Contractile properties of muscle: control by pattern of muscle activity in the rat

Abstract The denervated slow twitch rat soleus muscle was stimulated electrically for 3-6 weeks with brief trains of stimuli at 100 Hz or long trains at 10 Hz. In both cases the mean stimulation frequency was 2 Hz. Muscles stimulated at 100 Hz acquired several properties characteristic of fast muscle, whereas muscles stimulated at 10 Hz remained slow. The results demonstrate the importance of pattern of muscle activity in determining the contractile properties of muscle.