Spinal loads during two-person team lifting: effect of load mass distribution

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Title Spinal loads during two-person team lifting: effect of load mass distribution
Author Dennis, Gary John; Barrett, Rod
Journal Name International Journal of Industrial Ergonomics
Year Published 2003
Place of publication Netherlands
Publisher Elsevier Science BV
Abstract The purpose of this study was to examine the relationship between load mass distribution (LMD) and spinal load during team lifting tasks. Two-person lifting teams were required to lift a box containing a mass of 30 or 60 kg from the floor to standing knuckle height. Adjusting the position of the centre of mass within the box by ±15 and ±7.5 cm relative to the evenly distributed position (0 cm) yielded three LMD ratios (69:31, 59:41 and 50:50), which represented the percentage of the total mass lifted by each team member. The external force acting on the hands and sagittal plane segmental kinematics were measured and used in a simple dynamic biomechanical model to calculate the torque, compression and shear forces experienced at L4/L5. Spinal load estimates (i.e. maximum and average L4/L5 torque, compression force and shear force) significantly increased with load mass and were positively correlated with LMD (r=0.860.99, p<0.05), indicating that the person at the heavier end of the asymmetrical load experienced higher spinal loads than their lifting partner. However, the asymmetry in spinal loads between the two team members was found to be significantly lower than the asymmetry in the LMD ratios. This result was primarily due to: (i) a significant positive correlation between LMD and the horizontal pulling force acting on the hand and (ii) a significant negative correlation between LMD and the moment arm of the vertical force acting through the hand relative to L4/L5. Thus, when lifting an unevenly balanced load a two-person lifting team seems to adopt a lifting strategy that partially alleviates the larger spinal loads experienced by the team member at the heavier end of the load.
Peer Reviewed Yes
Published Yes
Publisher URI http://www.elsevier.com/wps/find/journaldescription.cws_home/505654/description#description
Copyright Statement Copyright 2003 Elsevier : Reproduced in accordance with the copyright policy of the publisher : This journal is available online - use hypertext links.
Volume 32
Page from 349
Page to 358
ISSN 0169-8141
Date Accessioned 2004-01-08
Language en_AU
Research Centre Menzies Health Institute Qld; Centre for Musculoskeletal Research
Faculty Griffith Health Faculty
Subject Biomechanics
URI http://hdl.handle.net/10072/6180
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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