We have measured tension transients from tetanically stimulated intact single fibres of the M. lumbricalus and the M. tibialis anterior of the frog. The measurements were carried out between 5.5 and 7°C at a sarcomere length of 2.1 and 3.1 μm with a dsiplacement servo system capable of performing displacements of 50 μm in 40 μs. We found a very fast recovery process in the tension transients thus obtained and quantified the speed of the observed recovery process in terms of elasticity and damping.
If a ramp-shaped input signal of 150 μs duration is applied to the system, the velocity is constant over about 100 μs. This property of the system enables us to study the velocity-dependent part of the initial drop in tension in more detail. The first part of the tension transients thus obtained, show three phases: an initial rapid drop in tension, a slower steady decrease in tension and a rapid recovery (30 μs).