LOAD DEPENDENCE OF CHANGES IN FOREARM AND PERIPHERAL VASCULAR-RESISTANCE AFTER ACUTE LEG EXERCISE IN MAN

1. It is known that acute exercise is often followed by a reduction in arterial blood pressure. Little is known about the time course of the recovery of the blood pressure or the influence of the intensity of the exercise on this response. Controversy exists, in particular, concerning the changes in peripheral resistance that occur during this period. 2. Eight normal volunteers performed, in random order on separate days, voluntary upright bicycle exercise of three different intensities (maximal, moderate and minimal load) and, on another day, a control period of sitting on a bicycle. They were monitored for 60 min after each test. 3. Diastolic pressure fell after maximal exercise at 5 min (-15.45 mmHg) and 60 min (-9.45 mmHg), compared with the control day. Systolic and mean pressure also fell (non-significantly) after 45 min; heart rate was significantly elevated for the whole hour of recovery (at 60 min, +7.23 beats min(-1)). No changes in post-exercise blood pressure and heart rate were observed on the days of moderate and minimal exercises. 4. An increase in cardiac index was observed after maximal exercise compared with control (at 60 min, 2.6 +/- 0.3 vs. 1.9 +/- 0.21 min(-1) m(-2)). This was entirely accounted for by the persistent increase in heart rate, with no significant alteration in stroke volume after exercise on any day. 5. Systemic vasodilatation was present immediately after maximal exercise compared with control (after a 5 min rest, total peripheral resistance was 17.9 +/- 3.5 vs. 27.8 +/- 3.4 mmHg (l min(-1))(-1) on the control day) and lasted at least 60 min (at 60 min, 23.3 +/- 3.5 vs. 31.0 +/- 3.8 mmHg (l min(-1))(-1) on the control day). No significant changes in total peripheral vascular resistance mere observed after moderate or minimal exercise days. 6. After this predominantly leg exercise, minimal and moderate loads significantly increased forearm vascular resistance with respect to baseline pre-exercise resistance (at 60 min, +26.7% and +20.5%, respectively), but there were no significant differences with respect to the control day; maximal leg exercise significantly decreased the forearm vascular resistance for 1 h (at 60 min, -17.2% vs. baseline pre-exercise value and -46.0% compared to the control day). This suggests that prolonged forearm vasodilatation occurred only after higher exercise loads.