Exercise science and health-enhancing physical activity.

The objective of this special issue of the "Journal of Sports Sciences," is to critically review the scientific evidence underpinning health enhancing physical activity (HEPA) as a public health intervention in Great Britain. In so doing, it is hoped that the special issue will help define future research agendas, inform NHS policy on health-enhancing physical activity and promote the development of evidence-based practice. The issue is divided into two parts and is made up of six commissioned papers for which the authors were asked to write against specific briefs. While the managerial instincts disposed the author to a rigorous enforcement of the briefs issued for both part one and two of this special issue, as the project unfolded that he was persuaded to give the authors a freer hand largely because of the quality of the work they produced and because they, quite correctly, followed where the literature took them.