Retrospective case-control studies and case series of younger athletes and middle-aged adults have suggested an adverse association between physical activity and development of atrial fibrillation. However, these studies have evaluated subjects engaged in either vigorous exertion or endurance training. On the other hand, habitual physical activity might be expected through salutatory effects on blood pressure, vascular compliance, coronary disease, and heart failure to reduce the incidence of atrial fibrillation in the general population. The aim of this study was to assess the effect of habitual light to moderate physical activity on the incidence of atrial fibrillation among older adults.