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

Abstract

Two experiments were carried out in male subjects. In the first experiment heart rate and blood pressures were measured before, during and for 90 min after a 50 min period of intermittent exercise in seven 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 second experiment heart rate and blood pressures were measured before and during the rest periods in a 50 min session of intermittent exercise in nine hypertensive and nine normotensive subjects. Following the first 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 fifth bout of exercise had been completed. In the second 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. Furthermore, after exercise, exposure to lower body subatmospheric pressure elicited greater increases in heart rate and forearm vascular resistance than were seen before exercise.

Potential causes, mechanisms, and implications of post exercise hypotension

“…In hypertensive subjects, Bennett et al 73 suggested that the magnitude of the pressure decrement increases with a longer duration of exercise, although this could not be substantiated in a normotensive population. However, in that study, blood pressure was measured during 3 min rest periods following successive 10 min exercise bouts.…”

“…PEH has been observed after as little as 10 min 12,73 and as long as 170 min 74 of exercise, although the majority of studies have used endurance exercise lasting between 20 and 60 min. 9,10,15,16,19,24,32,[34][35][36][37][38][39][41][42][43]45,47,[57][58][59][60]63,[75][76][77] Inter-experimental comparisons are difficult across studies, since a variety of exer-Journal of Human Hypertension cise intensities and blood pressure measurement techniques have been used.…”

“…Additionally, using the phenylephrine 11 and nitroprusside 59 methods, baroreceptor sensitivity has been found to be depressed during at least some, but not all, periods of hypotension. However, using the lower body negative pressure method of baroreceptor sensitivity assessment, Bennett et al 73 found an increased baroreceptor sensitivity following exercise that elicited PEH. Similar increases in sensitivity have been observed using neck suction, indicating a baroreceptor mediated restraint of PEH.…”

Postexercise decrease in arterial blood pressure, total peripheral resistance and in circulatory responses to brief hyperoxia in subjects with mild essential hypertension

“…4,5 In recent years, there has been considerable interest in circulatory after-effects of single physical exercise. [6][7][8][9][10][11][12][13][14][15][16] Many studies demonstrated that arterial BP in hypertensive patients is decreased for hours after single dynamic exercise. [6][7][8]11,[14][15][16] These studies were done mostly in middle-aged subjects with essential hypertension.…”

“…[6][7][8][9][10][11][12][13][14][15][16] Many studies demonstrated that arterial BP in hypertensive patients is decreased for hours after single dynamic exercise. [6][7][8]11,[14][15][16] These studies were done mostly in middle-aged subjects with essential hypertension. [6][7][8]16,17 There are inconsistencies with regard to the sys- temic and regional haemodynamic changes responsible for the postexercise fall in BP.…”