TIME-COURSE OF HEMODYNAMIC-CHANGES AFTER MAXIMAL EXERCISE

The haemodynamic changes during 4 h following maximal upright bicycle exercise were evaluated in six normals in a randomized controlled cros sover design. Total peripheral resistance was reduced to 2 h (-6.7 mmH g min l(-1), P < 0.05); exercising and nonexercising vascular beds wer e vasodilated for 2 h (-24.1 and -23.8 mmHg min ml(-1) 100 ml(-1) tiss ue, respectively, P < 0.05), associated with reductions in systolic (- 5.8 mmHg, P < 0.05) and diastolic pressure (-8.3 mmHg, P < 0.05). Rise in cardiac index for 1 h (+0.51 min(-1) m(-2), P < 0.05) was accounte d for by an elevated heart rate (+14.4 beats min(-1), P < 0.01) as str oke volume was unchanged. Body temperature was elevated until 40 min ( +0.20 degrees C, P < 0.05). The return of all haemodynamic variables t o control by 3 h suggests a 3 h limit for a hypotensive effect of exer cise. Rise in body temperature is not the only factor responsible for the hypotension.