RUI: Body Size, Limb Posture and Muscle Strain During Terrestrial Locomotion

瑞：陆生运动中的身体大小、肢体姿势和肌肉劳损加里·B·吉利斯圣霍利奥克山学院四足哺乳动物在运动时通常会有不同的肢体姿势。小动物使用蹲着的姿势，四肢更弯曲，而大型动物使用更直立的姿势，四肢相对伸直。尽管我们了解肢体结构的这种比例，但我们对这种姿势差异如何影响不同大小动物的同种肢体肌肉的动作知之甚少。事实上，我们对四足哺乳动物四肢肌肉的活体行为还知之甚少，因为没有一种动物能够很好地理解任何步态的髋关节、膝盖和脚踝伸展肌的动作。这项拟议的工作涉及研究在大小上有很大差异的选定哺乳动物物种的主要后肢肌肉的长度变化和激活模式。两种实验方法将被用来探索身体大小和肢体姿势如何在运动过程中影响肢体肌肉功能。首先，使用声学显微镜和肌电图仪，将测量和比较大小超过三个数量级的多种啮齿类动物(从老鼠到水豚)的四肢肌肉的应变和激活模式。数据将被用来检验这一普遍假设，即在大小和肢体姿势不同的密切相关动物中，同源肌肉的功能不同。在第二种方法中，肢体姿势、肌肉结构以及肌肉紧张和激活的模式将在个体发育过程中描述几个哺乳动物物种的特征。这种方法将解决在生长过程中发生的大小变化是否会影响四肢肌肉，其方式类似于不同哺乳动物物种之间进化出的大小差异。总之，这些不同的方法将(1)提供关键的洞察力，了解哺乳动物后肢肌肉在运动过程中如何在体内运行，(2)将有助于阐明动物大小在塑造个体发育和跨系统发育的个体肢体肌肉活动方面的重要性。拟议的工作还将对培养对生物科学感兴趣的有才华的年轻女性的研究机会产生更广泛的影响。PI在一个单一性别的机构工作，每年有两名学生在项目上合作，学习宝贵的研究技能，在全国会议上展示他们的工作成果，并共同撰写论文。

RUI: Body Size, Limb Posture and Muscle Strain During Terrestrial LocomotionGary B. GillisMount Holyoke CollegeQuadrupedal mammals that differ greatly in size generally adopt distinct limb postures during locomotion. Small animals use a crouched posture with their limbs held more flexed while large animals use a more upright posture with their limbs held relatively straight. Despite our understanding of this scaling of limb configuration, we know little about how such postural differences influence the actions of homologous limb muscles in animals of varying size. Indeed, we have little appreciation for the in vivo behavior of quadrupedal mammalian limb muscles more generally; for no animal are actions of a hip, knee and ankle extensor well understood for any gait. The proposed work involves studying patterns of length change and activation in major hindlimb muscles of select mammalian species that differ widely in size. Two experimental approaches will be used to explore how body size and limb posture affect limb muscle function during locomotion. First, using sonomicrometry and electromyography, strain and activation patterns will be measured and compared among limb muscles of multiple rodent species ranging in size over three orders of magnitude (mice to capybara). Data will be used to test the general hypothesis that homologous muscles function differently in closely related animals that differ in size and limb posture. In the second approach, limb posture, muscle architecture and patterns of muscle strain and activation will be characterized in several mammal species over ontogeny. This approach will address whether changes in size that occur during growth influence limb muscles in a manner similar to size differences that have evolved among various mammalian species. Together, these distinct approaches will (1) provide critical insight into how muscles throughout the mammalian hindlimb operate in vivo during locomotion and (2) will help clarify the importance of animal size in shaping the actions of individual limb muscles both through ontogeny and across phylogeny. The proposed work will also have the broader impact of fostering research opportunities for talented young women interested in the biological sciences. The PI works at a single-gender institution and two students each year will collaborate on the projects, learning valuable research skills, presenting results from their work at national meetings, and co-authoring papers.