Abstract: The present disclosure relates to a method for preparing a Gynostemma pentaphyllum leaf extract, a Gynostemma pentaphyllum leaf extract prepared by the method, and a composition for improving exercise performance capacity containing the same as an active ingredient. The Gynostemma pentaphyllum leaf extract according to the present disclosure exhibits superior effect of improving exercise performance capacity and enhancing muscle strength, endurance and physical strength. In addition, the Gynostemma pentaphyllum leaf extract according to the present disclosure has the efficacy of increasing AMPK activity, facilitating beta oxidation and facilitating glucose uptake and, thus, has superior effect of reducing body weight and body fat and preventing, alleviating or treating diabetes. Because the composition of the present disclosure is derived from a natural product, it can be used usefully and safely for drugs, foods, etc. without side effects.