Einfluss eines passiven Exoskeletts zur Rückenunterstützung auf die subjektive körperliche Beanspruchung und subjektive Beschwerdewahrnehmung bei simulierten Tätigkeiten mit statischer Oberkörpervorneigung und dynamischen Hebebewegungen

Abstract

Influence of a passive trunk exoskeleton on subjective physical strain and perceived discomfort during simulated tasks with static trunk flexion posture and dynamic lifting Objective: The influence of a passive back-supporting exoskeleton on perceived physical strain and discomfort was investigated in two occupational tasks. Methods: Thirty-six men (average age 26 years) performed simulated occupational tasks with and without the Laevo® exoskeleton in a balanced and randomised within-subject design. One of the activities was a dynamic lifting task (2 x 5 lifting processes, 11.6 kg load), which was performed with and without exoskeleton in a stoop (stretched knees) and squat position (flexed knees). The second activity was a 90-second sorting task with a static and 40° flexed upper body posture. Subjective physical strain was recorded by the “physical demand” dimension of the NASA-TLX questionnaire, discomfort by an 11-level numeric rating scale. The localisation of discomfort was also reported. The differences between the conditions with and without exoskeleton were analysed for both tasks and lifting postures (stretched vs. flexed knees). Results: With exoskeleton, there was always a small reduction in perceived physical strain levels (p < 0.05). Discomfort was rare, low and mainly in the lower back. For the sorting task with exoskeleton, the median level of discomfort intensity was one point lower (p < 0.05) than without exoskeleton. The frequency of discomfort was also lower with exoskeleton. There were no differences in the intensity of discomfort during dynamic lifting. When the exoskeleton was applied during lifting with stretched knee joints, the frequency of discomfort was slightly reduced; no differences occurred with flexed knee joints. Conclusion: The main potential of the studied exoskeleton appears to lie in activities with a static bent upper body posture. Longitudinal studies with a randomised controlled design are necessary to evaluate whether the possible potential described here is relevant to the prevention of work-related back complaints. Keywords: workplace design – back pain – assistive device