Regular exercise or physical activity benefits the cardiovascular system, lowers mortality and morbidity,

and is a particularly important factor for maintaining the health of blood vessels by improving the function of

endothelial cells. Shear stress and increased metabolic rate caused by exercise induce vasodilation by generating

endothelium-derived relaxing factors (EDRF) such as nitric oxide. In addition, some studies suggest that vasodilation

is also induced by endothelium-derived hyperpolarizing factors (EDHF) and substances such as H2O2. Thus, we

undertook this study to show that reactive oxygen species such as H2O2 that have not previously been investigated

in the field of exercise science may induce vasodilation and an increase in blood pressure, and to provide

information for application in the field of exercise science. In this review, we discuss reports on H2O2 published

in the fields of basic science and exercise science while focusing on vasodilation induced by H2O2. H2O2 induces

vasodilation by simultaneously increasing endothelial NOS (eNOS) and directly activating the Ca2+- activated K+

channels of vascular smooth muscle cells. A novel study should be conducted in the field of H2O2 as a factor of

vasodilation via increased metabolic rate during exercise.