Using a Back Exoskeleton During Industrial and Functional Tasks-Effects on Muscle Activity, Posture, Performance, Usability, and Wearer Discomfort in a Laboratory Trial.

Tessy Luger,Mona Bär,Monika A Rieger,Benjamin Steinhilber,Robert Seibt

doi:10.1177/00187208211007267

Abstract

To investigate the effect of using a passive back-support exoskeleton (Laevo V2.56) on muscle activity, posture, heart rate, performance, usability, and wearer comfort during a course of three industrial tasks (COU; exoskeleton worn, turned-on), stair climbing test (SCT; exoskeleton worn, turned-off), timed-up-and-go test (TUG; exoskeleton worn, turned-off) compared to no exoskeleton. Back-support exoskeletons have the potential to reduce work-related physical demands. Thirty-six men participated. Activity of erector spinae (ES), biceps femoris (BF), rectus abdominis (RA), vastus lateralis (VL), gastrocnemius medialis (GM), trapezius descendens (TD) was recorded by electromyography; posture by trunk, hip, knee flexion angles; heart rate by electrocardiography; performance by time-to-task accomplishment (s) and perceived task difficulty (100-mm visual analogue scale; VAS); usability by the System Usability Scale (SUS) and all items belonging to domains skepticism and user-friendliness of the Technology Usage Inventory; wearer comfort by the 100-mm VAS. During parts of COU, using the exoskeleton decreased ES and BF activity and trunk flexion, and increased RA, GM, and TD activity, knee and hip flexion. Wearing the exoskeleton increased time-to-task accomplishment of SCT, TUG, and COU and perceived difficulty of SCT and TUG. Average SUS was 75.4, skepticism 11.5/28.0, user-friendliness 18.0/21.0, wearer comfort 31.1 mm. Using the exoskeleton modified muscle activity and posture depending on the task applied, slightly impaired performance, and was evaluated mildly uncomfortable. These outcomes require investigating the effects of this passive back-supporting exoskeleton in longitudinal studies with longer operating times, providing better insights for guiding their application in real work settings.

Highlights

In many professions, employees suffer low back pain (LBP) with prevalence rates ranging from 26% in the United States (3 month prevalence rate; Yang et al, 2016) to 30% in the European Union
Activity of erector spinae (ES), biceps femoris (BF), rectus abdominis (RA), vastus lateralis (VL), gastrocnemius medialis (GM), trapezius descendens (TD) was recorded by electromyography; posture by trunk, hip, knee flexion angles; heart rate by electrocardiography; performance by time-to- task accomplishment (s) and perceived task difficulty (100-mm visual analogue scale; VAS); usability by the System Usability Scale (SUS) and all items belonging to domains skepticism and user-friendliness of the Technology Usage Inventory; wearer comfort by the 100-mm VAS
Using the exoskeleton modified muscle activity and posture depending on the task applied, slightly impaired performance, and was evaluated mildly uncomfortable

Summary

Introduction

Employees suffer low back pain (LBP) with prevalence rates ranging from 26% in the United States (3 month prevalence rate; Yang et al, 2016) to 30% in the European Union (point prevalence; Paoli & Merllié, 2001). There is no unequivocal evidence for their effectiveness, reducing physical demands could be realized by eliminating heavy lifting (Coenen et al, 2014), introducing job rotation (Leider et al, 2015; Padula et al, 2017), or implementing assisting devices (Verbeek et al, 2011). The latter category includes exoskeletons, which have gained in popularity in recent years. Exoskeletons are worn on the body by the user to support task performance, technically adding mechanical power to one or more joints of the human body for reducing the biomechanical load (de Looze et al, 2016). Back-s upport exoskeletons have the potential to reduce work-related physical demands

Methods

Results

Discussion

Conclusion