Saskia Baltrusch

50 Chapter 3 different postures. Assistive devices might reduce the mechanical load in one specific task but might obstruct performance in other tasks. Thus, the practical implementation of exoskeletons might be limited due to low user acceptance, based on discomfort at the physical user interface with the device [13] and movement limitations by the device. By being limited to only one stereotypical task, these studies do not represent the variability in tasks and trunk movement patterns that characterize many work environments. Thus, results presented above cannot be generalized to environments with more versatile working tasks. Therefore, evaluating the functional performance, i.e. the ability to perform relevant functional tasks beyond manual materials handling, is essential to assess user acceptance of exoskeletons in realistic work situations. This will provide insight into design problems of existing devices, necessary to improve designs and make them more usable and acceptable in a realistic work setting. The purpose of this study was to assess the effect of a passive exoskeleton on functional performance in healthy individuals in 12 different work-related tasks, based on objective and subjective outcome measures. We selected a series of tasks based on their relevance and occurrence in physically stressful jobs, such as construction, logistics and manufacturing. Among these tasks, three types can be considered: (1) tasks in which the user potentially benefits from the exoskeleton, such as lifting and working in a static forward bend position, (2) functional tasks in which the user is potentially hindered by resistance against movement generated by the device and (3) basic movements requiring participants to use a large range of motion (ROM). We expected positive effects of the device for the first set of tasks (1) and negative effects for the latter ones (2 and 3). By testing a passive exoskeleton that is already used at work sites (Laevo; Intespring, Delft, The Netherlands), we aimed to test these assumptions and to create a benchmark for further developments of low-back assistive devices. 2 Methods 2.1 Passive Exoskeleton The device tested in this study was the passive exoskeleton “Laevo” (Intespring, Delft, The Netherlands), which is currently available on the market and used