Force generation and relaxation at the sarcomere level

Sarcomeres are modeled by parallel and series arrangements of thick (myosin) and thin (actin) filaments whose masses are considered. Contractile force is generated by viscoelastic crossbridge bonds which link the filaments. If bond formation is not perfectly synchronous throughout the sarcomere, small movements of thick with respect to thin filaments result. Such movements lead to bond detachment hence muscle relaxation is proposed to be a mechanism intrinsic to muscle structure and activation mode.<>