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首页> 外文期刊>Journal of Biomechanics >Viscous elements have little impact on measured passive length-tension properties of human gastrocnemius muscle-tendon units in vivo.
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Viscous elements have little impact on measured passive length-tension properties of human gastrocnemius muscle-tendon units in vivo.

机译：粘性元素对人体腓肠肌肌腱单位的体内被动长度-张力特性的影响很小。

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摘要

Several studies have measured the elastic properties of a single human muscle-tendon unit in vivo. However the viscoelastic behavior of single human muscles has not been characterized. In this study, we adapted QLV theory to model the viscoelastic behavior of human gastrocnemius muscle-tendon units in vivo. We also determined the influence of viscoelasticity on passive length-tension properties of human gastrocnemius muscle-tendon units. Eight subjects participated in the experiment, which consisted of two parts. First, the stress relaxation response of human gastrocnemius muscle-tendon units was determined at a range of knee and ankle angles. Subsequently, passive ankle torque and ankle angle were collected during cyclic dorsiflexion and plantarflexion at a range of knee angles. Viscous parameters were determined by fitting the stress relaxation experiment data with a two-term exponential function, and elastic parameters were estimated by fitting the QLV model and viscous parameters to the cyclic experiment data. The model fitted the experimental data well at slow speeds (RMSE: 1.7 ± 0.5N) and at fast speeds (RMSE: 1.9 ± 0.2N). Muscle-tendon units demonstrated a large amount of stress relaxation. Nonetheless, viscoelastic passive length-tension curves estimated with the QLV model were similar to elastic passive length-tension curves obtained using a model that ignored viscosity. There was little difference in the elastic passive length-tension curves at different loading rates. We conclude that (a) the QLV model can be used to quantify viscoelastic behaviors of relaxed human gastrocnemius muscle-tendon units in vivo, and (b) over the range of velocities we examined, the velocity of loading has little effect on the passive length-tension properties of human gastrocnemius muscle-tendon units.
机译：多项研究已经测量了人体单个肌腱单元的弹性特性。然而，单个人体肌肉的粘弹性行为尚未被表征。在这项研究中，我们采用了QLV理论来模拟人体腓肠肌肌腱单位在体内的粘弹性行为。我们还确定了粘弹性对人腓肠肌肌腱单位被动长度-张力特性的影响。八名受试者参加了该实验，该实验包括两个部分。首先，在一定范围的膝盖和脚踝角度确定人腓肠肌肌腱单位的应力松弛响应。随后，在周期性的背屈和足底屈曲期间，在一定的膝角范围内收集被动的踝关节扭矩和踝关节角度。通过将应力松弛实验数据与二项指数函数拟合来确定粘性参数，并通过将QLV模型和粘性参数拟合到循环实验数据来估计弹性参数。该模型在低速（RMSE：1.7±0.5N）和高速（RMSE：1.9±0.2N）时均能很好地拟合实验数据。肌腱单元表现出大量的应力松弛。尽管如此，用QLV模型估算的粘弹性被动长度-张力曲线类似于使用忽略粘度的模型获得的弹性被动长度-张力曲线。在不同的加载速率下，弹性被动长度-张力曲线几乎没有差异。我们得出结论，（a）QLV模型可用于量化体内松弛的人腓肠肌肌腱单位的粘弹性行为，（b）在我们研究的速度范围内，加载速度对被动长度的影响很小腓肠肌肌腱单位的拉伸特性

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