The effect of extended reach on manual arm strength

Work-related musculoskeletal disorders (WMSDs) are a concern in occupational settings, particularly in tasks requiring repetitive arm movements, forceful exertions, and prolonged postures. Manual arm strength (MAS) predictions, from ergonomics tools such as the Arm Force Field Method, supports ergonomics analyses by comparing manual force task demands to human capability, particularly between arm lengths less than 80% of maximum reach. Much fewer MAS data exist for when the arm is fully extended or even extended past the natural arm length via scapular movement. This thesis conducted a laboratory study evaluating how extended reach affects MAS across several force directions and shoulder horizontal abduction angles. The main finding was that MAS decreased as reach increased, but the magnitude of this result depended on the direction of force application. These findings provide a framework for estimating strength in these maximum reach postures to hopefully improve strength-based ergonomics assessments.

Name thesis:degree_name

Master of Health Sciences (MHSc)

Discipline thesis:degree_discipline

Kinesiology

Grantor

University of Ontario Institute of Technology

Year dc:date.issued

2025

Author dc:creator

• Auray, William M.

Advisor dc:contributor.advisor

• La Delfa, Nicholas

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10155/1957

OAI identifier oai:identifier

oai:ontariotechu.scholaris.ca:10155/1957