Saskia Baltrusch

182 Chapter 7 Figure 2: Angle-torque relationship of the spinal module (a) and a single hip actuator (b) (adopted from Näf et al., 2018 [23]). 2.2 Participants We recruited 11 male employees, working in the luggage handling department of the Dutch airline company KLM, who had ample experience with lifting tasks at work. The age, height and body mass of these participants were mean (sd): 47.4 years (7.1 years), 175 cm (7 cm), and 84 kg (15 kg). Data from one participant had to be discarded from the analysis, since this participant failed to complete the 5 minutes repetitive lifting task without the exoskeleton, due to pain in the back. Since our group of participants included people with and without a history of low-back pain, they were asked to indicate their current pain level before the start of the measurement on a scale from 0 (no pain) to 10 (maximum pain). The average pain level before the start of the measurement was (median [IQR]): 2.5 [0.75 - 5]. The participants received an information letter prior to the experiment and signed an informed consent form on the measurement day. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (VUmc, Amsterdam, The Netherlands, NL57404.029.16) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.