title: External timing constraints facilitate performance of everyday interceptive actions in children with Spastic Hemiparetic Cerebral Palsy.
abstract: We examined how children with Spastic Hemiparetic Cerebral Palsy (SHCP) perform interceptive actions they experience in daily life. Children were required to walk towards and intercept a stationary ball or a moving ball, with either their impaired or non-impaired arm. In the stationary ball condition the child was free to determine the speed of their response (internal timing), whereas in the moving ball condition there was a restricted time available (external timing). It was found that the reach movements of the non-impaired arm were different to the impaired arm, and were characterized by some of the typical movement limitations imposed by SHCP. However, there was no evidence of increased contribution from trunk motion or a lengthening of reach movement time or deceleration time. Instead, there was a coordinated change with the walking kinematics, whereby the children spent proportionately more time slowing down as they approached the point of interception when reaching with the impaired arm. There were also several differences in the response when intercepting a moving ball compared to a stationary ball. When the timing constraints were imposed externally (moving ball) rather than internally (stationary ball), children reached with a reduced movement time and deceleration time, and an increased peak wrist velocity and elbow excursion. These adaptations to behaviour were necessary to deal with the restricted time available to make the interception in the moving ball condition compared to when the ball was stationary, and reveal how children with SHCP coordinate walking and reaching when performing natural interceptive actions.
authors.affiliation: Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human Movement Sciences, Free University of Amsterdam, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands.
authors.forename: Annieck X C
authors.initials: AX
authors.lastname: Ricken
authors.forename: G J P
authors.initials: GJ
authors.lastname: Savelsbergh
authors.forename: S J
authors.initials: SJ
authors.lastname: Bennett
mesh_terms: D000203:Activities of Daily Living; D000704:Analysis of Variance; D001132:Arm / Q000503:physiopathology; D001696:Biomechanical Phenomena; D002547:Cerebral Palsy / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D006429:Hemiplegia / Q000503:physiopathology*; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D013647:Task Performance and Analysis