Ionic polymers are a promising material for the development of muscle-like actuators. These materials are capable of undergoing significant deformation when structured as metal-polymer-metal composite sheets. The mechanical characteristics of these sheets, such as flexibility, softness, and ability to undergo large deformation in direct contact with water, have led some to consider these as possible artificial muscles. This paper describes the numerical analysis of an electrochemical model of the deformation of muscle-like polymers. A general continuum model describing the transport and deformation processes of these actuators is briefly presented, along with a detailed description of the simulation scheme used to predict deformation, current, and mass transport. The predictions of the model are compared with experimental data, indicating a significant role of water transport in the large-scale deformation. The model is also used to draw a comparison between the performance of natural muscles and muscle-like polymer actuators.