Journal of Applied Physiology, Vol 52, Issue 6 1648-1651, Copyright © 1982 by American Physiological Society
Effect of habitual exercise on left ventricular response to exercise
J. D. Anholm, C. Foster, J. Carpenter, M. L. Pollock, C. K. Hellman and D. H. Schmidt
To evaluate the effects of chronic physical exercise on left ventricular
ejection fraction (LVEF) and ejection rate (LVER), radionuclide angiography
was performed at rest and during upright-bicycle exercise in 45 healthy
men. The subjects varied widely in exercise habits and working capacity.
They were divided into three subgroups on the basis of habitual physical
activity. Aerobic training was done more than 7, 2-4, and less than 1 h/wk
by subgroups of athletes, trained, and untrained men, respectively. The
results indicate marked differences in work capacity (298, 233, and 181 W
in the athletes, trained, and untrained groups, respectively). Resting LVEF
(72, 69, and 68%) and LVER (4.1, 3.4, and 3.6 s-1) were not significantly
different among the groups. With maximal exercise, however, small but
statistically significant differences in LVEF (75, 69, and 68%; P less than
0.05 athletes vs. trained and athletes vs. untrained) and in LVER (7.5,
6.3, and 5.2 s-1; P less than 0.05 among all groups) were observed. Work
capacity was, however, poorly correlated with exercise LVEF (r = 0.18) and
LVER (r = 0.47). The results of this study indicate that the enhanced
working capacity observed secondary to increases in habitual physical
activity can be attributed to differences in LVEF and LVER only in the most
general terms. Accordingly the results agree with previous suggestions
based primarily on echocardiographic data that the primary cardiac
adaptation to exercise is dimensional rather than functional in character.
