Laura Peeters

Summary |115 6 center of pressure displacement, trunk sway parameters, and/or force profiles). Out of 188 potentially eligible articles, 32 articles were eventually included in the review. No studies were found involving patients with neuromuscular disorders, like DMD and SMA. Interactions between trunk, head and UE change with age in typically developing children, where trunk movement decreases with age when performing UE tasks. Trunk involvement was also dependent on reaching distance in healthy children, as well as in healthy adults and in patients with CP and SCI. Main differences in trunk movement strategies between CP and SCI patients were seen when reaching towards targets within 90% arm length: increased trunk flexion in CP versus increased trunk extension in SCI. Various strategies were found to maintain trunk stability during reaching: reduce degrees of freedom, reduce movement speed of the arm, counterbalance the perturbing effect of UE movement by moving the trunk or the other arm in the opposite direction, and change the base of support. For the head, stabilizing its orientation in space (i.e. not with respect to the trunk) is the most common strategy in healthy children and adults. However, stabilizing the head appeared more difficult in CP children with a flaccid trunk, because of trunk instability. It is concluded that the key role of the trunk in performing activities should be kept in mind when developing interventions to improve seated task performance in neurological patients with a flaccid trunk, and that more research is needed on these interactions in patients with DMD and SMA. Measurements: trunk function during seated upper extremity tasks The literature review showed the gap in knowledge of interactions between trunk, UE and the head in people with DMD and SMA when performing daily tasks. To increase this knowledge, we performed laboratory measurements with healthy controls ( chapter 3 ), DMD patients ( chapter 4 ) and type 2 and 3 SMA patients ( chapter 5 ). The methods were comparable for all groups. All participants performed two series of tasks when sitting unsupported (no back or armrests, feet on the floor). First, they performed maximum active range of motion (ROM) tasks of the trunk and head in all three movement planes. Thereafter, participants performed various daily tasks at self-selected speed, like reaching and placing objects in forward and sideward directions, drinking, and displacing a dinner plate from left to right. Movement of the trunk, pelvis, head and UE were captured with an optical motion capture system when performing these tasks, together with surface electromyography (sEMG) signals from the back (i.e. iliocostalis, longisimus), abdominal (i.e. external oblique) and shoulder muscles (i.e. trapezius descendens and medial deltoid). These sEMG signals were normalized to the maximum sEMG signals obtained during maximum voluntary isometric contraction (MVIC) measurements in a seated position, so that values represented a percentage of the maximum muscle capacity. Maximum trunk