Saskia Baltrusch

168 Chapter 6 Table 3: User’s Impression assessed by VAS scales Category Median Interquartile Range VAS scale Adjustability Donning and Doffing 1.9 0.4-4.3 0=very easy 10=very difficult Length Adjustment 1.3 0.5-2.7 0=very easy 10=very difficult Range of Motion 1.4 0.7-2.3 0=not restricted 10=heavily restricted Efficacy Reduction of back loading 3.9 1.9-6.9 0=high reduction 10=no reduction Support of tasks 4.6 1.3-7.7 0=high support 10=no support Interference with tasks 2 0.9-3.3 0=no interference 10=high interference Use at work 6.8 5.7-7.5 0=daily use 10=no use 4 Discussion This study assessed the effect of wearing the SPEXOR exoskeleton on functional performance and user satisfaction. Specifically, we evaluated the effects on objective and subjective performance in people with and without a history of low-back pain. Within the group of tasks to test the potential support of the exoskeleton, objective performance increased for lifting and static forward bending. We did not find a change in objective performance for carrying. Since this task requires little trunk flexion, only the hip actuators were loaded during this task and not the spinal module, leading probably more to hindrance while walking than helping for load carriage. Subjective performance showed similar results. Perceived task difficulty and local discomfort in the lower back were reduced in lifting and in both static postural tolerance tasks. Wearing the exoskeleton during the static postural tolerance tasks, yielded decreased discomfort in upper and lower back, but also in abdomen and upper legs. These findings demonstrate that the SPEXOR exoskeleton supports tasks that are known to be risk factors for low- back pain due to their high back loading [5,6]. The support of these tasks is also in line with previous studies that found reduced back loading during lifting and forward bending when wearing assistive body worn devices [10-12,15,17]. Still,