title: Intersubject variability in cardiac output-O2 uptake relation of men during exercise.
abstract: Intersubject variability in the relation between cardiac output (Q) and O2 uptake (VO2) was examined during supine cycling up to the maximum level in 40 normal untrained men age 27 +/- 4 (SD) yr. In individual subjects, Q increased linearly against VO2 in the submaximum exercise range. The SD of Q on VO2 was so small (0.47 +/- 0.25 l/min) that Q could be given by a linear function of VO2 as Q = K(VO2 - VO2 r) + Qr, where K, VO2 r, and Qr are the slope of the regression line, the resting VO2, and resting Q, respectively. K varied widely among the subjects studied, ranging from 5.5 to 10.3 and was independent of both physical characteristics and Qr, which ranged from 3.7 to 8.3 l/min. However, K correlated significantly with changes in heart rate, stroke volume, mean arterial pressure, and systemic vascular conductance. From these results, we concluded that the intersubject variability in the Q-VO2 relation was caused independently by individual variations in resting hemodynamics and in cardiovascular response to exercise.
mesh_terms: D000328:Adult; D001794:Blood Pressure; D002302:Cardiac Output; D006339:Heart Rate; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D005082:Physical Exertion; D012146:Rest