The effects of Canavalia gladiata ethanolic extract on endurance swimming capacity were evaluated in a mouse model. The mice were orally administered distilled water (CON), hot water extract (CGW), or 80% ethanol extract (CGE). The swimming time to exhaustion was significantly prolonged in the CGE group. Of the three groups, the CGE showed the lowest blood lactate and the highest nonesterified fatty acid and muscle glycogen levels. These results suggest that the administration of CGE could improve endurance swimming capacity by enhancing lipid catabolism and thereby preserving glycogen stores.