Linking muscle-tendon dynamics and energetics to inform exoskeleton design for improved locomotor economy in aging.

将肌肉肌腱动力学和能量学联系起来，为外骨骼设计提供信息，以改善衰老过程中的运动经济性。

• 批准号: 10400361
• 负责人: Owen Beck
• 金额: $ 2.48万
• 依托单位: GEORGIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2021-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10400361
• 关键词: Aging; Link; Muscle; Tendon structure; design; exoskeleton; improved

Abstract Among older adults, walking speed is an excellent predictor of health, happiness, and longevity. Unfortunately as adults mature, their preferred walking speeds rapidly decline as their corresponding metabolic costs increase; changes that impair older adult's ability to navigate their communities. Based on recent scientific findings, I posit that the age-related decline in tendon stiffness contributes to the increased metabolic cost and reduced walking speeds of older versus young adults. That is because compared to youthful (stiffer) tendons, aged (compliant) tendons shift the in-series muscle contractile dynamics to presumably less economical states, which I theorize relates to slower and less economical locomotor movement in older versus young adults. Accordingly, this project's 1st Aim seeks to uncover the relationships between tendon stiffness, in-series muscle dynamics (i.e. operating lengths and shortening velocities), and the corresponding metabolic cost of cyclic contractions. To fulfill this aim, I will systematically alter older adult soleus muscle and Achilles tendon dynamics during cyclic, non-invasive isolated muscle contractions. I will characterize the corresponding physiological responses using a battery of physiological measurements, highlighted by the use of 1) ultrasound imaging that enables me to track muscle and tendon movement 'underneath the skin' and 2) open-circuit respirometry that enables me to quantify participant metabolic rates. I hypothesize that effectively reducing Achilles tendon stiffness elicits less economical in-series muscle dynamics. The results of this aim will uncover fundamental relationships between aged-musculoskeletal systems and the corresponding metabolic costs of performing locomotor tasks. For the 2nd Aim, I will determine how soleus muscle contractile dynamics independently affect older adult metabolic rates during walking. To do this, I will employ passive (custom footwear) and active (ankle exoskeleton emulator) assistive devices that each systematically alter older adult soleus dynamics during walking, while I assess relevant biomechanical and physiological measures: muscle/tendon dynamics, metabolic cost, muscle activation, stride kinetics and kinematics. I hypothesize that the assistive device that optimizes the interplay of soleus operating length and shortening velocity will minimize the metabolic cost of walking and improve older adult preferred walking speed. The results of Aim 2 will reveal the optimal soleus muscle dynamics to improve older adult walking economy and speed. Study implications may be used to inform assistive device design, surgical procedures, and rehabilitation/exercise programs aimed to enhance older adult leg function and walking performance. Altogether, this study is set to comprehensively test the space of cyclic muscle contractions to reveal the fundamental links between tendon stiffness, muscle dynamics, and energetics, with special regard to older adult mobility.

摘要 在老年人中，步行速度是健康，幸福和长寿的一个很好的预测因素。不幸的是，随着成年人的成熟，他们喜欢的步行速度迅速下降，因为他们相应的代谢成本增加;这些变化损害了老年人在社区中导航的能力。根据最近的科学发现，我认为与年龄相关的肌腱硬度下降导致老年人与年轻人相比代谢成本增加和步行速度降低。这是因为与年轻（更僵硬）的肌腱相比，老年（顺应性）肌腱将串联肌肉收缩动力学转移到可能不太经济的状态，我认为这与老年人与年轻人的运动速度较慢和不太经济有关。因此，该项目的第一个目标旨在揭示肌腱刚度，串联肌肉动力学（即操作长度和缩短速度）和周期性收缩的相应代谢成本之间的关系。为了实现这一目标，我将系统地改变老年人比目鱼肌和跟腱动力学周期性，非侵入性孤立肌肉收缩。我将使用一系列生理测量来表征相应的生理反应，其中突出显示的是使用1）超声成像，使我能够跟踪“皮肤下”的肌肉和肌腱运动，以及2）开路呼吸测量，使我能够量化参与者的代谢率。我假设，有效地减少跟腱僵硬elessless经济的串联肌肉动力学。这一目标的结果将揭示老年肌肉骨骼系统和相应的代谢成本执行运动任务之间的基本关系。对于第二个目标，我将确定比目鱼肌收缩动力学如何独立地影响老年人在步行过程中的代谢率。为此，我将使用被动（定制鞋类）和主动（脚踝外骨骼模拟器）辅助设备，每种设备都系统地改变老年人步行过程中的比目鱼肌动力学，同时我评估相关的生物力学和生理测量：肌肉/肌腱动力学、代谢成本、肌肉激活、步幅动力学和运动学。我假设，辅助设备，优化比目鱼肌操作长度和缩短速度的相互作用，将最大限度地减少步行的代谢成本，提高老年人的首选步行速度。目标2的结果将揭示最佳比目鱼肌动力学，以提高老年人步行的经济性和速度。研究意义可用于告知辅助装置设计，外科手术和康复/锻炼计划，旨在提高老年人的腿部功能和行走性能。总之，这项研究旨在全面测试周期性肌肉收缩的空间，以揭示肌腱刚度，肌肉动力学和能量学之间的基本联系，特别是老年人的流动性。