Exercise-Induced Left Ventricular Remodeling Among Competitive Athletes A Phasic Phenomenon

Background- Contemporary understanding of exercise-induced cardiac remodeling is based on cross-sectional data and relatively short duration longitudinal studies. Temporal progression of exercise-induced cardiac remodeling remains incompletely understood. Methods and Results-A longitudinal repeated-measures study design using 2-dimensional and speckle-tracking echocardiography was used to examine acute augmentation phase (AAP; 90 days) and more extended chronic maintenance phase (39 months) left ventricular (LV) structural and functional adaptations to endurance exercise training among competitive male rowers (n=12; age 18.60.5 years). LV mass was within normal limits at baseline (93 +/- 9 g/m(2)), increased after AAP (105 +/- 7 g/m(2); P=0.001), and further increased after chronic maintenance phase (113 +/- 10 g/m(2); P<0.001 for comparison to post-AAP). AAP LV hypertrophy was driven by LV dilation (LV end-diastolic volume, 9 +/- 3 mL/m(2); P=0.004) with stable LV wall thickness (LV wall thickness, 0.3 +/- 0.1 mm; P=0.63). In contrast, chronic maintenance phase LV hypertrophy was attributable to LV wall thickening ( LV wall thickness, 1.1 +/- 0.4 mm; P=0.004) with stable LV chamber volumes (LV end-diastolic volume, 1 +/- 1 mL/m(2); P=0.48). Early diastolic peak tissue velocity increased during AAP (-11.7 +/- 1.9 versus -13.6 +/- 1.3 cm/s; P<0.001) and remained similarly increased after chronic maintenance phase. Conclusions-In a small sample of competitive endurance athletes, exercise-induced cardiac remodeling follows a phasic response with increases in LV chamber size, early diastolic function, and systolic twist in an acute augmentation phase of exercise training. This is followed by a chronic phase of adaptation characterized by increasing wall thickness and regression in LV twist. Training duration is a determinant of exercise-induced cardiac remodeling and has implications for the assessment of myocardial structure and function in athletes.