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

项目摘要 本提案将满足对新的和可修改的目标的迫切需求，以增强机动性和恢复能力， 在我们迅速老龄化的人口中独立。由于踝关节蹬离力降低，老年人步行 比年轻的成年人更慢，代谢能量消耗更高。作为我们的中心前提，我们认为， 在行走过程中，与年龄相关的蹬离强度缺陷常常被错误地认为是 仅归因于跖屈肌，而是与活动中的那些肌肉相互依赖地起源， 被动的和结构性的足部机械动力调节。这一前提为翻译铺平了道路 增加足部结构和功能的机会，以提高独立性和生活质量。本研究 结合了两位高效率研究人员的研究议程，并利用研究基础设施 两个同行机构。目标1将是第一个研究人类足部之间的机械动力相互作用的项目。 和踝关节在控制减少推离强度和步行经济性的老年人在各种各样的， 每天的行走任务。通过将代谢测量与最先进的生物力学和 生物能量模型，我们将测试的假设，老年人表现出较高的机械能损失，通过 足部结构比年轻成人-老化效应：（i）对于增加足部需求的行走任务更大， (ii)蹬地过程中踝关节力矩和力量不当，因此（iii）与6分钟步行时间缩短相关 与年轻人相比，距离和代谢能量成本增加。目标2将提供机械的洞察力 老化对足踝机械动力相互作用的主动、被动和结构调节的影响 在走路的时候。在测力计上使用一系列受控加载范例， 体内超声成像和新的肌电生物反馈，我们将测试的假设，老年人 表现出：（i）降低的足和跖屈肌肌肉强度和（ii）降低的结构刚度和（iii）降低的 跨越足部和脚踝的一系列弹性组织之间的结构连接-需要升高的变化 足底固有肌激活以维持必要的足部刚度并与减少的踝关节力矩相关 和行走时蹬离时的动力输出。最后，作为一个翻译基准，目标3将表明，鞋- 与足底腱膜和内在肌肉平行作用的刚度修改可以减轻年龄， 行走时推离功能的相关缺陷。在有希望的试点数据的支持下，我们将测试 假设老年人在鞋垫刚度增加的情况下行走将表现出：（i）较小的机械强度， 足部能量损失，（ii）更有利的跖屈肌收缩动力学，（iii）更大的踝关节峰值 力矩和功率输出，因此（iv）6分钟步行距离延长，全身代谢能量减少 成本最终，这项工作将在我们的生物力学理解和临床实践中建立一个范式转变。 管理与年龄相关的活动障碍，采用可行且具有成本效益的设备来修改足踝 功能-这一成果具有提高数百万人的独立性和生活质量的巨大潜力。

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.