The article aims to study changes in the longitudinal electrical resistivity of muscle in the process of contraction. A two-layer mathematical model was proposed to calculate the longitudinal electrical resistivity, which implies the division of tissues of the forearm area into two layers - skin with resistivity ρ1 and thickness h, and muscle with resistivity ρ2. The inverse problem was solved at different depths of electrode system attachment, for which a laboratory complex was designed, requirements to electrode systems - to their design, location, quantity and accuracy of manufacturing - were presented and justified. A new approach of experimental-theoretical determination of layer parameters using the controlled movement of the electrode system was proposed and tested. Electrical impedance was measured in the state of relaxation and after the subjects performed an action with different positioning of the electrode system on 3 healthy volunteers. An example of the study on a healthy female volunteer, 23 years old is described. The data obtained can be used in proprioceptive control systems for increasing the reliability of action type recognition when using electrical impedance myography as a control signal.