Hemodynamic responses associated with post-exercise hypotension in normotensive black males.

The purpose of this study was to characterize the hemodynamic responses during recovery from moderate intensity exercise in young black normotensive males. Nineteen normotensive men (age 25.0 +/- 1.0 yrs, VO2peak 48.8 +/- 1.5 ml.kg-1.min-1) walked continuously on a treadmill for 40 minutes at 50-60% heart rate reserve. Following exercise, blood pressure (by auscultation) and hemodynamic variables (impedance cardiography) were monitored for two hours in a quiet room with subjects in a seated posture. During the initial 40 minutes of recovery, cardiac output, (Q) was significantly greater than the pre-exercise baseline (p < 0.05). This was mediated by heart rate, which was elevated above the pre-exercise baseline for 75 minutes. Mean systolic blood pressure (SBP) was reduced by at least 7 mm Hg from 30 minutes to 2 hours post-exercise, compared to the pre-exercise baseline, (mean = 112 +/- 1.6) (p < 0.05). Total peripheral resistance (TPR, dyne.s.cm-5) was depressed for 60 minutes compared to the pre-exercise baseline (BL, 959.8 +/- 40.6), p < 0.05, but was fully recovered by two hours. It was concluded that in this group of young black normotensive males, moderate intensity aerobic exercise led to a prolonged reduction in SBP through relative changes in Q and TPR. These observations have not been consistently observed by other investigators in normotensive white males under similar experimental conditions.