Characterization of the spectrum of cardiac adaptation to endurance exercise: Impact of gender and training load

The beneficial impact of regular physical activity on cardiovascular health is well established. However, the ideal amount of exercise required to provide these benefits is not well defined, with some recent reports showing no further cardiovascular benefits and even detrimental effects when performing exercise with high training loads, particularly for endurance sports disciplines. Indeed, during the last two decades, an increasing amount of data has related high endurance training loads with an increased susceptibility for atrial arrhythmias as well as with a detrimental right ventricle remodelling. In our study, we analysed structural and functional acute changes after an endurance race at three different distances and demonstrated a dose-response relationship between endurance exercise “doses” and acute impairment in right ventricular (RV) and atrial performance without left ventricle involvement. However, high interindividual variability was observed between participants performing the same amount of exercise. We identified different patterns of RV and atrial adaptation to exercise and highlighted RV diastolic dysfunction at rest as a potential early sign of RV maladaptation to exercise. Although we could not determine if these acute RV and atrial changes induced by a bout of endurance exercise would persist or are reversible, our experimental model of long-term endurance exercise showing impairment in RV performance promoted by very high endurance training loads suggested that, independently of individual factors, there is a threshold for safe exercise, determined by both intensity and duration, beyond which cardiac adaptation might be no longer benign but become deleterious. Additionally, we observed that the RV segments showed different adaptations to exercise, with the basal segment playing the major role in increasing stroke volume during exercise but also, due to its thinner wall and bigger cavity, being more vulnerable to the exercise-induced high wall stress, compared to the RV apex. Finally, we ...