Multivariable dynamic ankle mechanical impedance with active muscles.
Multivariable dynamic ankle mechanical impedance with active muscles.
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DOI：
10.1109/tnsre.2014.2328235
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发表时间：
2014-09
期刊：
影响因子：
--
通讯作者：
Hogan N
中科院分区：
文献类型：
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作者：
Lee H;Krebs HI;Hogan N
多变量动态踝关节机械阻抗在两个耦合度的自由度（DOF）进行量化时，肌肉活跃。在胫骨前肌和比目鱼肌的五个不同的目标激活水平下进行测量，从最大自主收缩（MVC）的10%到30%，增量为5%MVC。有趣的是，在我们先前的放松踝关节研究中观察到的几种踝关节行为特征与肌肉活动有关：关节坐标中的踝关节机械阻抗显示出与由惯性、粘性和刚度组成的二阶系统基本一致的响应;所有受试者在所有激活条件下矢状面的刚度大于额状面;背屈-跖屈和内翻-外翻之间的耦合很小，这两个自由度测量值可以用严格的对角阻抗矩阵很好地解释。在一般情况下，踝关节刚度线性增加与肌肉激活在所有方向上的2-D空间形成的矢状面和额状面，但更多的矢状面比在额状面，导致加重的“花生形状”。年轻健康受试者的踝关节机械阻抗与活动肌肉的这种表征将用作研究生物力学和/或神经受损患者的病理生理踝关节行为的基线。
Multivariable dynamic ankle mechanical impedance in two coupled degrees-of-freedom (DOFs) was quantified when muscles were active. Measurements were performed at five different target activation levels of tibialis anterior and soleus, from 10% to 30% of maximum voluntary contraction (MVC) with increments of 5% MVC. Interestingly, several ankle behaviors characterized in our previous study of the relaxed ankle were observed with muscles active: ankle mechanical impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness; stiffness was greater in the sagittal plane than in the frontal plane at all activation conditions for all subjects; and the coupling between dorsiflexion–plantarflexion and inversion–eversion was small—the two DOF measurements were well explained by a strictly diagonal impedance matrix. In general, ankle stiffness increased linearly with muscle activation in all directions in the 2-D space formed by the sagittal and frontal planes, but more in the sagittal than in the frontal plane, resulting in an accentuated “peanut shape.” This characterization of young healthy subjects’ ankle mechanical impedance with active muscles will serve as a baseline to investigate pathophysiological ankle behaviors of biomechanically and/or neurologically impaired patients.