Haemodynamics of recovery after strenuous exercise in physically trained hypertensive and normotensive subjects

Acute Effects of Exercise on Blood Pressure: A Meta-Analytic Investigation

Hypertension affects 25% of the world's population and is considered a risk factor for cardiovascular disorders and other diseases. The aim of this study was to examine the evidence regarding the acute effect of exercise on blood pressure (BP) using meta-analytic measures. Sixty-five studies were compared using effect sizes (ES), and heterogeneity and Z tests to determine whether the ES were different from zero. The mean corrected global ES for exercise conditions were -0.56 (-4.80 mmHg) for systolic BP (sBP) and -0.44 (-3.19 mmHg) for diastolic BP (dBP; z ≠ 0 for all; p < 0.05). The reduction in BP was significant regardless of the participant's initial BP level, gender, physical activity level, antihypertensive drug intake, type of BP measurement, time of day in which the BP was measured, type of exercise performed, and exercise training program (p < 0.05 for all). ANOVA tests revealed that BP reductions were greater if participants were males, not receiving antihypertensive medication, physically active, and if the exercise performed was jogging. A significant inverse correlation was found between age and BP ES, body mass index (BMI) and sBP ES, duration of the exercise's session and sBP ES, and between the number of sets performed in the resistance exercise program and sBP ES (p < 0.05). Regardless of the characteristics of the participants and exercise, there was a reduction in BP in the hours following an exercise session. However, the hypotensive effect was greater when the exercise was performed as a preventive strategy in those physically active and without antihypertensive medication.

Influence of population and exercise protocol characteristics on hemodynamic determinants of post-aerobic exercise hypotension

Due to differences in study populations and protocols, the hemodynamic determinants of post-aerobic exercise hypotension (PAEH) are controversial. This review analyzed the factors that might influence PAEH hemodynamic determinants, through a search on PubMed using the following key words: “postexercise” or “post-exercise” combined with “hypotension”, “blood pressure”, “cardiac output”, and “peripheral vascular resistance”, and “aerobic exercise” combined only with “blood pressure”. Forty-seven studies were selected, and the following characteristics were analyzed: age, gender, training status, body mass index status, blood pressure status, exercise intensity, duration and mode (continuous or interval), time of day, and recovery position. Data analysis showed that 1) most postexercise hypotension cases are due to a reduction in systemic vascular resistance; 2) age, body mass index, and blood pressure status influence postexercise hemodynamics, favoring cardiac output decrease in elderly, overweight, and hypertensive subjects; 3) gender and training status do not have an isolated influence; 4) exercise duration, intensity, and mode also do not affect postexercise hemodynamics; 5) time of day might have an influence, but more data are needed; and 6) recovery in the supine position facilitates systemic vascular resistance decrease. In conclusion, many factors may influence postexercise hypotension hemodynamics, and future studies should directly address these specific influences because different combinations may explain the observed variability in postexercise hemodynamic studies.

Relaxation versus fractionation as hypnotic deepening: do they differ in physiological changes?

After rapid hypnotic induction, 12 healthy volunteers underwent hypnotic deepening with relaxation or with fractionation (without relaxation) in a random latin-square protocol. Electroencephalographic occipital alpha activity was measured, low-resolution brain electromagnetic tomography was performed, and hemodynamics (stroke volume, heart rate, cardiac output, mean arterial blood pressure, forearm arterial flow and resistance) were monitored in basal conditions and after deepening. After relaxation, both forearm flow (-18%) and blood pressure (-4%) decreased; forearm resistance remained unchanged. After fractionation, a forearm flow decrease comparable to that recorded after relaxation was observed, but blood pressure remained unchanged, leading to an increase of forearm resistance (+51%). Central hemodynamics did not change. Alpha activity increased in the precuneus after fractionation only. In conclusion, both relaxation and fractionation have vasoconstrictor effects, but fractionation is also associated with an increase in peripheral resistance.

Factors affecting post-exercise hypotension in normotensive and hypertensive humans

BACKGROUND

Post-exercise hypotension has been extensively described under laboratory conditions. However, studies investigating the persistence of this post-exercise decrease in blood pressure for longer periods have produced controversial results. The present investigation was conducted to verify the effect of a single bout of exercise on ambulatory blood pressure and to identify potential factors that might influence this post-exercise ambulatory blood pressure fall.

DESIGN

The study was a randomized controlled clinical trial.

METHODS

Thirty normotensive and 23 hypertensive subjects were submitted to two ambulatory blood pressure monitorings (using the SpaceLabs 90207, SpaceLabs, Redmond, Washington, USA), which were performed after 45min of seated rest (control session) or cycling exercise at 50% peak oxygen uptake (exercise session).

RESULTS

Normotensive subjects demonstrated a lower 24h blood pressure level in the exercise session. Hypertensive patients showed no significant difference in ambulatory blood pressure level between the two experimental sessions. Further data analysis revealed that approximately 65% of the subjects in both groups experienced a fall in blood pressure after exercise. Moreover, in the normotensive subjects, this blood pressure fall was significantly and positively correlated with clinic and ambulatory blood pressure, and negatively correlated with weight and body mass index. The blood pressure response to exercise was also greater in women. In the hypertensive patients, the post-exercise blood pressure decrease was significantly and positively correlated with clinic and ambulatory blood pressure as well as with the peak oxygen uptake, and negatively correlated with age and body mass index.

CONCLUSIONS

The post-exercise ambulatory blood pressure fall observed in normotensive and hypertensive humans depends on individual characteristics. Moreover, in both normotensive and hypertensive humans, post-exercise ambulatory hypotension is greater in subjects with a higher initial blood pressure level.

Dynamic exercise normalizes resting blood pressure in mildly hypertensive premenopausal women

BACKGROUND

Dynamic exercise acutely and transiently lowers resting blood pressure in hypertensive men and is termed postexercise hypotension (PEH). We examined 18 premenopausal women (7 hypertensive and 11 normotensive) to determine if PEH occurs in women and to elucidate possible hemodynamic and hormonal mechanisms.

METHODS AND RESULTS

Patients wore an ambulatory blood pressure monitor throughout the day after 40 minutes of a rest sham session and 40 minutes of cycle exercise, of which 30 minutes was performed at 60% of maximal oxygen consumption. Cardiac output and total systemic vascular resistance were determined by Doppler echocardiography before and 15 minutes after sham and exercise. Catecholamines, plasma renin activity, and beta-endorphin were measured over this same period. PEH occurred only in the hypertensive women. Systolic, diastolic, and mean arterial blood pressure decreased in the hypertensive women by a mean of 9.5 +/- 2. 8 mm Hg (P <.01), 6.7 +/- 2.4 mm Hg (P <.05), and 7.7 +/- 2.4 mm Hg (P <.05), respectively, for up to 7 hours after versus before exercise, whereas blood pressure was similar in the normotensive women (P >.05). After exercise, total systemic vascular resistance was lower (P <.01), and cardiac output, catecholamines, and plasma renin activity were greater (P <.01) than before exercise in both groups of women.

CONCLUSIONS

PEH was observed for up to 7 hours after exercise in mildly hypertensive women and was not explained by the hemodynamic and hormonal adjustments that occurred after exercise. The magnitude and duration of PEH may be sufficient to normalize the blood pressure of certain hypertensive women throughout most of the day.

Postexercise vasodilatation reduces diastolic blood pressure responses to stress

Regular physical exercise is known to reduce cardiovascular risk. We examined the effects of a single bout of moderate bicycle exercise on hemodynamic measures at rest and in response to the foot cold pressor (CP) and mental arithmetic (MA). Sedentary males and females (N = 32) were tested twice, following 20 minutes of moderate exercise (exercise day) versus 20 minutes of quiet rest (control day). Although resting blood pressure was no lower 20 minutes after exercise relative to the same time point on the control day, diastolic blood pressure responses to CP (p = .05) and MA (p = .06) were attenuated on the exercise day. Furthermore, recovery from moderate exercise versus control rest was also associated with reduced vascular resistance index (VRI) at rest and during exposure to both stressors (p's < or = .02). VRI reductions were largest in subjects with elevated vascular tone on the control day and were accompanied by increases in heart rate throughout the postexercise period (p's < or = .004) and higher cardiac index during exercise recovery and in response to CP (p's < or = .05). Thus, the cardiovascular benefit of exercise may in part be due to reduced VRI and attenuated cardiovascular responses to stress during the acute postexercise period.

Hemodynamics following real and hypnosis-simulated phlebotomy

Forearm arterial flow was measured in 22 healthy first-time blood donors during a 300-ml. blood letting and during the subsequent recovery. Blood pressure (BP) was also taken simultaneously and forearm peripheral resistance calculated. Following a transient BP and flow increase due to tachycardia related to needle insertion, both systolic BP and flow progressively and significantly decreased, while resistance increased. In a further 22 sex- and aged-matched highly hypnotizable subjects, blood donation was simulated by means of verbal hypnotic suggestions. The BP, flow and resistance curves were similar to those obtained with the real blood letting, without any between-subject difference or group/time interaction. Mere hypnosis without suggestion of phlebotomy and the simple bed resting did not produce any effect. These results indicate that the hemodynamic changes observed during and after a blood loss are partly due to mental involvement rather than merely to the hydraulic effects of the removal of blood.

Hemodynamic patterns and duration of post-dynamic exercise hypotension in hypertensive humans

We investigated: 1) the mechanism of the hypotensive effect of a single bout of dynamic exercise in hypertensive subjects by measuring hemodynamic parameters before and for 2 h after treadmill exercise, and 2) the duration of the effect using ambulatory blood pressure (BP) monitoring once the subjects left the test site. Ten minutes after exercise there was a significant decrease from baseline systolic pressure (SP; -14 +/- 3 mm Hg), mean arterial pressure (MAP; -7 +/- 2 mm Hg), total peripheral resistance (TPR; -3.7 +/- 1.2 units), calf vascular resistance (CVR; -25.4 +/- 4.1 units), and an increase in HR (19 +/- 2 bpm). The changes in SP, DP, MAP, and HR were maintained during the 2 h of post-exercise monitoring; CVR remained decreased for 1 h; TPR returned to baseline within 20 min and then tended to be slightly elevated. CO was significantly decreased at 50, 60, and 120 min after exercise. We conclude that the early decline in BP after dynamic exercise in hypertensive subjects follows a biphasic pattern: 1) an initial decrease in total and regional vascular resistance with maintained CO, 2) followed by increasing resistance and decrease CO. Pre-exercise hypertensive BP values returned during subsequent ambulatory monitoring.

Abnormal cardiovascular and catecholamine responses to supine exercise in human subjects with sympathetic dysfunction

1. The cardiovascular and catecholamine responses to supine leg exercise were measured in fifteen normal subjects (controls) and in three groups with sympathetic dysfunction: fifteen with central failure (Shy-Drager syndrome; SDS), fifteen with peripheral failure (pure autonomic failure; PAF) and two with isolated dopamine beta-hydroxylase deficiency (DBH deficiency). 2. With exercise, blood pressure increased in controls, fell markedly in SDS and PAF and was unchanged in DBH deficiency. After exercise, blood pressure rapidly returned to baseline in controls, but remained low in SDS and PAF. With exercise, heart rate increased more in controls than SDS or PAF; the response varied in DBH deficiency. 3. With exercise, cardiac output increased similarly in controls, SDS and PAF, with a larger increase in DBH deficiency. Vascular resistance fell less in controls than SDS, PAF and DBH deficiency. 4. With exercise, plasma noradrenaline increased in controls only; plasma adrenaline remained unchanged in all groups. In DBH deficiency, plasma noradrenaline and adrenaline were undetectable, but plasma dopamine was elevated and rose further with exercise. 5. Supine exercise substantially lowered blood pressure in sympathetic failure due to SDS and PAF. In DBH deficiency blood pressure was unchanged; this lack of fall may have been due to vasoconstriction induced by dopamine and other substances released from otherwise intact sympathetic terminals, or to preserved cardiac vagal function.