Endurance exercise training attenuates natriuretic peptide release during maximal effort exercise: biochemical correlates of the "athlete's heart".

Endurance exercise training (ET) stimulates eccentric left ventricular hypertrophy (LVH) with left atrial dilation. To date, the biochemical correlates of exercise-induced cardiac remodeling (EICR) remain incompletely understood. Collegiate male rowers (n = 9) were studied with echocardiography and maximal-effort cardiopulmonary exercise testing (MECPET) before and after 90 days of ET intensification. Midregional proatrial natriuretic peptide (MR-proANP), NH2-terminal pro B-type natriuretic peptide (NT-proBNP), and high-sensitivity troponin T were measured at rest, peak MECPET, and 60 min post-MECPET at both study time points. Endurance exercise training resulted in eccentric LVH (LV mass = 102 ± 8 vs. 110 ± 11 g/m2, P = 0.001; relative wall thickness = 0.36 ± 0.04 vs. 0.37 ± 0.04, P = 0.103), left atrial dilation (74 ± 18 vs. 84 ± 15 ml, P < 0.001), and increased exercise capacity (peak V̇o2 = 53.0 ± 5.9 vs. 67.3 ± 8.2 ml·kg-1·min-1, P < 0.001). Left ventricular remodeling was characterized by an ~7% increase in LV wall thickness but only a 3% increase in LV chamber radius. The magnitude of natriuretic peptide release, examined as percent change from rest to peak exercise, was significantly lower for both MR-proANP (115 [95,127]% vs. 78 [59,87]%, P = 0.04) and NT-proBNP (46 [31,70]% vs. 27 [25,37]%, P = 0.02) after ET. Rowing-based ET and corollary EICR appear to result in an attenuated natriuretic peptide response to maximal effort exercise. This may occur as a function of decreased cardiac wall stress after ET as seen by disproportionally higher ventricular wall thickening compared with chamber dilation.NEW & NOTEWORTHY Using longitudinal pre- and postendurance training natriuretic peptide measurements, we demonstrate that the development of exercise-induced cardiac remodeling results in an attenuated natriuretic peptide response to acute bouts of maximal intensity exercise. Exercise-induced cardiac remodeling was associated with a disproportionally higher ventricular wall thickening compared with chamber dilation, a pattern that reduces cardiac wall stress. These observations advance our understanding of both the structural and biochemical adaptations that underlie the cardiovascular response to endurance training.