Abstract 15384: Endurance Exercise Training Impairs the Myocardial Response to Acute Pressure Challenge
Background: Endurance exercise training (EET) imparts volume loading on the left ventricle (LV) leading to eccentric hypertrophy. The effect of exercise-induced eccentric hypertrophy on the myocardial response to the alternate hemodynamic perturbation, pressure challenge, is unknown.
Methods: Competitive male collegiate rowers (n=12) were studied with echocardiography and isometric handgrip testing (IHGT) before and after 3 months of rowing EET. IHGT, a validated laboratory-based technique to acutely increase LV afterload, was performed for 3 minutes (40% max force generation) at both study time points. Speckle-tracking echocardiography was used to assess indices of myocardial mechanics at rest and at peak IHGT.
Results: Subjects developed eccentric hypertrophy after EET (LV mass 195.1±36.5 vs. 233.1±30.8 g, p=0.006). Both before and after EET, IHGT produced significant increases in blood pressure (pre-EET: systolic, 115±7 vs. 155±13, p<0.001; diastolic, 59±5 vs. 91±18, p<0.001; post-EET: systolic, 120±8 vs. 155±16, p<0.001; diastolic, 60±5 vs. 86±10, p<0.001) and reductions in stroke volume (pre-EET: 84.0±13.7 vs. 73.3±15.2 mL, p=0.004; post-EET: 87.8±13.7 vs. 67.3±9.9, p<0.001). Compared to pre-EET IHGT, post-EET IHGT produced greater myocardial impairment (Table) characterized by larger decrements in apical rotation (-2.3±2.5 vs. -4.8±2.9 deg., p=0.04), LV torsion (-3.3±2.3 vs. -6.4±3.5 deg., p=0.05) and peak LV untwisting rate (-5.3±43.5 vs. -57.3±37.0 s-1, p=0.01).
Conclusions: EET-induced eccentric hypertrophy impairs the myocardial response to acute afterload challenge. This suggests that EET-induced hypertrophy, a volume-driven form of remodeling, may be associated with impaired myocardial response to pressure challenge. Clarifying the clinical implications of this finding and determining its relevance to other forms of cardiac remodeling (i.e. pathologic cardiomyopathies) represent important areas of future work.
- © 2011 by American Heart Association, Inc.