Efficiency and mechanical performance of muscles

可以根据代谢经济(运输成本、肌肉效率)和机械性能(功和功率输出)的需要来确定运动的优先顺序。我们的目标是了解如何提高机械性能，以及在不同类型的动作和动物中，性能的机械和能量方面如何相互作用。这项研究结合了对整个动物、分离组织和计算机建模的测量来解决这些问题。1)柔顺/弹性结构如何改善机械性能并改变移动的能量成本。我们开发了一种通过顺应性(肌腱)连接到负荷(动物)上的肌肉(其特性可以定义为与我们选择的任何肌肉相匹配)的计算机模拟。我们正在探索通过改变肌腱的特性和收缩方面来增加力量/功的多种方法。此外，我们最近开发了一个实时系统，其中活的肌肉通过高速接口为计算机模拟的运动提供动力。这保留了活体肌肉复杂收缩的真实性，并允许直接测量肌肉所使用的能量(氧气)。我们将确定顺应性结构如何改变肌肉收缩的效率和运动的经济性。2)在游动的鱼中，肌肉具有哪些功能？我们正在建立对其在各种鱼类中的复杂性的理解，并首次调查了经济性和机动性的作用。这需要测量游动的鱼的肌肉活动和张力，离体肌的功和能量，以及鱼和肌肉的能量消耗。3)通过人工选择小鼠的高活动，肌肉中基于基因的改变如何影响收缩效率，以及这如何影响整个动物的表现？在加州大学河滨分校的Ted Garland的帮助下，我们在这些小鼠身上展示了机械力和肌肉抗疲劳性的戏剧性变化。我们建议测量这些肌肉的收缩效率，以了解它与选择范式的关系。这是一个难得的机会，可以研究在被选择的有机体中，权力和效率之间潜在的直接权衡。

Movement can be prioritized based on needs for metabolic economy (cost of transport, muscle efficiency) and for mechanical performance (work and power output). Our objectives are to understand how mechanical performance can be enhanced and how mechanical and energetic aspects of performance interact in different types of movements and animals. This research integrates measurements from whole animals, isolated tissue and computer modeling to tackle these questions. 1) How do compliant/elastic structures improve mechanical performance and alter the energetic cost of moving. We developed a computer simulation of a muscle (whose properties we can define to match any muscle we choose) attached to a load (animal) through a compliance (tendon). We are probing the multitude of ways by which power/work may be increased by altering the characteristics of tendons and aspects of contraction. Further, we recently developed a real-time system where a living muscle powers computer simulated movement via a high speed interface. This retains the realism of complex contractions from living muscle and allows direct measurement of the energy (oxygen) used by muscle. We will determine how compliant structures alter the efficiency of muscle contraction and the economy of movement. 2) What functions are ascribed to muscles in swimming fish? We are establishing an understanding of its complexity in various fish, and are the first to investigate the roles of economy and manoeuvrability. This entails measures of muscle activation and strain in swimming fish, work and power from isolated muscle, and energy consumption by fish and muscle. 3) How do genotypic based alterations in muscle through artificial selection for high activity in mice impact efficiency of contraction and how does this bear on whole animal performance? With Ted Garland (UC Riverside), we demonstrated dramatic shifts in mechanical power and fatigue resistance of muscles in these mice. We propose to measure efficiency of contraction in these muscles to understand its relationship with the selection paradigm. This is a rare opportunity to study a potential direct trade off between power and efficiency in an organism under selection.