Seated whole body vibrations with high-magnitude accelerations - relative roles of inertia and muscle forces

被引:49
作者
Bazrgari, B. [1 ]
Shirazi-Adl, A. [1 ]
Kasra, M. [2 ]
机构
[1] Ecole Polytech, Dept Mech Engn, Montreal, PQ H3C 3A7, Canada
[2] McMaster Univ, Dept Mech Engn, Hamilton, ON L8S 4L7, Canada
基金
加拿大自然科学与工程研究理事会;
关键词
whole body vibration; shock; muscle force; spinal loads; stability; finite elements;
D O I
10.1016/j.jbiomech.2008.06.026
中图分类号
Q6 [生物物理学];
学科分类号
071011 [生物物理学];
摘要
Reliable computation of spinal loads and trunk stability under whole body vibrations with high acceleration contents requires accurate estimation of trunk muscle activities that are often overlooked in existing biodynamic models. A finite element model of the spine that accounts for nonlinear load- and direction-dependent properties of lumbar segments, complex geometry and musculature of the spine, and dynamic characteristics of the trunk was used in our iterative kinematics-driven approach to predict trunk biodynamics in measured vehicle's seat vibrations with shock contents of about 4g (g: gravity acceleration of 9.8 m/s(2)) at frequencies of about 4 and 20 Hz. Muscle forces, spinal loads and trunk stability were evaluated for two lumbar postures (erect and flexed) with and without coactivity in abdominal muscles. Estimated peak spinal loads were substantially larger under 4 Hz excitation frequency as compared to 20 Hz with the contribution of muscle forces exceeding that of inertial forces. Flattening of the lumbar lordosis from an erect to a flexed posture and antagonistic coactivity in abdominal muscles, both noticeably increased forces on the spine while substantially improving trunk stability. Our predictions clearly demonstrated the significant role of muscles in trunk biodynamics and associated risk of back injuries. High-magnitude accelerations in seat vibration, especially at near-resonant frequency, expose the vertebral column to large forces and high risk of injury by significantly increasing Muscle activities in response to equilibrium and stability demands. (c) 2008 Elsevier Ltd. All rights reserved.
引用
收藏
页码:2639 / 2646
页数:8
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