Bitter melon (Momordica charantia) is used in traditional herbal medicine in many Asian countries for the treatment of several diseases such as diabetes, eczema, night blindness, psoriasis, and rheumatism. Especially, most reports concerning the biological activities of bitter melon have focused on its effects on diabetes and hyperglycemia. Also, bitter melon is regarded as a longevity food, suggesting that it has several beneficial effects on anti-aging and the maintenance of a healthy state. Thus, we investigated whether bitter melon could increase the capacity of exercise in this study. Interestingly, bitter melon fruit extract activated AMP-activated protein kinase (AMPK), which is important for regulating glucose homeostasis, mitochondrial content and exercise capacity. In addition, bitter melon extract increased the expression of enzymes involved in fatty acid oxidation such as mitochondrial uncoupling protein 3 (UCP3), carnitine palmitoyl transferase 1b (CPT1b), and pyruvate dehydrogenase lipoamide kinase isozyme 4 (PDK4). Moreover, exercise tolerance was much more enhanced in bitter melon treated animals compared to the non-treated control group. These results suggest that bitter melon is a promising candidate for the development of functional foods beneficial for physical strength and the enhancement of exercise capacity.