title: Predicted endurance times during overhead work: influences of duty cycle and tool mass estimated using perceived discomfort.
abstract: A need for overhead work remains in several industries and such work is an important risk factor for shoulder musculoskeletal problems. In this study, we evaluated the effects of duty cycle and tool mass on endurance times during overhead work. A psychophysical approach was used, via a new methodology that was implemented to more efficiently estimate endurance times (rather than through direct measurements). Participants performed a simulated overhead task in specified combinations of tool mass and duty cycle. Both duty cycle and tool mass have substantial effects on the development of fatigue and estimated endurance times, though the former was more substantial and an interactive effect was evident. Gender differences were not substantial, except when using the largest tool mass. We recommend that, for two-hour periods of overhead work, tool masses greater than 1.25 kg should be avoided, as should duty cycles greater than 50%. Practitioner Summary: The current results may facilitate enhanced design and evaluation of overhead work tasks. In addition, the new estimation approach that was employed may enhance the efficiency of future studies using a psychophysical approach (ie using extrapolation of patterns of reported discomfort to predict longer term outcomes).
authors.affiliation: a Industrial and Systems Engineering , Virginia Tech , Blacksburg , VA , USA.
authors.forename: Deepti
authors.initials: D
authors.lastname: Sood
authors.affiliation: a Industrial and Systems Engineering , Virginia Tech , Blacksburg , VA , USA.
authors.forename: Maury A
authors.identifier: http://orcid.org/0000-0002-1887-8431
authors.initials: MA
authors.lastname: Nussbaum
authors.affiliation: a Industrial and Systems Engineering , Virginia Tech , Blacksburg , VA , USA.
authors.forename: Kris
authors.initials: K
authors.lastname: Hager
authors.affiliation: b Department of Physical Therapy , Federal University of São Carlos , São Carlos , Brazil.
authors.forename: Helen C
authors.initials: HC
authors.lastname: Nogueira
mesh_terms: D000293:Adolescent; D000328:Adult; D006804:Ergonomics; D005260:Female; D006801:Humans; D008297:Male; D018763:Muscle Fatigue; D016272:Occupational Health; D010465:Perception; D010807:Physical Endurance; D011603:Psychophysiology; D020069:Shoulder Pain / Q000523:psychology; D013647:Task Performance and Analysis; D013997:Time Factors; D055815:Young Adult
keywords: Overhead work; fatigue; gender; guideline; perceived discomfort; psychophysics