Effect of stretching on the elastic characteristics and the contractile component of frog striated muscle

1. The force—velocity relationship and the stress—strain curve of the so‐called series elastic component (s.e.c.) of frog sartorius, semitendinosus and gastrocnemius have been determined during shortening against a given force (isotonic quick‐release) and at high speed (controlled release): (a) from a state of isometric contraction and (b) after stretching of the contracted muscle. In both cases the muscle was released from the same length: this was usually slightly greater than the muscle's resting length.