Abstract
An exoskeleton system can be an effective ergonomic intervention for mitigating the risks of developing work-related musculoskeletal disorders, yet little attention is given to the effects of its application on physical risk factors and subjective responses. Therefore, the objective of this study was to examine the effects of a passive exoskeleton system on spinal biomechanics and subjective responses during manual repetitive handling tasks among construction workers. Muscle activity of the Thoracic Erector Spinae (TES), Lumbar Erector Spinae (LES) at L3 vertebrae level, Rectus Abdominis (RA), and External Oblique (EO) during the repetitive handling tasks were measured by surface electromyography (sEMG). Additionally, the Borg categorical rating scale (Borg CR 10), local perceived pressure (LPP), and system usability scale (SUS) were used to measure the ratings of perceived discomfort, perceived musculoskeletal pressure, and system usability, respectively. Our results found that: (1) the use of the passive exoskeleton system significantly reduced LES muscle activity (11-33% MVC), with a greater reduction in LES muscle activity (32.71% MVC) for the heaviest lifting load; (2) the use of the passive exoskeleton system significantly reduced perceived discomfort scores (42.40%) of the lower back for the heaviest lifting load; (3) increased lifting load significantly increased LPP scores of the shoulder, lower back, and leg body parts; and (4) majority of the participants rated the passive exoskeleton system as having acceptable usability. The findings of these results indicate that the developed passive exoskeleton system could reduce the internal muscle force, extensor moments, and spinal forces in the lumbar region.