Elliott AD, et al. - Considering that atrial remodeling, vagal tone, and atrial ectopic triggers are thought to contribute to increased incidence of atrial fibrillation (AF) in endurance athletes, researchers theorized that atrial remodeling occurs in proportion to total training history, thus contributing to elevated risk of AF. In 99 recreational endurance athletes, subsequently grouped according to lifetime training hours, they assessed the atrial size, autonomic modulation, and atrial ectopy. Study participants exhibited left atrial dilation in the absence of increased vagal parameters or atrial ectopy, which may promote incidence of AF in recreational endurance athletes, in relation to increased lifetime training.