This study investigated the effect of physical training on the utilization and recuperation of stored fuel with exercise in rats. For physical training, animals were exercised on treadmill for 30 minutes everyday. Forty eight rats were given either a physical training or no training for 4 weeks and were then subdivided into 3 groups: before-exercise (BE); during-exercise (DE); after-exercise (AE). The DE group was exercised on treadmill for 1 hour just before being sacrificed Animals in the AE group were allowed to take a rest for 2 hours after being exercised like the DE group. Glucose and free fatty acids were compared in plasma. Glycogen and triglycerides were compared in liver and skeletal muscle. Protein were compared in plasma, liver and skeletal muscle of rats. Plasma glucose levels of trained group were not significantly different from those of non-trained group. Muscle glycogen levels of trained group were significantly higher than those of non-trained group. Liver glycogen level of trained group was also significantly higher than that of non-trained group in DE while was not significantly different from those of non-trained group in BE and AF. Plasma free fatty acid levels of trained group were significantly higher than those of non-trained group in BE and AE. Muscle triglyceride levels of trained group tended to be higher than those of non-trained group in BE and DE and significantly higher than those of non-trained group in AF. Plasma and muscle protein levels of trained group were not significantly different from those of non-trained group. liver protein levels of trained group were not significantly different from those of non-trained group in BE and DE but were significantly higher than that of non-trained group in AE. Thus, it is suggested that an even moderate physical training may delay the onset of fatigue and improve exercise performance by facilitating the mobilization and oxidation of fat and conserving limited carbohydrate store.