Psychophysical estimates guidelines for maximal acceptable loads during unilateral overhead work while wearing an exoskeleton in construction workers

Introduction This study examined how passive shoulder exoskeletons, body archetype, sex, and shoulder elevation influence maximal drill-weight selection during overhead tasks. Methods Twenty-nine construction workers (11 females, 18 males) completed high-frequency drilling every 12 seconds at a target force of 70 N across three shoulder elevations (90°, 120°, 150°), each performed for 5 minutes with and without a passive exoskeleton. Participant anthropometrics were captured using a 3D body scanner, and body archetypes were derived through k cluster analysis following variable extraction. A Psychophysical approach was used to determine maximal acceptable drill weight. Results Mixed linear regression showed exoskeleton use increased selected weight by 336 g (~18%) ( p < 0.001) compared to not wearing an exoskeleton. Smaller body archetypes selected 317 g (~17%) less than larger builds ( p < 0.001), while medium builds showed no difference (p = 0.63). Males selected weights 300 g (~16%) heavier than females (p = 0.030). Shoulder elevation had no significant effect. Conclusions These findings highlight key anthropometric and equipment related factors shaping overhead task demands.