Strenuous Endurance Exercise and the Heart: Physiological versus Pathological Adaptations

Abstract

Although the benefits of regular physical activity on cardiovascular health are well established, the effects of strenuous endurance exercise (SEE) have been a matter of debate since ancient times. In this article, we aim to provide a balanced overview of what is known about SEE and the heart-from epidemiological evidence to recent cardiac imaging findings. Lifelong SEE is overall cardioprotective, with endurance master athletes showing in fact a youthful heart. Yet, some lines of research remain open, such as the need to elucidate the time-course and potential relevance of transient declines in heart function (or increases in biomarkers of cardiac injury) with SEE. The underlying mechanisms and clinical relevance of SEE-associated atrial fibrillation, myocardial fibrosis, or high coronary artery calcium scores also remain to be elucidated.

Myocardial Fibrosis and Coronary Calcifications Caused by Endurance Exercise? Insights from Former Professional Cyclists

“…T he benefits of regular physical activity (PA; e.g., walking or brisk walking) on cardiovascular risk and mortality are irrefutable (1), with growing evidence for an inverse dose-response association (2,3). However, concerns exist as to whether long-term exposure to strenuous endurance exercise (SEE), especially at the competition level (e.g., marathon running, cross-country skiing, cycling) could induce some deleterious cardiac effects (4)(5)(6). At the morphological level, these would include mainly an increased risk of myocardial fibrosis and coronary calcification (7).…”

Aortic Diameters and Calcifications in Former World-Class Cyclists

“…In this regard, some evidence suggests that aortic calcifications are positively associated with cardiovascular risk, but this association disappears when adjusting for coronary calcifications (14). In addition, it remains unclear whether calcifications translate into a higher risk in athletes (1,29). Notwithstanding, given the association reported by previous studies between thoracic aorta calcifications and cardiovascular events in the general population (33) (with this association being potentially independent of coronary calcifications, at least in women) (13), future research should confirm the clinical relevance of our findings.…”

“…espite traditionally receiving less attention than changes in cardiac dimensions (i.e., the so-called athlete's heart) (1), aortic remodeling can also occur in athletes, as they usually show larger aortic root diameters than the general population (2). Controversy exists, however, on the prevalence of clinically relevant aortic dilatation (conventionally defined as diameters ≥40 mm for male athletes) (3), with this condition being infrequent (~1%) in young athletes (mean age, 19-25 yr) (4)(5)(6) but not in their master peers (i.e., 21%-30% in those age 57-71 yr) (7,8).…”

“…Another matter of concern in sports cardiology is vascular calcifications, particularly in the coronary arteries of veteran athletes (1,12). However, to the best of our knowledge, no evidence on the prevalence of aortic calcifications in athletes exists.…”