Saskia Baltrusch

184 Chapter 7 Figure 3: Experimental setup without (left) and with exoskeleton (right). Red circles show the cluster markers on the body (left) and on the exoskeleton (right). The yellow boxes show the EMG location. 2.4 Experimental procedure At the start of the measurement, the oxygen mask was fitted to the participants and resting metabolic rate was measured, while participants were sitting in a chair for 5 minutes. Subsequently, the exoskeleton was fitted and adjusted to the participant. Anthropometric data were obtained and participants got familiarized with the exoskeleton. EMG electrodes were then placed on the participant, and maximal voluntary isometric contractions (MVCs) were performed. During MVC contractions, participants had to maximally activate the recorded muscles against resistance of upper body weight and added manual resistance for 5 s. The maximum values across 3 repetitions were later used to normalize EMG data of the subsequent trials. In preparation of the following protocol, cluster markers were attached to the participant’s body, calibration measurements were performed. During the actual experimental conditions, participants were instructed to lift and lower a box of 10 kg (0.39 x 0.37 x 0.11 m, with 2.5 cm diameter handles) from ankle height to hip height, at a rate of 8 lifts per minute. The weight of