The human and financial costs of low back and neck disorders to our society are overwhelming. The causes of most of these disorders are unknown, but biomechanical factors are clearly involved. Research is proposed to continue to examine mechanical functioning of the human trunk and neck. Some emphasis will be given to pathological functioning, but major emphasis will be placed on normal functioning. To understand the mechanics of spine pathologies, a good understanding of healthy spine mechanics seems required. Quasic-static biomechanical models of the cervical region, and dynamic models of the cervical and lumbar regions will be constructed to predict muscle contraction forces and spine motion segment reactions required for physical task performances. Model prediction validity will be tested in-vivo through quantitative myoelectric measurements. Slow motions, fast single motions and fact cyclic motions will be studied. Spine manipulation biomechanics will be explored, both experimentally and analytically. Whole body vibration response and pathological intervertebral disc/posterior element load sharing will be analyzed. Muscle relaxation phenomena will be measured experimentally, and heavy lifts-with-twists examined both experimentally and analytically.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
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University of Michigan Ann Arbor
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Thelen, D G; Ashton-Miller, J A; Schultz, A B (1996) Lumbar muscle activities in rapid three-dimensional pulling tasks. Spine (Phila Pa 1976) 21:605-13
Thelen, D G; Schultz, A B; Ashton-Miller, J A (1995) Co-contraction of lumbar muscles during the development of time-varying triaxial moments. J Orthop Res 13:390-8
Thelen, D G; Schultz, A B; Fassois, S D et al. (1994) Identification of dynamic myoelectric signal-to-force models during isometric lumbar muscle contractions. J Biomech 27:907-19
Thelen, D G; Schultz, A B; Ashton-Miller, J A (1994) Quantitative interpretation of lumbar muscle myoelectric signals during rapid cyclic attempted trunk flexions and extensions. J Biomech 27:157-67
Ashton-Miller, J A; McGlashen, K M; Schultz, A B (1992) Trunk positioning accuracy in children 7-18 years old. J Orthop Res 10:217-25
Janevic, J; Ashton-Miller, J A; Schultz, A B (1991) Large compressive preloads decrease lumbar motion segment flexibility. J Orthop Res 9:228-36
Schultz, A B; Faulkner, J A; Kadhiresan, V A (1991) A simple Hill element-nonlinear spring model of muscle contraction biomechanics. J Appl Physiol 70:803-12
Cromwell, R; Schultz, A B; Beck, R et al. (1989) Loads on the lumbar trunk during level walking. J Orthop Res 7:371-7
Scholten, P J; Schultz, A B; Luchies, C W et al. (1988) Motions and loads within the human pelvis: a biomechanical model study. J Orthop Res 6:840-50
Bean, J C; Chaffin, D B; Schultz, A B (1988) Biomechanical model calculation of muscle contraction forces: a double linear programming method. J Biomech 21:59-66

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