Promoting physical activity among the entire population has clearly become a public health priority. This initiative took concrete form in 2004 with the launch of a campaign to combat sedentary lifestyles. It is reaffirmed in the strategic priorities of the 2011–2015 National Nutrition and Health Program. The 2008 Inserm report highlighted the beneficial effects of regular physical activity on health and the reduction of the risk of developing chronic diseases (certain cancers, cardiovascular diseases, type 2 diabetes, etc.). The concept of physical activity is, however, quite ambiguous and does not carry the same meanings depending on whether it is used in scientific or lay contexts. This seriously complicates the measurement of physical activity and requires that questionnaires and tools precisely define its various aspects. In its current physiological sense, the term "physical activity" is very broad and includes "all bodily movements that result in an increase in energy expenditure above resting levels."