Antihypertensive and volume-depleting effects of mild exercise on essential hypertension

The renoprotective potential of montelukast: a scoping review

Introduction

Kidney damage can result from various factors, leading to structural and functional changes in the kidney. Acute kidney injury (AKI) refers to a sudden decline in kidney function, while chronic kidney disease involves a gradual deterioration lasting more than 3 months. Mechanisms of renal injury include impaired microcirculation, inflammation, and oxidative stress. Cysteinyl-leukotrienes (CysLTs) are inflammatory substances contributing to tissue damage. Montelukast, a leukotriene receptor antagonist, has shown potential renoprotective effects in experimental models of kidney injury.

Methods

The authors conducted a scoping review using PubMed, Scopus, and Web of Science databases to identify relevant studies investigating the impact of montelukast on renal diseases. Articles published until 2022 were included and evaluated for quality. Data extraction and analysis were performed based on predetermined inclusion criteria.

Results

The scoping review included 30 studies from 8 countries. Montelukast demonstrated therapeutic effects in various experimental models of nephrotoxicity and AKI induced by agents such as cisplatin, lipopolysaccharide, diclofenac, amikacin, Escherichia coli, cyclosporine, methotrexate, cobalt-60 gamma radiation, doxorubicin, and cadmium. Studies involving human subjects with nephrotic syndrome, pyelonephritis, and other renal diseases also reported positive outcomes with montelukast treatment. Montelukast exhibited anti-inflammatory, anti-apoptotic, antioxidant, and neutrophil-inhibiting properties, leading to improved kidney function and histopathological changes.

Conclusions

Montelukast shows promise as a renoprotective medication, particularly in early-stage kidney injury. Its ability to mitigate inflammation, oxidative stress, and neutrophil infiltration contributes to its therapeutic effects. Further research is needed to explore the clinical applications and mechanisms underlying the renoprotective action of montelukast.

Effect of exercise training on the renin-angiotensin-aldosterone system: a meta-analysis

Blood pressure (BP) management reduces the risk of cardiovascular disease (CVD). The renin-angiotensin-aldosterone system (RAAS) plays an important role in regulating and maintaining blood volume and pressure. This analysis aimed to investigate the effect of exercise training on plasma renin, angiotensin-II and aldosterone, epinephrine, norepinephrine, urinary sodium and potassium, BP and heart rate (HR). We systematically searched PubMed, Web of Science, and the Cochrane Library of Controlled Trials until 30 November 2022. The search strategy included RAAS key words in combination with exercise training terms and medical subject headings. Manual searching of reference lists from systematic reviews and eligible studies completed the search. A random effects meta-analysis model was used. Eighteen trials with a total of 803 participants were included. After exercise training, plasma angiotensin-II (SMD -0.71; 95% CI -1.24, -0.19; p = 0.008; n = 9 trials), aldosterone (SMD -0.37; 95% CI -0.65, -0.09; p = 0.009; n = 8 trials) and norepinephrine (SMD -0.82; 95% CI -1.18, -0.46; p < 0.001; n = 8 trials) were reduced. However, plasma renin activity, epinephrine, and 24-h urinary sodium and potassium excretion remained unchanged with exercise training. Systolic BP was reduced (MD -6.2 mmHg; 95% CI -9.9, -2.6; p = 0.001) as was diastolic BP (MD -4.5 mmHg; 95% CI -6.9, -2.1; p < 0.001) but not HR (MD -3.0 bpm; 95% CI -6.0, 0.4; p = 0.053). Exercise training may reduce some aspects of RAAS and sympathetic nervous system activity, and this explains some of the anti-hypertensive response.

Aerobic training-mediated DNA hypermethylation of Agtr1a and Mas1 genes ameliorate mesenteric arterial function in spontaneously hypertensive rats

BACKGROUND

The imbalance of vasoconstrictor and vasodilator axes of the renin-angiotensin system (RAS) is observed in hypertension. Exercise regulates RAS level and improves vascular function. This study focused on the contribution of RAS axes in vascular function of mesenteric arteries and exercise-induced DNA methylation of the Agtr1a (AT_1aR) and Mas1 (MasR) genes in hypertension.

METHODS

Spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats were randomized into exercise or sedentary group. Levels of plasma RAS components, vascular tone, and DNA methylation markers were measured.

RESULTS

Blood pressure of SHR was markedly reduced after 12 weeks of aerobic exercise. RAS peptides in plasma were all increased with an imbalanced upregulation of Ang II and Ang-(1-7) in SHR, exercise revised the level of RAS and increased Ang-(1-7)/Ang II. The vasoconstriction response induced by Ang II was mainly via type 1 receptors (AT₁R), while this contraction was inhibited by Mas receptor (MasR). mRNA and protein of AT₁R and MasR were both upregulated in SHR, whereas exercise significantly suppressed this imbalanced increase and increased MasR/AT₁R ratio. Exercise hypermethylated Agtr1a and Mas1 genes, associating with increased DNMT1 and DNMT3b and SAM/SAH.

CONCLUSIONS

Aerobic exercise ameliorates vascular function via hypermethylation of the Agtr1a and Mas1 genes and restores the vasoconstrictor and vasodilator axes balance.

Effect of virtual reality-simulated exercise on sympathovagal balance

Discovery of therapeutic avenues to provide the benefits of exercise to patients with enforced sedentary behavior patterns would be of transformative importance to health care. Work in model organisms has demonstrated that benefits of exercise can be provided to stationary animals by daily intermittent stimulation of adrenergic signaling. Here, we examine as a proof of principle whether exposure of human participants to virtual reality (VR) simulation of exercise can alter sympathovagal balance in stationary humans. In this study, 24 participants performed 15 minutes of cycling exercise at standardized resistance, then repeated the exercise with a virtual reality helmet that provided an immersive environment. On a separate day, they each controlled a virtual environment for 15 minutes to simulate exercise without actual cycling exercise. Response to each treatment was assessed by measuring heart rate (HR), norepinephrine, and heart rate variability, and each participant's response to virtual exercise was compared internally to his/her response to the actual cycling. We found that neither post-exercise norepinephrine nor post-exercise HR was significantly increased by VR simulation. However, heart rate variability measured during virtual exercise was comparable to actual cycling in participants that engaged in moderate exercise, but not in those that engaged in high-intensity exercise. These findings suggest that virtual exercise has the potential to mimic some effects of moderate exercise. Further work will be needed to examine the longitudinal effects of chronic exposure to VR-simulated exercise.

Rationale, design and study protocol of the randomised controlled trial: Diabetes Interventional Assessment of Slimming or Training tO Lessen Inconspicuous Cardiovascular Dysfunction (the DIASTOLIC study)

INTRODUCTION

Despite their young age and relatively short duration of disease, younger adults with type 2 diabetes (T2D) already have diastolic dysfunction and may be at risk of incipient heart failure. Whether weight loss or exercise training improve cardiac dysfunction in people with T2D remains to be established.

METHODS AND ANALYSIS

Prospective, randomised, open-label, blind endpoint trial. The primary aim of the study is to determine if diastolic function can be improved by either a meal replacement plan or a supervised exercise programme, compared with guideline-directed care. A total of 90 obese participants with T2D (aged 18-65 years), diabetes duration <12 years and not on insulin treatment will be randomised to either guideline-directed clinical care with lifestyle coaching, a low-energy meal replacement diet (average ≈810 kcal/day) or a supervised exercise programme for 12 weeks. Participants undergo glycometabolic profiling, cardiopulmonary exercise testing, echocardiography and MRI scanning to assesses cardiac structure and function and dual-energy X-ray absorptiometry scanning for body composition. Key secondary aims are to assess the effects of the interventions on glycaemic control and insulin resistance, exercise capacity, blood pressure, changes in body composition and association of favourable cardiac remodelling with improvements in weight loss, exercise capacity and glycometabolic control.

ETHICS AND DISSEMINATION

The study has full ethical approval, and data collection was completed in August 2018. The study results will be submitted for publication within 6 months of completion.

TRIAL REGISTRATION NUMBER

NCT02590822; Pre-results.

Effects of Exercise on the Resting Heart Rate: A Systematic Review and Meta-Analysis of Interventional Studies

Resting heart rate (RHR) is positively related with mortality. Regular exercise causes a reduction in RHR. The aim of the systematic review was to assess whether regular exercise or sports have an impact on the RHR in healthy subjects by taking different types of sports into account. A systematic literature research was conducted in six databases for the identification of controlled trials dealing with the effects of exercise or sports on the RHR in healthy subjects was performed. The studies were summarized by meta-analyses. The literature search analyzed 191 studies presenting 215 samples fitting the eligibility criteria. 121 trials examined the effects of endurance training, 43 strength training, 15 combined endurance and strength training, 5 additional school sport programs. 21 yoga, 5 tai chi, 3 qigong, and 2 unspecified types of sports. All types of sports decreased the RHR. However, only endurance training and yoga significantly decreased the RHR in both sexes. The exercise-induced decreases of RHR were positively related with the pre-interventional RHR and negatively with the average age of the participants. From this, we can conclude that exercise-especially endurance training and yoga-decreases RHR. This effect may contribute to a reduction in all-cause mortality due to regular exercise or sports.

Regular aerobic exercise and blood pressure in East Asians: A meta-analysis of randomized controlled trials

The aim of this meta-analysis was to evaluate the effects of regular aerobic exercise on blood pressure in East Asians. The inclusion criteria of the randomized controlled trials were healthy East Asian adults, exercise group performing regular aerobic exercise and control group not exercising, and a description of the mean systolic blood pressure or diastolic blood pressure at rest. This study included 31 study groups and 1994 subjects. Pooled changes in blood pressure showed significant reductions (systolic blood pressure: -4.7 mmHg; diastolic blood pressure: -3.2 mmHg). In subgroup analyses, the change in systolic blood pressure for randomized controlled trials meeting the America Heart Association and American College of Sports Medicine guidelines for physical activity to maintain health was significantly larger than in randomized controlled trials not meeting the guidelines. In addition, meta-regression indicated that the change in systolic blood pressure was significantly related to "exercise time × exercise frequency." The ideal volume of exercise is that for a long time at a high frequency, such as the volume recommended in the America Heart Association and American College of Sports Medicine guidelines: moderate intensity and >150 min per week. List of abbreviations: BP: blood pressure; BMI: body mass index; SBP: systolic blood pressure; DBP: diastolic blood pressure; RCT: randomized controlled trial; AHA: America Heart Association; ACSM: America College of Sports Medicine; SD: standard deviation; HDL-C: high-density lipoprotein cholesterol; LDL-C: low-density lipoprotein cholesterol; TC: total cholesterol; TG: triglycerides; PEDro: Physiotherapy Evidence Database; CI: confidence intervals; %HR_max: percentage of maximal heart rate.

Visit-to-Visit Variability and Reduction in Blood Pressure After a 3-Month Cardiac Rehabilitation Program in Patients With Cardiovascular Disease

Visit-to-visit variability (VVV) in blood pressure (BP) has been shown to be a predictor of cardiovascular events. It is unknown whether CR can improve VVV in BP as well as reducing BP. We enrolled 84 patients who had cardiovascular disease (CVD) and participated in a 3-month CR program. We measured systolic and diastolic BP (SBP and DBP), pulse pressure (PP), and heart rate (HR) before exercise training at each visit and determined VVV in BP or HR expressed as the standard deviation of the average BP or HR. Patients who had uncontrolled BP at baseline and who did not change their antihypertensive drugs throughout the study period showed a significant reduction of both SBP and DBP with a decrease in PP after 3 months. Patients who did not change their antihypertensive drugs were divided into larger (L-) and smaller (S-) VVV in the SBP groups and L- and S-VVV in the DBP groups according to the average value of VVV in SBP or DBP. In the L-VVV in the SBP and DBP groups, VVV in SBP and DBP in the 1st month was significantly decreased after the 3rd month in both groups. HR at baseline was significantly decreased after 3 months. In addition, CR induced a significant increase in the level of high-density lipoprotein cholesterol (HDL-C) in blood. In conclusion, CR improved VVV in BP in patients with L-VVV in BP and evoked a significant reduction in HR and an increase in HDL-C. These effects due to the CR program may be cardioprotective.

Randomized Controlled Trial on Lifestyle Modification in Hypertensive Patients

The authors examined the effects of a comprehensive lifestyle modification intervention on blood pressure (BP) and other cardiovascular risk factors in hypertensive patients. A total of 70 participants were randomly placed into either a lifestyle intervention or a control group. Four education classes and individual counseling sessions were held for the intervention group. Participants in the control group were provided with routine outpatient services and were asked to maintain their usual lifestyle. Data were gathered at baseline and at the end of 6 months. At the end of 6 months, BP, body weight, body mass index, waist circumference, and fasting lipids, apart from high-density lipoprotein cholesterol, significantly declined in the intervention group. Healthpromoting lifestyle scores of the intervention group had increased significantly compared to those of the control group. In conclusion, the results demonstrate the feasibility of comprehensive lifestyle modification and show its beneficial effects.

The Importance of Walking for Control of Blood Pressure: Proof Using a Telemedicine System

BACKGROUND

Regular physical activity (PA), including daily walking, reduces the risk of many chronic diseases, especially hypertension. Pedometer is a potential motivational aid for increasing PA. In the present study, we used a telemedicine system and analyzed the relationship between daily walking, calculated by pedometers, and blood pressure (BP).

METHODS

BP was measured at home twice a day (morning and evening) using an oscillometric automatic device. Body weight (BW) and percent body fat (%BF) were measured after BP measurement. Daily walking steps (DWS) were calculated by a pedometer. These daily parameters were transmitted through the Internet to a central server computer and sent to the Medical Health Center.

RESULTS

Sixty-nine (N = 69) hypertensive patients were included in this study. The mean follow-up period was 378 days. Electronic data from a pedometer (DWS) were associated with reduced BW, body mass index, and %BF. Hypertensive patients were divided into two groups based on the DWS. In the high DWS group, morning systolic BP and diastolic BP and evening systolic BP were reduced after induction of the telemedicine system.

CONCLUSION

A telemedicine system confirmed the usefulness of walking to control BP in hypertensive patients.

Effect of exercise training on the renin-angiotensin-aldosterone system in healthy individuals: a systematic review and meta-analysis

The aim of this systematic review and meta-analysis was to evaluate the effect of exercise training on parameters of the renin-angiotensin-aldosterone system (RAAS) in healthy adults, and to investigate the relation with training induced changes in blood pressure. A systematic search was conducted and we included randomized controlled trials lasting ⩾4 weeks investigating the effects of exercise on parameters of the RAAS in healthy adults (age ⩾18 years) and published in a peer-reviewed journal up to December 2013. Fixed effects models were used and data are reported as weighted means and 95% confidence limits (CL). Eleven randomized controlled trials with a total of 375 individuals were included. Plasma renin activity was reduced after exercise training (n= 7 trials, standardized mean difference -0.25 (95% CL -0.5 to -0.001), P=0.049), whereas no effect was observed on serum aldosterone ((n= 3 trials; standardized mean difference -0.79 (-1.97 to +0.39)) or angiotensin II (n=3 trials; standardized mean difference -0.16 (-0.61 to +0.30). Significant reductions in systolic blood pressure -5.65 mm Hg (-8.12 to -3.17) and diastolic blood pressure -3.64 mm Hg (-5.4 to -1.91) following exercise training were observed. No relation was found between net changes in plasma renin activity and net changes in blood pressure (P>0.05). To conclude, although we observed a significant reduction in plasma renin activity following exercise training this was not related to the observed blood pressure reduction. Given the small number of studies and small sample sizes, larger well-controlled randomized studies are required to confirm our results and to investigate the potential role of the RAAS in the observed improvements in blood pressure following exercise training.

Effects of exercise training on arterial stiffness in older hypertensive females

PURPOSE

Regular physical exercise is recommended for the prevention and treatment of cardiovascular disease. However, it is unclear whether the effects of exercise training on arterial stiffness are the same in older hypertensive individuals as those observed in older healthy subjects. The aim of this study was to compare the effects of exercise training on arterial stiffness between older hypertensive and healthy females.

METHODS

Ninety-two females with untreated hypertension and 108 healthy females were randomly assigned to either the control group or to participate in a 12-week training program. In the training groups, the subjects engaged in 90 min of training twice a week for 12 weeks. Each training program included recreational activities, six to eight resistance exercises for circuit training and chair-based exercise for the lower extremities. The systolic/diastolic blood pressure (SBP/DBP) and brachial to ankle pulse wave velocity (baPWV) were obtained in the supine position using an automatic pulse wave form analyzer.

RESULTS

Compared with that observed in the control group, greater reductions in the baPWV and SBP/DBP were achieved in both training groups (P < 0.05). Furthermore, a significant difference in the delta baPWV values obtained before and after training was noted between the hypertensive (-72.5 ± 8.1 cm s(-1)) and healthy females (-131.5 ± 107.3 cm s(-1)) who participated in the training program (P < 0.05).

CONCLUSIONS

These data indicate that exercise training produces fewer improvements in arterial stiffness in older hypertensive females than in older healthy females.

Predictive impact of daily physical activity on new vascular events in patients with mild ischemic stroke

BACKGROUND

Daily physical inactivity is associated with a substantially increased risk of cardiovascular events. However, the target level of daily physical activity remains unclear.

AIM

We aimed to evaluate the impact of physical activity on long-term vascular events in patients with mild ischemic stroke.

METHODS

We designed a single hospital-based prospective observational study and studied 166 ischemic stroke patients (mean age: 63.9 ± 9.2) who had a modified Rankin Scale 0-1. We measured the daily step count as a variable of the daily physical activity after three-months from the stroke onset. Other clinical characteristics including age, body mass index, blood pressure, blood laboratory tests, vascular function and medications were also assessed. The primary outcomes were hospitalization due to stroke recurrence, myocardial infarction, angina pectoris and peripheral artery disease. Survival curves were calculated by a Kaplan-Meier survival analysis, and the hazard ratios for recurrences were determined by univariate and multivariate Cox proportional hazards regression models.

RESULTS

After a median follow-up periods of 1332 days, 34 vascular events (23 stroke recurrences, 11 coronary artery disease) and 7 drop-outs occurred, and the remaining patients were divided into two groups: the without recurrence group (n = 125) and the with recurrence group (n = 34). The daily step count was lower in the nonsurvivor group than in the survivor group. Univariate and multivariate Cox proportional hazards analyses revealed that the daily step counts was independent predictors of new vascular events. A daily step count cutoff value of 6025 steps per day was determined by analyzing the receiver-operating characteristics that showed a sensitivity of 69.4% and a specificity of 79.4%. The Kaplan-Meier survival curves after a log-rank test showed a significantly lower event rate in the more than 6025 steps per day group compared with the less than 6025 steps per day group (P = 0.0002). The positive and negative predictive values of less than 6025 steps were 38.0% and 91.6%, respectively.

CONCLUSION

Our data indicate that daily physical activity evaluated by step counts may be useful for forecasting the prognosis in patients with mild ischemic stroke. Daily step counts of approximately 6000 steps per day may be an initial target level for reducing new vascular events.

[Hypertension and exercise]

Levels of physical activity in modern urbanized society are clearly insufficient to maintain good health, and to prevent cardiovascular and other disease. Aerobic exercise is almost completely free of secondary effects, and is a useful adjunctive therapy in treating hypertension. There are several possible mechanisms to account for the beneficial effects of exercise in reducing blood pressure, the resulting physiological effects usually being classified as acute, post-exercise or chronic. Variations in genetic background, hypertension etiology, pharmacodynamics and pharmacokinetics may explain the different blood pressure responses to exercise among hypertensive patients. The present review discusses the different pathophysiological aspects of the response to exercise in hypertensives, including its modulators and diagnostic and prognostic usefulness, as well as the latest guidelines on prescribing and monitoring exercise regimes and drug therapy in the clinical follow-up of active hypertensive patients.

Long-term effects of home-based bench-stepping exercise training on healthcare expenditure for elderly Japanese

Background

We examined the long-term effects of home-based bench-stepping exercise training on total healthcare expenditure (TOHEX) and number of outpatient visits (NOVIS) in elderly adults.

Methods

A total of 189 elderly Japanese (age 73 ± 4 years) participated in this study. They were randomly assigned to either an exercise or control group. TOHEX, NOVIS, and outpatient expenditure (OPEX) were evaluated every 6 months from 1 year before the start to the end of the intervention period, as well as 1 year after the end of the intervention. The exercise group was encouraged to perform home-based bench-stepping exercise training on most, and preferably all, days of the week for 18 months.

Results

The exercise group showed significant increases in lactate threshold as compared with pre-intervention values. There were no significant differences in TOHEX, OPEX, or NOVIS between the exercise and control groups 1 year before the start of the intervention, and the values remained similar during the first 12 months of the intervention period. However, at 18 months, TOHEX, NOVIS, and OPEX were significantly lower in the exercise group than in the control group (TOHEX: 170 007 ± 192 072 vs. 294 705 ± 432 314 yen, P = 0.008; NOVIS: 19.2 ± 26.3 vs. 28.2 ± 32.1 days, P = 0.012; OPEX: 132 973 ± 132 016 vs. 187 799 ± 158 167 yen, P = 0.005).

Conclusions

The data indicate that a long-term home-based bench-stepping exercise program can reduce healthcare expenditure in elderly Japanese.

Lifestyle Modifications for Its Prevention and Management

Therapeutic lifestyle changes (TLC) are important for the prevention and management of, as well as adjuncts to, pharmacotherapy of hypertension. This article reviews relevant TLC and their effects on blood pressure (BP) levels, with emphasis on exercise and dietary habits. Regular, moderate-intensity (40%-70% of heart rate reserve) aerobic exercise training for 30 to 60 minutes, 3 to 5 times per week, can lower systolic and diastolic BP levels, with a greater reduction observed in patients with hypertension compared with those with normal BP levels. A diet rich in fruits, vegetables, and whole grains, with a moderate intake of fat-free or low-fat dairy products, and low in saturated and total fat, sodium, and alcohol, such as the Dietary Approaches to Stop Hypertension eating pattern, also significantly reduces BP levels. A TLC program including regular exercise and dietary modifications along with weight management appears to result in a greater BP reduction than either intervention alone. TLC can also significantly reduce other risk factors for cardiovascular disease commonly accompanying hypertension. Multiple mechanisms appear to contribute to BP reduction by dietary intervention (reduced weight, sodium, and alcohol and increased calcium, potassium, and magnesium). For exercise, these include improvements in arterial endothelial function and compliance, left ventricular structure and function, and perhaps vascular blood supply with increased cardiorespiratory endurance. The available evidence is robust in support of TLC for management of elevated BP and for the primary prevention of hypertension, supporting the recommendations by the Joint National Committee Seventh Report on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.

Habitual exercise for the elderly

Available research indicates that participation in a regular exercise program is an effective intervention to reduce and prevent a number of functional and health-associated impairments known to occur with advancing age. Functional benefits of regular exercise include increases in cardiovascular fitness, muscle strength, and functional capacity, allowing older individuals to maintain their independence and freely participate in daily activities. In addition, habitual exercise, endurance training, or both can prevent or markedly attenuate the age-related increases in risk factors for coronary heart disease. Taken together, these benefits associated with regular exercise can significantly improve the quality of life in older populations.

Low-intensity voluntary running lowers blood pressure with simultaneous improvement in endothelium-dependent vasodilatation and insulin sensitivity in aged spontaneously hypertensive rats

Our objective is to examine the effects of voluntary running at different intensity levels on blood pressure, endothelium-dependent vessel dysfunction and insulin resistance in aged spontaneously hypertensive rats (SHR) with severe hypertension. Ten-month-old male and female SHR with severe hypertension were assigned to voluntary running at either low intensity (30% of maximal aerobic velocity) or moderate intensity (60% of maximal aerobic velocity) on a motor-driven treadmill for 6 weeks, 20 min per day and 7 days per week. Age-matched Wistar-Kyoto rats and SHR were kept under sedentary conditions as controls. Blood pressure and heart rate were measured by the tail-cuff method. At the end of the exercise training, blood samples were collected for glucose, insulin and lipids assay, and aortae were isolated to examine their function in vitro. Low-intensity but not moderate-intensity running significantly lowered blood pressure in both male and female SHR (p<0.01). There was significant impairment in acetylcholine-induced vasorelaxation in SHR (p<0.01), which was improved by low-intensity training (p<0.05). Nitric oxide synthase blockade abrogated the improvement in endothelium-dependent relaxation. Hypertensive rats had elevated blood glucose and insulin levels with lowered insulin sensitivity that was ameliorated by low-intensity running. A significant increase in blood high-density lipoprotein (HDL)-cholesterol and a significant decrease in triglycerides were found in exercised SHR. In conclusion, low-intensity voluntary exercise lowers hypertension in aged SHR with severe hypertension. Exercise-induced simultaneous improvement in endothelium-dependent vessel relaxation and insulin sensitivity may act concomitantly in attenuating cardiovascular risk factors in aged hypertensive rats with significantly high blood pressure.

The alpha-adducin Gly460Trp polymorphism and the antihypertensive effects of exercise among men with high blood pressure

The alpha-adducin Gly460Trp polymorphism alters renal sodium transport and is associated with hypertension. Despite the immediate sodium- and volume-depleting effects of aerobic exercise, the influence of the alpha-adducin Gly460Trp polymorphism on PEH (postexercise hypotension) has not been studied. In the present study we examined the effects of the alpha-adducin Gly460Trp polymorphism on PEH among 48 men (42.6+/-1.6 years; mean+/-S.E.M.) with high BP (blood pressure; 144.0+/-1.7/84.7+/-1.1 mmHg). Subjects completed three experiments: non-exercise control and two cycle exercise sessions at 40% (light exercise) and 60% (moderate exercise) of maximal oxygen consumption. Subjects left the laboratory wearing an ambulatory BP monitor. PCR and restriction enzyme digestion determined the genotypes. No subjects had the Trp460Trp genotype due to the low frequency of 5% in the population. Repeated measure ANCOVA tested whether BP differed over time between experimental conditions and genotypes (Gly460Gly, n=36; Gly460Trp, n=12). Among Gly460Gly genotypes, SBP (systolic BP) was reduced by 5.2+/-1.4 mmHg after moderate exercise compared with non-exercise controls over 9 h (P<0.01). Among Gly460Trp genotypes, SBP was lowered by 7.8+/-2.3 mmHg; after light exercise compared with non-exercise controls over 9 h (P<0.05). The SBP reductions after light exercise (0.6+/-1.3 compared with 7.8+/-2.3 mmHg; P<0.05) but not moderate exercise (5.2+/-1.4 compared with 3.8+/-2.4 mmHg; P> or =0.05) differed between the Gly460Gly and Gly460Trp genotypes respectively. Men with Gly460Gly had a reduced SBP after moderate exercise, whereas men with Gly460Trp had a reduced SBP after light exercise. However, only the SBP reductions after light exercise differed between genotypes. Our findings indicate that the alpha-adducin Gly460Trp genotype may be useful in identifying men who have a reduced BP after lower intensity aerobic exercise.

Evidence for prescribing exercise as therapy in chronic disease

Considerable knowledge has accumulated in recent decades concerning the significance of physical activity in the treatment of a number of diseases, including diseases that do not primarily manifest as disorders of the locomotive apparatus. In this review we present the evidence for prescribing exercise therapy in the treatment of metabolic syndrome-related disorders (insulin resistance, type 2 diabetes, dyslipidemia, hypertension, obesity), heart and pulmonary diseases (chronic obstructive pulmonary disease, coronary heart disease, chronic heart failure, intermittent claudication), muscle, bone and joint diseases (osteoarthritis, rheumatoid arthritis, osteoporosis, fibromyalgia, chronic fatigue syndrome) and cancer, depression, asthma and type 1 diabetes. For each disease, we review the effect of exercise therapy on disease pathogenesis, on symptoms specific to the diagnosis, on physical fitness or strength and on quality of life. The possible mechanisms of action are briefly examined and the principles for prescribing exercise therapy are discussed, focusing on the type and amount of exercise and possible contraindications.

Lifestyle interventions to reduce raised blood pressure: a systematic review of randomized controlled trials

PURPOSE

To quantify effectiveness of lifestyle interventions for hypertension.

DATA SOURCES

Electronic bibliographic databases from 1998 onwards, existing guidelines, systematic reviews.

STUDY SELECTION AND DATA ABSTRACTION

We included randomized, controlled trials with at least 8 weeks' follow-up, comparing lifestyle with control interventions, enrolling adults with blood pressure at least 140/85 mmHg. Primary outcome measures were systolic and diastolic blood pressure. Two independent reviewers selected trials and abstracted data; differences were resolved by discussion.

RESULTS

We categorized trials by type of intervention and used random effects meta-analysis to combine mean differences between endpoint blood pressure in treatment and control groups in 105 trials randomizing 6805 participants. Robust statistically significant effects were found for improved diet, aerobic exercise, alcohol and sodium restriction, and fish oil supplements: mean reductions in systolic blood pressure of 5.0 mmHg [95% confidence interval (CI): 3.1-7.0], 4.6 mmHg (95% CI: 2.0-7.1), 3.8 mmHg (95% CI: 1.4-6.1), 3.6 mmHg (95% CI: 2.5-4.6) and 2.3 mmHg (95% CI: 0.2-4.3), respectively, with corresponding reductions in diastolic blood pressure. Relaxation significantly reduced blood pressure only when compared with non-intervention controls. We found no robust evidence of any important effect on blood pressure of potassium, magnesium or calcium supplements.

CONCLUSIONS

Patients with elevated blood pressure should follow a weight-reducing diet, take regular exercise, and restrict alcohol and salt intake. Available evidence does not support relaxation therapies, calcium, magnesium or potassium supplements to reduce blood pressure.

Effects of endurance training on blood pressure, blood pressure-regulating mechanisms, and cardiovascular risk factors

Previous meta-analyses of randomized controlled trials on the effects of chronic dynamic aerobic endurance training on blood pressure reported on resting blood pressure only. Our aim was to perform a comprehensive meta-analysis including resting and ambulatory blood pressure, blood pressure-regulating mechanisms, and concomitant cardiovascular risk factors. Inclusion criteria of studies were: random allocation to intervention and control; endurance training as the sole intervention; inclusion of healthy sedentary normotensive or hypertensive adults; intervention duration of > or =4 weeks; availability of systolic or diastolic blood pressure; and publication in a peer-reviewed journal up to December 2003. The meta-analysis involved 72 trials, 105 study groups, and 3936 participants. After weighting for the number of trained participants and using a random-effects model, training induced significant net reductions of resting and daytime ambulatory blood pressure of, respectively, 3.0/2.4 mm Hg (P<0.001) and 3.3/3.5 mm Hg (P<0.01). The reduction of resting blood pressure was more pronounced in the 30 hypertensive study groups (-6.9/-4.9) than in the others (-1.9/-1.6; P<0.001 for all). Systemic vascular resistance decreased by 7.1% (P<0.05), plasma norepinephrine by 29% (P<0.001), and plasma renin activity by 20% (P<0.05). Body weight decreased by 1.2 kg (P<0.001), waist circumference by 2.8 cm (P<0.001), percent body fat by 1.4% (P<0.001), and the homeostasis model assessment index of insulin resistance by 0.31 U (P<0.01); HDL cholesterol increased by 0.032 mmol/L(-1) (P<0.05). In conclusion, aerobic endurance training decreases blood pressure through a reduction of vascular resistance, in which the sympathetic nervous system and the renin-angiotensin system appear to be involved, and favorably affects concomitant cardiovascular risk factors.

American College of Sports Medicine position stand. Exercise and hypertension

Hypertension (HTN), one of the most common medical disorders, is associated with an increased incidence of all-cause and cardiovascular disease (CVD) mortality. Lifestyle modifications are advocated for the prevention, treatment, and control of HTN, with exercise being an integral component. Exercise programs that primarily involve endurance activities prevent the development of HTN and lower blood pressure (BP) in adults with normal BP and those with HTN. The BP lowering effects of exercise are most pronounced in people with HTN who engage in endurance exercise with BP decreasing approximately 5-7 mm HG after an isolated exercise session (acute) or following exercise training (chronic). Moreover, BP is reduced for up to 22 h after an endurance exercise bout (e.g.postexercise hypotension), with greatest decreases among those with highest baseline BP. The proposed mechanisms for the BP lowering effects of exercise include neurohumoral, vascular, and structural adaptations. Decreases in catecholamines and total peripheral resistance, improved insulin sensitivity, and alterations in vasodilators and vasoconstrictors are some of the postulated explanations for the antihypertensive effects of exercise. Emerging data suggest genetic links to the BP reductions associated with acute and chronic exercise. Nonetheless, definitive conclusions regarding the mechanisms for the BP reductions following endurance exercise cannot be made at this time. Individuals with controlled HTN and no CVD or renal complications may participated in an exercise program or competitive athletics, but should be evaluated, treated and monitored closely. Preliminary peak or symptom-limited exercise testing may be warranted, especially for men over 45 and women over 55 yr planning a vigorous exercise program (i.e. > or = 60% VO2R, oxygen uptake reserve). In the interim, while formal evaluation and management are taking place, it is reasonable for the majority of patients to begin moderate intensity exercise (40-<60% VO2R) such as walking. When pharmacological therapy is indicated in physically active people it should be, ideally: a) lower BP at rest and during exertion; b) decrease total peripheral resistance; and, c) not adversely affect exercise capacity. For these reasons, angiotensin converting enzyme (ACE) inhibitors (or angiotensin II receptor blockers in case of ACE inhibitor intolerance) and calcium channel blockers are currently the drugs of choice for recreational exercisers and athletes who have HTN. Exercise remains a cornerstone therapy for the primary prevention, treatment, and control of HTN. The optimal training frequency, intensity, time, and type (FITT) need to be better defined to optimize the BP lowering capacities of exercise, particularly in children, women, older adults, and certain ethnic groups. based upon the current evidence, the following exercise prescription is recommended for those with high BP: Frequency: on most, preferably all, days of the week. Intensity: moderate-intensity (40-<60% VO2R). Time: > or = 30 min of continuous or accumulated physical activity per day. Type: primarily endurance physical activity supplemented by resistance exercise.

Exercise in hypertension. A clinical review

The current exercise prescription for the treatment of hypertension is: cardiovascular mode, for 20-60 minutes, 3-5 days per week, at 40-70% of maximum oxygen uptake (VO2(max)). Cardiovascular exercise training is the most effective mode of exercise in the prevention and treatment of hypertension. Resistance exercise is not the preferred mode of exercise treatment, but can be incorporated into an exercise regime provided the diastolic blood pressure response is within safe limits. It is inconclusive whether durations longer than 30 minutes produce significantly greater reductions in blood pressure. A frequency of three exercise sessions per week has been considered to be the minimal frequency for blood pressure reduction. Higher frequencies tended to produce greater reductions, although not significantly different. Evidence still exists that high intensity exercise (>75% VO2(max)) may not be as effective as low intensity exercise (<70% VO2(max)) in reducing elevated blood pressures. Exercise can be effective without a change in bodyweight or body fat. Bodyweight or body fat loss and anti-hypertensive medications do not have an added effect on blood pressure reduction associated with exercise. beta-blockade is not the recommended anti-hypertensive medication for effective exercise performance in non-cardiac patients. Not all hypertensive patients respond to exercise treatment. Differences in genetics and pathophysiology may be responsible for the inability of some hypertensive patients to respond to exercise. Ambulatory technology may allow advances in individualising a more effective exercise prescription for low-responders and non-responders.

Multivariate analysis of the prognostic determinants of the depressor response to exercise therapy in patients with essential hypertension

This study investigated the contribution of hemodynamic and humoral factors to the variation in the depressor responses to exercise therapy and the significance of the baseline values of these factors in predicting the depressor response of essential hypertensives to mild exercise therapy. Patients with mild to moderate essential hypertension (n=122, F/M: 97/25) performed a bicycle ergometer exercise at a workload equivalent to the lactate threshold for 10 weeks. In all of the patients, systolic and diastolic blood pressures (BP) significantly decreased after 1 week of exercise, continued to decrease until 4 weeks, and were stable from 4 weeks to 10 weeks. Changes in the plasma volume and humoral factors during the study did not differ significantly between responders and non-responders. A multiple logistic regression analysis showed that higher baseline mean BP (MBP) was significantly associated with a poor depressor response (odds ratio 1.84, p=0.002). A variance component analysis indicated that baseline MBP accounted for only 11.2% of the total variance of the depressor response. In conclusion, these summarized results showed that variations in the depressor response to mild exercise therapy were partly determined by baseline MBP, but not by humoral factors, suggesting the possible involvement of other factors, including genetic factors.

Increase of human MTH1 and decrease of 8-hydroxydeoxyguanosine in leukocyte DNA by acute and chronic exercise in healthy male subjects

To investigate the effects of exercise on oxidative DNA damage, we measured the levels of 8-hydroxydeoxyguanosine (8-OH-dG, 7,8,dihydro-8-oxo-deoxyguanosine), and mRNA of its sanitization enzyme, human MutT homologue (hMTH1), after mild acute exercise in healthy male subjects. The basal 8-OH-dG levels of physically active subjects were significantly lower than those of sedentary subjects. After mild exercise for 30min, the 8-OH-dG levels of the sedentary subjects significantly decreased. In correspondence with the change of 8-OH-dG levels, the hMTH1 mRNA levels of the physically active subjects were significantly higher than those of the sedentary subjects. The levels of hMTH1 mRNA of sedentary subjects significantly increased after mild exercise. Furthermore, there was a significant negative correlation between the levels of 8-OH-dG and hMTH1 mRNA. These results suggest that a mild exercise has a beneficial effect on the maintenance of low levels of 8-OH-dG probably by keeping the sanitization system at higher levels.

Respiratory uncoupling lowers blood pressure through a leptin-dependent mechanism in genetically obese mice

Insulin resistance is commonly associated with hypertension, a condition that causes vascular disease in people with obesity and type 2 diabetes. The mechanisms linking hypertension and insulin resistance are poorly understood. To determine whether respiratory uncoupling can prevent insulin resistance-related hypertension, we crossed transgenic mice expressing uncoupling protein 1 (UCP1) in skeletal muscle with lethal yellow (A(y)/a) mice, genetically obese animals known to have elevated blood pressure. Despite increased food intake, UCP-A(y)/a mice weighed less than their A(y)/a littermates. The metabolic rate was higher in UCP-A(y)/a mice than in A(y)/a mice and did not impair their ability to alter oxygen consumption in response to temperature changes, an adaptation involving sympathetic nervous system activity. Compared with their nontransgenic littermates, UCP-A(y)/a mice had lower fasting insulin, glucose, triglyceride, and cholesterol levels and were more insulin sensitive. Blood pressure, serum leptin, and urinary catecholamine levels were also lower in uncoupled mice. Independent of sympathetic nervous system activity, low-dose peripheral leptin infusion increased blood pressure in UCP-A(y)/a mice but not in their A(y)/a littermates. These data indicate that skeletal muscle respiratory uncoupling reverses insulin resistance and lowers blood pressure in genetic obesity without affecting thermoregulation. The data also suggest that uncoupling could decrease the risk of atherosclerosis in type 2 diabetes.

Sympathetic activity and the heterogenous blood pressure response to exercise training in hypertensives

To test whether changes in sympathetic nervous system (SNS) activity or insulin sensitivity contribute to the heterogeneous blood pressure response to aerobic exercise training, we used compartmental analysis of [3H]norepinephrine kinetics to determine the extravascular norepinephrine release rate (NE2) as an index of systemic SNS activity and determined the insulin sensitivity index (S(I)) by an intravenous glucose tolerance test, before and after 6 mo of aerobic exercise training, in 30 (63 +/- 7 yr) hypertensive subjects. Maximal O2 consumption increased from 18.4 +/- 0.7 to 20.8 +/- 0.7 ml x kg(-1) x min(-1) (P = 0.02). The average mean arterial blood pressure (MABP) did not change (114 +/- 2 vs. 114 +/- 2 mmHg); however, there was a wide range of responses (-19 to +17 mmHg). The average NE2 did not change significantly (2.11 +/- 0.15 vs. 1.99 +/- 0.13 microg x min(-1) x m(-2)), but there was a significant positive linear relationship between the change in NE2 and the change in MABP (r = 0.38, P = 0.04). S(I) increased from 2.81 +/- 0.37 to 3.71 +/- 0.42 microU x 10(-4) x min(-1) x ml(-1) (P = 0.004). The relationship between the change in S(I) and the change in MABP was not statistically significant (r = -0.03, P = 0.89). When the changes in maximal O2 consumption, percent body fat, NE2, and S(I) were considered as predictors of the change in MABP, only NE2 was a significant independent predictor. Thus suppression of SNS activity may play a role in the reduction in MABP and account for a portion of the heterogeneity of the MABP response to aerobic exercise training in older hypertensive subjects.

Exercise training in obesity lowers blood pressure independent of weight change

PURPOSE

We used the rabbit model of obesity and exercise training to determine effects of exercise training during the development of obesity on resting blood pressure and heart rate, ventricular hypertrophy, blood volume, and hormonal profile.

METHODS

Female New Zealand white rabbits were assigned to one of four groups: lean sedentary (L-S, N = 17), lean exercise-trained (L-EX, N = 16), obese sedentary (O-S, N = 18), and obese exercise-trained (O-EX, N = 15). Lean rabbits were fed a maintenance diet whereas obese rabbits were fed an ad libitum high fat (10% added fat) diet. Simultaneously, exercise-trained animals underwent a progressive treadmill exercise training protocol for 12 wk. After 12 wk of diet and exercise regimens, resting blood pressure and heart rate were measured from a central ear artery catheter. Ventricular hypertrophy was evaluated using wet ventricular weights. Blood volume was measured using the Evans blue dye procedure; hormonal profile was evaluated from arterial plasma/serum samples.

RESULTS

After 12 wk, O-S and O-EX had similar body weights and similar percentage increases in body weight. Despite similar body weights, O-EX had an approximate 6-mm Hg lower mean blood pressure compared with the elevated pressure seen in O-S (P < or = 0.05). Obese rabbits had greater resting heart rate, plasma cholesterol and triglycerides, and plasma renin activity compared with lean rabbits, and these values were unaffected by exercise training. Plasma and blood volumes, as well as plasma insulin, cortisol, and aldosterone were unaffected by exercise training.

CONCLUSION

These data suggest that exercise training, in the absence of differences in body weight, may be useful in the reduction of obesity-induced hypertension but that other therapies may be needed in order to control other cardiovascular risk factors.

Reduced risk of intracerebral hemorrhage with dynamic recreational exercise but not with heavy work activity

BACKGROUND AND PURPOSE

It is unclear whether intracerebral hemorrhage (ICH) is associated with dynamic or static exercise. Our aim was to assess whether such an association exists.

METHODS

A case-control study was undertaken involving 331 consecutive cases of primary ICH and 331 age- and sex-matched community-based neighborhood controls. Cases, verified by CT or autopsy, were identified from 13 major hospitals in Melbourne, Australia. A questionnaire was used to elicit information about lifetime physical activity at leisure and work and other potentially confounding factors.

RESULTS

Individuals undertaking recent regular dynamic exercise exhibited an odds ratio (OR) for ICH of 0.63 (95% CI 0.39 to 1.01) when adjustment was made for all potential confounding factors, except hypertension, cholesterol, and body mass index. Among men and women separately, the ORs were 0.51 (95% CI 0.27 to 0.97) and 1.22 (95% CI 0.52 to 2.87), respectively. When hypertension, cholesterol, and body mass index were also included in the multivariate model, the OR among men was 0.57 (95% CI 0.28 to 1.14). There was no association between physical activity at work and ICH (OR 1.14, 95% CI 0.58 to 2.25).

CONCLUSIONS

These results provide preliminary evidence for a role of exercise in reducing the likelihood of ICH among men. In women, the CI was wide, and the association was not statistically significant. There was further support that factors other than blood pressure status, cholesterol, and body mass index may play a role in the observed inverse association between dynamic exercise and ICH among men.

Effects of a community-based lifestyle-modification program on cardiovascular risk factors in middle-aged women

We investigate the effectiveness of a community-based lifestyle-modification program for reducing blood pressure and other cardiovascular risk factors in sedentary Japanese middle-aged women. Among an initial cohort of 210 middle-aged sedentary women, 195 subjects completed a community-based 12-week lifestyle-modification program for reducing cardiovascular risk factors. Blood pressure, body weight and the serum lipid profile were measured both at baseline and at the end of the 12-week lifestyle-modification program. The program consisted of mild aerobic exercise and a mild hypocaloric diet. After the 12-week program, both systolic and diastolic blood pressure were significantly reduced, especially in subjects who were hypertensive at baseline. Desirable changes in body weight and the serum lipid profile were also found after the 12-week program. Multiple linear regression analysis revealed that, in obese subjects, the decrease in systolic blood pressure was correlated with both the initial systolic blood pressure and the change in estimated maximum oxygen consumption. In addition, the decrease in diastolic blood pressure was correlated with the initial diastolic blood pressure and the change in body weight. On the other hand, in non-obese subjects, the decrease in blood pressure was correlated with the initial blood pressure and the change in salt intake. A community-based lifestyle-modification program that consisted of mild aerobic exercise and a mild hypocaloric diet was considered to be practically effective for reducing multiple cardiovascular risk factors. Individuals who already have one or more mild cardiovascular risk factors still could be good candidates for a community-based lifestyle-modification program.

Exercise characteristics and the blood pressure response to dynamic physical training

PURPOSE

The purpose of this study was to assess the influence of the characteristics of the exercise program, particularly exercise intensity, on the blood pressure response to dynamic physical training in otherwise healthy normotensive and hypertensive subjects.

METHODS

This study is a meta-analysis of randomized controlled intervention trials and a description of studies in which different training regimens have been compared.

RESULTS

The weighted net reduction of blood pressure in response to dynamic physical training averaged 3.4/2.4 mm Hg (P < 0.001). Interstudy differences in the changes in pressure were not related to weekly frequency, time per session, or exercise intensity, which ranged from approximately 45--85%; these three characteristics combined explained less than 5% of the variance of the blood pressure response. The response of diastolic blood pressure was not different according to training intensity in studies that randomized patients to training programs with different intensities. Some studies reported a greater reduction of systolic blood pressure when intensity was about 40% than when participants exercised at about 70%, but this finding was not consistent, neither within nor between studies.

CONCLUSION

Training from three to five times per week during 30--60 min per session at an intensity of about 40--50% of net maximal exercise performance appears to be effective with regard to blood pressure reduction. The evidence that higher intensity exercise would be less effective is at present inconsistent.

Aerobic exercise and resting blood pressure: a meta-analytic review of randomized, controlled trials

In this study the authors used the meta-analytic approach to examine the effects of aerobic exercise on resting systolic and diastolic blood pressure in adults. Forty-seven clinical trials representing a total of 72 effect sizes in 2543 subjects (1653 exercise, 890 control) met the criteria for inclusion. Statistically significant exercise-minus-control decreases were found for changes in resting systolic and diastolic blood pressure in both hypertensive (systolic, -6 mm Hg, 95% CI, -8 to -3; diastolic, -5 mm Hg, 95% CI, -7 to -3) and normotensive (systolic, -2 mm Hg, 95% CI, -3 to -1; diastolic, -1 mm Hg, 95% CI, -2 to -1) groups. The differences between groups were statistically significant (systolic, p=0.008; diastolic, p=0.000). Relative decreases were approximately 4% (systolic) and 5% (diastolic) in hypertensives, and 2% (systolic) and 1% (diastolic) in normotensives. It was concluded that aerobic exercise reduces resting systolic and diastolic blood pressure in adults. (c) 2001 by CHF, Inc.

Exercise training normalizes wall-to-lumen ratio of the gracilis muscle arterioles and reduces pressure in spontaneously hypertensive rats

OBJECTIVE

To investigate mechanisms underlying the training-induced blood pressure-lowering effect we analyzed the hemodynamic responses and morphometric changes of the skeletal muscle microcirculation of spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats during an exercise training program. DESIGN TRAINING: (50-60% VO2 max) was performed on a treadmill for 13 weeks and control groups were kept sedentary over the same period of time. Trained and sedentary rats were chronically instrumented for hindlimb flow and arterial pressure (AP) recordings under conscious unrestrained conditions. Gracilis and myocardial muscle samples were obtained for morphometric analysis after transcardiac perfusion of fixative.

RESULTS

SHR, when compared to WKY presented an elevated blood pressure, an increased relative hindlimb vascular resistance, capillary rarefaction in both gracilis and myocardium and an increased wall-to-lumen ratio of gracilis arterioles. Training increased significantly both capillary density and capillary/fiber ratio in the gracilis and myocardium of WKY and SHR groups, causing a complete reversal of capillary rarefaction in trained SHR. In SHR, training also reduced resting blood pressure and caused normalization of both relative hindlimb vascular resistance and gracilis arterioles wall-to-lumen ratio. Regression analysis revealed strong positive correlation between hindlimb vascular resistance and mean AP (MAP) and between arterioles wall-to-lumen ratio and MAP.

CONCLUSIONS

The results suggest that low-intensity training can significantly reduce pressure in SHR while normalizing both the arteriole morphology and the resistance of the skeletal muscle microcirculation.

The effects of exercise and training on human cardiovascular reflex control

During physical activity, there is a graded withdrawal of vagal cardiac tone and a graded increase in sympathetic cardiac and vasomotor tone, initiated through both central command from the somatic motor cortex and muscle chemoreceptive and mechanoreceptive inputs. In parallel, there is an upward resetting of the operating point of the arterial baroreflex, with preserved reflex sensitivity. In contrast to the traditional interpretation that blood flow through exercising muscle is independent of vasomotor neural influences because of the dominance of local dilator metabolites, recent evidence suggests that both constrictor and dilator sympathetic neural influences may be involved in determining absolute levels of perfusion. Post-exercise, there is a period of relative hypotension that is associated with decreased peripheral resistance. Some, but not all, evidence indicates a causal role for reduced sympathetic drive. Chronic exercise training appears to reduce resting sympathetic activity, with parallel changes in the gain of a variety of cardiovascular autonomic reflexes initiated from cardiovascular sites. These changes may be attributable at least partly to masking of arterial baroreflexes by the impact of elevated blood volume on low-pressure baroreceptors. The reductions in sympathetic drive that follow training are more pronounced in patients with essential hypertension than in normotensive individuals and are likely to underlie the anti-hypertensive effect of exercise.

Physical activity in the prevention and treatment of hypertension in the obese

Physical activity in the prevention and treatment of hypertension in the obese.

PURPOSE

The purpose of this paper was to assess the value of physical exercise in the prevention and treatment of hypertension with particular attention to possible interactions with relative weight.

METHODS

We describe epidemiological studies and report meta-analyses of randomized intervention trials, i.e., randomized controlled trials on dynamic physical training and randomized comparative trials of exercise and diet.

RESULTS

Epidemiological studies show an inverse relationship between physical activity or fitness and the incidence of hypertension, which was either independent of body size or more pronounced in the overweight. The weighted net reduction of blood pressure in response to dynamic physical training averages 3.4/2.4 mm Hg (P < 0.001), which appears to be unrelated to the initial body mass index (BMI) and to its training-induced changes. Exercise is less effective than diet in lowering blood pressure (P < 0.02), and adding exercise to diet does not appear to further reduce blood pressure. Future studies should observe scientific criteria more strictly, address the truly obese (BMI > or = 30 kg x m(-2)) and attempt to resolve the blood pressure lowering mechanisms.

CONCLUSION

Physical activity contributes to the control of blood pressure in overweight as well as in lean subjects.

State-of-the-Art lecture: influence of exercise training on neurogenic control of blood pressure in spontaneously hypertensive rats

Exercise training plays an important role in the reduction of high blood pressure. In this review, we discuss the effect of distinct intensities of exercise training on the reduction of high blood pressure in spontaneously hypertensive rats (SHR). In addition, we present some hemodynamic mechanisms and associated neural controls by which exercise training attenuates hypertension in SHR. Low-intensity exercise training is more effective in reducing high blood pressure than is high-intensity exercise training in SHR. The decrease in blood pressure is due to resting bradycardia, and in consequence, lower cardiac output. Sympathetic attenuation to the heart is the major explanation for the resting bradycardia. Recovery of the sensitivity of baroreflex control of heart rate, which is usually impaired in SHR, is an important neurogenic component involved in the benefits elicited by exercise training.

Influence of age and gender on exercise training-induced blood pressure reduction in systemic hypertension

Regular exercise has been reported to lower blood pressure in young and older adults with essential hypertension. However, it is not known how age and gender influence the hypotensive effects of exercise. A total of 109 sedentary subjects with stage 1 or 2 essential hypertension performed exercise training at mild intensity for 8 weeks with a combination of various exercises at 22 fitness clubs. Blood pressure (BP) was reduced significantly during the program in all of the 4 exercise subgroups classified by age and gender (-15/-11 mm Hg in men aged 30 to 49 years, -10/-5 mm Hg in men aged 50 to 69 years, -16/-14 mm Hg in women aged 30 to 49 years, and -10/-6 mm Hg in women aged 50 to 69 years). There was a significant (p <0.01) age x time interaction for both systolic and diastolic BP. However, no significant gender x time interaction was observed over the same time period. After adjustment for baseline BP, exercise duration, and changes in body mass and salt intake, a significant (p <0.01) age effect difference also was observed with reduction in BP at weeks 4 and 8. There were no significant changes in any of these variables in the 42 other hypertensive control subjects. Thus, (1) a clinically significant reduction in BP was produced with the combination of various exercises performed at fitness clubs, (2) older hypertensive subjects experienced smaller reductions in BP than younger counterparts at weeks 4 and 8, and (3) gender did not influence the efficacy of physical activity for lowering elevated BP.

Exercise, a measure to lower blood pressure and reduce other risks

By 1990, exercise had been proven to lower blood pressure, and subsequently the intensity of exercise recommended was lowered from moderate to mild (lactic threshold or 50% maximum oxygen uptake). Exercise is now recommended as a useful measure to lower blood pressure in many guidelines for the management of hypertension. The antihypertensive mechanism is multifactorial involving sympathicolytic as well as diuretic actions through activation of relevant metabolic pathways; that is, decrease in endogenous ouabain-like substance, increase in s-taurine and prostaglandin E and urinary dopamine and kallikrein excretion, etc. Other metabolic changes seem to operate simultaneously, and other risk factors, such as sugar and lipid metabolism and insulin resistance are improved. Prospective epidemiologic study has suggested that a physically active lifestyle will prevent cardiovascular complications.

Training in swimming reduces blood pressure and increases muscle glucose transport activity as well as GLUT4 contents in stroke-prone spontaneously hypertensive rats

Exercise improves muscle insulin sensitivity and GLUT4 contents. We investigated the beneficial effects of swimming training on insulin sensitivity and genetic hypertension using stroke-prone hypertensive rats (SHRSP). We studied the relationship between genetic hypertension and insulin resistance in SHRSP and Wistar Kyoto rats (WKY) as a control. The systolic blood pressure of SHRSP was significantly reduced by 4-week swimming training (208.4 +/- 6.8 mmHg vs. 187.2 +/- 4.1 mmHg, p < 0.05). The swimming training also resulted in an approximately 20% increase in the insulin-stimulated glucose transport activity (p < 0.05) of soleus muscle strips and an approximately 3-fold increase in the plasma membrane GLUT4 protein expression (p < 0.01) in SHRSP. However, basal and insulin-stimulated glucose transport activity and GLUT4 contents were not significantly different between WKY and SHRSP. There was no difference in insulin resistance in skeletal muscle of SHRSP as compared with WKY. Our results indicated swimming training exercise improved not only hypertension but also muscle insulin sensitivity and GLUT4 protein expression in SHRSP.

Blood pressure lowering effect of low intensity aerobic training in elderly hypertensive patients

PURPOSE

The purpose of this investigation was to determine the effect of 9 months of low intensity aerobic training on blood pressure in elderly hypertensive patients who were receiving antihypertensive medication.

METHODS

The training group (N = 13; mean age 75.4 +/- 5.4 yr) agreed to take part in physical training using a treadmill with an exercise intensity at the blood lactate threshold (LT) for 30 min three to six times a week for 9 months. The rest (N = 13; mean age 73.1 +/- 4.2 yr) served as controls.

RESULTS

The resting systolic (-15 +/- 8 mm Hg), mean (-11 +/- 6 mm Hg), and diastolic blood pressures (-9 +/- 9 mm Hg) decreased significantly after 3 months of training and the blood pressure of all participants stabilized at a significantly lower level by the end of the study (9 months) in the training group, whereas no significant changes in blood pressure were found in the control group. Both the pretraining systolic and diastolic blood pressure of those recruited patients negatively correlated with those changes after the training (SBP: P < 0.01; DBP: P < 0.05, respectively). After 1 month of detraining in five patients, the blood pressure levels were similar to those in the pretraining state. The LT increased significantly in the training group (P < 0.01).

CONCLUSION

In conclusion, an additional antihypertensive effect of mild aerobic training at the LT was confirmed in elderly patients receiving antihypertensive medication. The cessation of such training in five patients, however, resulted in a relatively rapid return to pretraining levels within a month.

Low-intensity exercise training decreases cardiac output and hypertension in spontaneously hypertensive rats

The decrease in cardiac sympathetic tone and heart rate after low-intensity exercise training may have hemodynamic consequences in spontaneously hypertensive rats (SHR). The effects of exercise training of low and high intensity on resting blood pressure, cardiac output, and total peripheral resistance were studied in sedentary (n = 17), low- (n = 17), and high-intensity exercise-trained (n = 17) SHR. Exercise training was performed on a treadmill for 60 min, 5 times per week for 18 weeks, at 55% or 85% maximum oxygen uptake. Blood pressure was evaluated by a cannula inserted into the carotid artery, and cardiac output was evaluated by a microprobe placed around the ascending aorta. Low-intensity exercise-trained rats had a significantly lower mean blood pressure than sedentary and high-intensity exercise-trained rats (160 +/- 4 vs. 175 +/- 3 and 173 +/- 2 mmHg, respectively). Cardiac index (20 +/- 1 vs. 24 +/- 1 and 24 +/- 1 ml.min-1 x 100 g-1, respectively) and heart rate (332 +/- 6 vs. 372 +/- 14 and 345 +/- 9 beats/min, respectively) were significantly lower in low-intensity exercise-trained rats than in sedentary and high-intensity exercise-trained rats. No significant difference was observed in stroke volume index and total peripheral resistance index in all groups studied. In conclusion, low-intensity, but not high-intensity, exercise training decreases heart rate and cardiac output and, consequently, attenuates hypertension in SHR.

Improvement of insulin sensitivity by short-term exercise training in hypertensive African American women

African American women have a high prevalence of insulin resistance, non-insulin-dependent diabetes mellitus, obesity, and hypertension that may be linked to low levels of physical activity. We sought to determine whether 7 days of aerobic exercise improved glucose and insulin metabolism in 12 obese (body fat >35%), hypertensive (systolic blood pressure > or =140 and/or diastolic blood pressure > or =90 mmHg) African American women (mean age 51+/-8 years). Insulin-assisted frequently-sampled intravenous glucose tolerance tests were performed at baseline and 14 to 18 hours after the 7th exercise session. There was no significant change in maximal oxygen consumption, body composition, or body weight after the 7 days of aerobic exercise. The insulin sensitivity index increased (2.68+/-0.45 x 10[-5] to 4.23+/-0.10 x 10[-5] [min(-1)/pmol/L], P=.02). Fasting (73+/-9 to 50+/-9 pmol/L, P=.02) and glucose-stimulated (332+/-58 to 261+/-45 pmol/L, P=.05) plasma insulin levels decreased. Additional measures related to the insulin resistance syndrome also changed with the 7 days of exercise: basal plasma norepinephrine concentrations were reduced (2.46+/-0.27 to 1.81+/-0.27 nmol/L, P=.02) and sodium excretion rate increased from 100+/-13 to 137+/-7 mmol/d (P=.03); however, there was no change in potassium excretion or 24-hour ambulatory blood pressure. We conclude that a short-term aerobic exercise program improves insulin sensitivity in African American hypertensive women independent of changes in fitness levels, body composition, or body weight. The present study indicates that short-term exercise can improve insulin resistance in hypertensive, obese, sedentary African American women and confirms previous reports that a portion of the exercise-induced improvements in glucose and insulin metabolism may be the result of recent exercise.