Activation-Dependent Changes in Soleus Length-Tension Behavior Augment Ankle Joint Quasi-Stiffness
Activation-Dependent Changes in Soleus Length-Tension Behavior Augment Ankle Joint Quasi-Stiffness
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DOI：
10.1123/jab.2018-0297
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发表时间：
2019-06-01
影响因子：
1.4
通讯作者：
Franz, Jason R.
中科院分区：
文献类型：
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作者：
Clark, William H.;Franz, Jason R.
小腿三头肌肌肉-肌腱单元在控制行走性能中是重要的，通过主动肌肉和被动弹性结构之间的相互作用来调节踝关节的机械行为。踝关节准刚度（踝关节力矩和踝关节旋转之间的关系的斜率，k（A））是这种机械行为的有用的综合度量。然而，肌肉激活和长度-张力行为在增加k（A）中的作用仍不清楚。在这项研究中，10名受试者完成离心等速收缩在休息和2比目鱼肌激活水平（25%和75%等长自愿收缩）规定使用肌电生物反馈。超声成像量化了比目鱼肌长度-张力行为的激活依赖性调制及其在增加k（A）中的作用。作者发现，比目鱼肌刚度（k（M））和k（A）与肌肉激活呈非线性关系，两者对激活的开始比随后的激活增加更敏感。我们的研究结果还表明，k（A）可以通过激活比目鱼肌长度-张力行为的变化来调节。然而，这种调制比以前认识到的更复杂，反映了主动肌肉和被动弹性组织之间的相互作用。我们的研究结果可能对理解正常和病理踝关节功能以及基于阻抗的假体的设计具有意义。
The triceps surae muscle-tendon units are important in governing walking performance, acting to regulate mechanical behavior of the ankle through interaction between active muscle and passive elastic structures Ankle joint quasi-stiffness (the slope of the relation between ankle moment and ankle rotation, k(A)) is a useful aggregate measure of this mechanical behavior. However, the role of muscle activation and length-tension behavior in augmenting k(A) remains unclear. In this study, 10 subjects completed eccentric isokinetic contractions at rest and at 2 soleus activation levels (25% and 75% isometric voluntary contraction) prescribed using electromyographic biofeedback. Ultrasound imaging quantified activation-dependent modulation of soleus muscle length-tension behavior and its role in augmenting k(A). The authors found that soleus muscle stiffness (k(M)) and k(A) exhibit nonlinear relations with muscle activation and both were more sensitive to the onset of activation than to subsequent increases in activation. Our findings also suggest that k(A) can be modulated via activation through changes in soleus muscle length-tension behavior. However, this modulation is more complex than previously appreciated-reflecting interaction between active muscle and passive elastic tissues. Our findings may have implications for understanding normal and pathological ankle joint function and the design of impedance-based prostheses.