Journal of Applied Physiology, Vol 49, Issue 6 994-999, Copyright © 1980 by American Physiological Society
Gas transport capacity and echocardiographically determined cardiac size in children
C. J. Blimkie, D. A. Cunningham and P. M. Nichol
One hundred and seventeen boys (10, 12, and 14 yr of age) were studied to
determine the relation between maximal gas transport capacity (VO2 max) and
cardiac size and the interaction of growth and physical activity on this
relation. VO2 max was measured during treadmill exercise and heart size was
obtained during supine rest by M-mode echocardiography. Left ventricular
end-diastolic diameter (LVIDd), resting stroke volume (SV), and calculated
left ventricular mass (LVM) were highly correlated (0.75 < r < 0.84)
with VO2 max within all age categories. Subjects with high VO2 max had
significantly (P < 0.05) larger LVIDd, end-diastolic volumes, resting
SV, calculated LVM, and, with the exception of the 12 yr olds, larger left
ventricular end-systolic diameters and volumes than subjects with lower VO2
max. Multiple linear regression analysis revealed that fat-free weight
accounted for most of the variance in VO2 max and that cardiac dimensions
were only of minimal importance in determining maximal gas transport
capacity in this study. The seemingly good relationship between cardiac
dimensions and VO2 max was mainly attributable to the shared influence of
body size on both these factors.
