The computational model with internal crossbridge dynamics and detachment rate decreasing with crossbridge force accurately reproduces Hill's 1938 muscle force-velocity curve and heat of shortening and fits steady-state shortening experimental data with stiffness k = 3.3 pN/nm.
A novel mathematical model of muscle crossbridge dynamics successfully reproduces classical force-velocity and heat of shortening data by incorporating internal crossbridge dynamics across two time scales.
Effect estimate: Model fits steady-state force-velocity data; crossbridge detachment rate decreases linearly with force (β(p) = α/4 (1 + 20 (1 - p/p_∞)))
Abstract We develop a crossbridge model in which an attached crossbridge behaves like a linear spring with a variable rest length. We assume in particular that the rest length has a linear force–velocity relation, and that the force and rest length are both zero at the moment of crossbridge attachment. Crossbridges that are not attached in our model have a fixed probability per unit time of attachment, and attached crossbridges have a probability per unit time of detachment that is a function of the crossbridge force. This detachment rate is uniquely determined by the requirement that a limiting form of the model should reproduce the force-velocity curve and heat of shortening discovered by A.V. Hill (A. V. Hill, The heat of shortening and the dynamic constants of muscle , Proc. Roy. Soc. Lond. B – Biol. Sci. 126 (1938), 136–195), and the detachment rate turns out to be a linearly decreasing function of the crossbridge force. The parameters of the model are determined by a fit to steady-state experimental data; and then an event-driven stochastic simulation methodology is introduced in order to study the behavior of the model in a simulated quick-release experiment. The model explains how the crossbridge can act like a linear spring on a fast time scale but have very different properties on a slower time scale.
Hua et al. (Thu,) conducted a other in Skeletal muscle crossbridges in steady state shortening and quick-release experiments as modeled by computational muscle contraction theory. Computational muscle crossbridge model with internal crossbridge dynamics and event-driven stochastic simulation vs. Existing crossbridge models without internal dynamics, e.g. Huxley model was evaluated on Force-velocity relation and heat of shortening of contracting skeletal muscle; probability of crossbridge attachment; expected force per crossbridge; mean step length of crossbridge (Model fits steady-state force-velocity data; crossbridge detachment rate decreases linearly with force (β(p) = α/4 (1 + 20 (1 - p/p_∞)))). The computational model with internal crossbridge dynamics and detachment rate decreasing with crossbridge force accurately reproduces Hill's 1938 muscle force-velocity curve and heat of shortening and fits steady-state shortening experimental data with stiffness k = 3.3 pN/nm.