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

Effect of leisure-time physical activity on blood pressure in people with hypertension: a systematic review and meta-analysis

High blood pressure is a major risk factor for premature death. Leisure-time physical activities have been recommended to control hypertension. Studies examining how leisure-time physical activity affects blood pressure have found mixed results. We aimed to conduct a systematic review examining the effect of leisure-time physical activity (LTPA) on lowering blood pressure among adults living with hypertension. We searched studies in Embase, Medline/PubMed, Web of Science, Physical Education Index, Scopus and CENTRAL (the Cochrane Library). The primary outcome variables were systolic blood pressure (SBP) and diastolic blood pressure (DBP). This systematic review is registered on PROSPERO (CRD42021260751). We included 17 studies out of 12,046 screened articles in this review. Moderate-intensity LTPA (all types) reduced SBP compared to the non-intervention control group (MD -5.35 mm Hg, 95% CI -8.06 to -2.65, nine trials, n = 531, low certainty of the evidence). Mean DBP was reduced by -4.76 mm Hg (95% CI -8.35 to -1.17, nine trials, n = 531, low certainty of the evidence) in all types of LTPA (moderate intensity) group compared to the non-intervention control group. Leisure-time walking reduced mean SBP by -8.36 mmHg, 95% CI -13.39 to -3.32, three trials, n = 128, low certainty of the evidence). Walking during leisure time reduced -5.03 mmHg mean DBP, 95% CI -8.23 to -1.84, three trials, n = 128, low certainty of the evidence). Performing physical activity during free time probably reduces SBP and DBP (low certainty of the evidence) among adults with hypertension.

Comparison of Baroreflex Sensitivity and Cardiac Autonomic Function Between Adolescent Athlete and Non-athlete Boys - A Cross-Sectional Study

Introduction: It is well known that regular physical activity improves cardiovascular health, and higher baroreflex sensitivity and heart rate variability are associated with cardiovascular health. Adolescence is the age when an individual’s behavior is easily modified; early intervention at this stage in terms of physical conditioning or training prevents future cardiovascular risk. Hence, we conceived the present study to assess and compare the baroreflex sensitivity and autonomic function between adolescent athletes and non-athletes.

Methods: We recruited school going athletes (n = 30) and non-athlete boys (n = 30) in the 10–19 age group after obtaining their assent and consent from their parents. We assessed height, weight, heart rate, blood pressure, baroreflex sensitivity, and cardiac autonomic function. Comparison between groups was made using the unpaired t-test for height, weight, body mass index, heart rate, blood pressure, and baroreflex sensitivity and using Mann-Whitney U test for cardiac autonomic function parameters.

Results: There was a trend for higher baroreflex sensitivity in athletes. Heart rate variability (total power and SDNN) was higher in athletes. The parasympathetic tone was higher in terms of higher RMSSD, and higher HF power. Parasympathetic reactivity was higher in athletes in terms of higher 30:15 ratio and EI ratio.

Conclusion: Athletic level physical conditioning has a positive influence on baroreflex function and autonomic function that may prove beneficial to the adolescents’ cardiovascular health.

Effects of exercise modalities on central hemodynamics, arterial stiffness and cardiac function in cardiovascular disease: Systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Exercise is accepted as an important contribution to the rehabilitation of patients with cardiovascular disease (CVD). This study aims to better understand the possible causes for lack of consensus and reviews the effects of three exercise modalities (aerobic, resistance and combined exercise) on central hemodynamics, arterial stiffness and cardiac function for better rehabilitation strategies in CVD.

METHODS

The electronic data sources, Cochrane Library, MEDLINE, Web of Science, EBSCO (CINAHL), and ScienceDirect from inception to July 2017 were searched for randomized controlled trials (RCTs) investigating the effect of exercise modalities in adult patients with CVD. The effect size was estimated as mean differences (MD) with 95% confidence intervals (CI). Subgroup analysis and meta-regression were used to study potential moderating factors.

RESULTS

Thirty-eight articles describing RCTs with a total of 2089 patients with CVD were included. The pooling revealed that aerobic exercise [MD(95%CI) = -5.87 (-8.85, -2.88), P = 0.0001] and resistance exercise [MD(95%CI) = -7.62 (-10.69, -4.54), P<0.00001] significantly decreased aortic systolic pressure (ASP). Resistance exercise significantly decreased aortic diastolic pressure [MD(95%CI) = -4(-5.63, -2.37), P<0.00001]. Aerobic exercise significantly decreased augmentation index (AIx) based on 24-week exercise duration and patients aged 50-60 years. Meanwhile, aerobic exercise significantly improved carotid-femoral pulse wave velocity (cf-PWV) [MD(95%CI) = -0.42 (-0.83, -0.01), P = 0.04], cardiac output (CO) [MD(95% CI) = 0.36(0.08, 0.64), P = 0.01] and left ventricular ejection fraction (LVEF) [MD(95%CI) = 3.02 (2.11, 3.93), P<0.00001]. Combined exercise significantly improved cf-PWV [MD(95%CI) = -1.15 (-1.95, -0.36), P = 0.004] and CO [MD(95% CI) = 0.9 (0.39, 1.41), P = 0.0006].

CONCLUSIONS

Aerobic and resistance exercise significantly decreased ASP, and long-term aerobic exercise reduced AIx. Meanwhile, aerobic and combined exercise significantly improved central arterial stiffness and cardiac function in patients with CVD. These findings suggest that a well-planned regime could optimize the beneficial effects of exercise and can provide some evidence-based guidance for those involved in cardiovascular rehabilitation of patients with CVD.

Effects of hypervolemia by protein and glucose supplementation during aerobic training on thermal and arterial pressure regulations in hypertensive older men

In Japan, the incidence of heat illness in older people has rapidly increased during midsummer in the last decade, and we suggested that whey-protein+carbohydrate supplementation during aerobic training would increased plasma volume (PV) to enhance thermoregulatory adaptation in older men (J Appl Physiol 107: 725-733, 2009); however, >60% of people age 65 and older suffer from hypertension, and the symptoms may be worsened by hypervolemia. To examine this, we randomly divided 21 older men (∼69 yr) with ∼160 mmHg for systolic and ∼90 mmHg for diastolic blood pressure at rest into two groups: Glc (n = 11) consuming glucose alone (25 g) and Pro-Glc (n = 10) consuming whey protein (10 g) + glucose (15 g), immediately after cycling exercise at 60-75% of peak aerobic capacity (V̇o_{2 peak}) for 60 min/day, 3 days/wk, for 8 wk. Before and after training, we measured PV (dye dilution), baroreflex sensitivity (BRS) of heart rate (Valsalva maneuver), and carotid arterial compliance (CAC) from carotid arterial diameter (ultrasound imaging) responses to pulsatile arterial pressure change (photoplethysmography) at rest. Additionally, we measured esophageal temperature (T_es) and forearm skin blood flow (plethysmography) during exercise at 60% pretraining V̇o_{2 peak} for 20 min in a warm environment. We found that the forearm skin vascular conductance response to increased T_es was enhanced in Pro-Glc with increased PV, but this was not found in Glc; however, despite the increased PV, arterial blood pressures rather decreased with increased CAC and BRS in Pro-Glc. Thus, the prescription was applicable to older men with hypertension to prevent heat illness during exercise.

The impact of aerobic exercise training on arterial stiffness in pre- and hypertensive subjects: a systematic review and meta-analysis

BACKGROUND

Debate concerning aerobic exercise decreasing arterial stiffness in pre- and hypertensive individuals still exists. We sought to systematically review and quantify the effect of aerobic exercise training on arterial stiffness in pre- and hypertensive subjects.

METHODS

MEDLINE, Cochrane, Scopus and Web of Science were searched up until August 2013 for trials assessing the effect of aerobic exercise interventions lasting 4 or more weeks on arterial stiffness in (pre)hypertensive subjects. Standardized mean difference (SMD) in arterial stiffness parameters (PWV, B-stiffness, Compliance, AIx) was calculated using a random-effects model. Subgroup and meta-regression analyses were used to study potential moderating factors.

RESULTS

Fourteen trials comprising a total of 472 (pre)hypertensive subjects met the inclusion criteria. Arterial stiffness was not significantly reduced by aerobic training in (pre)hypertensive subjects (14 trials, SMD=-0.19; P=.06). Likewise, post-intervention arterial stiffness was similar between the aerobic exercise-trained and control (pre)hypertensive subjects (8 trials, SMD=-0.10; P=.43). Neither heterogeneity nor publication bias was detected in either of these analyses. In the subgroup analyses, arterial stiffness was significantly reduced in aerobic exercise-trained (pre)hypertensive subgroups below the median value in post minus pre-intervention systolic blood pressure (SBP) (SMD=-0.38, P=.04) and in subgroups above the median value in the duration of the intervention (SMD=-0.28, P=.03). Similar results were obtained in the meta-regression analysis.

CONCLUSIONS

Arterial stiffness is not reduced in (pre)hypertensive subjects in response to aerobic training unless associated with a substantial reduction in SBP and/or prolonged duration.

Effects of aerobic and resistance exercise intensities on 24-hours blood pressure in normotensive women

The present study aimed to determine the effect of the intensity of aerobic and resistance exercise on the 24h BP response in normotensive women. Twenty-four women (aged 33 ± 9 years) performed five experimental sessions in randomized order: CON - no exercise; AE50 - 50% of heart rate reserve (HRR); AE70 - 70% of HRR; RE40 - 40% of 1repetition maximum (RM) and RE70 - 70% of 1RM. Systolic and diastolic BP and HR measurements were measured during 24h post-exercise at the participant's workplace. The AE50, AE70 and RE40 sessions led to the greatest and longest-lasting effects on the SBP, which persisted for up to 24h. For the DBP, the experimental sessions led to similar results; post exercise hypotension was observed until 7h post-exercise, with the exception of the AE70 session, which produced effects that persisted for 24h. Results shows that both aerobic and resistance exercise performed during the morning can decrease the mean BP above the baseline lasting 24 hours during a normal daily work. The aerobic exercise performed around 50% of HRR can better regulate both systolic and diastolic BP in this population.

Effects of high-intensity and blood flow-restricted low-intensity resistance training on carotid arterial compliance: role of blood pressure during training sessions

We examined the effects of high-intensity resistance training (HIT) and low-intensity blood flow-restricted (LI-BFR) resistance training on carotid arterial compliance. Nineteen young men were randomly divided into HIT (n = 9) or LI-BFR (n = 10) groups. The HIT and LI-BFR groups performed 75 and 30 %, respectively, of one-repetition maximum (1-RM) bench press exercise, 3 days per week for 6 weeks. During the training sessions, the LI-BFR group wore elastic cuffs around the most proximal region of both arms. Muscle cross-sectional area (CSA), 1-RM strength, and carotid arterial compliance were measured before and 3 days after the final training session. Acute changes in systolic arterial pressure (SAP), plasma endothelin-1 (ET-1), nitrite/nitrate (NOx), and noradrenalin concentrations were also measured during and after a bout of training session. The training led to significant increases (P < 0.01) in bench press 1-RM and arm and chest muscle CSA in the two training groups. Carotid arterial compliance decreased significantly (P < 0.05) in the HIT group, but not in the LI-BFR group. There was a significant correlation (r = -0.533, P < 0.05) between the change in carotid arterial compliance and the acute change in SAP during training sessions; however, ET-1 and NOx did not correlate with carotid arterial compliance. Our results suggest that muscle CSA and strength increased following 6 weeks of both HIT and LI-BFR training. However, carotid arterial compliance decreased in only the HIT group, and the changes were correlated with SAP elevations during exercise sessions.

Effects on blood pressure and autonomic nervous system function of a 12-week exercise or exercise plus DASH-diet intervention in individuals with elevated blood pressure

AIM

Hypertension is related to abnormalities in autonomic nervous system (ANS) function, with increased sympathetic output and decreased parasympathetic tone. Lifestyle interventions are the first line of treatment in hypertension, and decreased blood pressure (BP) effects may be related to changes in ANS function. Using heart rate recovery (HRR) from exercise as an index of parasympathetic tone and plasma noradrenaline as an index of sympathetic tone, we investigated the effects of lifestyle interventions on ANS function in patients with elevated BP.

METHODS

Sedentary participants with elevated BP were randomly assigned to either an exercise only (N = 25), exercise plus dietary approaches to stop hypertension (DASH) diet (N = 12), or waitlist control (N = 15) 12-week intervention. Plasma noradrenaline was measured at rest and participants performed a peak exercise test before and after the intervention. HRR was calculated as peak heart rate (HR) minus HR at 1 min post-exercise.

RESULTS

Heart rate recovery showed a significant group by time interaction; both intervention groups showed increases in HRR from pre- to post-intervention, while waitlist showed no change. Similarly, both exercise plus diet and exercise groups, but not waitlist, showed significant reductions in BP from pre- to post-intervention. Linear regression revealed that BP post-intervention was significantly predicted by change in HRR when controlling for pre-BP, age, gender and BMI.

CONCLUSIONS

Lifestyle interventions induced training-reduced BP and altered autonomic tone, indexed by HRR. This study indicates the importance of behavioural modification in hypertension and that increased parasympathetic function is associated with success in reduction of BP.

Short-term aerobic exercise reduces nitroglycerin-induced orthostatic intolerance in older adults with type 2 diabetes

AIMS/HYPOTHESIS

Older adults are at a high risk for syncope due to orthostatic intolerance (OI), and this risk increases with comorbid type 2 diabetes and vasoactive medications. Despite many benefits, previous investigations have shown worsening OI with aerobic training. We examined whether aerobic exercise reduced OI in older adults with type 2 diabetes who were given a short-acting vasoactive agent (nitroglycerin).

METHODS

Forty older adults (25 males and 15 females, mean age 71.4 ± 0.7 years, ranging in age from 65 to 83 years) with type 2 diabetes were recruited. Subjects were randomized to each of 2 groups: an aerobic group (3 months of vigorous aerobic exercise) and a nonaerobic (no aerobic exercise) group. Exercise sessions were supervised by a certified exercise trainer 3 times per week. After being given 400 μg of sublingual nitroglycerin, each subject was placed in a 70° head-up tilt for 30 minutes.

RESULTS

When the 2 groups were compared using a Cox proportional hazards model, tilt table tolerance was significantly better in the aerobic group as compared to in the nonaerobic group (χ(2)(MC) = 7.271, P = 0.007).

CONCLUSIONS

Our findings indicate that a relatively short aerobic exercise intervention can improve postnitroglycerin orthostatic tolerance in older adults with type 2 diabetes.

Improvements in insulin sensitivity and muscle blood flow in aerobic-trained overweight-obese hypertensive patients are not associated with ambulatory blood pressure

To verify whether there are relationships between vascular and hormonal responses to aerobic training in hypertensive persons, sedentary hypertensive patients were randomized to an aerobic training or a callisthenic exercise group. The patients' 24-hour blood pressure, arterial compliance, forearm blood flow, and hormonal profile were evaluated at baseline and after 3-month training protocols. Mean maximal oxygen consumption (VO(2) max) increased by 8% in the aerobic group (P<.001), while no change was observed in the control group. There was a decrease in insulin resistance (homeostatic model assessment of insulin resistance, P=.039) and plasma cortisol (P=.006) in the aerobic group only, that also demonstrated an increase in forearm blood flow (P<.001) after training. No relationship was observed between change in blood pressure or change in body mass and other parameters. Aerobic training can promote a decrease in cardiovascular risk in hypertensive adults by improving vascular function and insulin resistance, despite no changes in ambulatory blood pressure after a 3-month intervention.

Resistance training reduces the blood pressure response of older men during submaximum aerobic exercise

OBJECTIVE

The objective of this study was to determine whether 16 weeks of resistance training (RT) can reduce the blood pressure response and improve the cardiovascular function of men aged 70-80 years during submaximum aerobic exercise.

METHODS

Twenty-four men aged between 70 and 80 years were randomly assigned to an RT group (n = 12) and control group (n = 12). Training consisted of three sets of six to 10 repetitions at 70-90% of one repetition maximum, three times per week, on an incline squat machine for 16 weeks. Blood pressure and cardiovascular function were assessed during submaximum cycle exercise at 40 W, and 50 and 70% of maximum oxygen consumption (VO2max) before training and after 16 weeks of training. Leg strength and VO2max were assessed every 4 weeks of the 16-week study.

RESULTS

At 40 W, heart rate, systolic blood pressure, and rate pressure product were lower and stroke volume was significantly higher after 16 weeks of training. At 50% VO2max, heart rate and rate pressure product were lower after 16 weeks of training and at 70% VO2max, cycle ergometry power, VO2, and arterio-venous oxygen difference were higher after 16 weeks of training. Leg strength significantly increased after 16 weeks of training.

CONCLUSION

Sixteen weeks of RT significantly reduces the blood pressure response and improves the cardiovascular function of older men during submaximum aerobic exercise. Therefore, RT not only increases muscular strength and hypertrophy but also provides significant cardiovascular benefits for older individuals.

Vascular adaptations to 8-week cycling training in older men

AIM

Because age-related changes in the large conduit arteries (increased wall thickness, and attenuated arterial compliance and endothelial function) are associated with cardiovascular pathology, prevention is of paramount importance. The effects of endurance training (i.e. walking or cycling) in older humans are assessed in cross-sectional studies, examining the brachial and carotid arteries (supplying non-trained areas). The purpose of this study was to assess the effects of 8-week endurance training in older men on conduit artery characteristics in the trained and non-trained vascular beds.

METHODS

In eight healthy sedentary older men (70 +/- 3 years), characteristics of the large conduit arteries [common femoral (CFA), superficial femoral (SFA), carotid (CA), and brachial artery (BA)] were measured before and after 8-week cycling training. Functional [arterial compliance and flow-mediated dilation (FMD)] and structural (diameter and intima-media thickness) conduit artery properties were measured using echo-Doppler. Peak blood flow, representing structural peripheral adaptations, was measured using venous occlusion plethysmography.

RESULTS

After training, peak leg blood flow was increased (P < 0.01) and baseline diameter and flow were increased in the CFA (P < 0.05). Cycling training enhanced arterial compliance of the SFA (P = 0.03), but did not affect the FMD (P = 0.32) or the intima-media thickness of the SFA. Exercise training did not alter characteristics of the BA or CA.

CONCLUSION

Eight weeks of endurance training in older men altered functional and structural characteristics of the lower extremity vasculature, whereas no changes are reported for the conduit arteries in the non-trained areas (BA or in the CA).

Exercise training for patients with cardiovascular disease

This review surveys effort training, a validated and recommended therapy, in patients with atheromatous cardiovascular disease. This true therapy reduces mortality by 25-35%, reduces clinical manifestations and complications (rhythm problems, thrombosis) and improves physical capacity, reintegration and quality of life. The effects are essentially linked to improved metabolic performance of muscles and reduced endothelial dysfunction, insulin resistance and neurohormonal abnormalities. Training also has an impact on the evolution of major risk factors, especially diabetes and arterial hypertension. The risks are limited as long as the contraindications are respected and the programmes supervised. The indications (stable angina, chronic heart failure, peripheral arterial disease) should be described more precisely by taking into account functional criteria: physical deconditioning, exclusion, compliance, mood swings, and seriousness of risk factors. The training programme should be tailor made and based on evaluation of the patient's adaptation to effort, in terms of frequency, intensity and duration of the exercises. Various types of exercise include overall or segmental physical training; concentric, eccentric, even isokinetic muscle contraction exercises; and proprioceptive rehabilitation. However, knowledge is lacking about the molecular mechanisms of the effects of training, the most effective intensity of effort, and strategies to develop physical activity in this ever-growing population for both primary and secondary prevention.

Acute resistance exercise does not change the hormonal response to sublingual androstenediol intake

Sublingual intake of 21.4 mg androstenediol increases serum testosterone concentrations whereas swallowing 200 mg androstenediol does not. The duration of increase in serum testosterone following sublingual androstenediol (SL-DIOL) is unknown. Resistance exercise (EX) following SL-DIOL may cause larger increases in serum estradiol concentrations than while at rest. This project evaluated the duration of change in, and the effects of acute EX on, the hormonal response to SL-DIOL. Six young resistance trained males consumed either placebo (PL) or SL-DIOL before a single session of EX or no exercise (Rest) in a random, double blind, crossover manner (for a total of four trials). Blood samples were collected before supplementation, and at 60, 120, 180, 240, 480, and 720 min post-supplementation, with the exercise occurring between 60 and 120 min. The serum [total testosterone] increased (P < 0.05) at 60 min similarly in SL-DIOL-EX and SL-DIOL-Rest by approximately 115%, and at 120 min by approximately 107% with no differences due to exercise. The serum [estradiol] increased (P < 0.05) similarly in SL-DIOL-EX and SL-DIOL-Rest by approximately 33% at 60 min and approximately 45% at 120 min, with no differences due to exercise. Serum [testosterone] returned to baseline by 240 min and serum [estradiol] returned to baseline by 720 min post-intake. These findings indicate that SL-DIOL acutely elevates serum testosterone and estradiol concentrations, that EX does not alter the endocrine response to SL-DIOL, and that the increases in serum estradiol last between 480 and 720 min while the increases in serum testosterone last <240 min following acute SL-DIOL intake.

Effects of RM-β-CD on sublingual bioavailability of Δ9-tetrahydrocannabinol in rabbits

The purpose of the present study was to develop novel cyclodextrin-containing sublingual formulations of cannabinoids. Complexation of model cannabinoids, Delta(9)-tetrahydrocannabinol (THC) and cannabidiol (CBD), with randomly methylated beta-cyclodextrin (RM-beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD), were studied by the phase-solubility method. Due to better complexation efficiency, RM-beta-CD was selected for further studies. Solid THC/RM-beta-CD and CBD/RM-beta-CD complexes were prepared by freeze-drying. The dissolutions of both THC and CBD in the presence and absence of RM-beta-CD were determined. THC was selected for in vivo studies: the pharmacokinetics of THC after both sublingual and oral administrations of ethanolic THC and THC/RM-beta-CD complex solutions were studied in rabbits. The aqueous solubility of CBD and THC increased as a function of CD concentration, showing A(L)- and A(P)-type diagrams for HP-beta-CD and RM-beta-CD, respectively. Dissolution rates of THC/RM-beta-CD and CBD/RM-beta-CD complexes were significantly (p < 0.05) higher than those of plain THC and plain CBD, respectively. The absolute bioavailability (F) of THC decreased in the following order: sublingual THC/RM-beta-CD solution (F = 12.1+/-1.4%; mean+/-S.D.; n = 4) > oral THC/RM-beta-CD solution (F = 4.0+/-6.0%) > or = sublingual ethanolic THC solution (F = 3.8+/-2.8%) > oral ethanolic THC solution (F = 1.3+/-1.4%). These results demonstrate that RM-beta-CD increases both the aqueous solubility and dissolution rate of these cannabinoids, making the development of novel sublingual formulation possible. These results also suggest that the sublingual administration of a THC/RM-beta-CD complex substantially increases the bioavailability of THC in rabbits.

Hormonal responses and adaptations to resistance exercise and training

Resistance exercise has been shown to elicit a significant acute hormonal response. It appears that this acute response is more critical to tissue growth and remodelling than chronic changes in resting hormonal concentrations, as many studies have not shown a significant change during resistance training despite increases in muscle strength and hypertrophy. Anabolic hormones such as testosterone and the superfamily of growth hormones (GH) have been shown to be elevated during 15-30 minutes of post-resistance exercise providing an adequate stimulus is present. Protocols high in volume, moderate to high in intensity, using short rest intervals and stressing a large muscle mass, tend to produce the greatest acute hormonal elevations (e.g. testosterone, GH and the catabolic hormone cortisol) compared with low-volume, high-intensity protocols using long rest intervals. Other anabolic hormones such as insulin and insulin-like growth factor-1 (IGF-1) are critical to skeletal muscle growth. Insulin is regulated by blood glucose and amino acid levels. However, circulating IGF-1 elevations have been reported following resistance exercise presumably in response to GH-stimulated hepatic secretion. Recent evidence indicates that muscle isoforms of IGF-1 may play a substantial role in tissue remodelling via up-regulation by mechanical signalling (i.e. increased gene expression resulting from stretch and tension to the muscle cytoskeleton leading to greater protein synthesis rates). Acute elevations in catecholamines are critical to optimal force production and energy liberation during resistance exercise. More recent research has shown the importance of acute hormonal elevations and mechanical stimuli for subsequent up- and down-regulation of cytoplasmic steroid receptors needed to mediate the hormonal effects. Other factors such as nutrition, overtraining, detraining and circadian patterns of hormone secretion are critical to examining the hormonal responses and adaptations to resistance training.

Effect of exercise training on interdialytic ambulatory and treatment-related blood pressure in hemodialysis patients

BACKGROUND

Exercise training improves blood pressure (BP) in the general population, but prior studies in hemodialysis (HD) patients only used pill counts or treatment-related BPs. We evaluated the effect of 3 to 6 months of intradialytic exercise training on ambulatory blood pressure (ABP) and treatment-related pre- and postdialysis BP.

PATIENTS AND METHODS

Nineteen chronic HD patients trained with an exercise bicycle for 30 to 60 min in the first 1 to 2 hr of each of thrice weekly HD. Interdialytic 44-hr ABP was performed a week before training began and repeated at 3 and 6 months. Pre- and post-HD systolic and diastolic BP and pre- and post-HD weight were recorded for 2 months prior to training, throughout the training, and, if available, for the 2 months after training ended. BP medications were recorded throughout. Body composition by bioimpedance, and norepinephrine and epinephrine levels by RIA were done at 0, 3, and 6 months.

RESULTS

Thirteen subjects who completed at least 3 months of training exercised 90% of HD sessions for 56 min +/- 23 SD each. Systolic and diastolic 44-hr interdialytic ABP fell during training (systolic 138.4 mmHg +/- 19.6 vs. 125.7 mmHg +/- 20.0 vs. 125.9 mmHg +/- 22.9; diastolic 83.2 mmHg +/- 10.2 vs. 74.7 mmHg +/- 9.0 vs. 73.9 mmHg +/- 11.8 at 0, 3, and 6 months; p < .05 ANOVA). Norepinephrine and epinephrine levels did not independently predict systolic BP. Pre-HD systolic BP was stable during the pretraining period, fell significantly during the training period (p < .03), and returned toward preexercise levels during the posttraining period (p < .001). Pre- or postweight, erythropoietin dose, total body water, and number of BP meds were unchanged.

CONCLUSION

Exercise training during HD significantly improves both interdialytic ABP and treatment-related BP.

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.