Efficiency and mechanical performance of muscles

点击翻译按钮获取中文摘要

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.