Influence of Age-Related Changes in Tendon on Motor Performance

 描述(由申请人提供)：在步行的推离阶段，足屈肌力量的减少会导致首选的步行速度随着年龄的增长而减慢，这反过来又会对老年人的健康和独立性产生不利影响。尽管通常被认为与此有关，但仅靠肌肉量减少和肌肉无力并不能完全解释足屈肌力的降低或伴随的协调性变化。我们推测，这种脱节是由于跟腱行为的年龄相关变化引起的，这些变化改变了运动中的肌肉-肌腱动力学。这项研究紧密结合了新颖的活体成像、计算建模和运动分析，以前所未有的详细程度研究与生理负荷和运动相关的肌腱变形。我们的主要假设是，与年龄相关的肌腱弹性变化和肌束间粘连对肌肉在运动过程中产生足够的足屈肌力量的能力有实质性的影响。本研究有三个目的。第一个目的是确定在生理负荷下，在规定的踝关节屈曲运动中，高龄如何影响趾屈肌和跟腱的活体行为。我们将结合高分辨率静态MRI、动态MRI和剪切波弹性成像来验证这样的假设，即增龄会导致跟腱组织弹性的空间模式改变，从而预测测量到的肌肉组织变形模式。第二个目的是预测跟腱组织力学中与年龄相关的变化对运动中的趾屈肌功能的影响。我们将把人体运动的测量与一个独特的计算框架联系起来，该框架包括详细的足底屈肌-肌腱3D形态的结构表示及其动态相互作用。我们将验证最初的假设，即模拟跟腱弹性和肌束间粘连的年龄相关变化将减少功率产生并增加局部组织应变。第三个目的是调查步行过程中跟腱行为的年龄相关变化，以及它与功能性运动表现和步态干预反应的相关性。我们将在活体内测量跟腱变形、趾屈肌束行为和步行过程中的趾屈肌力。我们将把这些测量与生物反馈结合起来，旨在引起屈肌功率输出的规定增加。我们将使用这些数据来检验假设：1)随着年龄的增长，行走过程中更均匀的肌腱变形将反映肌腱束之间滑动的减少，这将预测脚踝关节动力学的降低和足屈肌束运动学的改变，以及2)随着年龄的增长，将使用不同的协调策略来增加足屈肌的力量，适应将与目标2模型预测一致。这些目标结合在一起，将揭示跟腱力学中与年龄相关的变化对运动过程中踝屈肌行为的影响，这些见解对于开发知情的干预措施以保持或恢复活动能力，同时降低肌肉-肌腱组织损伤的风险至关重要。

 DESCRIPTION (provided by applicant): A reduction in plantarflexor power during the push-off phase of walking leads to the slowing of preferred walking speed with age, which in turn negatively affects old adults' health and independence. Although commonly implicated, sarcopenia and muscle weakness alone cannot fully explain the reduction in plantarflexor power or accompanying changes in coordination. We postulate that this disconnect arises from age-related changes in Achilles tendon behavior that alter muscle-tendon dynamics during movement. This study tightly integrates novel in vivo imaging, computational modeling, and motion analysis to investigate tendon deformations associated with physiological loading and movement to an unprecedented level of detail. Our overarching hypothesis is that age-related changes in tendon elasticity and inter-fascicle adhesions have a substantial effect on the ability for muscles to generate sufficient plantarflexor power during movement. This study has three aims. The first aim is to determine how advancing age affects the in vivo behavior of the plantarflexor muscles and Achilles tendon during prescribed ankle flexion movements under physiological loading. We will combine high-resolution static MRI, dynamic MRI, and shear wave elastography to test the hypothesis that advancing age brings altered spatial patterns of Achilles tendon tissue elasticity that predict measured muscle tissue deformation patterns. The second aim is to predict the functional implications of age- related changes in Achilles tendon tissue mechanics on plantarflexor performance during movement. We will link measurements of human movement with a unique computational framework that includes detailed structural representations of the 3D morphology of the plantarflexor muscle-tendons and their dynamic interactions. We will test the primary hypothesis that simulating age-related changes in Achilles tendon elasticity and inter-fascicle adhesions will diminish power production and increase localized tissue strains. The third aim is to investigate age-related changes in Achilles tendon behavior during walking and its relevance to functional motor performance and response to gait interventions. We will measure in vivo Achilles tendon deformations, plantarflexor fascicle behavior, and plantarflexor power during walking. We will couple these measurements with biofeedback designed to elicit prescribed increases in plantarflexor power output. We will use these data to test the hypotheses that: 1) more uniform tendon deformations during walking with aging, which would reflect a reduction in sliding between tendon fascicles, will predict reduced ankle joint kinetics and altered plantarflexor muscle fascicle kinematics, and 2) with aging, different coordination strategies will be used to increase plantarflexor power, adaptations that will be consistent with Aim 2 model predictions. Combined, these aims will reveal the influence of age-related changes in Achilles tendon mechanics on plantarflexor muscle behavior during movement, insights critical for developing informed interventions to maintain or restore mobility while mitigating risk for muscle-tendon tissue damage.