[Recommending physical activity for primary prevention of chronic diseases]

Recommending physical activity for primary prevention of chronic diseases. Low level of physical activity (i.e. inactivity) is recognized as the second preventable common risk factor of chronic diseases after the tobacco use. Nonlinear dose-effect relationships are found between the volume and intensity of physical activity, and the global mortality and incidence of chronic diseases. A sedentary behavior, characterized by prolonged periods of very low energy expenditure, is also related to the global mortality and the incidence of chronic diseases. The deleterious effects of sedentary behavior are especially marked beyond seven hours a day sitting, or three hours a day in watching the television. All the results of recent survey demonstrate that in order to reduce the incidence of chronic diseases, both physical activity recommendations and decrease in sedentary time are recommended, whatever the age of the population.