Purpose: Monocarboxylates such lactate, pyruvate and the ketone bodies play major in metabolism and MCT 1 is present in the plasma membranes of skeletal muscle. The purpose of this study was to examine the effect of short-term swimming exercise training on lactate levels, MCT 1 contents and circulating ketone bodies in rat skeletal muscle. Methods: Male Sprague-Dawley rats (N = 32) were performed swimming exercise training for 60 minute/day and 7 days/week, for 3 weeks. Lactate in rat skeletal muscle was measured immediately after (IA, n = 8), and MCT 1 protein in soleus muscle, extensor digitorum longus muscle and liver were measured before exercise (pre, n = 8), after 7 days (7D, n = 8) and 21 days (21D, n = 8). In glucocorticoid administration, Male Sprague-Dawley rats (N = 14) were assigned to administration group (AG, n = 7) and control group (CON, n = 7). Administration group was subcutaneous injected prednisolone acetate (2 mg/kg) and normal saline in control group, for 4 days, and then MCT 1 protein and blood ketone bodies were measured after injections. Results: Lactate concentration in soleus muscle and extensor digitorum longus muscle were significantly increased immediately after of swimming exercise training compared with before exercise (p = .005, p = .008 respectively). MCT 1 protein in soleus muscle, extensor digitorum longus muscle were significantly increased after both 7 and 21 days of swimming exercise training compared with before exercise (p = .032, p=.005; p = .037, p = .028 respectively), and MCT 1 protein in liver was significantly increased after 21 days of swimming exercise training (p = .037). In glucocorticoid administration, MCT 1 protein in liver and blood ketone bodies concentration were significantly increased in the administration group than in the control group (p = .027, p = .021 respectively). Conclusion: These results suggest that product of intracellular endogenous monocarboxylic and proton induces MCT 1 in the skeletal muscle and liver during short-term swimming exercise training.