Journal of Applied Physiology, Vol 62, Issue 3 1097-1110, Copyright © 1987 by American Physiological Society

ARTICLES

Adaptation of the left ventricle to exercise-induced hypertrophy

F. C. White, M. D. McKirnan, E. A. Breisch, B. D. Guth, Y. M. Liu and C. M. Bloor

Cardiac functional and structural adaptations to exercise-induced hypertrophy were studied in 68 pigs. Pigs were exercise trained on a treadmill for 10 wk. Sequential measurements were made of cardiac dimensions, [left ventricular end-diastolic diameter (EDD), changes in diameter (delta D%), wall thickness (WTh), wall thickening (WTh%), left ventricular pressure (LVP), time derivative of pressure (dP/dt), stroke volume, total body O2 consumption (VO2), blood gases, and systemic hemodynamics] at rest and during moderate and severe exercise. Postmortem studies included morphometric measurements of capillary density, arteriolar density, mitochondria, and myofibrils. All of the exercise-trained pigs showed significant increases in aerobic capacity. Maximum O2 consumption (VO2 max) increased by 37.5% in group 1 (moderate exercise training) and 34% in group 3 (heavy exercise training). Cardiac hypertrophy ranged from less than 15% in a group (n = 8) subjected to moderate exercise training to greater than 30% in a group (n = 11) subjected to heavy exercise training. Before training, exercise was characterized by a decreasing EDD during progressive exercise; this was reversed after exercise training. Stroke volume and end-diastolic volumes during exercise showed a highly significant increase after exercise training and hypertrophy. Morphometric measurements showed that mitochondria and cell membranes increased with increasing myocyte growth in all exercise groups, but there was only a partially compensated adaptation of capillary proliferation. Arteriolar number and length increased in all exercise groups. Intrinsic contractility as measured by delta D%, WTh%, or left ventricular dP/dt did not increase with exercise training and in some instances decreased. Therefore, left ventricular adaptation to strenuous exercise in the pig heart is primarily one of changes in left ventricular dimensions and a compensated hypertrophy. Exercise-induced increases in EDD and stroke volume can be accounted for by decreases in peripheral resistance and increased cardiac dimensions.

This article has been cited by other articles:

				P. J. Schaeffer, A. R. Wende, C. J. Magee, J. R. Neilson, T. C. Leone, F. Chen, and D. P. Kelly Calcineurin and Calcium/Calmodulin-dependent Protein Kinase Activate Distinct Metabolic Gene Regulatory Programs in Cardiac Muscle J. Biol. Chem., September 17, 2004; 279(38): 39593 - 39603. [Abstract] [Full Text] [PDF]

				R. Van Kerckhoven, R. van Veghel, P. R Saxena, and R. G Schoemaker Pharmacological therapy can increase capillary density in post-infarction remodeled rat hearts Cardiovasc Res, February 15, 2004; 61(3): 620 - 629. [Abstract] [Full Text] [PDF]

				H. Jin, R. Yang, W. Li, H. Lu, A. M. Ryan, A. K. Ogasawara, J. Van Peborgh, and N. F. Paoni Effects of exercise training on cardiac function, gene expression, and apoptosis in rats Am J Physiol Heart Circ Physiol, December 1, 2000; 279(6): H2994 - H3002. [Abstract] [Full Text] [PDF]

				F. C. White, C. M. Bloor, M. D. McKirnan, and S. M. Carroll Exercise training in swine promotes growth of arteriolar bed and capillary angiogenesis in heart J Appl Physiol, September 1, 1998; 85(3): 1160 - 1168. [Abstract] [Full Text] [PDF]

				R. M. McAllister, B. L. Reiter, J. F. Amann, and M. H. Laughlin Skeletal muscle biochemical adaptations to exercise training in miniature swine J Appl Physiol, June 1, 1997; 82(6): 1862 - 1868. [Abstract] [Full Text] [PDF]