The biological basis of physical activity.

Successful efforts to improve levels of physical activity in the population are contingent upon an accurate understanding of the determinants of habitual activity. While most research has focused on psychosocial and environmental influences, the potential effect of intrinsic biological control on regular activity has received little attention. This review examines evidence for the existence of such central control, offers a rationale for its function, and suggests implications for preventive health strategies resulting from a biological contribution to habitual activity levels.