Psychophysical estimates guidelines for maximal acceptable loads during unilateral overhead work while wearing an...

This study examined how passive shoulder exoskeletons, body archetype, sex, and shoulder elevation influence maximal drill-weight selection during overhead tasks.

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.

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.

These findings highlight key anthropometric and equipment related factors shaping overhead task demands.