From Physiological to Potential Cardiovascular Maladaptation in Endurance Exercise

Emerging evidence suggests that the cardiovascular benefits of exercise may not increase indefinitely with training volume and intensity. As participation in ultraendurance sports continues to rise, concerns have been raised regarding the potential adverse cardiovascular effects of exposure to extreme or ultraendurance exercise. In this Review, we synthesize the current evidence and the pathophysiology regarding the structural, functional, and electrical cardiovascular maladaptations to endurance exercise and highlight the clinical implications of these changes. Several evidences demonstrate that extreme exertion can induce transient cardiac dysfunction; when sustained over years, it may contribute to myocardial fibrosis and associated arrhythmic events. Endurance athletes frequently exhibit a higher prevalence of coronary artery calcification, atherosclerotic plaque burden, and increased arterial stiffness. The alteration driven by long-term endurance training is also strongly implicated in the higher incidence of atrial fibrillation. Although definitive long-term outcomes remain debated, the assumption that limitless exercise yields exclusively protective cardiovascular effects might no longer seem prudent. While regular exercise is unequivocally cardioprotective, extreme endurance training may cross a threshold from physiological adaptation to potential maladaptation. Understanding the pathophysiological mechanisms of exercise-induced cardiac remodeling is critical to optimize the benefit of exercise and the potential risk associated with exercise.