Doctoral Dissertation Improvement Grant: Energetics and mechanics of quadrupedal walking and running in prosimians

长期以来，对于灵长类动物学家和古人类学家来说，能量学一直是一个重要的问题，他们对现存和灭绝物种的运动性能感兴趣。例如，以单位距离或单位时间衡量的移动成本已被纳入各种资源获取、领土防御和迁徙行为模型。对几种四足灵长类动物耗氧率的测量表明，像大多数动物一样，它们表现出一种模式，即随着速度的加快代谢成本增加，随着体重的增加而降低成本。这项研究试图通过关注四足灵长类动物的四肢肌肉在运动过程中如何产生力量和调节能量使用来了解陆地运动的力学和代谢成本之间的联系。四足灵长类在步态特征(肢体偏移角)和肢体设计(肌肉质量分布和肌腱结构)方面都不同于大多数其他四足哺乳动物。最近的研究表明，这两个变量都会影响在运动过程中招募的活跃肌肉的体积，而且因为能量消耗必须由骨骼肌活动来设定，所以将影响运动成本。这项研究将评估灵长类肌肉-肌腱系统如何产生力量，以及为了产生单位力量消耗了多少新陈代谢能量。为此，将进行两个不同的实验。将测量两种原猴在水平运动时的代谢率，并与之前公布的更曲折的陆生哺乳动物的数据进行比较。然后，将从一个灵长类物种和一个类似大小的非灵长类四足哺乳动物物种那里收集解剖学、视频和测力板数据，以确定它们在不同速度范围的水平上锻炼时各自的活跃肌肉体积、关节功和功率产生。这项研究将首次尝试将灵长类动物运动和肢体形态的独特方面与它们的代谢成本联系起来。总之，这些实验将产生检验新陈代谢和力学之间的基本关系的经验数据，这对于理解灵长类动物的能量使用和肌肉功能之间的关系具有重要意义。这项研究的结果将为灵长类生物学提供重要的见解，并为理解形态进化对运动能量成本的影响提供生理学基础。这项研究的更广泛影响包括开发了一系列计算工具，用于整合来自生物力学研究的视频和测力板数据，这些数据将在网上向国际社会提供。这项工作还将为约翰·霍普金斯大学的本科生创造研究机会。这些学生将被包括在代谢、运动学和力盘数据收集和分析以及计算机编程方面，提供跨越生物科学和物理科学的跨学科经验。

Energetics has long been an important issue to primatologists and paleoanthropologists interested in the locomotor performance of extant and extinct species. The cost of locomotion, measured per unit distance or per unit time, for example, has been incorporated into various models of resource acquisition, territory defense and migratory behavior. Measurements of the rate of oxygen consumption in several quadrupedal primate species have shown that, like most animals, they exhibit a pattern of increasing metabolic costs with faster speeds and decreasing costs with larger body weight. This study seeks to understand the link between the mechanics and metabolic cost of terrestrial locomotion in quadrupedal primates by focusing on how their limb muscles generate force and modulate energy use during exercise. Quadrupedal primates differ from most other quadrupedal mammals in both their gait characteristics (limb excursion angles) and limb design (muscle mass distribution and muscle-tendon architecture). Recent studies indicate that both of these variables will impact the volume of active muscle that is recruited during locomotion and, because energy use must be set by skeletal muscle activity, will impact the cost of movement. This study will evaluate how the primate muscle-tendon system produces force and how much metabolic energy is consumed in order to generate a unit force. To do this, two separate experiments will be carried out. Metabolic rate during locomotion on the level will be measured for two species of prosimians and compared with previously published data for more cursorial terrestrial mammals. Then, anatomical, video and force-plate data will be collected from one primate species and one similarly sized nonprimate quadrupedal mammal species in order to determine their respective active muscle volumes, joint work and power production during exercise on the level across a range of speeds. This study will be the first to attempt to link the unique aspects of primate locomotion and limb morphology to their metabolic costs. Together, these experiments will generate empirical data testing a fundamental relationship between metabolics and mechanics that is significant for understanding the relationship between energy use and muscle function in primates. The results of this study will provide critical insight into primate biology and provide a physiological basis for understanding the effects of morphological evolution on the energetic cost of locomotion. The broader impacts of this study include the development of a series of computational tools for integrating video and force-plate data from biomechanical studies, which will be made available online to the international community. This work will also create research opportunities for undergraduates at Johns Hopkins University. These students will be included in aspects of metabolic, kinematic and force-plate data collection and analysis as well as computer programming, providing an interdisciplinary experience that spans the biological and physical sciences.