CAREER: Establishing Links between Musculoskeletal Morphology and the Biomechanics of Bipedal Hopping in Desert Environments

在环境中运动是大多数动物的基本特征（例如，跑步、游泳、飞行），动物如何完成这项任务的机制对进化的成功有直接的影响，因为运动与防御、寻找配偶和以有效的方式觅食有关。几个世纪以来，生物力学研究为发展和测试各种假设提供了基础，从陆地运动的一般控制原则到四肢和肌肉的形式和功能之间的特定关系。然而，这些研究绝大多数是在实验室的跑步机和轨道上进行的，与动物实际生活的环境几乎没有相似之处。为了真正理解动物的肌肉和骨骼解剖结构与运动表现之间的关系，有必要了解动物在自然环境中执行任务的机械需求。了解自然栖息地中的这些关系仍然是一个重要的挑战。因此，本研究的目的是通过一系列旨在详细了解不同肌肉如何参与运动任务的实验来研究解剖学和运动表现之间的关系。实验将揭示在机械挑战性的自然环境中运动时，肌肉和骨骼的特定特征如何影响特定肌肉的功能。这项研究的结果将促进对个体肌肉功能作用的了解，这是一个在比较生物力学研究中罕见的主题，并为更好地理解机械能如何通过复杂的肌肉骨骼系统传递奠定基础。应用这些知识可以改进自主机器人、下肢假肢和其他人类运动增强装置的设计。本研究以荒漠袋鼠大鼠为研究对象，探讨荒漠环境下肌肉骨骼形态与两足跳跃动力学之间的关系。人们普遍认为，两足跳跃之所以进化，是因为它提供了与后肢形态夸张相关的运动性能优势（例如，更快的最高速度、更高的耐力和加速能力）；然而，并不是所有的跳跃物种都具有特定的优势。为了实现提出的目标，本研究将结合野外栖息地使用分析、实验室步态动力学、体内肌肉动力学和详细的计算机建模和模拟。这将是第一个将所有这些方法结合起来的研究，以提供对肌肉骨骼形态和性能之间关系的全面理解。这种强大的综合方法将用于实现两个特定的研究目标：1)量化沙漠沙鼠在自然环境中对基质和地形的双足跳跃的机械需求；2)阐明肌肉骨骼形态与栖息地利用之间的关系。拟议研究的结果将以一种以前不可能的方式建立自然条件下运动表现与肌肉骨骼形态和肌肉功能之间的直接联系。加深对动物如何以及为什么跳跃的理解将推动进化生物学、比较解剖学和生物力学领域的发展，并导致自主机器人、下肢假肢和其他运动增强设备的设计改进。该提案支持一项教育计划，旨在开发一门实地课程，为学生提供机会，通过研究驱动的、基于实地的栖息地利用、功能形态和行为分析，将他们所学到的生态学和进化知识整合起来。本课程多年来的行为和栖息地使用数据将为解释形态学和生物力学结果提供更广泛的背景。

Movement through their environments is a fundamental characteristic of most animals, (e.g., running, swimming, flying) and the mechanics of how animals perform this task have direct implications for evolutionary success because locomotion is involved with defense, finding mates, and foraging for food in efficient ways. For centuries, biomechanics research has provided a foundation for developing and testing hypotheses ranging from general governing principles of terrestrial locomotion to specific relationships between form and function of limbs and muscles. However, the vast majority of these studies have been conducted in laboratories on treadmills and tracks that bear little resemblance to the environments in which animals actually live. To truly understand the relationship between an animal's muscular and skeletal anatomy and locomotor performance, it is necessary to understand the mechanical demands of the tasks performed in the animal's natural environment. Understanding these relationships in natural habitats remains an important challenge. Therefore, the goal of this study is to examine the relationships between anatomy and locomotor performance through a series of experiments aimed at understanding in detail how different muscles contribute to movement tasks. Experiments will reveal how specific features of muscles and skeletons impact the function of particular muscles during locomotion in mechanically challenging natural environments. The outcomes of this research will advance knowledge about the functional roles of individual muscles, a topic that is rare in comparative biomechanics studies, and lay the groundwork for a better understanding of how mechanical energy is transferred through complex musculoskeletal systems. Application of this knowledge can lead to improvements in the design of autonomous robots, lower limb prosthetics, and other human locomotor enhancement devices.The purpose of this research is to elucidate the relationships between musculoskeletal morphology and bipedal hopping dynamics in desert environments using desert kangaroo rats (D. deserti) as an animal model. It is generally believed that bipedal hopping has evolved because it provides a locomotor performance advantage (e.g., faster top speed, higher endurance, acceleration capacity) related to exaggerated hind limb morphology; however a specific advantage has not been identified for all hopping species. To achieve the proposed objectives, this study will incorporate analyses of habitat use in the field, gait dynamics in the lab, in-vivo muscle dynamics and detailed computer modeling and simulations. This will be the first study to combine all of these methods to provide a comprehensive understanding of the relationships between musculoskeletal morphology and performance. This powerful, integrated approach will be used to pursue two specific research objectives: 1) Quantify the mechanical demands of bipedal hopping on substrates and terrain utilized by D. deserti in their natural environment and, 2) Elucidate the relationship between musculoskeletal morphology and habitat use. The outcomes of the proposed research will establish direct links between locomotor performance under natural conditions and musculoskeletal morphology and muscle function in a way that has not been previously possible. An enhanced understanding of how and why animals hop will advance the fields of evolutionary biology, comparative anatomy, and biomechanics, and lead to improvements in the design of autonomous robots, lower limb prosthetics, and other locomotor enhancement devices. This proposal supports an Educational Plan to develop a field course to provide an opportunity for students to integrate what they have learned about ecology and evolution through research-driven, field-based analyses of habitat use, functional morphology, and behavior. Data for behavior and habitat use from multiple years of this course will provide a broader context for interpreting morphological and biomechanical results.