Affiliations: Industrial and Management Systems Engineering, West Virginia University, Morgantown, WV, USA
Correspondence:
[*]
Corresponding author: Ashish D. Nimbarte, Industrial and Management Systems Engineering, West Virginia University, PO Box 6070, Morgantown, WV 26506-6107, USA. Tel.: +1 304 293 9473; Fax: +1 304 293 4970; E-mail:Ashish.Nimbarte@mail.wvu.edu
Abstract: BACKGROUND: Forceful exertions of the arm/shoulder are common
during material handling and many other industrial tasks. Determination of
how the risk of shoulder injury changes in conjunction with direction of
force exertion could provide useful guidance on the design of workplaces and
tasks. OBJECTIVE: This research was conducted to determine how direction
of force exertion and muscle recruitment algorithm effect shoulder strain
computed by musculoskeletal modeling. METHODS: Musculoskeletal modeling software was used to perform
simulations of static force exertions of the right upper limb. A series of
36 force exertions in directions at 30° intervals in the
transverse, sagital, and frontal planes were performed using three muscle
recruitment optimization algorithms. A previously validated strain index
equation was used to calculate risk injury for each force exertion based on
the magnitude and direction of the resultant glenohumeral force. RESULTS: Generally, highest strain values were found in the
downward, backward, and leftward direction and lowest strain values were
found in the upward, forward, and rightward direction, or, in other words,
during force exertions opposing forces in those directions. CONCLUSIONS: When designing workplace tasks that involve forceful
exertions of the shoulder, pulling and downward pushing exertions should be
given preference over pushing and lifting exertions.
Keywords: Musculoskeletal modeling, static force exertions, shoulder strain
