The study of the electromechanical activity of the heart through computational models is important for the interpretation of several cardiac phenomena. However, computational models for this purpose can be computationally expensive. In this work, we present the simplified models at the cellular level which were able to qualitatively reproduce the cardiac electromechanical activity based on the contraction of myocytes. To create these models a parameter adjustment was performed via genetic algorithms. The proposed models with adjusted parameters presented satisfactory results for the reproduction of the active force of the heart with the advantage of being based on only two ordinary differential equations.