Laura Peeters

General discussion |125 6 motors) were developed in the project and knowledge from this thesis helped in the development. First of all, we saw clear trunk involvement in healthy participants when performing UE tasks (chapter 3), which confirmed that trunk movement is essential and should be supported in patients to optimize task performance. Based on the ROM found in healthy participants when performing tasks, we could set requirements for the amount of trunk and head movement that should be provided by the supportive devices. Supporting both trunk and head flexion-extension had the highest priority and axial rotation should either be allowed or supported. Control of the supportive devices should preferably not be based on displacement of the hand, since trunk and head movement onsets were earlier than arm movement onset (chapter 2). Last but not least, we saw that contribution of individual trunk segments to the ROM varied with movement direction and therefore with the task performed, so the devices should provide or allow movement in different segments or continuous movement. In DMD patients we saw that UE function (i.e. Brooke scale) seemed to decrease before trunk function. This indicates that the trunk supportive device for DMD patients will usually be integrated with an UE supportive device. Since previous research showed that compensatory trunk movements decrease when an UE supportive device is used [44], we did not increase the requirements for the amount of trunk movement that should be provided by the device, although increased trunk movements were seen in DMD patients compared to HC (chapter 4). It remains difficult to predict whether an UE or trunk support should be provided first in SMA patients or that both should be combined from the start, because we could not compare different disease stages in SMA patients. Increasing demands of support can be expected in both groups due to progressive muscle weakness. Therefore, support levels should be adaptable to the disease stage or even during the day to prevent excessive fatigue. When the support level is higher than required, there is a risk of deterioration of function due to disuse. On the other hand, providing more support than needed can also give possibilities to perform more activities or with a longer duration. Clearly, more research is needed to quantify the required support level and to determine factors that influence this level. Ultimately, adaptive devices are needed. In other words, devices that automatically adapt their support level based on predicted user needs, or systems that adapt based on intentional user-driven signals. Evaluation of the developed passive trunk support device for trunk flexion and extension showed reduced normalized back muscle activity by 10-35% in healthy man and boys with DMD [45, 46]. This means that patients need up to 1/3 less muscle effort to perform tasks, which would reduce development of fatigue and provide the option to increase the frequency or duration of performing tasks. Using a passive head support system also reduced normalized upper trapezius muscle activity