Circulation, Vol 65, 484-488, Copyright © 1982 by American Heart Association
BZ Bar-Shlomo, MN Druck, JE Morch, G Jablonsky, JD Hilton, DH Feiglin and PR McLaughlin
Left ventricular function was compared in 18 normal sedentary controls
(mean age 28 years, range 22 - 34 years) and nine endurance-trained
athletes (mean age 19 years, range 15 - 25 years) at rest and during supine
bicycle exercise. Gated radionuclide angiocardiograms were performed at
rest and at each level of graded maximal supine bicycle exercise. Heart
rate, blood pressure, left ventricular ejection fraction and the relative
changes in left ventricular end-diastolic and end-systolic volumes were
assessed. Athletes attained a much greater work load than controls (mean
22.1 kpm/kg body weight vs 13 kpm/Kg body weight). Both groups achieved
similar increased in heart rate, blood pressure and ejection fractions. In
the controls, the mean end- diastolic volume increased to 124% of that at
rest (p less than 0.02) during exercise and the mean end-systolic volume
decreased to 81% of the rest level (p less than 0.02). In contrast, the
mean end-diastolic volume did not significantly change during exercise in
the athletes, and the mean end-systolic volume decreased to 64% of rest (p
less than 0.05). Thus, although trained and untrained healthy subjects had
similar increases in the left ventricular ejection fraction during
exercise, different mechanisms were used to achieve these increases.
Untrained subjects increased end-diastolic volumes, whereas trained
subjects decreased the end-systolic volumes. The ability of athletes to
exercise without increasing preload may be an effect of training amd might
have important implications in reducing myocardial oxygen demand during
exercise.
ARTICLES
Left ventricular function in trained and untrained healthy subjects
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