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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.apergo.2006.04.026 Byline: Stephan Milosavljevic (a), Allan B. Carman (a), Anthony G. Schneiders (a), Peter D. Milburn (a), Barry D. Wilson (b) Keywords: Sheep shearing; 3D spinal movement; Low back pain Abstract: Sheep shearers are known to work in sustained flexed postures and have a high prevalence of low back pain (LBP). As sustained posture and spinal movement asymmetry under substantial loads are known risk factors for back injury our aim was to describe the 3D spinal movement of shearers while working. We hypothesised that thoraco-lumbar and lumbo-sacral movement would be tri-axial, asymmetric, and task specific. Sufficient retro-reflective markers were placed on the trunk of 12 shearers to define thoraco-lumbar and lumbo-sacral 3D motion during three tasks. Thoraco-lumbar movement consistently involved flexion, left lateral flexion, and right rotation. Lumbo-sacral movement consistently involved right lateral flexion in flexion with minimal rotation. Shearers therefore work in sustained spinal flexion where concurrent, asymmetric spinal movements into both lateral flexion and rotation occur. These asymmetric movements combined with repetitive loading may be risk factors leading to the high incidence of LBP in this occupational group. Author Affiliation: (a) School of Physiotherapy, University of Otago, PO Box 56, Dunedin, New Zealand (b) School of Physical Education, University of Otago, PO Box 56, Dunedin, New Zealand Article History: Received 27 June 2005; Accepted 19 April 2006

Sheep shearers are known to work in sustained flexed postures and have a high prevalence of low back pain (LBP). As sustained posture and spinal movement asymmetry under substantial loads are known risk factors for back injury our aim was to describe the 3D spinal movement of shearers while working. We hypothesised that thoraco-lumbar and lumbo-sacral movement would be tri-axial, asymmetric, and task specific. Sufficient retro-reflective markers were placed on the trunk of 12 shearers to define thoraco-lumbar and lumbo-sacral 3D motion during three tasks. Thoraco-lumbar movement consistently involved flexion, left lateral flexion, and right rotation. Lumbo-sacral movement consistently involved right lateral flexion in flexion with minimal rotation. Shearers therefore work in sustained spinal flexion where concurrent, asymmetric spinal movements into both lateral flexion and rotation occur. These asymmetric movements combined with repetitive loading may be risk factors leading to the high incidence of LBP in this occupational group. Keywords: Sheep shearing; 3D spinal movement; Low back pain

Researches indicate that sheep shearing can be classified as a very heavy work where the spine and hips are flexed for long periods of time, while handling awkward and heavy loads, expending high amounts of energy. The results of this study demonstrate the production of high levels of compressive and sheer forces within the spine of shearers during the three shearing tasks studied and that the use of a back support can substantially reduces the forces.