Sedentary behavior: target for change, challenge to assess.

Sedentary behavior is not a new topic, but trying to examine the direct links between sedentary behavior and health outcomes, independent of time spent in moderate- and vigorous-intensity physical activity, is a relatively new addition to the relationships between physical activity and health. Defining sedentary behavior as a risk factor and target for intervention opens up novel avenues for disease prevention and health promotion. The relationship between sedentary behavior and obesity is complex and not well understood, but the increased risk of disease due to sedentary behavior may be even greater in obese patients. Objective measurement of sedentary behavior is an important link in being able to understand the real effects of being sedentary, and a few measurement devices are described. Interventions targeting sedentary behavior should reduce total sedentary time, break long bouts of sitting with intermittent activity and encourage light-intensity activity throughout the day. New technologies can both measure and deliver an intervention aimed at reducing sitting time, the most common category of sedentary behavior. An optimal activity profile will include minimal amounts of sedentary behavior, in addition to regular physical activity and healthy sleep patterns.