Saskia Baltrusch

179 Chapter 7 1 Introduction Low-back pain (LBP) has become a major health problem worldwide [1]. With a lifetime prevalence reported to be as high as 84 % [2], LBP causes a considerable burden on industry. Negative consequences for companies are, amongst others, decreased productivity [3] and increased sickness absence from work [4]. The wide range of complex exposure patterns at workplaces complicates the introduction of interventions, aiming to prevent LBP and support return-to-work management. An important risk factor for the onset of LBP is mechanical loading of the low back, which can occur during manual materials handling and lifting [5,6]. Despite technical innovations and the knowledge that exposure to occupational lifting should be reduced, physically demanding jobs remain. For example, one-third of employees in the Netherlands indicate that they regularly perform repetitive, physical tasks at work (Statistics Netherlands, 2016), indicating that the skills and versatility of employees often can’t be replaced by automated processes. Within the challenge of reducing mechanical loading of the low back in the work environment, body-worn assistive devices (exoskeletons) have been designed and introduced in industry [7]. Exoskeletons, as a mechanical intervention, are intended to reduce the mechanical load on the back by decreasing muscular activity in the back muscles, needed to counteract external moments caused by inertial and external forces. Previous research has shown that this concept of providing an assisting external extension moment can be effective in reducing lumbar L5S1 moments, back muscle activity, and compression forces in the low back [7-16]. Due to the reduction in low back moment and back muscle activity when wearing an exoskeleton, metabolic cost is also expected to decrease. Besides mechanical loading, metabolic cost should also be considered when it comes to preventing LBP. McGill et al. (2007) [17] have shown that, the metabolic cost of lifting objects may cause a ventilatory challenge that interferes with control of trunk movement. Additionally, this may cause fatigue, while fatigue-related changes in spinal stability may increase the risk of injury in the low back [18]. Keeping 7