The influence of using exoskeletons during occupational tasks on acute physical stress and strain compared to no exoskeleton - A systematic review and meta-analysis

Objectives: This systematic review and meta-analysis determined the effects of using an exoskeleton during occupational tasks on physical stress and strain compared to not using an exoskeleton. Methods: Systematic electronic database searches were performed and the review was prepared according to the PRISMA guidelines. Treatment effects on the predefined outcomes were calculated using standardized mean differences for continuous outcomes in several meta-analyses using Review Manager 5.3. Registration: PROSPERO (CRD42020168701). Results: 63 articles were included in qualitative syntheses and 52 in quantitative, but most of them did not extensively evaluate musculoskeletal stress and strain and the risk of bias was rated high for all included studies. Statistically significant effects of using back, upper-limb, or lower-limb exoskeletons have been observed in the supported body areas (e.g. reduced muscle activity, joint moments and perceived strain). Studies which did not exclusively focus on the supported body area also showed statistically significant effects in the non-supported areas (e.g. changed muscle activity and perceived strain) and in physiological outcomes (e.g. reduced energy expenditure). Conclusions: Using an exoskeleton during occupational tasks seems to reduce user's acute physical stress and strain in the exoskeleton's target area. However, impact on workers' health is still unknown, primarily because of missing long-term evaluations under real working conditions. Furthermore, this systematic review highlights a lack of studies (1) following high quality methodological criteria, (2) evaluating various inter-related stress and strain parameters instead of only focusing on one specific, and (3) evaluating non-target body areas instead of only the directly supported body area.