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The haemodynamic changes during 4 h following maximal upright bicycle exercise were evaluated in six normals in a randomized controlled crossover design. Total peripheral resistance was reduced to 2 h (-6.7 mmHg min l-1, P < 0.05); exercising and non-exercising vascular beds were vasodilated for 2 h (-24.1 and -23.8 mmHg min ml-1 100 ml-1 tissue, 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 accounted for by an elevated heart rate (+14.4 beats min-1, P < 0.01) as stroke volume was unchanged. Body temperature was elevated until 40 min (+0.20 degrees C, P < 0.05). The return of all haemodynamic variables to control by 3 h suggests a 3 h limit for a hypotensive effect of exercise. Rise in body temperature is not the only factor responsible for the hypotension.
Isea et al. (Thu,) studied this question.