de Looze M P, Kingma I, Bussmann J B, Toussaint H M
Department of Health Science, Faculty of Human Movement Sciences, Vrije Universiteit, Amsterdam, The Netherlands.
Clin Biomech (Bristol). 1992 Aug;7(3):161-9. doi: 10.1016/0268-0033(92)90031-X.
A two-dimensional dynamic linked segment model was constructed and applied to a lifting activity. Reactive forces and moments were calculated by an instantaneous approach involving the application of Newtonian mechanics to individual adjacent rigid segments in succession. The analysis started once at the feet and once at a hands/load segment. The model was validated by comparing predicted external forces and moments at the feet or at a hands/load segment to actual values, which were simultaneously measured (ground reaction force at the feet) or assumed to be zero (external moments at feet and hands/load and external forces, beside gravitation, at hands/load). In addition, results of both procedures, in terms of joint moments, including the moment at the intervertebral disc between the fifth lumbar and first sacral vertebra (L5-S1), were compared. A correlation of r = 0.88 between calculated and measured vertical ground reaction forces was found. The calculated external forces and moments at the hands showed only minor deviations from the expected zero level. The moments at L5-S1, calculated starting from feet compared to starting from hands/load, yielded a coefficient of correlation of r = 0.99. However, moments calculated from hands/load were 3.6% (averaged values) and 10.9% (peak values) higher. This difference is assumed to be due mainly to erroneous estimations of the positions of centres of gravity and joint rotation centres. The estimation of the location of L5-S1 rotation axis can affect the results significantly. Despite the numerous studies estimating the load on the low back during lifting on the basis of linked segment models, only a few attempts to validate these models have been made. This study is concerned with the validity of the presented linked segment model. The results support the model's validity. Effects of several sources of error threatening the validity are discussed.
构建了一个二维动态链接节段模型并将其应用于举重活动。通过一种瞬时方法计算反作用力和力矩，该方法涉及将牛顿力学相继应用于各个相邻的刚性节段。分析从脚部开始一次，从手部/负载节段开始一次。通过将脚部或手部/负载节段处预测的外力和力矩与实际值进行比较来验证该模型，实际值是同时测量的（脚部的地面反作用力）或假定为零（脚部和手部/负载处的外力矩以及手部/负载处除重力外的外力）。此外，比较了两种方法在关节力矩方面的结果，包括第五腰椎和第一骶椎（L5 - S1）之间椎间盘处的力矩。计算得出的垂直地面反作用力与测量值之间的相关系数r = 0.88。手部计算得出的外力和力矩与预期的零水平仅有微小偏差。从脚部开始计算与从手部/负载开始计算得出的L5 - S1处的力矩，相关系数r = 0.99。然而，从手部/负载计算得出的力矩平均高3.6%，峰值高10.9%。这种差异主要被认为是由于重心位置和关节旋转中心估计错误所致。L5 - S1旋转轴位置的估计会显著影响结果。尽管有大量研究基于链接节段模型估计举重过程中腰部的负荷，但只有少数尝试对这些模型进行验证。本研究关注所提出的链接节段模型的有效性。结果支持该模型的有效性。讨论了威胁有效性的几个误差来源的影响。
