(HealthDay News) – Excessive endurance training may induce adverse cardiovascular remodeling in some individuals.

James H. O’Keefe, MD, from Saint Luke’s Hospital of Kansas City in Missouri, and colleagues reviewed the literature to investigate the potential adverse cardiovascular effects of excessive endurance training.

The investigators found that transient acute volume overload of the atria and right ventricle may be triggered by chronic training for and competing in endurance events. This overload was associated with transient reductions in right ventricular ejection fractions and increases in cardiac biomarkers, all of which returned to normal within one week. In some individuals, this process of repetitive injury over months to years appeared to trigger patchy myocardial fibrosis, especially in the atria, interventricular septum, and right ventricle, creating a substrate for atrial and ventricular arrhythmias. In addition, long-term excessive endurance exercise was linked with coronary artery calcification, diastolic dysfunction, and large-artery wall stiffening, although there was some inconsistency in the literature. The authors further note that low mortality rates and excellent functional capacity were often seen in lifelong vigorous exercisers.

“For now, on the basis of animal and human data, cardiovascular benefits of vigorous aerobic exercise training appear to accrue in a dose-dependent fashion up to about one hour daily, beyond which further exertion produces diminishing returns and may even cause adverse cardiovascular effects in some individuals,” the authors write.

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