Fritz M
Institut für Arbeitsphysiologie Universität Dortmund, Germany.
Aviat Space Environ Med. 1997 Jun;68(6):512-9.
Several investigations reveal that long-term exposure to whole-body vibrations can induce degenerative changes in the lumbar spine. In analogy to the activities of lifting or carrying loads, an assessment of the health risk should be possible if the forces transmitted in the spine during vibration stress are known.
To estimate the spine forces a biomechanical model was developed. In the model the human trunk, neck, and head were represented by 10 rigid bodies connected by visco-elastic elements. Some 56 force elements imitated the muscles of the body. The motion equations of the model were derived by means of the dynamics of systems of rigid bodies.
The transfer functions of the model accelerations in x- and z-direction satisfactorily corresponded to data reported in the literature. Transfer functions were computed between the forces transmitted from the seat to the pelvis and in the lumbar spine, respectively.
The forces between seat and pelvis were measured, then the spine forces were computed by means of the transfer functions. To assess the health risk the computed forces must be compared with the strength of the spine because the strength is dependent on the age and gender of the worker and decreases with the number of load cycles.
多项调查显示，长期全身振动会诱发腰椎的退行性改变。类似于举重或搬运重物的活动，如果知道振动应激期间脊柱传递的力，就应该能够评估健康风险。
为了估算脊柱受力，开发了一个生物力学模型。在该模型中，人体躯干、颈部和头部由通过粘弹性元件连接的10个刚体表示。约56个力元件模拟了身体的肌肉。该模型的运动方程通过刚体系统动力学推导得出。
模型在x方向和z方向的加速度传递函数与文献报道的数据令人满意地相符。分别计算了从座椅传递到骨盆和腰椎的力之间的传递函数。
测量座椅和骨盆之间的力，然后通过传递函数计算脊柱受力。为了评估健康风险，必须将计算出的力与脊柱强度进行比较，因为脊柱强度取决于工人的年龄和性别，并且会随着负荷循环次数的增加而降低。
