Coordination of reaching with the impaired and non-impaired arm in 10 children with spastic hemiparetic cerebral palsy (SHCP) was examined in a stationary ball and moving ball context. Kinematic data on trunk, arm, and wrist movements, and coordination patterns between joint angles of elbow, shoulder, and trunk, were analyzed to determine how reaching was influenced by impairment and object motion. Results showed longer deceleration time and movement time and greater trunk contribution following decreased elbow and shoulder excursion when reaching with the impaired arm compared to the non-impaired arm. The coordination of joint angle pairs showed little linearity for the impaired arm, indicating more segmented movements of shoulder and elbow. It was also found that coordination patterns between elbow, shoulder, and trunk displayed less similarity when reaching with the impaired arm compared to the non-impaired arm in both stationary and moving ball conditions. Regardless of the timing constraints, children with SHCP could make successful interceptions using the impaired arm, indicating that they coordinated and controlled the degrees of freedom within their own functional possibilities.

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The aim of the experiment was to examine how children coordinate the degrees of freedom of the arm and trunk when performing interceptive actions that correspond to daily life activities. For that purpose, children were required to reach and grasp a stationary ball while standing (condition C1), a stationary ball while walking (C2), and a moving ball while standing (C3). The resulting movements were measured in world-centered and bodycentered coordinates, and then subjected to three-dimensional kinematic analysis. The different coordinate frames of reference were used to determine the interaction between arm and trunk movements. Children adapted their coordination in the two moving conditions (C2 and C3) by decelerating longer towards the ball and exhibiting more interaction between the arm and trunk movements than in the stationary condition (C1). These results indicate that, like adult participants, children adapt to the constraints imposed by complex, interceptive actions by recruiting additional degrees of freedom of the trunk, which are coordinated with the hand to produce a movement that preserves an appropriate level of impact at hand/object collision.

Purpose. The purpose of the study was to examine the coordination of reaching and walking behaviour when children with Spastic Hemiparetic Cerebral Palsy (SHCP) intercept an approaching and hence externally-timed object. Method. Using either the impaired or non-impaired arm, children intercepted a ball approaching from a fixed distance with one of three velocities. Each participant's initial starting position was scaled to their maximum walking velocity determined prior to testing; for the medium ball velocity, participants would arrive at the point of interception at the correct time if they walked with their maximum velocity. Results. Children with SHCP adapted their reaching and walking behaviour to the different ball approach velocities. These adaptations were exhibited when using the impaired and non-impaired arm, and resulted in similar outcome performance irrespective of which arm was used. Still, children with SHCP found it necessary to increase trunk movement to compensate for the decreased elbow excursion and a decreased peak velocity of the impaired arm. Conclusion. Children with SHCP exhibited specific adaptations to their altered movement capabilities when performing a behaviourally-realistic task. The provision of an external timing constraint appeared to facilitate both reaching and walking movements and hence could represent a useful technique in rehabilitation.