Physical activity and the prevention of cardiovascular disease: from evolution to epidemiology.

For most of human history, the environmental demands of survival necessitated prodigious amounts of physical exertion. The avoidance of predators, hunting, gathering, and the literal "chopping wood and carrying water" of daily existence provided a wholesome dose of physical activity that obviated the need for deliberate exercise. Nevertheless, 21st century humans are now immersed within an environment explicitly designed to eliminate physical labor. Over the past century and especially the past 50 years, an accrual of epidemiological evidence has established that the unintended consequence of humankind's predilection for labor-saving contrivances is an epidemic of hypokinetically induced cardiovascular disease, morbidity, and mortality. This review surveys data from observational studies supporting the premise that physical activity, exercise training, and improvements in cardiorespiratory fitness are essential elements in the prevention and treatment of the cardiovascular diseases induced by an environment in which survival no longer obligates physical exertion.