The kinetics of cross-bridge attachment and detachment studied by high frequency stiffness measurements

Muscle fiber stiffness, supposedly an indication of attached cross-bridges, was measured throughout tetanic contraction and subsequent relaxation. Stiffness increased at a rate faster than the development of force during the rise of tetanic contraction and decreased more slowly than force during relaxation. One explanation for these results is that long-lived cross-bridge states may exist between attachment, force generation and detachment.