ABSTRACT
To evaluate the effect of exercise intensity on post-exercise cardiovascular responses, 12 young normotensive subjects performed in a randomized order three cycle ergometer exercise bouts of 45 min at 30, 50 and 80 per cent of VO2peak, and 12 subjects rested for 45 min in a non-exercise control trial. Blood pressure (BP) and heart rate (HR) were measured for 20 min prior to exercise (baseline) and at intervals of 5 to 30 (R5-30), 35 to 60 (R35-60) and 65 to 90 (R65-90) min after exercise. Systolic, mean, and diastolic BP after exercise were significantly lower than baseline, and there was no difference between the three exercise intensities. After exercise at 30 per cent of VO2peak, HR was significantly decreased at R35-60 and R65-90. In contrast, after exercise at 50 and 80 per cent of VO2peak, HR was significantly increased at R5-30 and R35-60, respectively. Exercise at 30 per cent of VO2peak significantly decreased rate pressure (RP) product (RP = HR x systolic BP) during the entire recovery period (baseline = 7930 ñ 314 vs R5-30 = 7150 ñ 326, R35-60 = 6794 ñ 349, and R65-90 = 6628 ñ 311, P<0.05), while exercise at 50 per cent of VO2peak caused no change, and exercise at 80 per cent of VO2peak produced a significant increase at R5-30 (7468 ñ 267 vs 9818 ñ 366, P<0.05) and no change at R35-60 or R65-90. Cardiovascular responses were not altered during the control trial. In conclusion, varying exercise intensity from 30 to 80 per cent of VO2peak in young normotensive humans did not influence the magnitude of post-exercise hypotension. However, in contrast to exercise at 50 and 80 per cent of VO2peak, exercise at 30 per cent of VO2peak decreased post-exercise HR and RP.