OPTIMUM MUSCLE DESIGN FOR OSCILLATORY MOVEMENTS

A simple model represents oscillatory movements such as many animals u se for running, swimming or flight. A plate is oscillated in a fluid b y a pair of muscles that exert the forces needed to overcome its inert ia and hydrodynamic drag. The muscles have spring-like tendons. Empiri cally-based equations that take account of the force exerted by a musc le and the rate at which it is shortening are used to estimate the met abolic energy cost of the oscillation. The maximum shortening speed (v (max)) of the muscles and the elastic compliance of their tendons are varied to find the optimum combination that minimizes metabolic cost. If hydrodynamic forces predominate (as in swimming), the cost is highl y sensitive to muscle speed (which should be relatively high) but less sensitive to compliance. If inertial forces predominate (as in runnin g) the cost is highly sensitive to tendon compliance, and less sensiti ve to muscle speed (which should preferably be low). The muscles that power the locomotion of various animals are discussed in the light of these conclusions. (C) 1997 Academic Press Limited.