Passive Shoulder Exoskeletons: More Effective in the Lab Than in the Field?

Abstract

Shoulder exoskeletons potentially reduce overuse injuries in industrial settings including overhead work or lifting tasks. Previous studies evaluated these devices primarily in laboratory setting, but evidence of their effectiveness outside the lab is lacking. The present study aimed to evaluate the effectiveness of two passive shoulder exoskeletons and explore the transfer of laboratory-based results to the field. Four industrial workers performed controlled and in-field evaluations without and with two exoskeletons, ShoulderX and Skelex in a randomized order. The exoskeletons decreased upper trapezius activity (up to 46%) and heart rate in isolated tasks. In the field, the effects of both exoskeletons were less prominent (up to 26% upper trapezius activity reduction) while lifting windscreens weighing 13.1 and 17.0 kg. ShoulderX received high discomfort scores in the shoulder region and usability of both exoskeletons was moderate. Overall, both exoskeletons positively affected the isolated tasks, but in the field the support of both exoskeletons was limited. Skelex, which performed worse in the isolated tasks compared to ShoulderX, seemed to provide the most support during the in-field situations. Exoskeleton interface improvements are required to improve comfort and usability. Laboratorybased evaluations of exoskeletons should be interpreted with caution, since the effect of an exoskeleton is task Manuscript

Effects of an arm‐support exoskeleton on perceived work intensity and musculoskeletal discomfort: An 18‐month field study in automotive assembly

“…Earlier field studies have indicated that ASEs can reduce physical demands in an actual work environment, as evidenced by reductions in shoulder muscle activity 23,27 and in perceived strain in the neck and shoulders or MSD scores. 21,24 Our results, however, indicate that after accounting for age, body mass, stature, and job demand, using an ASE had little impact on perceived work intensity or MSD scores (Figure 3).…”

“…To support the safe adoption and use of EXOs in practice, however, field-based evidence is critical to an understanding of actual effectiveness, practicality, safety, and user acceptance. 19,20 Some work has been reported from field testing of EXOs, ranging from less than an hour to up to a 3-month period, in automotive assembly, 9,[21][22][23][24] manufacturing, 25 warehousing, 26,27 and agriculture settings. 28,29 Arm-support exoskeletons (ASEs) were typically fieldtested for jobs that involve overhead assembly and overhead lifting, while back-support exoskeletons (BSEs) were tested for jobs that involve manual material lifting, shoveling, or require prolonged trunk bending.…”

“…Subjective measures were typically the primary outcomes in the noted field studies, though some have assessed muscle activity in two to four muscle groups and/or heart rate while workers used an EXO. 23,[25][26][27]29 Specific to ASEs, their use has led to~10%-26% reductions in the shoulder (anterior deltoid, biceps brachii, and trapezius) and low back muscle groups (lumbar erector spinae) during overhead automotive assembly and overhead lifting tasks. ASE use also reduced mean heart rate, with De Bock et al 27 reporting up to a 19% reduction during overhead work in a distribution facility, and Marino 30 finding a 3.4% decrease during stocking tasks in a retail store.…”

“…23,[25][26][27]29 Specific to ASEs, their use has led to~10%-26% reductions in the shoulder (anterior deltoid, biceps brachii, and trapezius) and low back muscle groups (lumbar erector spinae) during overhead automotive assembly and overhead lifting tasks. ASE use also reduced mean heart rate, with De Bock et al 27 reporting up to a 19% reduction during overhead work in a distribution facility, and Marino 30 finding a 3.4% decrease during stocking tasks in a retail store. The prior study, however, demonstrated that the magnitude of beneficial effects of an ASE can be substantially less in the field (picking orders from a high rack), compared to a controlled laboratory setting.…”

A physiological and biomechanical investigation of three passive upper-extremity exoskeletons during simulated overhead work

“…These exoskeletons assist individuals working in jobs that require arm elevation, such as supporting the weight of the arms or a tool during overhead work. Yin et al, 2020;Bock et al 2021). However, there are some limitations of this type of approach that are worth noting.…”