ИСТИНА

The model of muscle fiber contraction developed at the Institute of Mechanics of Moscow State University was used to describe the work of skeletal muscles when the body is tilted. The model takes into account that muscle force is produced by myosin crossbridges interacting with the actin filaments in muscle myofibrils. The input of the model is the rate of inflow of calcium ions into muscle cells, which is assumed to be proportional to the potential of motor neurons. The description of muscle force was based on an averaging over the ensemble of motor units. To verify the model, we used the results of a test, in which a person inclined his/her body by changing the angle in the ankle joint.The readings of the force plate and the myogram of the gastrocnemius, soleus, and tibialis anterior muscles were recorded simultaneously. Averaged myogram signals were used as the input to the model. Numerical integration made it possible to estimate the value of the angle of inclination of the human body. The parameters of the model of muscle contraction providing the smallest discrepancy between the calculated and experimental data were chosen.