Mechanics of In Vivo Muscle Function During Locomotion

小行星9306793 这项研究的主要目的是直接记录动物运动过程中肢体肌肉的功能。 尽管对脊椎动物骨骼肌的生理学、生物化学和机械特性进行了大量的研究，但关于正常运动活动期间肌肉功能的体内力学的直接数据很少。特别是，对人类肢体肌肉的研究必然依赖于对肌肉力量和延长的间接评估。通过直接在体内测量选择的肌肉施加的力和它们经历不同动物物种的长度变化，我们可以更好地了解肌肉如何动态地支持和推动动物的运动。将通过使用植入的肌腱力传感器或通过在骨骼上肌肉附着部位进行力校准的体内骨骼应变记录来测量肌肉力。将使用植入肌肉内的超声发射声测微电极进行肌纤维长度变化的体内测量。在这个建议中，我们将研究在两个陆地和两个飞行物种的肌肉在体内的性能。 在对沙袋鼠踝伸肌的研究中，这些测量将使我们能够探索肌肉肌腱“弹簧”中弹性能量储存的要求如何节省能量消耗，从而影响神经系统如何激活这些肌肉以提供动力跳跃，而不是动物需要加速和改变方向。在对白色来航鸡腓肠肌内侧（MG）和外侧（LG）的研究中，我们将研究在行走和跑步过程中与缩短相关的肌肉力量产生的募集。这两种肌肉的不同纤维特征（LG：主要是快速和MG：主要是缓慢），结合独立的力输出记录，提供了一个独特的机会，研究在一个单一的肌肉recrublation。在第三组实验中，我们将直接测量鸽子和乌鸦在飞行过程中胸肌中的力产生和纤维缩短。这些测量将提供第一个直接测量肌肉机械功率，以及整个动物的权力，在运动过程中的脊椎动物物种。这些研究将扩展我们以前的工作，开发了骨骼应变的方法来测量在飞行过程中直接由胸大肌i椋鸟和鸽子在体内产生的力。 总之，骨骼肌力学的大多数研究都依赖于实验控制的模拟缩短和力的发展孤立的整个肌肉或肌肉纤维束在准静态条件下，不太可能适用于肌肉进行正常运动。因此，从拟议的研究中获得的结果，将提供有价值的信息，在正常功能条件下的肌肉的动态力-速度特性。从这些研究中获得的结果将有助于更好地建立动物运动中肌肉功能的一般原则，并与运动控制和机器人研究相关。 ***

9306793 Biewener The main objective of this research is to record directly how limb muscles function during the locomotion of animals. Despite the considerable interest and extensive research that has been carried out on the physiology, biochemistry and mechanical properties of vertebrate skeletal muscles, little direct data exist concerning the in vivo mechanics of muscle of function during normal locomotor activity. In particular, studies of human limb muscles necessarily rely on the indirect assessments of muscle force and lengthening . By making direct in vivo measurements of the forces exerted by select muscles and length changes that they undergone different animal species, we can better understand how muscles function dynamically to support and power the movement of an animal. Measurements of muscle force will be made by using either implanted tendon force tranducers or by making force-calibrated in vivo skeletal strain recordings at the muscle's attachment site on the bone. In vivo measurements of muscle fiber length change will be made using ultrasound emitting sonomicrometry electrodes implanted within the muscle. In this proposal, we will examine the in vivo performance of muscles in two terrestrial and two flying species. In studies of ankle extensor muscles of wallabies, these measurements will enable us to explore how requirements for elastic energy storage in muscle-tendon 'springs' to conserve energy expenditure affect how the nervous system activates these muscles to power hopping versus the animal's need to accelerate and change direction. In studies of the medial(MG) and lateral(LG) gastrocnemius muscles in white leghorn chickens, we will study the recruitment of muscle force generation in relation to shortening during walking and running. The differing fiber characteristics of these two muscles (LG: mainly fast and MG: mainly slow), combined with independent recordings of force output, provides a unique opportunity to study recr uitment within a single muscle. I a third set of experiments we will obtain direct measurements of force generation and fiber shortening in the pectoralis muscle of pigeons and crows during flight. These measurements will provide the first direct measurement of muscle mechanical power, as well as whole animal power, during locomotion in a vertebrate species. These studies will extend our previous work, which developed the skeletal strain approach to measure in vivo force generation directly by the pectoralis during flight i starlings and pigeons. In summary, most studies of skeletal muscle mechanics have relied either on experimentally controlled simulations of shortening and force development isolated whole muscles or muscle fiber bundles under quasi-static conditions that are unlikely to apply to muscles performing normal movements. The results obtained from the proposed studies, therefore, will provide valuable information concerning the dynamic force-velocity properties of muscles under normal functional conditions. The results obtained from these studies will help to better establish general principles underlying muscle function in animal locomotion, as well as have relevance for motor control and robotics research. ***