Physical Activity, Resting Heart Rate, and Atrial Fibrillation

Study Questions:

What is the relationship between exercise, resting heart rate, and atrial fibrillation (AF)?

Methods:

The subjects of this study were 20,484 adults (mean age 38 years) who participated in a survey in Norway in 1986-1987. Physical activity was assessed with a detailed questionnaire and resting heart rate (RHR) was measured. The individuals then were followed for a mean of 20 years. Individuals who developed AF were identified on the basis of a hospital-based diagnosis.

Results:

AF was diagnosed in 750 individuals during follow-up. The AF incidence was 2.62/1,000 person-years in men and 1.07/1,000 person-years in women. In a multivariate analysis, moderate activity (walking, cycling, or other exercise for ≥4 hours/week) was independently associated with a 19% lower risk of AF compared to low activity. The risk of AF associated with high activity or vigorous activity (intense training or competition several times/week) did not differ significantly from the risk in low-activity individuals. There was a weak but significant inverse relationship between physical activity and RHR. The risk of AF decreased by 8% for every 10 bpm increase in RHR.

Conclusions:

The authors concluded that moderate exercise reduces the risk of AF and a low RHR increases the risk of AF.

Perspective:

The finding that a low RHR heightens the risk of AF suggests that the increase in baseline vagal tone associated with vigorous exercise may play a role in attenuating or eliminating the protective effects of moderate exercise on the development of AF.


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