Laura Peeters

Trunk, head and pelvis interactions in healthy children | 67 3 terms of trunk movement. The trunk segments that showed a significant increased ROM with reaching height, distance and object weight, correspond to the segments contributing the most in the maximum trunk movement tasks: in the frontal plane the thoracic segments and in the sagittal plane all trunk segments, with an exception of the lower thoracic segment when reaching laterally. In the transverse plane, there was no consistent, significant increase in trunk movement between all segments and reaching conditions. This could be explained by the fact that too much trunk rotation will cause an overshoot in arm alignment with the target. Although there was no consistent, significant difference found in axial rotation between the different reaching conditions, axial rotation of the lower thoracic segment was present in each reaching task and therefore seems to be necessary. Again, this is consistent with the finding that the lower thoracic segment contributed the most in the maximum trunk rotation task. When performing the reaching and daily tasks, anterior tilt of the pelvis and flexion in the lower lumbar segment was seen, while extension was seen in the thoracic segments, indicating that subjects prefer to erect their trunk (decrease thoracic kyphosis and lumbar lordosis) when performing arm tasks. This is in line with suggestions that an erect sitting posture has benefits compared to a slumped posture when performing arm tasks, as it elongates the spine so less arm elevation is needed, and consequently less arm muscle strength, and it ensures a larger shoulder range of motion [16]. Also, the maximum range of axial rotation of the trunk itself increases with a more erect sitting posture [17]. Strong correlations were found between total trunk ROM and age when reaching forward and laterally. Younger children used more trunk movement compared to older children and the variability was higher, indicating maturation of coordination between trunk and arm movements. The strongest correlations were found when reaching near, at shoulder height and without weight, but the effect (in degrees per year) was the least. This maturation effect with age is in line with findings of Schneiberg, et al. [4] and Sveistrup, et al. [5], and should be taken into account when evaluating children with NMD. Age-matched comparison is very important to distinguish between natural and pathologic trunk movements. Interactions between trunk and head could already be seen when performing maximal head movements, where the upper thoracic segment contributed quite substantial in (mainly) the maximum neck flexion and extension movement, in agreement with Tsang, et al. [18]. When performing daily tasks, the chosen strategy for head movement relative to the trunk, likely depends on maintaining, or achieving, gaze on the target [19]. This could be seen in the transverse plane, where axial rotation of the head was used in the opposite direction to the trunk when reaching forward and contra-laterally, compared to movement in the same direction when reaching