Saskia Baltrusch

206 Chapter 8 (1999) [22], self-efficacy is defined as a person’s confidence to succeed at a given activity, and it also is an important factor in the development of disability as a result of low-back pain. If people show low levels of self-efficacy, they more likely shy away from tasks they perceive as a personal threat in regard to their musculoskeletal disorder [23]. High levels of self-efficacy have been found to be associated with decreased pain and disability levels in patients suffering from chronic pain [24]. A longitudinal study concluded that self-efficacy is an important variable that mediates the relationship between low back pain and disability over time [25]. This suggests the importance of increasing self-efficacy in low-back pain patients. An exoskeleton for the low back that decreases spinal loading during certain activities might increase self-efficacy in low-back pain patients. As a result, the users’ acceptability of the exoskeleton is likely to improve. In this study, we aimed to involve potential end-users to investigate factors that are important for acceptability of an exoskeleton in the working environment. We used a mixed method design, in which quantitative research and qualitative research are combined to derive complementary information. In the quantitative part of the study we specifically aimed to assess the effect of the SPEXOR exoskeleton on self-efficacy, given the importance of self-efficacy as a mediator between low-back pain and disability and in view of its effect on acceptability . In the qualitative part of the study we used a focus group and interviews to get more insight into the potential of the device to change behavior when suffering from low-back pain and to assess acceptability of the exoskeleton to potential end-users. 2 Methods 2.1 Mixed Method Approach We applied a mixed method approach; thus, quantitative and qualitative methods were integrated to achieve our research aim. We used a serial exploratory design, by first collecting quantitative data, followed by qualitative data collection [26]. This allows to check for convergence in the findings and leads to final inferences that are based on both results [27]. For participants, we approached the Dutch airline company KLM and the Dutch automotive industry Mitsubishi Turbochargers and Engine Europe, aiming to include workers with a history of