The Role of Muscle Dynamics in Governing Achilles Subtendon Behavior Across the Lifespan

项目摘要 在年轻人中，通过小腿三头肌(即腓肠肌、比目鱼肌)产生的机械正能量。 肌肉-肌腱的相互作用占行走所需总能量的绝大部分。近期 证据表明，气体和溶胶通过不同的，也许是机械的方式传递它们的力量 独立的亚肌腱，合并并扭转形成跟腱(AT)。与我们的初步调查一致 超声成像在人类和动物衰老模型中的结果暗示相邻的 副肌腱。我们认为，这些粘连不利于气体和溶胶的结合，从而对 影响肌腱-肌腱相互作用动力学和小腿三头肌力学的基本机制 行走时的输出量。使用一种新的双探头成像技术，我们的初步数据显示，三头肌 腓肠肌动力学可能在复杂的小腿关节结构中产生不均匀的移位模式。 年轻人，从而促进气体的机械独立性(负责向前推进)和 SOL(负责干线支持)。目标1：我们的计划将利用我们的新型双探头成像技术 确定肌肉收缩动力学在调节青年局限性AT组织移位中的作用 成年人。目标2：然后我们将量化衰老对肌肉收缩动力学在控制中的作用的影响 跟腱下移(反之亦然)。目标3：最后，我们将整合我们测量到的肌肉- 将肌腱相互作用动力学引入到下肢的计算模型中以确定机械性原因 相关建筑因素与神经肌肉因素在加速衰老相关改变中的关系 走路。这项研究的发现将直接影响我们对肌肉骨骼的理解 与年龄相关的行动能力障碍的潜在机制是为了改善我们老龄化的健康和福利 人口。此外，我们在肌肉骨骼成像方面的技术进步将彻底改变 体内超声在功能性运动行为中的作用，在人类和其他动物中具有广泛的意义。 更广泛地说，从这项研究中获得的知识可以显著加快工程化的开发 组织、再生医学方法和疗法，以及整形外科手术干预。

Project Summary In young adults, the positive mechanical power generated via triceps surae (i.e., gastrocnemius -GAS, soleus- SOL) muscle-tendon interaction is responsible for a large majority of the total power needed to walk. Recent evidence suggests that GAS and SOL transmit their forces through distinct, and perhaps mechanically independent, subtendons that merge and twist to form the Achilles tendon (AT). Consistent with our preliminary ultrasound imaging results in humans, animal models of the aging AT allude to adhesions between adjacent subtendons. We propose that these adhesions unfavorably couple the GAS and SOL, thereby negatively affecting fundamental mechanisms that influence muscle-subtendon interaction dynamics and triceps surae mechanical output during walking. Using a novel dual-probe imaging technique, our preliminary data reveal that triceps surae muscle dynamics may precipitate non-uniform displacement patterns in the architecturally complex AT of young adults, thereby facilitating mechanical independence of GAS (responsible for forward propulsion) and SOL (responsible for trunk support). Aim 1: Our proposal will leverage our novel dual-probe imaging technique to determine the role of muscle contractile dynamics in governing localized AT tissue displacements in young adults. Aim 2: We will then quantify the effects of aging on the role of muscle contractile dynamics in governing Achilles subtendon displacement (and vice versa). Aim 3: Finally, we will integrate our measured muscle- subtendon interaction dynamics into a computational model of the lower extremity to identify mechanistic causal relations between relevant architectural and neuromuscular factors in precipitating age-related changes during walking. The findings from this study will have immediate impact on our understanding of musculoskeletal mechanisms underlying age-related mobility impairment toward improving the health and welfare of our aging population. Moreover, our technological advancements in musculoskeletal imaging will revolutionize the use of in vivo ultrasound during functional locomotor behavior, with broad implications in humans and other animals. More broadly, the knowledge gained from this study could significantly accelerate the development of engineered tissues, regenerative medicine approaches and therapies, and orthopaedic surgical intervention.