Prediction of Tetanic Force of Muscle Motor Units Evoked by Irregular Stimulation Patterns

The aim of the paper is to propose an approach for prediction of tetanic force of different motor units (MUs) knowing the stimulation pattern. Tetanic force curves obtained by electrophysiological experiments on 13 MUs of a rat muscle were processed. They were decomposed into a series of twitches using two own-made algorithms. The parameters of the decomposed twitches were correlated with interpulse intervals (IPIs) and the level of the force at which the successive contraction begins, i.e. MinTet. Using regression equations for prediction of these parameters, the same tetanic curves and others of the same MU, but with different stimulation patterns, were reconstructed. The reconstructed curves resembled the experimental ones much better than these obtained by summation of equal twitches with the respective stimulation patterns. It was concluded that the best predictor is MinTet. In order to obtain the same prediction approach for all MUs, for arbitrary stimulation pattern, a proper normalization has to be obtained.