Effect of backpack shoulder strap lower attachment point on the load distribution to the torso


  1. Reid, S.A.
  2. Bryant, J.T.
  3. Stevenson, J.M.
  4. Doan, J.E.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN);Queen's Univ, Kingston ONT (CAN) Ergonomics Research Group
The objective of this study was to conduct biomechanical testing of pack component options to determine the optimal location for the lower attachment of the shoulder strap for the CTS Integrated Patrol Pack and Rucksack. A model of a 50 percentile male torso has been split transversely at T12/L1 and instrumented with two six degree of freedom load cells. One is located at T12/L1 and the second is positioned at the base. Using the load cell results, the force distribution between the upper and lower parts of the body can be calculated. The shoulder area of the manikin was instrumented with Fscan sensors to record the contact pressure distribution in the axilla (armpit) and anterior of the shoulder under the shoulder strap. The effects of moving the attachment point vertically, parallel to the body axis, and horizontally towards the body midline were examined. A 25 kg fixed payload was used for all test configurations. Waist belt, load lifter and should strap tensions were constant during testing. Output variables were: reaction forces at T12/L1, (which reflect the mangitude of shear and compressive force on the spine), waist belt lifting force, average, and peak contact pressures about the shoulder. These were examined as a function of the attachment point location and as a function of the angle the shoulder strap made with respect to the body long axis. TRUNCATED
Back (anatomy);Ergonomics;Biomechanical models;Spine (anatomy);Load carriage;Load optimization;Lumbar area
Report Number
DCIEM-CR-2001-088 — Contract Report
Date of publication
01 Mar 1998
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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