Modification of muscle models to simulate fatigue

Fatigue of striated muscle after intense exercise of moderate duration can be separated into two distinct types, distinguishable on the basis of their recovery rates. High-frequency fatigue (HF), a decrease in force produced by high-frequency stimulation of a muscle, recovers over the course of minutes to tens of minutes. Low-frequency fatigue (LF), a decrease in twitch tension or force elicited by low-frequency stimulation, recovers only over the course of hours. Models of muscle can be altered to simulate these two types of fatigue by modifying separate mechanisms. Modeling HF fatigue requires changes in the muscle mechanics and changes in troponin-calcium kinetics. Modeling LF fatigue simply requires reduction of the amount of Ca released per twitch.<>