Hormetic effects of reactive oxygen species by exercise: a view from animal studies for successful aging in human.

Numerous anti-aging measures have been proposed to cope with age-associated decline of physiological functions and/or onset of diseases, mostly based on free radical (or oxidative stress) theory of aging, though no robust scientific data have been reported to extend human healthspan. This is due to dual (harmful as well as essential) roles of reactive oxygen species (ROS) to a body. Regular moderate exercise provides benefits upregulating defense against oxidative stress in good balance between the opposing dual roles. Sources of ROS in exercise appear to be not only mitochondria as often claimed but also enzymatic reactions catalyzed by NADPH oxidase and other oxidases. It may, therefore, be possible to mimic this aspect of exercise to promote the defense for healthspan extension by other means such as modest alcohol consumption that could upregulate activity of enzymes against oxidative stress.