Saskia Baltrusch

51 Chapter 3 in various companies (Figure 1). It is worn around the waist with a belt and consists of pads at the anterior side of the chest and thighs and posterior at the level of the pelvis. The chest component is connected to the thigh component via the pelvis belt, through rigid bars running over a smart joint with spring-like characteristics. This joint generates a supporting extension moment at the level of the lower back when bending forward. The chest pad can rotate in the frontal plane of the trunk to allow trunk rotation. Figure 1: Laevo (Intespring, Delft, Netherlands). The hip centre of rotation of the device is to be aligned with the user’s trochanter major. The straps are used for personal length adjustment and do not have a mechanical role other than keeping the device in place. The chest pad can rotate in the frontal plane to facilitate walking. The Smart Joint allows hip/ trunk flexion/extension. Number of hip/trunk flexions while wearing the device is measured by the counter. 2.2 Participants Eighteen men with no low-back pain history, average age of 27.7 ± 5.1 years, average height of 1.78 ± 0.06m and average weight of 74.7 ± 8.0kg participated in this study. Their average Work Ability Index [14] was 9 on a scale of 10, with a range from 6-10. The participants received an information letter prior to the experiment and signed an informed consent form on the measurement day. The experiment was approved by the medical ethical committee of VU medical center (VUmc, Amsterdam, The Netherlands, NL57404.029.16). 3