An Olympic year brings intensified interest in sport and exercise,1 with the anticipation of competitors reaching new feats of athletic performance. But what recent progress has been made in the field of physical activity and health research? The last 50 years or so of epidemiological research in physical activity have provided strong evidence for the beneficial effects of physical activity on a range of health outcomes. The promotion of physical activity for health is supported by at least 39 different disease-specific clinical guidelines,2 including the National Institute for Health and Clinical Excellence. However, there remain several clinically relevant and interrelated issues in the field that have been the topic of much research and debate in recent years; these include, but are not limited to defining the minimal dose of physical activity required for health benefit; investigating the emerging role of sedentary behaviour in the physical activity—health area; developing interventions to effectively promote habitual physical activity in the general population.

One of the most significant developments in the field over the last decade has been the introduction of small solid-state accelerometer devices that now permit physical activity to be assessed objectively over several days at low cost, thus making it is feasible to incorporate such measures in large-scale population studies, such as the National Health and Nutrition Examination Survey and …