Boston, MA - Leisure activities, including walking, golfing, gardening, and outside chores, appear to reduce the risk of developing atrial fibrillation (AF), a new study suggests [1]. Investigators observed that light-to-moderate physical activity was associated with significantly lower AF incidence in older adults, but the association was not significant among those who participated in high-intensity exercise.

"Greater leisure-time activity and walking were associated with graded lower incidence of AF, with progressively lower risk as both leisure-time activity and distances and paces of walking increased," write lead investigator Dr Dariush Mozaffarian (Brigham and Women's Hospital, Boston, MA) and colleagues in a study published online August 5, 2008 in Circulation. "Conversely, intensity of exercise had a U-shaped relationship with AF, with lower risk among individuals exercising with moderate, but not high, intensity."

Physical activity has been previously reported to increase the risk of AF, but only intense exercise and endurance training have been evaluated, and only in retrospective case-control studies or case series of younger athletes and middle-aged adults. Among older adults—the risk of new-onset AF is approximately 2% per year in those 65 years and older—light-to-moderate physical activity might reduce the risk of developing the arrhythmia by reducing blood pressure, lowering heart rate, or improving vascular compliance.

Using data from the Cardiovascular Health Study, Mozaffarian and colleagues prospectively investigated associations of leisure-time activity, exercise intensity, and walking habits with incident AF in 5446 adults aged 65 years and older. Investigators report that light-to-moderate leisure-time activities, which included gardening, outside chores, golfing, and dancing, were associated with a significantly lower risk of developing AF. Walking distance and walking pace were also associated with a lower risk of AF.

Investigators also examined the association between the risk of AF and exercise intensity and observed a U-shaped relationship, with moderate exercise intensity significantly associated with a lower risk of AF. "These results suggest that long-term benefits for AF risk of light-to-moderate physical activities in older adults outweigh any potentially higher risks of AF associated with the short-term activity or exercise," writes Mozaffarian and colleagues.

The investigators also evaluated the extent to which the relationships between physical activity and AF might be mediated by lower risk of preceding MI or congestive heart failure. After adjustment for these preceding events, the relationship between physical activity and incident AF was slightly attenuated, but still significant.

Mozaffarian and colleagues point out that during follow-up, 1061 new cases of AF occurred, or roughly one in five adults aged 65 years and older. This study suggests that easily achievable lifestyle habits, such as walking, gardening, and outdoor chores, can reduce this risk. The group notes that more than 25% of new cases of AF could be attributed to the absence of these moderate activities and that such activities should be further evaluated as "potential preventive measures to reduce the incidence of AF in the particularly high-risk and growing population of older adults."