Societies and Academies

Abstract

LONDON. Royal Society, Mar. 10.—A. Levin and J. Wyman: The viscous elastic properties of muscle. ‘Viscosity’ is a term used to denote irreversible processes which cause a loss of work, greater with greater speeds, and prevent the muscle from contracting instantaneously. A mechanical model consisting of two elastic elements (springs), of which one only is damped, will imitate muscular effects, and it is argued that the muscle is mechanically a system of this type. When the muscle is stimulated isometrically, tension is shared by the damped elastic and free elastic elements. When the muscle is then released at a constant rate, the damped elements lag behind, causing thereby a drop of tension, which, however, is not instantaneous, owing to the presence of the free elastic elements. As the shortening proceeds, a steady state of lag is reached exponentially. When the release stops, the damped elements continue to shorten, stretching the free elements, and the tension redevelops exponentially. In a stretch the events occur in the opposite order. The actual contractile structures are the damped elements. The free elastic elements act as ‘buffers.’