Laura Peeters

Trunk, head and pelvis interactions in healthy children | 65 3 tasks, 79% of the participants). In the sagittal plane, more than 50% of the participants moved their head in opposite direction to the trunk. However, both for reaching forward and contra-laterally a substantial part of the participants moved their head in the same direction as the trunk (on average of tasks, 30% of the participants). In the frontal plane, 22% of all participants did not move their head relative to the trunk when reaching forward and contra-laterally and when performing daily tasks. This was higher compared to the other movement planes. For the four daily tasks, the head movement strategy varied. For the dexterity task, more than 36% of the participants did not move their head relative to the trunk in all planes, and when drawing more than half of the participants moved the head in the same direction as the trunk movement in all planes. Movement onset When trunk and head onset were equal to the start of the recording, data were excluded from analysis. It could not be guaranteed that these movements were related to the performed task. The number of included subjects is shown in Figure 10. Compared to the arm motion onset, the head movement onset was significantly earlier in all reaching tasks, and the trunk movement onset was significantly earlier in most reaching tasks (Figure 10). In some tasks when reaching forward, the head onset was also significantly earlier than the trunk onset, resulting in a ‘head-trunk-arm’ movement sequence. However, the inter quartile ranges were large and also passed the arm movement onset line, indicating that the movement onset for head and trunk was not prior to the arm movement for every subject. DISCUSSION The results of this study give insight in the interaction between arm, trunk, head and pelvis movements in children when reaching and performing daily tasks, and in the contribution of different trunk segments to the task in children and young adults. When performing maximum trunk movement tasks, contributions of individual trunk segments varied with movement direction. In flexion, the contribution was roughly equal among all segments, but in lateral bending the thoracic segments contributed more compared to the lumbar segments, and in trunk axial rotation the lower thoracic segment contributed most. This is in agreement with the study of Preuss and Popovic [14] for axial rotation, where subjects performed target-directed trunk movements. Their results contradict our results in the other two planes. They found the highest contribution in both flexion-extension and lateral bending from the most