Abstract des Autors

Previous investigations have shown blacks to have a significantly lower resting heart rate (HR) compared with whites. Our purpose was to determine if this difference exists during submaximal exercise and to compare other cardiovascular responses during submaximal exercise in black and white males. Sixteen black and 16 white males matched on age, body surface area, and maximal O2 consumption exercised at 0, 50, and 100 W on a cycle ergometer. HR, O2 consumption, and cardiac output via CO2 rebreathing were measured at rest and at each work rate. Stroke volume was then calculated. O2 consumption was not significantly different between blacks and whites at rest or at work rates of 0, 50, or 100 W. Cardiac output increased from rest with 0, 50, and 100 W work for both blacks and whites. The differences in cardiac output between blacks and whites at rest and all work rates were not statistically significant. At rest and work rates of 0, 50, and 100 W, HR was significantly lower in blacks compared with whites. The lower HR in blacks compared with whites was accompanied by a trend toward a higher stroke volume at rest and work rates of 0, 50, and 100 W. No differences in resting blood pressures were found. During exercise, systolic, diastolic, and mean arterial blood pressures were slightly, although not significantly, higher in blacks compared with whites. These results suggest that there are different cardiovascular responses to exercise between blacks and whites. Verf.-Referat