Exercise and Atrial Fibrillation: Prevention or Causation?

Regular exercise contributes to improved cardiovascular health and reduced cardiovascular mortality. Previous studies have shown that regular physical activity and high cardiorespiratory fitness both contribute to a reduction in incident atrial fibrillation (AF). However, the risk of AF appears to be paradoxically increased by participation in endurance exercise. Although the mechanisms are not well understood, exercise-induced changes in autonomic tone alongside the development of an arrhythmogenic atrial substrate, appear to contribute to an excess of AF amongst athletes, despite an overall reduction in cardiovascular disease incidence. This review will (i) summarise the evidence showing that regular physical activity and exercise reduces AF incidence, (ii) review the evidence that supports an increase in AF risk by regular endurance exercise, and (iii) discuss the mechanisms and risk factors that may contribute to AF susceptibility amongst otherwise healthy athletes.