Moderate intensity regular physical activity is a mainstay of cardiovascular prevention. However, it is under debate whether the effects of intensive endurance exercise induce chronic cardiac damage. It has been proposed that long-term endurance exercise may be associated with myocardial fibrosis detected by late gadolinium-enhancement (LGE) cardiac magnetic resonance (CMR), and/or with right ventricle contractile dysfunction, but these aspects are not constantly found across studies. Extracellular volume (ECV) determined by CMR, circulating cardiac biomarkers, and longitudinal global strain (LGS) assessed by echography are relevant tools to explore these potential adverse effects of exercise.

To assess the presence of myocardial fibrosis, and to evaluate ventricles function, in endurance senior athletes.

Thirty three asymptomatic endurance senior athletes (47±6yo, 9.6±1.7h of training per week for 26±6yrs), were compared to 18 sedentary controls (49±7yo). They underwent a CMR protocol including morphological and LGE analysis, T1 mapping and calculation of ECV. A maximal exercise echography with LGS analysis was performed. Cardiac biomarkers were analysed.

Athletes had higher ventricular volumes, biventricular mass, and stroke volume assessed by CMR versus controls. Native T1 and ECV were not significantly different in athletes compared with controls. LGE was not found in athletes. Peak exercise LGS values were higher in athletes for both ventricles. The levels of cardiac biomarkers were normal in all subjects.

Athletes showed signs of physiological cardiac remodelling, consistent with previous descriptions of athlete's heart. Despite this remodelling, there was no evidence of myocardial fibrosis or exercise ventricular dysfunction in athletes. Our results are not supporting the hypothesis of deleterious cardiac effects induced by long term and intensive endurance exercise training.