Post-Exercise Reduction of Blood Pressure in Hypertensive Men is Not Due to Acute Impairment of Baroreflex Function

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Abstract
Two experiments were carried out in male subjects. In the 1st experiment heart rate and blood pressures were measured before, during and for 90 min after a 50 min period of intermittent exercise in 7 hypertensive subjects. After exercise there was a marked reduction in systolic and diastolic blood pressures; this effect lasted throughout the 90 min observation period and was unaccompanied by tachycardia. In the 2nd experiment heart rate and blood pressures were measured before and during the rest periods in a 50 min session of intermittent exercise in 9 hypertensive and 9 normotensive subjects. Following the 1st 10 min bout of exercise, resting blood pressures were significantly reduced in the hypertensive subjects; the reduction in blood pressure progressively increased following successive exercise periods. The normotensive subjects did not show a significant reduction in resting blood pressures until the 5th bout of exercise was completed. In the 2nd experiment also, the competence of baroreflexes was assessed by measuring cardiovascular responses to lower body subatmospheric pressure (LBSP) 30 min before and 30 and 60 min after exercise. The post-exercise reduction in blood pressure was not due to exercise-induced impairment of baroreflex mechanisms since the reduced blood pressure after exercise was well maintained during lower body subatmospheric pressure. After exercise, exposure to lower body subatmospheric pressure elicited greater increases in heart rate and forearm vascular resistance than were seen before exercise.