Can back exosuits simultaneously increase lifting endurance and reduce musculoskeletal disorder risk?

Abstract

<p>Back exosuits are wearable technologies designed to make lifting easier and reduce work-related musculoskeletal disorder risks by relieving low back strain. The study objective was to test whether an elastic back exosuit could increase a wearer’s endurance when lifting heavy objects, and if so, to assess whether lifting more cancels out the exosuit’s risk reduction benefits. We performed two case series studies with field artillery Soldiers from the U.S. Army who frequently lift heavy objects. These participants repeatedly lifted 45-55 kg until failure. We counted the number of lifting repetitions to evaluate their lifting endurance with vs. without the exosuit. We found that seven of eight participants increased their lifting repetitions while wearing the exosuit, with endurance increases ranging from 28-75%. We then used these empirical data with an ergonomics assessment tool to model the effects on low back disorder risk when an exosuit is worn and more lifts are performed. Participants exhibited 34-89% lower cumulative back damage (an indicator of low back disorder risk) when wearing the exosuit. These results confirmed that participants wearing the exosuit increased their physical capacity to perform lifting work without canceling out the injury risk reduction benefits. Ergonomic models indicate that to achieve dual benefits—performance enhancement and risk reduction—it is better to increase lifting repetitions, not the weight of objects being lifted. These results have important implications for workers in civilian and defense sectors, suggesting that back exosuits may make it possible to simultaneously boost productivity and reduce musculoskeletal disorder risks.</p>

Benchmarking commercially available soft and rigid passive back exoskeletons for an industrial workplace

“…During flexion and extension, the loading and unloading force-elongation relations were, respectively, used to estimate the forces (F) exerted by the elastic bands. F was multiplied with a constant moment arm of 10 cm to estimate the sagittal moments M (Lamers et al, 2018;Rodzak et al, 2023). The apparent assistance provided by the two rigid exos was estimated by using the torque-angle relationship measured using the setup at Laevo B.V. (Van Harmelen et al, 2022).…”

“…These moments were estimated using a moment arm from the sacrum to the shoulder. A fixed moment arm was used to estimate the moments for the soft exos (Lamers et al, 2018;Moya-Esteban et al, 2023;Rodzak et al, 2023). This approach assumes that only tangential forces are exerted by the soft exos.…”