## 3 Results
### Angular Changes in Axial and Lower Extremity Components during the Hand Acceleration Phase
Basically, they could increase the range of trunk rotation to the medial side at medial reach and decrease the range of trunk rotation to the medial side at lateral reach (task effect: F = 46.774, df = 2, \(p\) < 0.001). Furthermore, children with CP and TD both demonstrated different angular adjustments of trunk rotation (interaction effect: F = 4.240, df = 2, \(p\) = 0.025). TD children showed several degrees of trunk rotation to the medial side for anterior reach, and then performed no trunk rotation for lateral reach. They showed the greatest degree of trunk rotation for medial reach (mean of anterior: \(-5.34^{\circ}\), mean of lateral: \(-0.04^{\circ}\), and mean of medial: \(-10.04^{\circ}\)). Children with CP did not show this apparent adjustment of trunk rotation (mean of anterior: \(-3.48^{\circ}\), mean of lateral: \(-1.29^{\circ}\), and mean of medial: \(-7.63^{\circ}\)). For pelvis movement, group (F = 7.187, df = 1, \(p\) = 0.001) and task effects (F = 4.925, df = 2, \(p\) = 0.015) existed in pelvis rotation. Children with CP rotated the pelvis toward the lateral side for anterior and lateral reaches, whereas TD children did not. At medial reach, children with CP did not demonstrate significant pelvis rotation to the medial side, as did TD children. A significant interactive effect was found in the pelvis tilting down to the lateral/medial sides (F = 3.680, df = 2, \(p\) = 0.039). Children with CP showed different directions of pelvis tilting (down to lateral or medial side) when reaching in different directions, especially when reaching medially. TD children maintained stable pelvis movement while reaching (Table 2). For hip movement, a group effect existed in hip adduction/abduction (F = 4.028 and F = 4.512, respectively, df = 1, \(p\) = 0.018 and 0.012, respectively). Children with CP showed certain degrees of lateral hip adduction and no movement of the medial hip (swaying the lower extremity toward the medial side of the trunk), whereas TD children showed certain degrees of lateral hip abduction and certain degrees of medial hip adduction (swaying the lower extremity away from the medial side of the trunk) during medial reach. An interaction effect between group and task did exist in the lateral hip adduction/abduction (F = 4.996, df = 2, \(p\) = 0.015), where children with CP adducted the lateral hip at medial reach, but TD children tended to about the lateral hip at medial reach. For ankle movement, a group effect was revealed in lateral ankle supination/pronation (F = 2.928, df = 1, \(p\) = 0.053). It seemed that children with CP demonstrated less stability of ankle motion (apparent ankle motion) than TD children (mild ankle motion) during the hand acceleration phase (Table 2). A task effect existed in medial ankle supination/pronation (F = 4.312, df = 2, \(p\) = 0.024), whereas an interaction effect was seen in medial ankle dorsiflexion/plantarflexion (F = 5.609, df = 2, \(p\) = 0.009). During lateral reach, children with CP supinated the lateral ankle, but TD children did not. For the task effect, children likely tried to pronate the medial ankle more during medial reach than during anterior reach. Interestingly, the two groups of children reacted differently during medial reach in the medial ankle dorsi/plantarflexion, where children with CP plantarflexed the medial ankle, but TD children dorsiflexed it. In summary, during the hand acceleration phase of reaching, the two groups of children were found to perform different angular motions with certain movement planes, such as the transverse plane, at medial reach. Children with CP extended and side-bent the trunk toward the medial side with decreased trunk rotation to that side while also tilting the pelvis down toward the medial side during medial reach. However, TD children rotated the trunk and pelvis (increased range of rotation) toward the medial side majorly to manage the medial reach task.