To define the effects of gender on stroke volume control during upright exercise in normal subjects, we examined central hemodynamics in 34 men and 27 women during staged bicycle ergometry. Central hemodynamics were assessed by right-sided cardiac catheterization and simultaneous radionuclide angiography. Left ventricular end-diastolic and end-systolic volumes were calculated from the stroke volume (by direct Fick) and the corresponding left ventricular ejection fraction. Men were larger than women (1.85 +/- 0.11 vs 1.65 +/- 0.13 m2, p less than 0.001) but groups were matched for age (39 +/- 12 vs 36 +/- 9 years, p = 0.27). Oxygen consumption at peak exercise was higher in men than in women (2.51 +/- 0.50 vs 1.74 +/- 0.30 liters/min, p less than 0.001) but was not different when adjusted for body weight (31.5 +/- 8.1 vs 28.4 +/- 6.4 ml/kg/min, p = 0.14), indicating similar levels of overall fitness in the 2 groups. At rest and during submaximal and maximal exercise, stroke volume and left ventricular end-diastolic and end-systolic volumes were higher in men than in women, but there were no intergroup differences in stroke volume index, left ventricular ejection fraction, and left ventricular end-diastolic or end-systolic volume indexes. Comparison of derived regression equations of cardiac index, stroke volume index and left ventricular end-diastolic and end-systolic volume indexes revealed no differences in the time course or magnitude of changes with respect to oxygen consumption, expressed as percentage of peak oxygen consumption, in the 2 groups.(ABSTRACT TRUNCATED AT 250 WORDS)