Mathematical model of muscular fatigue. II. Changes of metabolites level and of force during exercise in relation to a fatigability parameter.

In order to study muscular fatigue, a mathematical model allowing the simulation of changes of metabolites level and of force during exercise in human muscle is built. It results from the association of two previous models and from the introduction of two parameters (pH and ATP concentration) influencing directly the muscular force and of the fatigability parameter (A) which characterizes the oxidative capacity of a given fibre. Simulations of physiological conditions of exercise and recovery allow one to bring out a classification of muscular fibres in terms of the fatigability parameter. In addition, the study of successive exercises underlines the lactate level role in force generation. Computations have been carried out on a computer DPS 7.