We present a model for mechanical activation of the
cardiac tissue depending on the evolution of the
transmembrane electrical potential and certain
gating/ionic variables that are available in most of
electrophysiological descriptions of the cardiac
membrane. The basic idea consists in adding to the chosen
ionic model one ordinary differential equation for the
kinetics of the mechanical activation function. A
relevant example illustrates the desired properties of
the proposed model, such as delayed muscle contraction
and correct magnitude of the muscle fibers' shortening.