Xiao Ming, Higginson Jill S
Department of Mechanical Engineering, 126 Spencer Laboratory, University of Delaware, Newark, DE 19716, USA.
J Biomech. 2008 Nov 14;41(15):3236-42. doi: 10.1016/j.jbiomech.2008.08.008. Epub 2008 Sep 19.
The purpose of this study was to quantify how the predicted muscle function would change in a muscle-driven forward simulation of normal walking when changing the number of degrees of freedom in the model. Muscle function was described by individual muscle contributions to the vertical acceleration of the center of mass (COM). We built a two-dimensional (2D) sagittal plane model and a three-dimensional (3D) model in OpenSim and used both models to reproduce the same normal walking data. Perturbation analysis was applied to deduce muscle function in each model. Muscle excitations and contributions to COM support were compared between the 2D and 3D models. We found that the 2D model was able to reproduce similar joint kinematics and kinetics patterns as the 3D model. Individual muscle excitations were different for most of the hip muscles but ankle and knee muscles were able to attain similar excitations. Total induced vertical COM acceleration by muscles and gravity was the same for both models. However, individual muscle contributions to COM support varied, especially for hip muscles. Although there is currently no standard way to validate muscle function predictions, a 3D model seems to be more appropriate for estimating individual hip muscle function.
本研究的目的是量化在正常行走的肌肉驱动正向模拟中，当改变模型中的自由度数量时，预测的肌肉功能将如何变化。肌肉功能通过各肌肉对质心（COM）垂直加速度的贡献来描述。我们在OpenSim中构建了一个二维（2D）矢状面模型和一个三维（3D）模型，并使用这两个模型来重现相同的正常行走数据。应用摄动分析来推导每个模型中的肌肉功能。比较了2D和3D模型之间的肌肉兴奋情况以及对COM支撑的贡献。我们发现2D模型能够重现与3D模型相似的关节运动学和动力学模式。大多数髋部肌肉的个体肌肉兴奋情况不同，但踝部和膝部肌肉能够获得相似的兴奋。肌肉和重力引起的COM总垂直加速度在两个模型中是相同的。然而，各肌肉对COM支撑的贡献有所不同，尤其是髋部肌肉。尽管目前没有验证肌肉功能预测的标准方法，但3D模型似乎更适合估计个体髋部肌肉功能。
