Adjustment of muscle mechanics model parameters to simulate dynamic contractions in older adults
Adjustment of muscle mechanics model parameters to simulate dynamic contractions in older adults
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DOI：
10.1115/1.1531112
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发表时间：
2003-02-01
影响因子：
1.7
通讯作者：
Thelen, DG
中科院分区：
文献类型：
--
作者：
Thelen, DG
准确地代表老年人运动的肌肉驱动的模拟的产生需要一个模型，以解释衰老随着衰老而发生的肌肉特性的变化。这项研究的一个目的是调整山型Musculo-tendon模型的参数，以反映文献中报道的肌肉力学中与年龄相关的名义相关的变化。第二个目标是确定使用参数调整是否导致模拟动态踝关节扭矩行为，类似于健康的老年人。主要参数调整涉及降低最大等肌力量，以解释肌肉质量的损失和年龄特异性强度。对文献的综述表明，需要进行其他适度的调整，以延长肌肉失活，这是最大收缩速度的降低。在延长收缩期间，更大的被动肌肉刚度和增加的归一化力能力。随着年龄相关的变化，使用肌肉弯曲模型来模拟脚踝plotharflexor和背反射器肌肉的等距和同步收缩。该模型预测，与健康的年轻人相比，在120度/s缩短收缩期间，脚踝plot骨功率输出在缩短收缩期间将低40％以上。随着年龄的增长，这些功率损失超过了该模型中假定的等距强度的30％损失，但在大约70岁的健康老年人中测得的踝关节功率输出的降低39-44％。因此，在模拟需要大量功率开发的运动时，考虑到年龄相关的肌肉特性变化（最大等距降低）尤其重要。
The generation of muscle-actuated simulations that accurately represent the movement of old adults requires a model that accounts for changes in muscle properties that occur with aging. An objective of this study was to adjust the parameters of Hill-type musculo-tendon models to reflect nominal age-related changes in muscle mechanics that have been reported in the literature. A second objective was to determine whether using the parametric adjustments resulted in simulated dynamic ankle torque behavior similar to that seen in healthy old adults. The primary parameter adjustment involved decreasing maximum isometric muscle forces to account for the loss of muscle mass and specific strength with age. A review of the literature suggested the need for other modest adjustments that account for prolonged muscular deactivation, a reduction in maximum contraction velocity; greater passive muscle stiffness and increased normalized force capacity during lengthening contractions. With age-related changes incorporated, a musculo-tendon model was used to simulate isometric and isokinetic contractions of ankle plantarflexor and dorsiflexor muscles. The model predicted that ankle plantarflexion power output during 120 deg/s shortening contractions would be over 40% lower in old adults compared to healthy young adults. These power losses with age exceed the 30% loss in isometric strength assumed in the model but are comparable to 39-44% reductions in ankle power outputs measured in healthy old adults of approximately 70 years of age. Thus, accounting for age-related changes in muscle properties, other than decreased maximum isometric force, may be particularly important when simulating movements that require substantial power development.