Effects of Age on Mechanical Properties of Dorsiflexor and Plantarflexor Muscles
Effects of Age on Mechanical Properties of Dorsiflexor and Plantarflexor Muscles
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DOI：
10.1007/s10439-011-0481-4
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发表时间：
2012-05-01
影响因子：
3.8
通讯作者：
Caldwell, Graham E.
中科院分区：
文献类型：
--
作者：
Hasson, Christopher J.;Caldwell, Graham E.
人体肌肉系统中的冗余使得评估体内肌肉机械特性中与年龄相关的变化具有挑战性，因为伦理考虑禁止直接测量肌肉力量。我们克服了这一点，通过使用一种混合的方法，结合磁共振和超声成像，测力计测量，肌肉建模和数值优化，以获得特定对象的胫骨前肌，腓肠肌和比目鱼肌的力学性能的估计，从年轻人和老年人。我们假设老年受试者的最大等长力较低，收缩较慢，弹性较强，并且与通用属性相比，受试者特定的肌肉属性将提供更准确的关节扭矩预测。未知的肌肉模型参数，通过最小化模拟和实际受试者扭矩-时间的历史在等距和等速条件下的差异。由此产生的受试者特定的模型显示出年龄和性别相关的差异，老年人表现出减少的最大等长力，较慢的力速度和改变的力长度属性和更硬的弹性。胫骨前肌受年龄影响最小。受试者特定的模型给出了良好的预测实验同心扭矩-时间的历史（10-14%的误差），但偏心条件下不太准确。对于一般的肌肉特性，预测误差大约是两倍大。为了获得最大的预测能力，肌肉骨骼模型应针对个体受试者进行定制。
Redundancy in the human muscular system makes it challenging to assess age-related changes in muscle mechanical properties in vivo, as ethical considerations prohibit direct muscle force measurement. We overcame this by using a hybrid approach that combined magnetic resonance and ultrasound imaging, dynamometer measurements, muscle modeling, and numerical optimization to obtain subject-specific estimates of the mechanical properties of tibialis anterior, gastrocnemius, and soleus muscles from young and older adults. We hypothesized that older subjects would have lower maximal isometric forces, slower contractile and stiffer elastic characteristics, and that subject-specific muscle properties would give more accurate joint torque predictions compared to generic properties. Unknown muscle model parameters were obtained by minimizing the difference between simulated and actual subject torque-time histories under both isometric and isovelocity conditions. The resulting subject-specific models showed age- and gender-related differences, with older adults displaying reduced maximal isometric forces, slower force-velocity and altered force-length properties and stiffer elasticity. Tibialis anterior was least affected by aging. Subject-specific models gave good predictions of experimental concentric torque-time histories (10-14% error), but were less accurate for eccentric conditions. With generic muscle properties prediction errors were about twice as large. For maximum predictive power, musculoskeletal models should be tailored to individual subjects.