Biventricular Response of the Heart to Endurance Exercise Training in Previously Untrained Subjects

BACKGROUND: Functional adaptation of the heart to regular strenuous exercise has not been fully elucidated yet, with different patterns of alterations being reported. We evaluated the effect of endurance exercise training (EET) on left (LV) and right ventricular (RV) mechanics in amateur individuals preparing for triathlon competitions. METHODS: Twenty-one subjects aged 33 ± 6 years underwent conventional and speckle tracking echocardiography at rest before and after a high-intensity (12.3 ± 1.0 h/week) 12-month EET. RESULTS: At follow-up, in addition to the improvement in LV diastolic parameters, a significant decrease in longitudinal (26.0 ± 3.3% vs. 24.3 ± 3.2%, P < 0.04), circumferential (24.3 ±4.3% vs. 20.1 ± 3.8%, P < 0.002), and radial strains (46.8 ± 18.3% vs. 37.8 ± 12.9%, P < 0.03), and rotation (9.7 ± 4.8% vs. 7.1 ± 4.0 deg, P < 0.04) was demonstrated at the apex, whereas the LV base was found to show an increase in rotation (-3.9 ± 2.8% vs. -5.9 ± 1.8 deg, P < 0.01). Overall hemodynamic effectiveness of the LV was preserved, as evidenced by the unchanged ejection fraction, cardiac output, twist, and torsion. RV systolic function as assessed by strain was significantly reduced with EET (28.1 ± 6.7% vs. 23.7 ± 8.6%, P < 0.03). CONCLUSIONS: EET modifies both LV and RV performance at rest in previously untrained subjects. The true nature of these changes (adaptive or maladaptive) is unclear, but the hypothesis of different responses of the LV apex and base, with the reduction in contractility of the former and increase in rotation of the latter, representing a protective mechanism that reduces myocardial stress might be considered.