This study observed the changes of the glycogen content in extensor digitorum and soleus by electrical stimulation on the sciatic nerve with various frequencies, and the result were compared with those of treadmill running exercise. The results are summarized as follows ; The glycogen content of extensor digitorum longus was greater than that of the soleus in the normal group, and the reducing amount of glycogen content of extensor digitorum longus was greater than that of the soleus by overnight fasting. As the frepuency of electrical stimulation was increased by 2, 5 and 10Hz., the glycogen content of the extensor digitorum longus was slightly reduced or changed minimally. As the loading period of clectrical stimulation was increased to 30 and 90minutes, the glycogen content of extensor digitorum longus was much reduced from early stage, and that of the soleus was the same tendency as the frepuency increased. The glycogen content of the extensor digitorum longus was proportionally reduced by treadmill running excercise, and that of the soleus was much reduced from the early stage. In summary, based on the experimental evidence of this investigation, it showed the different physio-chemical responses of th fast and slow twitch muscle fibers by electrical stimulation, and also not the equal responses of muscle fibers by electrical stimulation and treadmill running exercise.