple their limbs to reduce the number of DF actively involved in the task.Developmental coordination disorder (DCD) describes children with a marked impairment in the development of motor coordination that significantly interferes with daily activities and, often, academic achievement. These coordination difficulties are not due to a general medical condition, be it physical or mental. 1 Published work shows that children with DCD are a heterogeneous group with a variety of patterns of strengths and weaknesses yet rarely highly skilled at any motor task. 2,3 Children with DCD have been shown by many to exhibit difficulties with ball-handling skills. [2][3][4][5][6][7] Studies that have investigated ball catching in children with DCD suggest their problems could be due to a disturbance of visual perception 8 or problems with visuospatial anticipation and information processing. 9 Research has shown that children with DCD require more time than children without DCD to determine which cues are useful for their decision-making process in catching. 5 These observations are consistent with the notion that children with DCD have difficulty selecting appropriate motor responses, 10 suggesting that this could contribute to the difficulties observed when catching balls.Published work has also shown that children with DCD have problems with both temporal and spatial aspects of catching a ball. They exhibit more grasping errors and showed less elbow flexion and arm extension than their peers, and less bending of the elbows to absorb the force of the ball. 6 These observations suggest that children with DCD place restrictions upon their movement system to restrict the number of joints or degrees of freedom (DF) involved when catching a ball. 6 Catching a ball with two hands requires the coordination of many DF. Simply put, a DF refers to how many axes a joint can move about. For example, the elbow only has one DF: the forearm can flex toward or extend away from the upper arm. 11 If we take into account the number of joints and/or muscles working in the arms, there are far more DF available than the minimum number required to successfully accomplish the task. 12 These redundant DF give flexibility to the motor apparatus tha...

Using the ICF Framework to Explore the Multiple Interacting Factors Associated with Developmental Coordination Disorder

“…Ball handling skills are important in many contexts for social interaction on the playground and for participating in sports. Ball skills performance has been studied by various authors and is considered a robust means of differentiating between skill levels, with children with DCD performing poorly [47,48].…”

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

“…To date, limited studies have examined catching performance in DCD using three-dimensional movement analysis [10][11][12][13][14]. Those that have, suggest that children with DCD rigidly fixate and couple their upper limbs [10,13], exhibit errors during the transport and grasp phases [12], and display less adaptable movement strategies [14].…”

“…Those that have, suggest that children with DCD rigidly fixate and couple their upper limbs [10,13], exhibit errors during the transport and grasp phases [12], and display less adaptable movement strategies [14]. While these studies have provided greater insight into the catching deficiencies of this population, they are not without design limitations, including: (i) investigating broad age ranges of children, (ii) selection of children who fall into the 'at risk' category of this disorder (between 5 and 15th percentile), and (iii) using less sophisticated 3D motion analysis systems and techniques.…”

Quiet eye training facilitates visuomotor coordination in children with developmental coordination disorder

“…Visual target perturbation 29 studies have demonstrated the significant difficulties children with DCD experience when making predictive online 30 movement adaptations to movement trajectories (Hyde and Wilson, 2011a,b). Importantly, the deficits experienced by 31 children with DCD are most pronounced in complex, interceptive tasks (Bairstow & Laszlo, 1989;Wilmut & Wann, 2008;32 Mak, 2010), and as such there is a need for research to further examine visuomotor control and motor performance in these 33 less constrained settings using 'real-world' tasks (Wilson, Miles, Vine, & Vickers, 2013 'freezing' their elbow angles in this position throughout the catch in an attempt to reduce the degrees of freedom they have 39 to coordinate in the movement (Utley et al, 2007;Astill, 2007). In this study we investigated whether this freezing strategy is 40 driven by deficits in perception of ball flight characteristics that can be corrected through the use of QET.…”