Load dependence of changes in forearm and peripheral vascular resistance after acute leg exercise in man

Critical power is a key threshold determining the magnitude of post-exercise hypotension in non-hypertensive young males

The effect of different exercise intensities on the magnitude of post-exercise hypotension has not been rigorously clarified with respect to the metabolic thresholds that partition discrete exercise intensity domains (i.e., critical power and the gas exchange threshold (GET)). We hypothesized that the magnitude of post-exercise hypotension would be greater following isocaloric exercise performed above versus below critical power. Twelve non-hypertensive men completed a ramp incremental exercise test to determine maximal oxygen uptake and the GET, followed by five exhaustive constant load trials to determine critical power and W' (work available above critical power). Subsequently, criterion trials were performed at four discrete intensities matched for total work performed (i.e., isocaloric) to determine the impact of exercise intensity on post-exercise hypotension: 10% above critical power (10% > CP), 10% below critical power (10% < CP), 10% above GET (10% > GET) and 10% below GET (10% < GET). The post-exercise decrease (i.e., the minimum post-exercise values) in mean arterial (10% > CP: -12.7 ± 8.3 vs. 10% < CP: v3.5 ± 2.9 mmHg), diastolic (10% > CP: -9.6 ± 9.8 vs. 10% < CP: -1.4 ± 5.0 mmHg) and systolic (10% > CP: -23.8 ± 7.0 vs. 10% < CP: -9.9 ± 4.3 mmHg) blood pressures were greater following exercise performed 10% > CP compared to all other trials (all P < 0.01). No effects of exercise intensity on the magnitude of post-exercise hypotension were observed during exercise performed below critical power (all P > 0.05). Critical power represents a threshold above which the magnitude of post-exercise hypotension is greatly augmented. NEW FINDINGS: What is the central questions of this study? What is the influence of exercise intensity on the magnitude of post-exercise hypotension with respect to metabolic thresholds? What is the main finding and its importance? The magnitude of post-exercise hypotension is greatly increased following exercise performed above critical power. However, below critical power, there was no clear effect of exercise intensity on the magnitude of post-exercise hypotension.

Usefulness of Aerobic Exercise for Home Blood Pressure Control in Patients with Diabetes: Randomized Crossover Trial

Hypertension usually coexists with diabetes mellitus and significantly increases the risk of macrovascular complications. Blood pressure measured at home, especially nocturnal blood pressure, is particularly important because it is more strongly associated with target organ damage than clinical blood pressure measurements. Regular moderate aerobic exercise has been shown to have anti-hypertensive effects. This study aimed to investigate the effects of aerobic exercise on home blood pressure in patients with diabetes. This randomized crossover trial was based on outpatient treatment at a university hospital. In this randomized crossover trial, 124 patients with type 2 diabetes were randomly assigned to two groups over 56 days: an exercise preceding group (exercise intervention for 28 days and then no exercise intervention for the following 28 days) and an exercise lagging group (no exercise intervention for 28 days and then exercise intervention for the following 28 days). The associations between the nocturnal blood pressure and exercise intervention were assessed accordingly. A decrease in blood pressure was observed in the morning and evening, at 2 a.m. and 3 a.m. after exercise intervention; however, there was no significant difference between groups. Moderate exercise was not effective in lowering nocturnal blood pressure in this study.

Acute Effects of Heart Rate-Controlled Exergaming on Vascular Function in Young Adults

Objective: Acute and regular moderate-intensity endurance exercise (MIEE) is known to positively affect vascular function. The present study assessed if an exercise session in an innovative exergame called the ExerCube can induce similar vascular reactions as an MIEE session. Materials and Methods: Twenty-eight healthy recreationally active participants (13 females and 15 males; aged 24.8 ± 3.9 years; with body mass index 23.2 ± 2.3 kg/m²) completed an exergaming session (EGS) in the ExerCube (25 minutes) and an MIEE session on a treadmill (35 minutes, 65%-70% of maximal heart rate [HR]) in a randomized order. Both before and throughout the 45 minutes after the training sessions, pulse wave velocity (PWV), total peripheral resistance (TPR), stroke volume (SV), and HR were recorded. The study was approved by the Research Ethics Board of the Martin-Luther-Universität Halle-Wittenberg (Medical Faculty of the Martin-Luther-Universität 2019-177). Results: There were different hemodynamic responses to both types of exercises. PWV was significantly decreased 45 minutes after the EGS (P < 0.001). No significant changes were detected after MIEE (P = 0.109). TPR was significantly lower after both exercise sessions (P < 0.01). Only the EGS resulted in a significant decrease in SV 15 minutes after exercise (P < 0.001). The HR was significantly (P < 0.05) higher after both exercise sessions. After the EGS, the increase in HR was still significantly higher (P = 0.011) 45 minutes after the session. The interaction effects revealed significant differences in PWV (15 minutes, P = 0.035; 30 minutes, P = 0.004; and 45 minutes, P < 0.001), favoring the EGS. Conclusion: The EGS seems to induce a relevant exercise stimulus that can modulate vascular function. Therefore, this exergame may present an effective tool for prevention of cardiovascular diseases.

Intense aerobic exercise lowers blood pressure in individuals with metabolic syndrome taking antihypertensive medicine

OBJECTIVE

There is a growing tendency for physicians to prescribe exercise in accordance with the 'exercise is medicine' global health initiative. However, the exercise-pharmacologic interactions for controlling blood pressure are not well described. Our purpose was to study whether angiotensin II receptor type 1 blocker (ARB) antihypertensive medicine enhances the blood pressure-lowering effects of intense exercise.

PARTICIPANTS AND METHODS

Fifteen hypertensive individuals with metabolic syndrome chronically medicated with ARB underwent two exercise trials in a blind randomized order. One trial was conducted after taking their habitual dose of ARB (ARB MED trial) and another after 48 h of placebo medicine (i.e. dextrose; PLAC trial).

RESULTS

After placebo medication, brachial systolic blood pressure increased by 5.5 mmHg [P=0.009; effect size (ES)=0.476] and diastolic by 2.5 mmHg (P=0.030; ES=0.373). Exercise reduced systolic and diastolic blood pressures to the same extent in ARB MED and PLAC trials (7 and 8 mmHg, respectively, for systolic and 5 and 4 mmHg, respectively, for diastolic, all P<0.05). Pulsatile measures of arterial stiffness did not reveal an interaction effect between exercise and medication. However, postocclusion reactive hyperemia increased after exercise only in the ARB MED trial (361±169 to 449±240% from baseline; P=0.033; ES=0.429).

CONCLUSION

ARBs and a bout of intense exercise each have an independent effect on lowering blood pressure in hypertensive individuals, and these effects are additive.

Ambulatory blood pressure response to a bout of HIIT in metabolic syndrome patients

PURPOSE

The effectiveness of exercise to lower blood pressure may depend on the type and intensity of exercise. We study the short-term (i.e., 14-h) effects of a bout of high-intensity aerobic interval training (HIIT) on blood pressure in metabolic syndrome (MetS) patients.

METHODS

Nineteen MetS patients (55.2 ± 7.3 years, 6 women) entered the study. Eight of them were normotensive and eleven hypertensive according to MetS threshold (≥130 mmHg for SBP and/or ≥85 mmHg for DBP). In the morning of 3 separated days, they underwent a cycling exercise bout of HIIT (>90% of maximal heart rate, ~85% VO_2max), or a bout of isocaloric moderate-intensity continuous training (MICT; ~70% of maximal heart rate, ~60% VO_2max), or a control no-exercise trial (REST). After exercise, ambulatory blood pressure (ABP; 14 h) was monitored, while subjects continued their habitual daily activities wearing a wrist-band activity monitor.

RESULTS

No ABP differences were found for normotensive subjects. In hypertensive subjects, systolic ABP was reduced by 6.1 ± 2.2 mmHg after HIIT compared to MICT and REST (130.8 ± 3.9 vs. 137.4 ± 5.1 and 136.4 ± 3.8 mmHg, respectively; p < 0.05). However, diastolic ABP was similar in all three trials (77.2 ± 2.6 vs. 78.0 ± 2.6 and 78.9 ± 2.8 mmHg, respectively). Motion analysis revealed no differences among trials during the 14-h.

CONCLUSION

This study suggests that the blood pressure reducing effect of a bout of exercise is influence by the intensity of exercise. A HIIT exercise bout is superior to an equivalent bout of continuous exercise when used as a non-pharmacological aid in the treatment of hypertension in MetS.

Cardiac autonomic and haemodynamic recovery after a single session of aerobic exercise with and without blood flow restriction in older adults

This study investigated the autonomic and haemodynamic responses to different aerobic exercise loads, with and without blood flow restriction (BFR). In a crossover study, 21 older adults (8 males and 13 females) completed different aerobic exercise sessions: low load without BFR (LL) (40% VO_2max), low load with BFR (LL-BFR) (40% VO_2max + 50% BFR) and high load without BFR (HL) (70% VO_2max). Heart rate variability and haemodynamic responses were recorded during rest and throughout 30 min of recovery. HL reduced R-R interval, the root mean square of successive difference of R-R intervals and high frequency during 30 min of recovery at a greater magnitude compared with LL and LL-BFR. Sympathetic-vagal balance increased the values for HL during 30 min of recovery at a greater magnitude when compared with LL and LL-BFR. Post-exercise haemodynamic showed reduced values of double product at 30 min of recovery compared to rest in LL-BFR, while HL showed higher values compared to rest, LL-BFR and LL. Reduced systolic blood pressure was observed for LL-BFR (30 min) compared to rest. Autonomic and haemodynamic responses indicate lower cardiovascular stress after LL-BFR compared to HL, being this method, besides the functional adaptations, a potential choice to attenuate the cardiovascular stress after exercise in older adults.

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.

The acute effect of maximal exercise on central and peripheral arterial stiffness indices and hemodynamics in children and adults

This study compared the effects of a bout of maximal running exercise on arterial stiffness in children and adults. Right carotid blood pressure and artery stiffness indices measured by pulse wave velocity (PWV), compliance and distensibility coefficients, stiffness index α and β (echo-tracking), contralateral carotid blood pressure, and upper and lower limb and central/aortic PWV (applanation tonometry) were taken at rest and 10 min after a bout of maximal treadmill running in 34 children (7.38 ± 0.38 years) and 45 young adults (25.22 ± 0.91 years) having similar aerobic potential. Two-by-two repeated measures analysis of variance and analysis of covariance were used to detect differences with exercise between groups. Carotid pulse pressure (PP; η(2) = 0.394) increased more in adults after exercise (p < 0.05). Compliance (η(2) = 0.385) decreased in particular in adults and in those with high changes in distending pressure, similarly to stiffness index α and β. Carotid PWV increased more in adults and was related to local changes in PP but not mean arterial pressure (MAP). Stiffness in the lower limbs decreased (η(2) = 0.115) but apparently only in those with small MAP changes (η(2) = 0.111). No significant exercise or group interaction effects were found when variables were adjusted to height. An acute bout of maximal exercise can alter arterial stiffness and hemodynamics in the carotid artery and within the active muscle beds. Arterial stiffness and hemodynamic response to metabolic demands during exercise in children simply reflect their smaller body size and may not indicate a particular physiological difference compared with adults.

Effects of exercise intensity on hypertension prevalence in Korean men with high sodium intake

[Purpose] The purpose of present study was to investigate the effects of exercise intensity on hypertension prevalence in Korean men with high sodium intake. [Subjects and Methods] This study was based on the data collected from 2007 to 2013 in the Korean National Health and Nutritional Examination Survey. A total of 8853 male adults were included in the analysis. The odds ratios for hypertension according to exercise groups were assessed by using logistic regression of each sodium intake group. [Results] Among the 8853 subjects, 6243 had an eating habit of 4000 mg or more sodium consumption per day, and 2619 had less than 4000 mg. Among the 2619 subjects with less than 4000 mg sodium consumption, 16.7% subjects were diagnosed as having hypertension. In the subjects with 4000 mg or more sodium consumption, compared to the no-exercise group, the moderate-exercise group showed a lower likelihood of developing hypertension, with an odds ratio of 0.63 (95% confidence interval, 0.47–0.85) after adjusting for age. In multivariate models 1 and 2, odds ratios for the likelihood of developing hypertension in the moderate-exercise group decreased to 0.63 (0.43–0.91) and 0.66 (0.45–0.96), respectively. [Conclusion] Moderate exercise is significantly associated with a lower likelihood of developing hypertension in cases of high sodium intake.

The training and detraining effect of high-intensity interval training on post-exercise hypotension in young overweight/obese women

PURPOSE

Studies evaluating the response in blood pressure (BP) following high-intensity interval training (HIIT) are scant even though there has been extensive work done on the BP response following acute and chronic low- to moderate-intensity aerobic and resistance exercise in both hypertensive and normotensive individuals. The present study sought to investigate the training and detraining effects of short-term HIIT on the post-exercise hypotension (PEH) response in overweight/obese young women.

METHOD

Twenty young untrained women volunteered for the study. Participants performed six HIIT sessions on a treadmill within 2 weeks (week 1: 10 × 1 min and week 2: 15 × 1 min intervals at 90-95% HRmax, separated by 1 min active recovery at 70% HRmax each session) and detrained for 2 weeks. Post-exercise BP was measured for 1 h following the first and last HIIT sessions.

RESULTS

Participants were normotensive (SBP: 119.2 ± 5.60 mmHg; DBP: 78.8 ± 4.12 mmHg) and had a BMI greater than 25 kg m(-2). The magnitude of the systolic hypotensive response was slightly greater after the six sessions HIIT compared to pre-training (5.04 and 4.28 mmHg, respectively), and both would be considered clinically significant (>3 mmHg decrease). After 2 weeks, detraining the PEH response was not clinically significant (1.08 mmHg decrease). The magnitude of the DBP response was only clinically significant following post- and detraining (4.26 and 3.87 mmHg, respectively).

CONCLUSION

The findings suggest that six HIIT sessions is sufficient to affect clinically significant PEH responses in young, overweight/obese women; however, the training effects are lost within 2 weeks of detraining.

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.

Effects of aerobic exercise intensity on 24-h ambulatory blood pressure in individuals with type 2 diabetes and prehypertension

[Purpose] To verify the effects of different intensities of aerobic exercise on 24-hour ambulatory blood pressure (BP) responses in individuals with type 2 diabetes mellitus (T2D) and prehypertension. [Subjects and Methods] Ten individuals with T2D and prehypertension (55.8 ± 7.7 years old; blood glucose 133.0 ± 36.7 mg·dL⁻¹ and awake BP 130.6 ± 1.6/ 80.5 ± 1.8 mmHg) completed three randomly assigned experiments: non-exercise control (CON) and exercise at moderate (MOD) and maximal (MAX) intensities. Heart rate (HR), BP, blood lactate concentrations ([Lac]), oxygen uptake (VO₂), and rate of perceived exertion (RPE) were measured at rest, during the experimental sessions, and during the 60 min recovery period. After this period, ambulatory blood pressure was monitored for 24 h. [Results] The results indicate that [Lac] (MAX: 6.7±2.0 vs. MOD: 3.8±1.2 mM), RPE (MAX: 19±1.3 vs. MOD: 11±2.3) and VO₂peak (MAX: 20.2±4.1 vs. MOD: 14.0±3.0 mL·kg⁻¹·min⁻¹) were highest following the MAX session. Compared with CON, only MAX elicited post-exercise BP reduction that lasted for 8 h after exercise and during sleep. [Conclusion] A single session of aerobic exercise resulted in 24 h BP reductions in individuals with T2D, especially while sleeping, and this reduction seems to be dependent on the intensity of the exercise performed.

Effect of infrared-C radiation on skin temperature, electrodermal conductance and pain in hemiparetic stroke patients

PURPOSE

A novel application of infrared-C (IR-C) radiation (3-1000 μm) on hemiparetic stroke patients was evaluated. Hot compresses (HC) were used on the paretic shoulders of patients in this placebo-controlled trial to investigate the effects of IR-C on skin temperature, electrodermal conductance (EC) and pain relief.

MATERIALS AND METHODS

Skin temperature at the center of the middle deltoid (CMD), Quchi (LI11), and the center of the third metacarpal bone on dorsum of hand (COT) of the subjects at Brunnstrom stage 3-5 before and after IR-C HC, were examined. Meanwhile, EC was measured on Hegu (LI4), Quchi and Juanyu (LI15). Pain intensity was evaluated before and after treatment.

RESULTS

Skin temperature increased significantly at the CMD and COT on the paretic side in males. In females after treatment, similar skin temperatures were found in each measured region on both the paretic and non-paretic sides. The EC on the paretic side tended to be higher than the non-paretic side before treatment. After treatment, the EC on paretic side declined in both sexes and became even lower than the non-paretic side in females. Pain intensity was lessened after treatment especially in males, which appeared to correspond with an increase in skin temperature and a decrease in EC.

CONCLUSION

IR-C hot compress is a promising method for stroke patients in rehabilitation. Physiological mechanisms of this treatment were proposed and summarized from this research.

Post-plyometric exercise hypotension and heart rate in normotensive individuals: influence of exercise intensity

Purpose

The purpose of this study was to compare the effects of high, moderate and low intensity plyometric exercise on the post-exercise systolic and diastolic blood pressure and heart rate responses.

Methods

Ten healthy normotensive men (age, 21.1±0.9 years; height, 175.8±6 cm; and body mass, 69.1±13.6 kg) volunteered to participate in this study and were evaluated for three non-consecutive days in depth jump exercise from 20-cm box (low intensity [LI]), 40-cm box (moderate intensity [MI]) and 60-cm box (high intensity [HI]) for 5 sets of 20 repetitions. After each exercise session, systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were measured every 10 min for a period of 90 min.

Results

No significant differences were observed among post-exercise SBP, DBP and HR when the protocols (LI, MI and HI) were compared. The LI and HI protocols showed greater reduction in SBP at 40^th-70^th min of post-exercise (~9%), whereas the LI and MI protocols indicated greater reduction in DBP at 10^th-50^th min of post exercise (~10%). In addition, the change in the DBP for HI was not significant and the increases in the HR were similar for all intensities.

Conclusion

It can be concluded that a plyometric exercise (PE) can reduce SBP and DBP post-exercise and therefore we can say that PE has significant effects for reducing BP and HR or post-exercise hypotension.

Caminhada/corrida ou uma partida de futebol recreacional apresentam efetividade semelhante na indução de hipotensão pós-exercício

INTRODUÇÃO: Os exercícios aeróbios são os mais investigados e recomendados para a promoção de redução da pressão arterial. Contudo, ainda não está claro a maneira como modalidades acíclicas (voleibol, futebol e outros) podem promover hipotensão pós-exercício (HPE). OBJETIVO: Comparar a resposta pressórica aguda entre partida de futebol e uma sessão de caminhada/corrida. MÉTODOS Oito sujeitos normotensos (59,7±5 anos) e oito hipertensos (57,3±7 anos) tiveram a pressão arterial (PA) monitorada antes das sessões de exercício e durante 30 minutos de um período de recuperação. RESULTADOS: Futebol e caminhada/corrida promoveram diminuição da PA sistólica de -13,8±11 e -6,8±9 mmHg respectivamente entre os indivíduos hipertensos e de -13,3±6 e -5,8±7 mmHg entre os indivíduos normotensos. A PA diastólica foi reduzida em 8,8±5 e -2,8±4,8 mmHg para hipertensos e -6,5±5 e -4,4±2 mmHg para normotensos. Não houve diferenças significativas entre futebol e caminhada/corrida. CONCLUSÃO: O futebol recreativo apresenta a mesma eficácia na promoção de HPE da caminhada/corrida.

Hypotensive response after water-walking and land-walking exercise sessions in healthy trained and untrained women

Background:

The aim of this study was to compare post-exercise hypotension after acute sessions of water-walking and land-walking in healthy trained and untrained women.

Methods:

Twenty-three untrained (n = 12) and trained (n = 11) normotensive women performed two walking sessions in water and on land at 40% of peak VO₂ for 45 minutes. Systolic and diastolic blood pressure and mean arterial pressure were measured 15, 30, 45, and 60 minutes after the exercise sessions.

Results:

No differences were found between the groups for age and anthropometric parameters, but peak VO₂ for the trained women (45 ± 8 mL/kg/minute) was higher than for the untrained women (31 ± 3 mL/kg/minute). No differences were found between the groups with regard to systolic and diastolic blood pressure and mean arterial pressure after water immersion. The heart rate in the trained group (62 ± 3 beats per minute [bpm]) was significantly lower (P < 0.05) than in the untrained group (72 ± 4 bpm) on land, and after water immersion, this difference disappeared (58 ± 5 bpm in the trained women and 66 ± 5 bpm in the untrained women). Sixty minutes after water-walking, systolic blood pressure (108 ± 8 mmHg vs 97 ± 3 mmHg), diastolic blood pressure (69 ± 5 mmHg vs 62 ± 5 mmHg), and mean arterial pressure (82 ± 6 mmHg vs 74 ± 4 mmHg) decreased significantly with rest in the untrained group, and no differences were found after land-walking. In the trained group, significant (P < 0.05) differences were found only for systolic blood pressure (110 ± 9 mmHg vs 100 ± 9 mmHg) after 60 minutes of water-walking; decreases in systolic blood pressure were found after 45 minutes (99 ± 7 mmHg) and 60 minutes (99 ± 6 mmHg) compared with rest (107 ± 5 mmHg) after land-walking.

Conclusion:

Single water-walking and land-walking sessions induced important hypotension following exercise. Additionally, walking performed in chest-deep water has a better effect on exercise-induced hypotension in untrained healthy women than walking at a similar intensity on land.

O2 uptake and blood pressure regulation at the onset of exercise: interaction of circadian rhythm and priming exercise

Circadian rhythm has an influence on several physiological functions that contribute to athletic performance. We tested the hypothesis that circadian rhythm would affect blood pressure (BP) responses but not O2 uptake (V̇o2) kinetics during the transitions to moderate and heavy cycling exercises. Nine male athletes (peak V̇o2: 60.5 ± 3.2 ml·kg−1·min−1) performed multiple rides of two different cycling protocols involving sequences of 6-min bouts at moderate or heavy intensities interspersed by a 20-W baseline in the morning (7 AM) and evening (5 PM). Breath-by-breath V̇o2 and beat-by-beat BP estimated by finger cuff plethysmography were measured simultaneously throughout the protocols. Circadian rhythm did not affect V̇o2 onset kinetics determined from the phase II time constant (τ2) during either moderate or heavy exercise bouts with no prior priming exercise (τ2 moderate exercise: morning 22.5 ± 4.6 s vs. evening 22.2 ± 4.6 s and τ2 heavy exercise: morning 26.0 ± 2.7 s vs. evening 26.2 ± 2.6 s, P > 0.05). Priming exercise induced the same robust acceleration in V̇o2 kinetics during subsequent moderate and heavy exercise in the morning and evening. A novel finding was an overshoot in BP (estimated from finger cuff plethysmography) in the first minutes of each moderate and heavy exercise bout. After the initial overshoot, BP declined in association with increased skin blood flow between the third and sixth minute of the exercise bout. Priming exercise showed a greater effect in modulating the BP responses in the evening. These findings suggest that circadian rhythm interacts with priming exercise to lower BP during exercise after an initial overshoot with a greater influence in the evening associated with increased skin blood flow.

Blood flow in the brachial artery increases after intense cycling exercise

During cycling blood flow is redistributed from physically inactive tissues to working leg muscles. It is unknown how long this situation persists after very intense exercise or whether it differs between intense exhausting and non-exhausting exercise. It is also not known to what extent the redistribution differs between different types of non-active tissues. Therefore nine healthy young men cycled first for 2 min at 328 W (non-exhausting exercise, mean). Blood velocity in thigh and arm (ultrasound-doppler), perfusion of forearm skin (non-acral skin) and finger tip (acral skin, with arterio-venous anastomoses) were measured for 30 min after exercise (laser-doppler). To be able to study vascular resistance and central circulation, blood pressure (Finometer), heart rate (ECG), and stroke volume (ultrasound-doppler) were measured. Thereafter the subjects cycled at the same power to exhaustion (4 min), and the measurements were repeated. After both exercises mean blood pressure was unchanged (< or = 80 mm Hg) despite increased cardiac output (> or = + 30% vs. pre-exercise). Blood velocity in the brachial artery was higher during the whole recovery period than at rest (p< or =0.02; no differences between exercises). Blood perfusion of non-acral skin was unchanged from pre-exercise level after 2 min of non-exhausting exercise, but it was twice as high after 4 min cycling to exhaustion as at rest (p=0.02). Blood perfusion of acral skin rose after both exercises and did not differ between exhausting and non-exhausting exercise. In conclusion, arm blood flow increases above the pre-exercise level in the recovery period after short-lasting, strenuous exercise.

Hipotensão pós-exercício aeróbio: uma revisão sistemática

Diversos estudos investigaram os efeitos hipotensores após uma sessão de exercício aeróbio em humanos. No entanto, vários aspectos permanecem obscuros em relação à hipotensão pós-exercício (HPE), uma vez que diversas variáveis podem influenciar a resposta hipotensora, como intensidade, duração, tipo de exercício, estado clínico, faixa etária, etnia, sexo e estado de treinamento. Nesse sentido, o objetivo do presente estudo foi revisar sistematicamente a literatura, relacionando as principais variáveis da prescrição de uma sessão de exercício aeróbio e a HPE, assim como apresentar os possíveis mecanismos envolvidos. Foram encontrados 55 estudos que abrangeram a temática HPE e exercício aeróbio em humanos. A ocorrência da HPE está bem estabelecida na literatura, já que vários estudos identificaram reduções da pressão arterial em normotensos e hipertensos. Porém, os possíveis moduladores das respostas hipotensoras, como intensidade e duração da sessão de exercício, ainda são contraditórios. Em relação ao tipo de exercício, porém, existem indicativos de que os realizados de forma intermitente e que utilizam maior massa muscular podem acarretar maior HPE. Além disso, hipertensos devem apresentar maior magnitude e duração da HPE. Contudo, existem lacunas em relação aos diversos mecanismos fisiológicos envolvidos, que parecem ser diferentes entre normotensos e hipertensos.

Is the magnitude of acute post-exercise hypotension mediated by exercise intensity or total work done?

The purpose of this study was to investigate the effects of exercise intensity on the magnitude of acute post-exercise hypotension while controlling for total work done over the exercise bout. Seven normotensive physically active males aged 28 +/- 6 years (mean +/- SD) completed four experimental trials, a no exercise control, 30 min of semi-recumbent cycling at 70% VO2peak (INT), cycling for 30 min at 40% VO2peak (SMOD) and cycling at 40% VO2peak for a time which corresponded to the same total work done as in the intense trial (LMOD). Blood pressure (BP), heart rate, stroke volume, cardiac output, total peripheral resistance, core body temperature and forearm skin and limb blood flow were measured prior to and for 20 min following the exercise bout. Post-exercise summary statistics were compared between trials with a one-factor general linear model. The change in systolic BP, averaged over the 20-min post-exercise period was significantly lower only following the INT (-5 +/- 3 mm Hg) and LMOD exercise (-1 +/- 7 mm Hg) compared to values in control (P < 0.04). The changes in systolic BP and MAP following INT and LMOD were not significantly different from each other (P > 0.05). Similar results were obtained when the minimum values of these variables recorded during the post-exercise period were compared. Mean changes in cardiac output (1.9 +/- 0.3 l min(-1)) and total peripheral resistance (-3 +/- 1 mm Hg l(-1 )min(-1)) after INT exercise were also different from those in CON (P < 0.0005). The acute post-exercise reduction in BP was clinically similar following high intensity short duration exercise and moderate intensity longer duration exercise that was matched for total work done.

Suppression of heart rate variability after supramaximal exertion

Wingate test is short anaerobic exercise, performed with maximal power, whereas aerobic exercise at 85% maximal heart rate (HR(max)) may be performed for long period. Sustained HR elevations and changes in autonomic activity indices have been observed after latter kind of exercise. Several studies reported reduction in mean interval between consecutive R peaks in ECG (RRI) 1 h after Wingate test; however, underlying changes in autonomic activity remain elusive. In eight young males, RRI and heart rate variability (HRV) were measured daily over two 5-day trials. Subjects exercised on third day of each trial, measurements were taken 1 h after (i) two consecutive 30-s bouts of Wingate tests or (ii) after a 30-min exercise at 85% HR(max), with subjects in supine rest and breathing either spontaneously or at controlled rates of 6 and 15 breaths / min. RRI was significantly shorter after Wingate and submaximal exercise, reduction of high- and low-frequency components of HRV attained reliability only after Wingate tests. This pattern remained preserved for three modes of breathing: spontaneous, 6 and 15 breaths /min. After 24 and 48 h, no exercise effects were traceable. We hypothesize that (i) anaerobic exertion is followed by sustained inhibition of vagal activity, (ii) parasympathetic system plays dominant role in mediating suppression of high- and low-HRV frequency components during postexercise recovery, (iii) degree of alteration of autonomic activity caused by anaerobic and strenuous aerobic exercise may be similar and (iv) normalization of vagal activity precedes normalization of sympathetic cardiac nerves activity during final stage of postexercise recovery.

Evidence of a greater onset threshold for sweating in females following intense exercise

We evaluated the hypothesis that females would show a greater postexercise hypotension and concurrently a greater increase in the onset threshold for sweating. Fourteen subjects (7 males and 7 females) of similar age, body composition, and fitness status participated in the study. Esophageal temperature was monitored as an index of core temperature while sweat rate was measured by using a ventilated capsule placed on the upper back. Subjects cycled at either 60% (moderate) or 80% (intense) of peak oxygen consumption (VO2speak) followed by 20-min recovery. Subjects then donned a liquid-conditioned suit used to regulate mean skin temperature. The skin was then heated (approximately 4.3 degrees C.h(-1)) until sweating occurred. Esophageal temperatures were similar to baseline before the start of whole body warming for all conditions. The postexercise threshold values for sweating following moderate and intense exercise were an esophageal temperature increase of 0.10+/-0.02 and 0.22+/-0.04 degrees C, respectively for males, and 0.15+/-0.03 and 0.34+/-0.01 degrees C, respectively for females. All were elevated above baseline resting (P<0.05) and a significant sex-related difference was observed for sweating threshold values following intense exercise (P<0.05). This was paralleled by a greater decrease in mean arterial pressure in females at the end of the 20-min recovery (P<0.05). In conclusion, females demonstrate a greater postexercise onset threshold for sweating, which is paralleled by a greater postexercise hypotensive response following intense exercise.

Disturbance of thermal homeostasis following dynamic exercise

Recovery from dynamic exercise results in significant perturbations of thermoregulatory control. These perturbations evoke a prolonged elevation in core body temperature and a concomitant decrease in sweating, skin blood flow, and skin temperature to pre-exercise baseline values within the early stages of recovery. Cutaneous vasodilation and sweating are critical responses necessary for effective thermoregulation during heat stress in humans. The ability to modulate the rate of heat loss through adjustments in vasomotor and sudomotor activity is a fundamental mechanism of thermoregulatory homeostasis. There is a growing body of evidence in support of a possible relationship between hemodynamic changes postexercise and heat loss responses. Specifically, nonthermoregulatory factors, such as baroreceptors, associated with hemodynamic changes, influence the regulation of core body temperature during exercise recovery. The following review will examine the etiology of the post-exercise disturbance in thermal homeostasis and evaluate possible thermal and nonthermal factors associated with a prolonged hyperthermic state following exercise.

Sex differences in postexercise esophageal and muscle tissue temperature response

Factors associated with blood pressure regulation during recovery from exercise dramatically influence core temperature regulation. However, it is unknown whether sex-related differences in postexercise hemodynamics affect core and muscle temperature response. Sixteen participants (8 males, 8 females) completed an incremental isotonic test on a Kin-Com isokinetic apparatus to determine their activity-specific peak oxygen consumption during bilateral knee extensions (V̇o2sp). On a separate day, participants performed 15 min of isolated bilateral knee extensions at a moderate (60% V̇o2sp) exercise intensity followed by a 90-min recovery. Esophageal temperature (Tes), mean arterial pressure (MAP), muscle temperature at four depths in the active vastus medialis (TVM) and three depths in the inactive triceps brachii (TTB) were measured concurrently with sweat rate and cutaneous vascular conductance (CVC). Relative to the preexercise resting Tes of 36.7°C (SD 0.1), between 10 and 50-min of recovery Tes was 0.19°C (SD 0.02) higher for females than males ( P = 0.037). All measurements of TVM (0.036 > P > 0.014) and TTB (0.048 > P > 0.008) were higher for females during the initial 30 min of recovery by between 0.46°C and 0.64°C for TVM and by between 0.53°C and 0.70°C for TTB. In parallel, females showed a 5 to 7 mmHg greater reduction in MAP during recovery relative to males ( P = 0.002) and a significantly lower CVC ( P = 0.020) and sweat rate ( P = 0.034). Therefore, it is concluded that females demonstrate a greater and more prolonged elevation in postexercise esophageal temperature and active and inactive muscle temperatures, which is paralleled by a greater postexercise hypotensive response.

Acute exercise and postexercise blood pressure in African American women

BACKGROUND

Limited data suggest that physical activity increases postexercise blood pressure in African-American women. The purpose of this study was to evaluate the postexercise blood pressure response to acute exercise in normotensive young adult African-American women.

METHODS

Eight healthy women (age 22.5+/-.9 years) performed a cycle ergometer bout of 30 minutes at 60% of peak ventilatory oxygen uptake (VO2 peak). Control arterial blood pressure, heart rate, lower leg blood flow, cardiac output, spectral analysis of blood pressure, heart rate variability, and baroreceptor sensitivity were measured for 5 minutes before exercise and were compared to postexercise measurements performed at rest intervals of 15-20, 35-40 and 55-60 minutes after exercise.

RESULTS

Exercise performed at 60% VO2 peak produced an arterial pressure of 172+/-10/ 70.1+/-4.0 mm Hg. Postexercise recovery values were not significantly different than the baseline control values.

CONCLUSION

These results do not support the hypothesis that acute physical activity exerts an adverse effect on postexercise blood pressure in African American women.

Effect of differences in post-exercise lactate accumulation in athletes' haemodynamics

To verify the relationship between exercise intensity and post-exercise haemodynamics, we studied haemodynamic and lactate responses during 10 min following 3 bicycle tests. Two tests were performed for 3 min at 70% and 130% of the workload corresponding to anaerobic threshold (70% W(at) and 130% W(at) tests), and 1 was performed until exhaustion at 150% of the maximum workload achieved during a previous incremental test (150% W(max) test). During the recovery period after the 150% W(max) test we observed the highest increases in blood lactate with respect to the baseline: at the 9th minute of recovery lactate concentration increased by +9.3 +/- 2.7, +6.4 +/- 3.1, and +1.1 +/- 0.9 mmol x L(-1) in the 150% W(max) (p > 0.05 with respect to the other protocol sessions), 130% W(at), and 70% W(at) tests, respectively. We also observed greater reductions in cardiac pre-load and systemic vascular resistance in the 150% W(max) test than in the 130% W(at) and 70% W(at) tests. However, the cardiac output response successfully faced the increased vasodilatation occurring during 150% W(max) test so that changes in mean blood pressure were similar in the 3 test conditions. This study shows that exercises that yielded different lactate concentrations also led to greater vasodilatation. Nevertheless, mechanisms controlling the cardiovascular apparatus successfully prevented a drop in blood pressure in spite of the cardiovascular stress.

Changes in finger-aorta pressure transfer function during and after exercise

Noninvasive finger blood pressure has become a surrogate for central blood pressure under widely varying circumstances. We tested the validity of finger-aorta transfer functions (TF) to reconstruct aortic pressure in seven cardiac patients before, during, and after incremental bicycle exercise. The autoregressive exogenous model method was used for calculating finger-aorta TFs. Finger pressure was measured noninvasively using Finapres and aortic pressure using a catheter-tip manometer. When applying the individual TFs found during rest for reconstruction of aortic pressure during all workloads, systolic pressure was increasingly underestimated, with large variation between subjects: +4.0 to −18.1 mmHg. In most subjects, diastolic pressure was overestimated: −3.9 to +5.5 mmHg. Pulse pressure estimation varied between +4.5 and −21.9 mmHg. In all cases, wave distortion was present. Postexercise, error in reconstructed aortic systolic pressure slowly declined, and diastolic pressure was overestimated. During rest, the TF gain had a minimum between 3.65 and 4.85 Hz (Fmin). During exercise, Fmin shifted to frequencies between 4.95 and 7.15 Hz at the maximum workload, with no change in gain. Postexercise, gain in most subjects shifted to values closer to unity, whereas Fmin did not return to resting values. Within each subject, aorta-Finapres travel time was linearly related to mean pressure. During exercise, Fmin was linearly related to both delay and heart rate. We conclude that, during increasing exercise, rest TFs give an increasingly unreliable reconstruction of aortic pressure, especially at higher heart rates.

Impact of moderate overweight and body composition on postexercise hemodynamic responses in healthy men

Postexercise hypotension (PEH) is a well-established phenomenon that may contribute to the antihypertensive mechanisms of exercise. The purpose of this study was to examine the impact of moderate overweight on postexercise hemodynamic responses in a group of healthy nonobese men (n = 16, aged 20.4+/-1.8 years) with apparently normal cardiovascular function at rest. Forearm blood flow, using strain gauge plethysmography, blood pressure, using a Finapres device, and cardiac output (CO), using impedance cardiography, were measured on a control day and on a separate day following a bout of moderate intensity exercise (20 min at 75% heart rate reserve). Linear regression analysis, adjusted for exercise intensity, revealed that body mass index (BMI) was associated with specific postexercise hemodynamic responses. Higher BMI was associated with greater reductions in CO and stroke volume, but lower reductions in total peripheral resistance. These findings suggest body composition impacts on mechanisms of PEH and should therefore be considered as an important confounding variable in future studies.

Acute exercise reduces vascular reactivity to mental challenge in offspring of hypertensive families

OBJECTIVE

To examine the effects of acute exercise on cardiac and vascular responses to mental challenge in males at risk of hypertension.

DESIGN

A within-subjects, counterbalanced design.

PARTICIPANTS

Normotensive, healthy males with (n = 22) and without (n = 8) family history of hypertension.

METHOD

A moderately stressful behavioural task was performed for 10 min after 20 min of moderate intensity cycle ergometry exercise, and on a separate occasion after an attentional control task. The blood pressure, heart rate, cardiac output, stroke volume, forearm blood flow, forearm vascular resistance, and total peripheral resistance were measured at rest, during the task, and at recovery. Stress reactivity was defined as the difference in values between the task and the baseline.

RESULTS

An enhanced peripheral vasodilatation response to the Stroop task was observed in men with familial risk of hypertension compared with the control group. However, this enhanced response was significantly blunted in offspring hypertensive participants following an acute bout of exercise so that differences in the vasodilatation response were no longer observed in comparison with men without familial risk of hypertension. The post-exercise heart rate reactivity in comparison with the control session was also significantly blunted in both groups (P < 0.05).

CONCLUSION

Acute exercise may be an important intervention strategy to reduce the impact of cardiovascular hyper-reactivity on disease progression in males with familial risk of hypertension.

Postexercise hypotension is not explained by a prostaglandin-dependent peripheral vasodilation

In normally active individuals, postexercise hypotension after a single bout of aerobic exercise occurs due to an unexplained peripheral vasodilation. Prostaglandin production has been suggested to contribute to the increases in blood flow during and after exercise; however, its potential contribution to postexercise hypotension has not been assessed. The purpose of this study was to determine the potential contribution of a prostaglandin-dependent vasodilation to changes in systemic vascular conductance underlying postexercise hypotension; this was done by inhibiting production of prostaglandins with the cyclooxygenase inhibitor ibuprofen. We studied 11 healthy normotensive men (aged 23.7 +/- 4.2 yr) before and during the 90 min after a 60-min bout of cycling at 60% peak O(2) uptake on a control and a cyclooxygenase inhibition day (randomized). Subjects received 10 mg/kg of oral ibuprofen on the cyclooxygenase inhibition day. On both study days, arterial blood pressure (automated auscultation) and cardiac output (acetylene uptake) were measured, and systemic vascular conductance was calculated. Inhibition of cyclooxygenase had no effect on baseline values of mean arterial pressure or systemic vascular conductance (P > 0.2). After exercise on both days, mean arterial pressure was reduced (-2.2 +/- 1.0 mmHg change with the control condition and -3.8 +/- 1.5 mmHg change with the ibuprofen condition, both P < 0.05 vs. preexercise) and systemic vascular conductance was increased (5.2 +/- 5.0% change with the control condition and 8.7 +/- 4.1% change with the ibuprofen condition, both P < 0.05 vs. preexercise). There were no differences between study days (P > 0.6). These data suggest that prostaglandin-dependent vasodilation does not contribute to the increased systemic vascular conductance underlying postexercise hypotension.

Light and diurnal cycle affect autonomic cardiac balance in human; possible role for the biological clock

The morning shift in cardiac sympatho-vagal balance seems involved in the increased risk of cardiovascular incidents at that time. To investigate the contribution of the biological clock in autonomic cardiac control, we investigated the presence of a diurnal rhythm independent of external factors, and of a circadian phase-dependent effect of moderate light in healthy volunteers. Recordings of heart rate (HR) and vagal and sympathetic cardiac tone were performed at different times over the day-night cycle during supine, awake, resting conditions, during exposure to different light intensities. The similarity between the diurnal rhythm in resting HR and that during previous constant routine conditions, demonstrated that our setup allowed accurate estimation of the endogenous circadian rhythm in HR. The present study suggests that, while a circadian rhythm in vagal cardiac tone is the main cause for the circadian rhythm in resting heart rate, the increase in sympathetic cardiac tone participates in the HR increase caused by early morning light.

Effect of exercise intensity on the postexercise sweating threshold

The hypothesis that the magnitude of the postexercise onset threshold for sweating is increased by the intensity of exercise was tested in eight subjects. Esophageal temperature was monitored as an index of core temperature while sweat rate was measured by using a ventilated capsule placed on the upper back. Subjects remained seated resting for 15 min (no exercise) or performed 15 min of treadmill running at either 55, 70, or 85% of peak oxygen consumption (V(o2 peak)) followed by a 20-min seated recovery. Subjects then donned a liquid-conditioned suit used to regulate mean skin temperature. The suit was first perfused with 20 degrees C water to control and stabilize skin and core temperature before whole body heating. Subsequently, the skin was heated ( approximately 4.0 degrees C/h) until sweating occurred. Exercise resulted in an increase in the onset threshold for sweating of 0.11 +/- 0.02, 0.23 +/- 0.01, and 0.33 +/- 0.02 degrees C above that measured for the no-exercise resting values (P < 0.05) for the 55, 70, and 85% of V(o2 peak) exercise conditions, respectively. We did note that there was a greater postexercise hypotension as a function of exercise intensity as measured at the end of the 20-min exercise recovery. Thus it is plausible that the increase in postexercise threshold may be related to postexercise hypotension. It is concluded that the sweating response during upright recovery is significantly modified by exercise intensity and may likely be influenced by the nonthermal baroreceptor reflex adjustments postexercise.

Cutaneous active vasodilation in humans during passive heating postexercise

The hypothesis that exercise causes an increase in the postexercise esophageal temperature threshold for onset of cutaneous vasodilation through an alteration of active vasodilator activity was tested in nine subjects. Increases in forearm skin blood flow and arterial blood pressure were measured and used to calculate cutaneous vascular conductance at two superficial forearm sites: one with intact alpha-adrenergic vasoconstrictor activity (untreated) and one infused with bretylium tosylate (bretylium treated). Subjects remained seated resting for 15 min (no-exercise) or performed 15 min of treadmill running at either 55, 70, or 85% of peak oxygen consumption followed by 20 min of seated recovery. A liquid-conditioned suit was used to increase mean skin temperature ( approximately 4.0 degrees C/h), while local forearm temperature was clamped at 34 degrees C, until cutaneous vasodilation. No differences in the postexercise threshold for cutaneous vasodilation between untreated and bretylium-treated sites were observed for either the no-exercise or exercise trials. Exercise resulted in an increase in the postexercise threshold for cutaneous vasodilation of 0.19 +/- 0.01, 0.39 +/- 0.02, and 0.53 +/- 0.02 degrees C above those of the no-exercise resting values for the untreated site (P < 0.05). Similarly, there was an increase of 0.20 +/- 0.01, 0.37 +/- 0.02, and 0.53 +/- 0.02 degrees C for the treated site for the 55, 70, and 85% exercise trials, respectively (P < 0.05). It is concluded that reflex activity associated with the postexercise increase in the onset threshold for cutaneous vasodilation is more likely mediated through an alteration of active vasodilator activity rather than through adrenergic vasoconstrictor activity.

Alpha-adrenergic vascular responsiveness during postexercise hypotension in humans

In sedentary individuals, postexercise hypotension following a single bout of aerobic exercise is due to an unexplained peripheral vasodilatation. We tested the hypothesis that alpha-adrenergic responsiveness in the forearm and leg vasculatures is blunted during postexercise hypotension. We studied 12 men and two women before and 30 min after a 60 min bout of cycling at 60 % VO2,peak. In the first five subjects, arterial pressure (brachial artery catheter) and forearm blood flow (plethysmography) were measured and vascular conductance was calculated during intraarterial infusions of the alpha1-agonist phenylephrine and the alpha2-agonist clonidine. Exercise reduced mean arterial pressure (89 +/- 2 vs. 95 +/- 2 mmHg, P < 0.05) and increased forearm vascular conductance 77 +/- 33 % (P < 0.05). Despite these changes in baseline vascular conductance, vasoconstrictor responses in the forearm to phenylephrine and clonidine were similar (or enhanced) postexercise vs. preexercise. In the remaining nine subjects, arterial pressure (femoral artery catheter) and leg blood flow (Doppler ultrasound of the femoral artery) were measured and vascular conductance was calculated during intraarterial infusions of phenylephrine and clonidine. Exercise reduced mean arterial pressure (80 +/- 2 vs. 89 +/- 2 mmHg, P < 0.05) and increased leg vascular conductance 94 +/- 16 % (P < 0.05). Despite these changes in baseline vascular conductance, vasoconstrictor responses in the leg to phenylephrine and clonidine were similar (or enhanced) postexercise vs. preexercise. These results suggest that vascular responsiveness to alpha-adrenergic agonists is maintained during postexercise hypotension in humans. Thus, while postexercise hypotension is associated with increased vascular conductance in the forearm and leg, it does not appear that blunting of alpha-adrenergic responsiveness is the cause.

Potential causes, mechanisms, and implications of post exercise hypotension

Post exercise hypotension (PEH) is a phenomenon of a prolonged decrease in resting blood pressure in the minutes and hours following acute exercise. Knowledge of PEH is potentially useful in designing first line strategies against hypertension as well as allowing a further understanding of blood pressure regulation in both health and disease. Following a brief review of blood pressure responses to exercise, this paper will provide a current and comprehensive summary of PEH and integrate the current state of knowledge surrounding it.

Effect of systemic nitric oxide synthase inhibition on postexercise hypotension in humans

An acute bout of aerobic exercise results in a reduced blood pressure that lasts several hours. Animal studies suggest this response is mediated by increased production of nitric oxide. We tested the extent to which systemic nitric oxide synthase inhibition [N(G)-monomethyl-L-arginine (L-NMMA)] can reverse the drop in blood pressure that occurs after exercise in humans. Eight healthy subjects underwent parallel experiments on 2 separate days. The order of the experiments was randomized between sham (60 min of seated upright rest) and exercise (60 min of upright cycling at 60% peak aerobic capacity). After both sham and exercise, subjects received, in sequence, systemic alpha-adrenergic blockade (phentolamine) and L-NMMA. Phentolamine was given first to isolate the contribution of nitric oxide to postexercise hypotension by preventing reflex changes in sympathetic tone that result from systemic nitric oxide synthase inhibition and to control for alterations in resting sympathetic activity after exercise. During each condition, systemic and regional hemodynamics were measured. Throughout the study, arterial pressure and vascular resistances remained lower postexercise vs. postsham despite nitric oxide synthase inhibition (e.g., mean arterial pressure after L-NMMA was 108.0+/-2.4 mmHg postsham vs. 102.1+/-3.3 mmHg postexercise; P<0.05). Thus it does not appear that postexercise hypotension is dependent on increased production of nitric oxide in humans.

The effect of submaximal exercise on recovery hemodynamics and thermoregulation in men and women

Five women and 5 men were studied to examine the effects of submaximal exercise on thermoregulatory and hemodynamic variables during recovery in two environments: (a) control (C), 22 degrees C, 33% rh; and (b) hot humid (H), 32 degrees C. The participants exercised on a cycle ergometer at 60% of peak oxygen consumption for 35 min prior to 90 min of seated recovery. Sessions were identical, except for environment. Variables evaluated (p < .05) were: core temperature (TR), mean skin temperature (Ts), sweat rate (SR), heart rate (HR), stroke index (SI), cardiac index (CI), forearm blood flow (FBF), systolic blood pressure (SBP), and diastolic blood pressure (DBP). Men and women exhibited similar patterns of TR, Ts, and SR in both environments. Ts and SR (collapsed means for gender) were higher in the H than in the C. DBP was higher in men than in women throughout recovery in both environments. With combined means for gender, HR was higher in the H than in the C. CI, SI, FBF, and SBP were similar in both environments and returned to baseline within 15 min into recovery. These data suggest that heat dissipation during extended recovery was accomplished with similar contributions of cutaneous vasodilation and sweating in M and F. Furthermore, the moderate exercise level did not influence hemodynamics beyond 15 min of recovery in either environment.

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.

Post-exercise changes in blood pressure, heart rate and rate pressure product at different exercise intensities in normotensive humans

To evaluate the effect of exercise intensity on post-exercise cardiovascular responses, 12 young normotensive subjects performed in a randomized order three cycle ergometer exercise bouts of 45 min at 30, 50 and 80% of VO2peak, and 12 subjects rested for 45 min in a non-exercise control trial. Blood pressure (BP) and heart rate (HR) were measured for 20 min prior to exercise (baseline) and at intervals of 5 to 30 (R5-30), 35 to 60 (R35-60) and 65 to 90 (R65-90) min after exercise. Systolic, mean, and diastolic BP after exercise were significantly lower than baseline, and there was no difference between the three exercise intensities. After exercise at 30% of VO2peak, HR was significantly decreased at R35-60 and R65-90. In contrast, after exercise at 50 and 80% of VO2peak, HR was significantly increased at R5-30 and R35-60, respectively. Exercise at 30% of VO2peak significantly decreased rate pressure (RP) product (RP = HR x systolic BP) during the entire recovery period (baseline = 7930 +/- 314 vs R5-30 = 7150 +/- 326, R35-60 = 6794 +/- 349, and R65-90 = 6628 +/- 311, P < 0.05), while exercise at 50% of VO2peak caused no change, and exercise at 80% of VO2peak produced a significant increase at R5-30 (7468 +/- 267 vs 9818 +/- 366, P < 0.05) and no change at R35-60 or R65-90. Cardiovascular responses were not altered during the control trial. In conclusion, varying exercise intensity from 30 to 80% of VO2peak in young normotensive humans did not influence the magnitude of post-exercise hypotension. However, in contrast to exercise at 50 and 80% of VO2peak, exercise at 30% of VO2peak decreased post-exercise HR and RP.

Non-invasive assessment of the changes in static and oscillatory components of peripheral pressure/flow relationships produced by moderate exercise in humans

OBJECTIVE

The generalized sympathetic activation induced by exercise is accompanied by an increase in heart rate, blood pressure and vascular resistance in non-exercising vascular beds. The aim of the present study was to test the feasibility of assessing, non-invasively, the static and oscillatory pressure/flow relationships of peripheral arteries and their continuous changes during dynamic exercise.

DESIGN

We studied 44 healthy humans at rest, during moderate exercise (recumbent bicycle exercise) and recovery using a totally non-invasive approach.

METHODS

Arterial pressure was measured using a plethysmographic device, and ipsilateral brachial artery flow and palmar skin microcirculation flow were assessed with continuous wave Doppler and laser Doppler, respectively. Continuous, long data segments (> 90 s) were acquired with a personal computer and used to determine the changes of pressure/flow relationships of peripheral arteries during dynamic exercise. A new simplified method utilizing a transfer function analysis extracted automatically unequivocal indexes of static and oscillatory properties of vascular system.

RESULTS

Moderate exercise induced significant increases of the static (Zo) and oscillatory (Zc) components of peripheral pressure/flow relationships in both brachial artery and skin microcirculation beds. Both indexes returned to control values during early recovery.

CONCLUSIONS

This simple, non-invasive approach was capable of assessing the changes of static and oscillatory vascular properties induced by dynamic exercise. This method could be applied for a better understanding of the vascular modifications that occur in other physiological or pathophysiological conditions also characterized by increases in sympathetic drive.

After-effects of exercise on haemodynamics and muscle sympathetic nerve activity in young patients with dilated cardiomyopathy

OBJECTIVE

To determine the after-effects on sympathetic nerve activity and calf and systemic haemodynamics of symptom-limited exercise in young patients with dilated cardiomyopathy.

PATIENTS

14 young patients with dilated cardiomyopathy (mean (SEM) age 35 (2) yr) and 17 healthy controls (age 29 (2) yr).

METHODS

Blood pressure, muscle sympathetic nerve activity, calf blood flow, plasma noradrenaline, and stroke volume were recorded during baseline rest and an hour after symptom-limited treadmill exercise (up to 45 min) at 70% of resting heart rate reserve.

RESULTS

Before exercise, sympathetic nerve activity (45 (6) v 21 (2) bursts.min-1; P = 0.001) and calf vascular resistance (55 (5) v 31 (3) units; P < 0.0005) were higher in the dilated cardiomyopathy group, and there was a significant correlation between these two variables (r = +0.64; P < 0.001). Patients with ventricular dysfunction exercised for 31 (3) min. In both groups there were significant and similar reductions in diastolic blood pressure, total peripheral resistance, and calf vascular resistance after exercise. Sympathetic nerve activity and plasma noradrenaline were unchanged and there was no longer any relation between muscle sympathetic nerve activity and calf vascular resistance. Cardiac output increased in both groups but, in contrast to healthy controls, mean values for systolic blood pressure and stroke volume (P < 0.005) did not decrease in the cardiomyopathy group. For similar reductions in total peripheral resistance, there were two to three fold greater increases in stroke volume after exercise in patients with left ventricular dysfunction (P < 0.03). There was no relation between exercise duration and the magnitude of these after-effects of exercise in these patients.

CONCLUSIONS

In young patients with dilated cardiomyopathy the haemodynamic after-effects of submaximal symptom-limited exercise resemble responses to pharmacological afterload reduction but are not accompanied by reflex sympathetic activation. Sustained calf and systemic vasodilation after exercise were not attenuated, as compared with healthy controls. These cardiac, peripheral, and sympathoneural after-effects provide further support for exercise training as a non-pharmacological adjunct to the management of chronic stable heart failure.