Regulation and Integration of Metabolism During Physical Activity

The survival of our ancestors was highly dependent on hunting, gathering”: and fighting, behaviors that demanded intense physical activity. A sedentary lifestyle in that environment would certainly result in the elimination of the individuals. This situation imposed a selective pressure directed to adaptations of human physiology to a high capacity of physical activity, resulting in the development of a very efficient locomotor system, in which the skeletal muscles correspond to about 40 % of the body mass and account for a great proportion of the average energy consumption of the organism. The present-day sedentarism is dissonant with the human genetic background selected to favor a physically active lifestyle and probably consists in one of the main causes of the increasing incidence of modern chronic diseases, such as hypertension, obesity, and insulin resistance.