Is physical activity always good for you? The physical activity paradox.

Regular physical activity is a known protective factor for the prevention of non-communicable diseases such as cardiovascular disease, type 2 diabetes, breast, and colon cancer. Physical activity also has benefits for mental health, delays the onset of dementia, contributes to the maintenance of an adequate body weight and to general well-being. Research on physical activity has mainly focused on leisure and total time, and less on the activity in the workplace. The current guidelines actually recommend physical activity in any form and do not distinguish between the different areas, e.g. physical activity carried out during leisure time, at home or at work. However, new evidence suggests a contrast between the health effects of physical activity in leisure time vs. that in the workplace. In particular, while physical activity, even of high intensity in leisure time, has been associated with positive health outcomes, adverse consequences have been documented for physical activity in the workplace, both in terms of cardiovascular diseases, work absences due to illness and mortality from all causes. These contrasting effects of physical activity in leisure time compared to that in the workplace constitute the so-called 'physical activity paradox'.