An Assessment of Training Characteristics Associated with Atrial Fibrillation in Masters Runners

Abstract

A growing body of literature supports an association between long-term endurance exercise and the development of atrial fibrillation (AF). Given the benefits of lifelong exercise, a better understanding of this association is critical to allow healthcare providers to counsel aging exercisers on the proper “dose” of exercise to maximize health benefits but minimize AF risk. The current study examines the relationship between specific aspects of training volume and intensity and the occurrence of AF among older runners in order to better understand what aspects of endurance exercise may contribute to the development of AF. The study was an Internet-based survey of endurance training and health characteristics of runners 35 years of age and older. A total 2819 runners participated and 69 (2.4%) reported a current or prior diagnosis of AF. Among “traditional” risk factors, runners reporting AF were older, more likely to be male, and had higher rates of hypertension and diabetes. Among training characteristics, only accumulated years of training was associated with AF. In contrast, average weekly mileage, training pace, and days of training per week were not associated with AF. In a multivariable analysis that included chronologic age, sex, diabetes, and hypertension, accumulated years of training remained significantly associated with the report of AF. These findings suggest that the relationship between chronic endurance exercise and AF is dependent on the accumulated training duration but does not appear to be influenced by specific training characteristics such as frequency or intensity of endurance exercise. Further confirmation of these relationships may help healthcare providers counsel exercisers on optimal training habits and identify endurance athletes who are at risk for the development of AF.

Could Repeated Cardio-Renal Injury Trigger Late Cardiovascular Sequelae in Extreme Endurance Athletes?

“…In this study the adjusted odds ratios per 10 years of regular endurance exercise were 1.16 (95% CI 1.06-1.29) for AF and 1.42 (1.20-1.69) for atrial flutter [102]. A recent study [103] focused on the potential impact of training characteristics on atrial arrhythmias in long-term endurance athletes. Based on multivariable analysis (adjusted for age), these authors identified accumulated training duration, but not specific training characteristics like frequency or intensity of endurance exercise, as the only significant predictor of AF [103].…”

“…A recent study [103] focused on the potential impact of training characteristics on atrial arrhythmias in long-term endurance athletes. Based on multivariable analysis (adjusted for age), these authors identified accumulated training duration, but not specific training characteristics like frequency or intensity of endurance exercise, as the only significant predictor of AF [103]. AF was present in 14% of athletes reporting 0-10 years of running and in 44% of those reporting more than 30 years of running [103].…”

“…Based on multivariable analysis (adjusted for age), these authors identified accumulated training duration, but not specific training characteristics like frequency or intensity of endurance exercise, as the only significant predictor of AF [103]. AF was present in 14% of athletes reporting 0-10 years of running and in 44% of those reporting more than 30 years of running [103]. On the other hand, insufficient training may also increase the risk for cardiac dysfunction and injury, for example after the completion of a marathon [94].…”

“…While those observations indicate a co-occurrence of and some interrelation between cardiac and kidney injury markers, they do not provide a strong link to permanent damage. However, the existence of such a link cannot be totally dismissed, due to the known adverse cardiac consequences of AKI [12] and the elevated risk of AF or atrial flutter in some life-long endurance athletes [102,103].…”

“…Despite the indisputable beneficial consequences of regular exercise, a small number of predominantly male and older long-term endurance athletes have an increased risk of certain CVDs, i.e., myocardial fibrosis, coronary artery calcification, and associated cardiac arrhythmias (e.g., AF, atrial flutter, and ventricular ectopy)], for insufficiently understood reasons [66,99,100,102,103]. Some of these events are likely related to subtle pre-existing comorbidities, but an unfavorable interplay between repeated (over years)] cardiac and renal injuries related to chronic EEE and incomplete recovery is plausible [38,100].…”