MUSCLE GLYCOGEN REPLETION AND PREEXERCISE GLYCOGEN-CONTENT - EFFECT OF CARBOHYDRATE LOADING IN RATS PREVIOUSLY FED A HIGH-FAT DIET

We have recently reported that rates of muscle glycogen repletion duri ng the early period of recovery were increased by carbohydrate (CHO) l oading in rats previously fed a high fat diet. However, the reason for this remained unanswered. The purpose of this study was to examine wh ether an increase of glycogen utilization due to an elevated pre-exerc ise glycogen store would enhance rates of glycogen repletion in muscle . Despite an equal degree of glycogen depletion, the rates of glycogen repletion of soleus, red and white gastrocnemius muscles by postexerc ise administration of glucose (3.0 g.kg(-1) body mass) and citrate (0. 5 g.kg(-1) body mass) were faster in the CHO loaded (3 days) rats than in the nonloaded rats, as a result of elevated pre-exercise glycogen content and consequently the greater glycogen utilization. The higher rate of muscle glycogen repletion may in part be explained by increase d postexercise glycogen synthase activity.