Background-Although cardiac output (CO) plays the vital role of delivering
nutrients to body tissues, few data are available concerning the relations
of stroke volume (SV) and CO to body composition in large population sample
s.
Methods and Results-Doppler and 2D echocardiography and bioelectric impedan
ce in 2744 Strong Heart Study participants were used to calculate SV and CO
and to relate them to fat-free body mass (FFM), adipose mass, and demograp
hic variables. Both SV and CO were higher in men than women and in overweig
ht than normal-weight individuals, but these differences were diminished or
even reversed by normalization for FFM or body surface area. In both sexes
, SV and CO were more strongly related to FFM than adipose mass, other body
habitus measures, arterial pressure, diabetes, or age. In multivariate ana
lyses using the average of Doppler and left ventricular SV to minimize meas
urement variability, FFM was the strongest correlate of SV and CO; other in
dependent correlates were adipose mass, systolic pressure, diabetes, age, a
nd use of digoxin and calcium channel and beta -blockers.
Conclusions-In a population-based sample, SV and CO are more strongly relat
ed to FFM than other variables; increased FFM may be the primary determinan
t of increased SV and CO in obesity.