A framework for feasible translation to enhance foot and ankle function in aging and mobility

项目总结 这项提议将解决对新的和可修改的目标的迫切需求，以增强机动性和恢复 我们迅速老龄化的人口中的那些人的独立性。由于脚踝推力降低，老年人走路 与年轻人相比，速度较慢，代谢能量成本较高。作为我们的中心前提，我们认为 行走过程中与年龄相关的推离强度方面的标志性缺陷经常被错误地认为 完全归因于趾屈肌，而不是相互依赖地起源于活跃的， 被动的、结构性的调节足部机械力量。这一前提为翻译奠定了基础 增强足部结构和功能的机会，以提高独立性和生活质量。本研究 结合了两个高生产率研究人员的研究议程，并利用研究基础设施 两个同级机构的。目标1将是第一个研究人脚之间机械动力相互作用的人 和脚踝在管理减少推下强度和步行经济性方面的老年人跨越各种 每天的步行任务。通过将代谢测量与最先进的生物力学和 生物能量模型，我们将检验老年人通过以下途径表现出更高的机械能损失的假设 足部结构比年轻人--衰老的影响：(I)对于增加足部需求的步行任务来说， (Ii)在推举过程中脚踝力矩和力量不当，因此(Iii)与较短的6分钟步行有关 与年轻人相比，距离更远，代谢能量成本更高。目标2将提供机械论的洞察力 衰老对足踝机械能相互作用的主动、被动和结构调节的影响 在走路的时候。在测功机上使用一系列控制加载范例，并结合先进的 活体超声成像和新颖的肌电生物反馈，我们将检验老年人的假设 展示：(一)足部和趾屈肌力量降低，(二)结构僵硬，(三)降低 跨越足部和脚踝的一系列弹性组织之间的结构连通性-需要抬起的变化 激活足底固有肌肉以维持必要的足部僵硬，并与减少脚踝扭矩有关 以及在行走时推离时的功率输出。最后，作为翻译基准，Aim 3将展示Shoes- 与足底腱膜和内在肌肉平行作用的僵硬改变可以缓解年龄- 行走过程中推开功能的相关缺陷。在有希望的试点数据的支持下，我们将测试 老年人走路时鞋垫硬度增加将表现出：(I)较小的机械性 足部的能量损失，(Ii)更有利的趾屈肌收缩动力学，(Iii)更大的踝关节峰值 力矩和功率输出，因此(Iv)更长的6分钟步行距离和降低全身代谢能量 成本。最终，这项工作将在我们的生物力学理解和临床上建立一个范式转变。 年龄相关性活动障碍的管理走向可行且经济有效的足踝矫形器 功能--这一成果具有显著的潜力，可提高数百万人的独立性和生活质量。

PROJECT SUMMARY This proposal will address the critical need for new and modifiable targets to enhance mobility and restore independence to those in our rapidly aging population. Due to reduced ankle push-off power, older adults walk slower and with higher metabolic energy cost than younger adults. As our central premise, we contend that hallmark age-associated deficits in push-off intensity during walking have been far too often mistakenly attributed solely to the plantarflexor muscles, and instead originate interdependently with those in the active, passive, and structural regulation of foot mechanical power. This premise paves the way for translational opportunities to augment foot structure and function to enhance independence and quality of life. This study combines the research agendas of two highly productive investigators and leverages the research infrastructure of two peer institutions. Aim 1 will be the first to study mechanical power interactions between the human foot and ankle in governing reduced push-off intensity and walking economy in older adults across a wide variety of everyday walking tasks. By combining metabolic measurements with state-of-the-art biomechanical and bioenergetic modeling, we will test the hypothesis that older adults exhibit higher mechanical energy losses via foot structures than young adults – aging effects that: (i) are larger for walking tasks that increase foot demand, (ii) misappropriate ankle moment and power during push-off, and thereby (iii) correlate with shorter 6 min walk distance and increased metabolic energy cost compared to young adults. Aim 2 will provide mechanistic insight into aging effects on the active, passive, and structural regulation of foot-ankle mechanical power interactions during walking. Using a series of controlled loading paradigms on a dynamometer combined with advanced in vivo ultrasound imaging and novel electromyographic biofeedback, we will test the hypotheses that older adults exhibit: (i) reduced foot and plantarflexor muscle strength and (ii) lower structural stiffness of and (iii) reduced structural connectivity between series elastic tissues spanning the foot and ankle – changes that require elevated plantar intrinsic muscle activation to maintain requisite foot stiffness and associate with reduced ankle moment and power output during push-off in walking. Finally, as a translational benchmark, Aim 3 will show that shoe- stiffness modifications that act in parallel with the plantar aponeurosis and intrinsic muscles can mitigate age- associated deficits in push-off function during walking. Supported by promising pilot data, we will test the hypotheses that older adults walking with increased shoe insole stiffness will exhibit: (i) smaller mechanical energy losses at the foot, (ii) more favorable plantarflexor muscle contractile dynamics, (iii) greater peak ankle moment and power output, and thus (iv) longer 6 min walk distance and reduced whole-body metabolic energy cost. Ultimately, this work will establish a paradigm shift in our biomechanical understanding and clinical management of age-related mobility impairment toward feasible and cost-effective devices to modify foot-ankle function – an outcome with significant potential to enhance independence and quality of life for millions.