Fig 9. Model of the half-sarcomere.

(a) Individual cross-bridges are linearly elastic elements that pass through three states: two attached states (A₁ and A₂) and a detached state (D). The transition from A₂ to D is irreversible, and the transition from A₁ to A₂ corresponds to the powerstroke. (b) Model of the half-sarcomere. The half-sarcomere was modeled as a cross-bridge element (CE), consisting of cross-bridges attached in parallel, which is in series with the series element (SE), which represents the myofilament compliance.