The Ascending Aortic Function In Elite Endurance Athletes: An Mri Study

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High-intensity chronic endurance training has chronotropic and inotropic effects on the heart; however, adaptations of the ascending aorta which is directly exposed to cardiac pulsations remain unclear. PURPOSE: We investigated the functional and structural properties of the thoracic aorta, including the ascending and descending locations, in elite endurance athletes. METHODS: Fourteen young endurance-trained men (21±1 years, peak oxygen uptake=69.6±3.1 ml/kg/min) were compared with 19 sedentary control men (21±2 years). The ascending and descending aortic cross-sectional areas were measured by 2D CINE phase-contrast magnetic resonance imaging (MRI), and the aortic strain, compliance, and distensibility were calculated. Aortic blood pressure was measured during MRI using the general transfer function method. Two-way mixed analysis of variance was used to determine the effects of exercise status and aortic locations. RESULTS: Endurance athletes had similar body mass index and aortic blood pressures to sedentary control subjects. At rest, heart rate was slower (58±9 vs. 48±5 bpm, P=0.001) and stroke volume was greater in athletes (82.1±10.8 vs. 95.8±18.5 ml/beat, P=0.012) while cardiac output was similar between the groups. The systolic aortic cross-sectional areas were increased in athletes compared with sedentary subjects (ascending: 6.32±0.99 vs. 6.95±1.00 cm2, descending: 4.08±0.64 vs. 4.85±0.83 cm2, P=0.012). The diastolic aortic areas (P=0.062) and the aortic compliances (P=0.069) showed a trend of elevations in athletes. The greater ascending aortic strain and compliance were associated with slower heart rate (r=-0.56 and -0.43 respectively) and higher stroke volume (r=0.44 and 0.35 respectively) across all participants (all P<0.05). CONCLUSIONS: Our findings suggest that endurance athletes have dilated thoracic aorta and better recoiling function of the ascending aorta due to increased systolic expansion and a longer time of relaxation with slower heart rate. This study was supported by the JSPS (19K19970, TT) and the ARIHHP Cooperative Grant (University of Tsukuba, TT)