Elastic energy storage and the efficiency of movement.

Movement is an integral part of animal biology. It enables organisms to escape from danger, acquire food, and perform courtship displays. Changing the speed or vertical position of a body requires mechanical energy. This energy is typically provided by the biological motor, striated muscle. Striated muscle uses chemical (metabolic) energy to produce force, to move this force over a distance to do work, and to do this work within some time to generate power. The metabolic energy consumed in producing these mechanical outputs is a major component of an organism's energy budget, particularly during repetitive, cyclical movements. This energy could otherwise be used for maintenance, growth, and reproduction. Hence, fitness may be enhanced by improving locomotor efficiency - the ratio between work done and metabolic energy consumed. This may be achieved by reducing the need for muscle to do work, and by increasing the efficiency with which muscle does work.