Affiliations: Department of Kinesiology, University of Windsor,
Windsor, ON, Canada | Department of Kinesiology, University of Waterloo,
Waterloo, ON, Canada
Note: [] Corresponding author: Nadia R. Azar, Department of Kinesiology,
University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada. Tel.:
+1 519 253 3000 x2473; Fax: +1 519 973 7056; E-mail: azar5@uwindsor.ca
Abstract: BACKGROUND: In order to obtain a complete understanding of the
etiology of upper extremity musculoskeletal disorders, a spectrum of risk
factors needs to be evaluated, within and external to the workplace. To date,
cumulative shoulder loads (forces and moments) have only been documented during
automotive assembly tasks. No information on shoulder loads during
non-occupational tasks has been reported. OBJECTIVE: To document 3D peak and cumulative shoulder loads and
postures associated with non-occupational tasks. METHODS: Seven male (35.8 ± 15.7 years) and six female (44.0
± 14.3 years) healthy working-aged individuals volunteered for this
study. A video-based 3D posture sampling approach was used to document shoulder
joint postures while participants performed non-repetitive tasks in and around
their own homes over a 2-hour period. A 3D rigid link segment model was used to
calculate reaction forces and moments at the shoulder. RESULTS: Peak shoulder moments approached, and in some cases
exceeded, published maximum isometric strength measurements, particularly in
female participants. When extrapolated to a 7-hour shift, cumulative shoulder
flexion and abduction moments, cumulative reaction caudal shear forces, and the
time spent in non-neutral flexion and abduction were comparable in magnitude to
those reported for light automotive assembly tasks. CONCLUSIONS: Non-occupational tasks should be evaluated more widely
if a complete picture of the risk of musculoskeletal injury associated with
shoulder loading is to be established. More work is needed to develop threshold
limits for both peak and cumulative shoulder loads to improve injury prevention
strategies.
Keywords: Video, posture sampling, biomechanical model
