Muscles more sensitive to stretch than previously thought

Almost 50 years after Nobel prize-winner Andrew Huxley published his seminal findings about muscle contraction, scientists from the University of Bristol have retraced Huxley's steps. Their findings, published today in the Biophysical Journal, could change our understanding of the response of muscles to changes in length during physical activity. Skeletal muscle is the basic motor in the body that drives the functionality of many activities such as breathing, talking, walking, running and jumping. Muscles change length and develop force by the sliding of two kinds of filament, thick and thin. Projections on the surface of the thick filament, called crossbridges 'row' the thick filaments past the thin filament, in a cyclic manner reminiscent of the oars in a rowing boat. Huxley showed that the rowing of crossbridges on the thick filaments could explain the main properties of muscles, for example the relation between the tension it exerted and the velocity of shortening. He later established that the crossbridges act independently of one another to produce tension.