Aortic Stiffness and Aerobic Exercise: Mechanistic Insight from Microarray Analyses

Association between leisure-time physical activity and arterial stiffness in adults of the ELSA-Brasil study: a mediation analysis

OBJECTIVES

We aimed at defining the direct and the mediated pathways for the association between leisure-time physical activity (LTPA) and carotid-to-femoral pulse wave velocity (cf-PWV), and also to identify whether these effects are influenced by sex and age.

METHODS

Cross-sectional data from 13 718 adults (35-74 years) were obtained at the baseline of the ELSA-Brasil study. The cf-PWV was obtained by measuring the pulse transit time and the distance traveled by the pulse between the carotid and the femoral, as well as clinical and anthropometric parameters were measured. The levels of LTPA were determined by applying the long form of the International Physical Activity Questionnaire (IPAQ).

RESULTS

Classical cardiovascular risk factors were independently associated with cf-PWV. Path analysis showed that increased levels of LTPA were directly associated with lower cf-PWV in both men and women (β: -0.123 ± 0.03 vs. 0.065 ± 0.029, P for sex = 0.165), except for diabetes. Also, the mediated effect of LTPA on SBP and DBPs, heart rate, BMI, and fasting glucose, was associated with lower cf-PWV in men and women (β: -0.113 ± 0.016 vs. -0.104 ± 0.016, P for sex = 0.692), except for diabetes. When age was tested as a moderator, the direct effect did not change significantly according to participants' age, regardless of sex. However, the mediated effect increases in both men and women over 50 years.

CONCLUSION

Our findings support that LTPA in adults reduces cf-PWV by acting in different ways according to age. Physical activity in older individuals improves cardiometabolic risk factors and thus mitigates the stiffening of large arteries.

Effects of acute cervical stretching on arterial wall elastic properties

Purpose: Acute (immediate) or regular (mid- or long-term) stretching increases arterial compliance and reduces arterial stiffness. Stretching is widely known to induce arterial functional factor changes, but it is unclear whether stretching alters arterial structural factors. Ultrasound shear wave elastography can quantify the distribution of tissue elastic properties as an index of arterial structural factors. This study thus aimed to examine the effects of acute cervical stretching on arterial wall tissue elastic properties. Methods: Seventeen healthy young adults participated in two different trials for 15 min in random order on separate days: a resting and sitting trial (CON) and a supervised cervical stretching trial (CS). In CS, subjects performed 10 different stretches. At each site, the stretch was held for 30 s followed by a 10-s relaxation period. In CON, subjects rested on a chair for 15 min. Results: After the experiment, carotid arterial compliance, assessed by combined ultrasound imaging and applanation tonometry, was significantly increased in CS, but not in CON. However, there was no significant change in tissue elasticity properties of the arterial wall in either trial, as assessed by ultrasound shear wave elastography. Conclusion: Acute cervical stretching significantly increased carotid artery compliance in young participants, but did not reduce elastic tissue properties (i.e., arterial structural factors) of the carotid artery wall. These results strongly suggest that changes in structural factors have little relation to stretching-induced acute increases in arterial compliance.

Dexamethasone-Induced Arterial Stiffening Is Attenuated by Training due to a Better Balance Between Aortic Collagen and Elastin Levels

PURPOSE

Although the cardioprotective benefits of exercise training are well known, the effects of training on dexamethasone (DEX)-induced arterial stiffness are still unclear. This study was aimed at investigating the mechanisms induced by training to prevent DEX-induced arterial stiffness.

METHODS

Wistar rats were allocated into 4 groups and submitted to combined training (aerobic and resistance exercises, on alternate days, 60% of maximal capacity, for 74 d) or were kept sedentary: sedentary control rats (SC), DEX-treated sedentary rats (DS), combined training control (CT), and DEX-treated trained rats (DT). During the last 14 d, rats were treated with DEX (50 μg/kg per body weight, per day, s.c.) or saline.

RESULTS

DEX increased PWV (+44% vs +5% m/s, for DS vs SC, p<0.001) and increased aortic COL 3 protein level (+75%) in DS. In addition, PWV was correlated with COL3 levels (r=0.682, p<0.0001). Aortic elastin and COL1 protein levels remained unchanged. On the other hand, the trained and treated groups showed lower PWV values (-27% m/s, p<0.001) vs DS and lower values of aortic and femoral COL3 compared with DS.

CONCLUSION

As DEX is widely used in several situations, the clinical relevance of this study is that the maintenance of good physical capacity throughout life can be crucial to alleviate some of its side effects, such as arterial stiffness.

The effect of aerobic exercise on pulse wave velocity in middle-aged and elderly people: A systematic review and meta-analysis of randomized controlled trials

A growing body of research examines the effect of aerobic exercise on pulse wave velocity (PWV) in middle-aged and elderly people, while findings of available studies were conflicting. The aim of this study was to explore the effect of aerobic exercise on PWV in middle-aged and elderly people. Searches were performed in PubMed, Web of Science, and EBSCO databases. Cochrane risk assessment tool was used to evaluate the methodological quality of the included literature. We included studies that satisfied the following criteria: (1) eligible studies should be randomized controlled trials (RCTs); (2) eligible studies should include both an intervention and a control group; (3) eligible studies should use the middle-aged or elderly people as subjects; and (4) eligible studies should use PWV as the outcome measure. From 972 search records initially identified, 11 studies with a total of 12 exercise groups (n = 245) and 11 control groups (n = 239) were eligible for meta-analysis. There was a significant effect of aerobic exercise on reducing PWV in middle-aged and elderly people [weighted mean difference (WMD), –0.75 (95% CI, –1.21 to –0.28), p = 0.002]. Specifically, a higher intensity [vigorous-intensity, –0.74 (–1.34 to –0.14), p = 0.02; moderate-intensity, –0.68 (–1.49 to 0.12), p = 0.10], a younger age [45 years ≤ age < 60 years, –0.57 (–0.78 to –0.37), p < 0.00001; age ≥ 60 years, –0.91 (–2.10 to 0.27), p = 0.13], a better health status [healthy, –1.19 (–2.06 to –0.31), p = 0.008; diseased, –0.32 (–0.64 to –0.01), p = 0.04], and a lower basal body mass index (BMI) [BMI < 25, –1.19 (–2.06 to –0.31), p = 0.008; 25 ≤ BMI < 30, –0.52 (–0.92 to –0.12), p = 0.01; BMI ≥ 30, –0.09 (–0.93 to 0.76), p = 0.84] were associatedwith larger reductions in PWV. Aerobic exercise, especially vigorous-intensity aerobic exercise, contributed to reducing PWV in middle-aged and elderly people. The effect of aerobic exercise on improving PWV was associated with characteristics of the participants. Specifically, a younger age, a better health status, and a lower basal BMI contributed to more significant reductions in PWV.

Vascular Function in Patients After Myocardial Infarction: The Importance of Physical Activity

Background: Patients after myocardial infarction have impaired vascular function. However, effects of lifestyle, e.g., physical activity level, on endothelial function and arterial stiffness remain scarce. The aim of our study was to investigate effects of physical activity level and risk factors on endothelial function and arterial stiffness.

Methods: In this cross-sectional study, we ultrasonographically assessed parameters of vascular function, namely flow mediated dilation (FMD) of the brachial artery and carotid artery stiffness in patients after myocardial infarction referred to the cardiac rehabilitation. The International Physical Activity Questionnaire (IPAQ) was obtained from all participants. Based on the IPAQ, patients were classified into three groups: vigorous, moderate, and low physical activity engagement. ANOVA was used for comparison among three groups using Bonferroni correction to determine differences between two sub-groups.

Results: One hundred and eight patients after myocardial infarction (mean age 53 ± 10 years) were included. There were significant differences in terms of FMD (8.2 vs. 4.2 vs. 1.9%, p < 0.001) and pulse wave velocity (PWV), a measure of arterial stiffness (6.1 vs. 6.4 vs. 6.9 m/s, p = 0.004) among groups of vigorous, moderate, and low physical activity engagement, respectively. However, in younger patients only FMD remained associated with physical activity level, while arterial stiffness was not. Low physical activity engagement was a significant predictor of both FMD and PWV in univariate and multivariate models, adjusted for age, sex, and other risk factors.

Conclusion: Low physical activity level is associated with impaired endothelial function and increased arterial stiffness in patients after myocardial infarction. Future studies are warranted to address this issue in a context of cardiac rehabilitation protocols optimization in order to improve vascular function in these patients.

The Effect of Aerobic Exercise Training Frequency on Arterial Stiffness in a Hyperglycemic State in Middle-Aged and Elderly Females

The frequency of aerobic exercise training in reducing the increase in arterial stiffness during acute hyperglycemia, a risk factor for cardiovascular disease, is unknown. The aim of the study was to determine the aerobic exercise training frequency on arterial stiffness in a hyperglycemic state in middle-aged and elderly females. Twenty healthy elderly people were randomly assigned to a two-times-a-week (T2, n = 10) and four-times-a-week (T4, n = 10) exercise group. All participants exercised for 35 min per session, which consisted of jogging exercises with a heart rate intensity of 65%. Brachial-ankle (ba), and heart-brachial (hb) pulse wave velocity (PWV) were measured before, 4 and 8 weeks after intervention; before the oral ingestion of 75-g of glucose; and 30, 60, and 90 min after ingestion. The baPWV before and 4 weeks after the intervention increased in both groups (p < 0.05), but only increased 8 weeks after intervention in the T2 group. hbPWV was unchanged before, 4 and 8 weeks after intervention in both groups. These findings show that frequent aerobic exercise suppresses the increase in arterial stiffness following glucose intake. The results of this study can be used to support the implementation of exercise programs for middle-aged and elderly patients.

Effects of Exercise and Weight Loss on Proximal Aortic Stiffness in Older Adults With Obesity

BACKGROUND

Obesity may accelerate age-related increases in aortic stiffness. Although aerobic exercise training generally has favorable effects on aortic structure and function, exercise alone may not be sufficient to improve aortic stiffness in older adults with obesity. We determined the effects of aerobic exercise training with and without moderate- to high-caloric restriction (CR) on the structure and function of the proximal aorta in 160 older (65-79 years) men and women with obesity (body mass index=30-45 kg/m²).

METHODS

Participants were randomly assigned to 1 of 3 groups: aerobic exercise training only (treadmill 4 days/week for 30 minutes at 65% to 70% of heart rate reserve; n=56), aerobic exercise training plus moderate CR (n=55), or aerobic exercise training plus more intensive CR (n=49) for 20 weeks. Aortic pulse wave velocity, aortic distensibility, and other measures of aortic structure and function were assessed by cardiovascular magnetic resonance imaging. Pearson correlation coefficients were examined to assess associations between changes in proximal aortic stiffness and changes in fitness, fatness, and other potential confounders.

RESULTS

Weight loss in the aerobic exercise training plus moderate CR (-8.0 kg [95% CI, -9.17 to -6.87]) and aerobic exercise training plus more intensive CR (-8.98 kg [95% CI, -10.23 to -7.73) groups was significantly greater compared with the aerobic exercise training-only group (-1.66 kg [95% CI, -2.94 to -0.38]; P<0.017 for both). There were significant treatment effects for descending aorta distensibility (P=0.008) and strain (P=0.004) and aortic arch pulse wave velocity (P=0.01) with the aerobic exercise training plus moderate CR group having a 21% increase in distensibility (P=0.016) and an 8% decrease in pulse wave velocity (P=0.058). None of the aortic stiffness measures changed significantly in the aerobic exercise training-only or aerobic exercise training plus more intensive CR groups, and there were no significant changes in any other measure of aortic structure or function in these groups. Overall, increases in aortic distensibility were correlated with improvements in body weight and body fat distribution, but these associations were not statistically significant after adjustment for multiple comparisons.

CONCLUSIONS

In older adults with obesity, combining aerobic exercise with moderate CR leads to greater improvements in proximal aortic stiffness than exercise alone. Registration: URL: https://clinicaltrials.gov; Unique identifier: NCT01048736.

Circulating products of C-type natriuretic peptide and links with organ function in health and disease

Paracrine actions of CNP and rapid degradation at source severely limit study of CNP's many roles in vivo. However provided sensitive and validated assays are used, there is increasing evidence that low concentrations of bioactive CNP in plasma, and the readily detectable concentrations of the bio-inactive processed product of proCNP (aminoterminal proCNP), can be used to advance understanding of the hormone's role in pathophysiology. Provided renal function is normal, concordant changes in both CNP and NTproCNP reflect change in tissue production of proCNP whereas change in CNP alone results from altered rates of bioactive CNP degradation and are reflected in the ratio of NTproCNP to CNP. As already shown in juveniles, where plasma concentration of CNP products are higher and are associated with concurrent endochondral bone growth, measurements of plasma CNP products in mature adults have potential to clarify organ response to stress and injury. Excepting the role of CNP in fetal-maternal welfare, this review examines evidence linking plasma CNP products with function of a wide range of tissues in adults, including the impact of extraneous factors such as nutrients, hormone therapy and exercise.

Aging and Physiological Lessons from Master Athletes

Sedentary aging is often characterized by physical dysfunction and chronic degenerative diseases. In contrast, masters athletes demonstrate markedly greater physiological function and more favorable levels of risk factors for cardiovascular disease, osteoporosis, frailty, and cognitive dysfunction than their sedentary counterparts. In many cases, age-related deteriorations of physiological functions as well as elevations in risk factors that are typically observed in sedentary adults are substantially attenuated or even absent in masters athletes. Older masters athletes possess greater functional capacity at any given age than their sedentary peers. Impressive profiles of older athletes provide insight into what is possible in human aging and place aging back into the domain of "physiology" rather than under the jurisdiction of "clinical medicine." In addition, these exceptional aging athletes can serve as a role model for the promotion of physical activity at all ages. The study of masters athletes has provided useful insight into the positive example of successful aging. To further establish and propagate masters athletics as a role model for our aging society, future research and action are needed. © 2020 American Physiological Society. Compr Physiol 10:261-296, 2020.

The effect of steady-state CO2 on regional brain blood flow responses to increases in blood pressure via the cold pressor test

The pressure-passive cerebrovasculature is affected by alterations in cerebral perfusion pressure (CPP) and arterial blood gases (e.g., pressure of arterial [Pa]CO₂), where acute changes in either stimulus can influence cerebral blood flow (CBF). The effect of superimposed increases in CPP at different levels of steady-state PaCO₂ on regional CBF regulation is unclear. In 17 healthy participants, we simultaneously recorded continuous heart rate (electrocardiogram), blood pressure (finometer), pressure of end-tidal CO₂ (P_ETCO₂; gas analyzer), and middle (MCA) and posterior (PCA) cerebral artery blood velocity (CBV; transcranial Doppler ultrasound). Three separate CPTs were administered by passive immersion of both feet into 0-1 °C of ice water for 3-min under three randomized and coached steady-state P_ETCO₂ conditions: normocapnia (room air), hypocapnia (-10 Torr; hyperventilation) and hypercapnia (+9 Torr; 5% inspired CO₂;). CBV responses were calculated as the absolute difference (∆) between baseline and mean MCAv and PCAv during the 3-min CPT. Both the ∆MCAv and ∆PCAv responses to the CPT were larger under hypercapnic conditions. The absolute ∆MCAv response was larger than the ∆PCAv during the CPT across all three CO₂ trials. Cerebrovascular CO₂ reactivity (CVR) was larger in the MCA than PCA in both CPT and baseline conditions, but there were no differences in CVR between CPT and baseline conditions. Our data indicate that (a) increases in CO₂ increases the CBV responses to a CPT, (b) the anterior cerebrovasculature is more responsive to a CPT-induced increases in MAP, and (c) although unchanged during a CPT, CVR is larger in the anterior cerebral circulation.

Nitric Oxide and Decreases in Resistance Exercise Blood Pressure With Aerobic Exercise Training in Older Individuals

An exaggerated blood pressure response to resistance exercise is a marker of masked hypertension and a risk factor for future essential hypertension. Habitual aerobic exercise decreases systolic blood pressure (SBP) during resistance exercise in older individuals, but the underlying mechanisms have not been explored. This study tested the hypothesis that nitric oxide (NO) mediates a reduction of resistance exercise SBP with aerobic training in older individuals. Normotensive older adults participated in a 6-week program as a part of the aerobic training group (n = 23, exercised for an average of 4.4 d/wk and 59 min/d) or the control group (n = 26, asked not to modify their lifestyle during the experimental period). The aerobic exercise intervention increased plasma concentrations of nitrite/nitrate (NOx, end products of NO) and decreased SBP during a one-hand arm curl exercise at 20% and 40% of one-repetition maximum and brachial-ankle pulse wave velocity (an index of arterial stiffness). In the control group, there were no differences in these measures before and after the experimental period. Changes in plasma NOx concentrations during the study period were correlated with changes in resistance exercise SBP. Stepwise regression revealed that changes in plasma NOx concentrations during the experimental period are a significant factor of changes in resistance exercise SBP, independent of age, sex, and changes in serum lipid profile, maximal oxygen uptake, resting SBP, and other variables. These results suggest that NO is associated with decreases in resistance exercise SBP with aerobic training in older individuals and help us better understand why habitual aerobic exercise prevents cardiovascular disease.

Arterial Stiffness is Associated With Moderate to Vigorous Physical Activity Levels in Post-Myocardial Infarction Patients

PURPOSE

Arterial stiffness has shown independent predictive value for all-cause and cardiovascular mortalities, as well as fatal and nonfatal coronary events. Physical activity (PA) is associated with reduced cardiovascular morbidity and mortality. The study aims to analyze the cross-sectional association of arterial stiffness with objectively measured PA in patients following acute myocardial infarction.

METHODS

One hundred patients were consecutively recruited after experiencing an acute myocardial infarction. Central arterial stiffness was measured through carotid-femoral pulse wave velocity (cf-PWV) and daily PA was assessed objectively during 7 consecutive days with accelerometers. To be valid, data required recordings of at least 8 hr/d on 5 d.

RESULTS

The cf-PWV showed a negative and significant association with total weekly time spent in moderate to vigorous PA (MVPA) (r = -0.416, P < .001). Patients classified as having higher risk according to arterial stiffness values (cf-PWV ≥10 m/sec) showed significantly lower time spent in MVPA than those below that threshold. The cf-PWV was significantly lower in patients performing >300 min of MVPA/wk than in those performing <150 min/wk (8.53 ± 2.08 vs 10.3 ± 2.44 m/sec, P = .021). Differences remained significant after adjustment for several confounders.

CONCLUSIONS

Moderate to vigorous PA was inversely associated with arterial stiffness and time spent in MVPA was lower in patients after acute myocardial infarction, with cf-PWV above the risk threshold value (≥10 m/sec). These results seem to reinforce the importance of PA as a nonpharmacological tool for secondary cardiovascular prevention.

Elevated C-type natriuretic peptide elicits exercise preconditioning-induced cardioprotection against myocardial injury probably via the up-regulation of NPR-B

To evaluate exercise preconditioning (EP)-induced cardioprotective effects against exercise-induced acute myocardial injury and investigate the alterations of C-type natriuretic peptide (CNP) and its specific receptor, natriuretic peptide receptor B (NPR-B), during EP-induced cardioprotection. Rats were subjected to treadmill exercise as an EP model (4 periods of 10 min each at 30 m/min with intervening periods of rest lasting 10 min). High-intensity exercise was performed 0.5 and 24 h after the EP. EP attenuated high-intensity exercise-induced myocardial injury in both the early and late phases. After EP and high-intensity exercise, CNP and NPR-B levels increased robustly, but no alterations in the plasma CNP were observed. The enhanced NPR-B, plasma and tissue CNP, and its mRNA levels after high-intensity exercise were significantly elevated by EP. These results suggest that cardiac CNP and NPR-B play an important role in EP-mediated cardioprotection against high-intensity exercise-induced myocardial injury in rats.

Objectively measured physical activity and sedentary-time are associated with arterial stiffness in Brazilian young adults

OBJECTIVE

To examine the associations between objectively measured physical activity and sedentary time with pulse wave velocity (PWV) in Brazilian young adults.

METHODS

Cross-sectional analysis with participants of the 1982 Pelotas (Brazil) Birth Cohort who were followed-up from birth to 30 years of age. Overall physical activity (PA) assessed as the average acceleration (mg), time spent in moderate-to-vigorous physical activity (MVPA - min/day) and sedentary time (min/day) were calculated from acceleration data. Carotid-femoral PWV (m/s) was assessed using a portable ultrasound. Systolic and diastolic blood pressure (SBP/DBP), waist circumference (WC) and body mass index (BMI) were analyzed as possible mediators. Multiple linear regression and g-computation formula were used in the analyses.

RESULTS

Complete data were available for 1241 individuals. PWV was significantly lower in the two highest quartiles of overall PA (0.26 m/s) compared with the lowest quartile. Participants in the highest quartile of sedentary time had 0.39 m/s higher PWV (95%CI: 0.20; 0.57) than those in the lowest quartile. Individuals achieving ≥30 min/day in MVPA had lower PWV (β = -0.35; 95%CI: -0.56; -0.14). Mutually adjusted analyses between MVPA and sedentary time and PWV changed the coefficients, although results from sedentary time remained more consistent. WC captured 44% of the association between MVPA and PWV. DBP explained 46% of the association between acceleration and PWV.

CONCLUSIONS

Physical activity was inversely related to PWV in young adults, whereas sedentary time was positively associated. Such associations were only partially mediated by WC and DBP.

Age-related vascular stiffening: causes and consequences

Arterial stiffening occurs with age and is closely associated with the progression of cardiovascular disease. Stiffening is most often studied at the level of the whole vessel because increased stiffness of the large arteries can impose increased strain on the heart leading to heart failure. Interestingly, however, recent evidence suggests that the impact of increased vessel stiffening extends beyond the tissue scale and can also have deleterious microscale effects on cellular function. Altered extracellular matrix (ECM) architecture has been recognized as a key component of the pre-atherogenic state. Here, the underlying causes of age-related vessel stiffening are discussed, focusing on age-related crosslinking of the ECM proteins as well as through increased matrix deposition. Methods to measure vessel stiffening at both the macro- and microscale are described, spanning from the pulse wave velocity measurements performed clinically to microscale measurements performed largely in research laboratories. Additionally, recent work investigating how arterial stiffness and the changes in the ECM associated with stiffening contributed to endothelial dysfunction will be reviewed. We will highlight how changes in ECM protein composition contribute to atherosclerosis in the vessel wall. Lastly, we will discuss very recent work that demonstrates endothelial cells (ECs) are mechano-sensitive to arterial stiffening, where changes in stiffness can directly impact EC health. Overall, recent studies suggest that stiffening is an important clinical target not only because of potential deleterious effects on the heart but also because it promotes cellular level dysfunction in the vessel wall, contributing to a pathological atherosclerotic state.

Higher cardiorespiratory fitness attenuates the risk of atherosclerosis associated with ADRB3 Trp64Arg polymorphism

PURPOSE

β3-Adrenergic receptor (ADRB3) Trp64Arg polymorphism is associated with atherogenic risk factors that include weight gain, insulin resistance, and diabetes. Habitual exercise brings higher cardiorespiratory fitness and results in the amelioration of atherosclerotic risk factors. However, the effects of cardiorespiratory fitness level and ADRB3 Trp64Arg polymorphism on the risk of cardiovascular disease remain unclear. A cross-sectional investigation of 877 Japanese men and women (18-75 years old) was performed to clarify the effects of cardiorespiratory fitness on the relationship between ADRB3 Trp64Arg polymorphism and risk of cardiovascular disease.

METHOD

Common carotid intima-media thickness (ccIMT) and blood lipid profiles were assessed as surrogate markers of atherosclerosis. We measured peak oxygen uptake (V̇O(2peak)) during incremental cycle ergometer exercise testing. Subjects were divided into groups with high (High-Fit) and low (Low-Fit) levels of cardiorespiratory fitness based on the median value of V̇O(2peak) for sex and decade.

RESULTS

Levels of body fat, triglycerides, and plasma glucose were lower and high-density lipoprotein cholesterol levels and V̇O(2peak) were higher in High-Fit subjects than Low-Fit subjects. ADRB3 Trp64Arg polymorphism did not significantly affect ccIMT or blood lipid profiles. In Low-Fit subjects, ccIMT was higher in individuals with the Arg/Arg genotype compared to the Trp/Trp and Trp/Arg genotypes (each P < 0.0001); however, ADRB3 polymorphism had no effect in High-Fit subjects.

CONCLUSION

Higher levels of cardiorespiratory fitness may attenuate the risk of atherosclerosis associated with ADRB3 Trp64Arg polymorphism.

The effects of exercise training on arterial stiffness in coronary artery disease patients: a state-of-the-art review

The purpose of this state-of-the-art review was to examine the effects of exercise training on arterial stiffness (AS) in patients with coronary artery disease (CAD). A PubMed and SCOPUS literature search was conducted up to March of 2013. Two authors performed the selection of the studies and the subsequent data extraction (e.g. information on study design, exercise programme characteristics and outcome measures). Of 34 papers identified, only five studies met the inclusion criteria, with no one being a randomized controlled trial. Within the selected studies, the sample size varied between 28 and 119 patients, with mean ages ranging from 48 to 67 years old in patients with CAD after an acute myocardial infarction, coronary artery bypass graft or percutaneous transluminal coronary angioplasty. Although all studies utilized the aerobic exercise mode, the other characteristics of the exercise programmes varied largely between the studies: programme length (from 6 to 20 weeks), exercise duration (15-20 to 50 min) and exercise intensity, which was based on heart rate reserve (40 to 85%) or heart rate at anaerobic threshold or ventilatory threshold. All the three studies evaluating pulse wave velocity, as well as one of two studies that assessed the augmentation index, reported significant reductions on those variables after exercise training. Results indicated that the majority of the AS and related measures improved after the different exercise training programmes. However, these results need to be confirmed in future randomized clinical studies controlling potential confounders.

Assessment of arterial stiffness using applanation tonometry

Augmentation index (AIx) and pulse wave velocity (PWV) assess functional and structural aspects of the vascular wall and are independent markers of cardiovascular morbidity and mortality. Like blood pressure, many factors, genetic, structural, and physiological, affect AIx and PWV. AIx and PWV can be assessed noninvasively using applanation tonometry. The technique is simple, but comes with a number of practical and technical limitations that have not been well documented and (or) explored. This review considers pulse wave analysis in the context of cardiovascular disease, and considers its limitations. Data are presented indicating that the placement of the probe is critical, and that the amplitude of the obtained signal is related to the variability in measurements. On a more theoretical note, issues are discussed regarding the applied transfer functions that are built in the devices to assess central AIx from peripheral waveforms. Altogether, PWV and its analysis are useful additions to the arsenal of parameters that can be used to assess vascular health and to estimate vascular risk. Yet, our analysis underscores the necessity for precise operating procedures, and calls for transparency regarding the applied transfer functions of commercial devices.

Role of exercise in the prevention of cardiovascular disease: results, mechanisms, and new perspectives

On an empirical basis, exercise has been regarded as a fundamental pre-requisite for human well-being and physical integrity since classical times. Only in the last decades, however, scientific evidence has accumulated proving its role in the prevention and treatment of multiple chronic diseases beyond any reasonable doubt. Few treatment strategies in medicine have been tested so rigorously in large cohorts of patients as regular physical exercise. With the advent of molecular biology, the underlying mechanisms, such as NO bioavailability and mobilization of progenitor cells, could be identified. This enhances our understanding of this therapeutic tool. Unfortunately, the low compliance rate of the patients is the major drawback of the intervention exercise training (ET). The objective of this manuscript is to summarize the current knowledge with respect to ET on cardiovascular disease (CVD) and the molecular changes elicited by ET. Finally, we will critically assess reasons why ET as therapeutic option is not as effective at the population level in preventing CVD and what we may change in the future to make ET the most effective intervention to fight the development of CVD.

Higher cardiorespiratory fitness attenuates arterial stiffening associated with the Ala54Thr polymorphism in FABP2

Fatty acid binding protein 2 (FABP2) Ala54Thr polymorphism is a candidate gene associated with the risk of cardiovascular disease. Habitual exercise brings higher cardiorespiratory fitness and results in the improvement of cardiovascular disease risk. However, the effect of cardiorespiratory fitness level and FABP2 Ala54Thr polymorphism on the risk of cardiovascular diseases remains unclear. In the present study, a cross-sectional investigation of 837 Japanese men and women was performed to clarify the effects of cardiorespiratory fitness on the relationship between risk of cardiovascular disease and FABP2 Ala54Thr gene polymorphism. The study subjects were divided into high-cardiorespiratory fitness (High-Fit) and low-cardiorespiratory fitness (Low-Fit) groups based on the median value of peak oxygen uptake in each sex and decade. The FABP2 Ala54Thr polymorphism did not significantly affect carotid β-stiffness or blood pressure. In the Low-Fit group, carotid β-stiffness, systolic blood pressure, and diastolic blood pressure were higher for individuals with the Ala/Ala genotype compared with those with the Ala/Thr or Thr/Thr genotype, whereas no differences were observed in the High-Fit group. Additionally, serum triglyceride and plasma glucose levels were lower and serum high-density lipoprotein cholesterol levels were higher in the High-Fit group compared with the Low-Fit group; the FABP2 Ala54Thr polymorphism did not significantly affect these parameters. These results suggest that the higher cardiorespiratory fitness may attenuate the changes in central arterial stiffness and blood pressure that are associated with the FABP2 genotype.

Moderate and heavy metabolic stress interval training improve arterial stiffness and heart rate dynamics in humans

Traditional continuous aerobic exercise training attenuates age-related increases of arterial stiffness, however, training studies have not determined whether metabolic stress impacts these favourable effects. Twenty untrained healthy participants (n = 11 heavy metabolic stress interval training, n = 9 moderate metabolic stress interval training) completed 6 weeks of moderate or heavy intensity interval training matched for total work and exercise duration. Carotid artery stiffness, blood pressure contour analysis, and linear and non-linear heart rate variability were assessed before and following training. Overall, carotid arterial stiffness was reduced (p < 0.01), but metabolic stress-specific alterations were not apparent. There was a trend for increased absolute high-frequency (HF) power (p = 0.10) whereas both absolute low-frequency (LF) power (p = 0.05) and overall power (p = 0.02) were increased to a similar degree following both training programmes. Non-linear heart rate dynamics such as detrended fluctuation analysis \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$({| {1 - \alpha_{1} }|})$$\end{document} also improved (p > 0.05). This study demonstrates the effectiveness of interval training at improving arterial stiffness and autonomic function, however, the metabolic stress was not a mediator of this effect. In addition, these changes were also independent of improvements in aerobic capacity, which were only induced by training that involved a high metabolic stress.

Effects of dietary macronutrient distribution on vascular integrity in obesity and metabolic syndrome

Metabolic syndrome is a condition characterized by a clustering of risk factors for cardiovascular disease. Emerging data suggest vascular integrity is disrupted in metabolic syndrome. Vascular integrity may be determined using several measurements, including pulse wave velocity, augmentation index, and flow-mediated dilation. Arterial stiffness has become an important clinical indicator of cardiovascular disease risk. Several circulating inflammatory peptides also impact vascular integrity. The present review examines the efficacy of nutritional interventions aimed at improving vascular integrity and reducing levels of associated inflammatory peptides in individuals with metabolic syndrome, with a specific focus on the effect of dietary macronutrient redistribution on these factors.

Impact of exercise training on endothelial transcriptional profiles in healthy swine: a genome-wide microarray analysis

While the salutary effects of exercise training on conduit artery endothelial cells have been reported in animals and humans with cardiovascular risk factors or disease, whether a healthy endothelium is alterable with exercise training is less certain. The purpose of this study was to evaluate the impact of exercise training on transcriptional profiles in normal endothelial cells using a genome-wide microarray analysis. Brachial and internal mammary endothelial gene expression was compared between a group of healthy pigs that exercise trained for 16-20 wk (n = 8) and a group that remained sedentary (n = 8). We found that a total of 130 genes were upregulated and 84 genes downregulated in brachial artery endothelial cells with exercise training (>1.5-fold and false discovery rate <15%). In contrast, a total of 113 genes were upregulated and 31 genes downregulated in internal mammary artery endothelial cells using the same criteria. Although there was an overlap of 66 genes (59 upregulated and 7 downregulated with exercise training) between the brachial and internal mammary arteries, the identified endothelial gene networks and biological processes influenced by exercise training were distinctly different between the brachial and internal mammary arteries. These data indicate that a healthy endothelium is indeed responsive to exercise training and support the concept that the influence of physical activity on endothelial gene expression is not homogenously distributed throughout the vasculature.

Changes in arterial distensibility and flow-mediated dilation after acute resistance vs. aerobic exercise

Previous research has shown significantly lower arterial distensibility (AD) after resistance exercise (RE) yet higher AD after aerobic exercise (AE). These changes may be related to exercise-induced differences in vasodilatory capacity. The purpose of this study was to investigate the vasodilatory and AD responses to acute AE and RE. Forearm blood flow (FBF) during reactive hyperemia (RH) was assessed before and 60 minutes after exercise, whereas aortic and femoral pulse wave velocity was measured as an index of arterial stiffness pre, 40, and 60 minutes after an acute bout of AE (30-minute leg ergometry at 65% of VO2peak) and RE (3 sets, 10 reps; upper and lower body at 65% 1 repetition maximum) in 10 male subjects (24.9 ± 0.86 years). Area under the curve (AUC) was employed to determine differences in flow. After the intervention, we found that central pulse wave velocity decreased 8% after AE and remained depressed at this level through 60 minutes of observation, whereas RE increased central pulse wave velocity 9.8% from pre to 40 and 60 minutes postexercise. Area under the curve for FBF-RH significantly increased 38% after RE, yet there was no significant change after AE. Forearm vasodilatory capacity increased after acute RE but not after acute AE. This suggests that changes in AD may be disassociated from changes in vasodilatory capacity after acute exercise. Further, in a direct comparison of RE vs. AE, we have shown that RE has greater increases in limb blood flow and augments postexercise hypotension greater at 40 minutes postexercise when compared to AE.

Lack of carotid stiffening associated with MTHFR 677TT genotype in cardiorespiratory fit adults

The TT genotype of C677T polymorphism in 5,10-methylenetetrahydrofolate reductase (MTHFR) induces elevation of homocysteine level and leads to atherosclerosis and arterial stiffening. Furthermore, cardiorespiratory fitness level is also associated with arterial stiffness. In the present study, a cross-sectional investigation of 763 Japanese men and women (18-70 yr old) was performed to clarify the effects of cardiorespiratory fitness on the relationship between arterial stiffness and MTHFR C677T gene polymorphism. Arterial stiffness was assessed by carotid beta-stiffness with ultrasonography and tonometry. The study subjects were divided into high-cardiorespiratory fitness (High-Fit) and low-cardiorespiratory fitness (Low-Fit) groups based on the median value of peak oxygen uptake in each sex and decade. The plasma homocysteine level was higher in the TT genotype of MTHFR C677T polymorphism compared with CC and CT genotype individuals. MTHFR C677T polymorphism showed no effect on carotid beta-stiffness, but there was a significant interaction effect between fitness and MTHFR C677T polymorphism on carotid beta-stiffness (P = 0.0017). In the Low-Fit subjects, carotid beta-stiffness was significantly higher in individuals with the TT genotype than the CC and CT genotypes. However, there were no such differences in High-Fit subjects. In addition, beta-stiffness and plasma homocysteine levels were positively correlated in Low-Fit subjects with the TT genotype (r = 0.71, P < 0.0001), but no such correlations were observed in High-Fit subjects. In CC and CT genotype individuals, there were also no such correlations in either fitness level. These results suggest that the higher cardiorespiratory fitness may attenuate central artery stiffening associated with MTHFR C677T polymorphism.

Quantifying in vivo hemodynamic response to exercise in patients with intermittent claudication and abdominal aortic aneurysms using cine phase-contrast MRI

PURPOSE

To evaluate rest and exercise hemodynamics in patients with abdominal aortic aneurysms (AAA) and peripheral occlusive disease (claudicants) using phase-contrast MRI.

MATERIALS AND METHODS

Blood velocities were acquired by means of cardiac-gated cine phase-contrast in a 0.5 Tesla (T) open MRI. Volumetric flow was calculated at the supraceliac (SC), infrarenal (IR), and mid-aneurysm (MA) levels during rest and upright cycling exercise using an MR-compatible exercise cycle.

RESULTS

Mean blood flow increased during exercise (AAA: 130%, Claudicants: 136% of resting heart rate) at the SC and IR levels for AAA participants (2.6 +/- 0.6 versus 5.8 +/- 1.6 L/min, P < 0.001 and 0.8 +/- 0.4 versus 5.1 +/- 1.7 L/min, P < 0.001) and claudicants (2.3 +/- 0.5 versus 4.5 +/- 0.9 L/min, P < 0.005 and 0.8 +/- 0.2 versus 3.3 +/- 0.9 L/min, P < 0.005). AAA participants had a significant decrease in renal and digestive blood flow from rest to exercise (1.8 +/- 0.7 to 0.7 +/- 0.6 L/min, P < 0.01). The decrease in renal and digestive blood flow during exercise correlated with daily activity level for claudicants (R = 0.81).

CONCLUSION

Abdominal aortic hemodynamic changes due to lower extremity exercise can be quantified in patients with AAA and claudication using PC-MRI. The redistribution of blood flow during exercise was significant and different between the two disease states.

Periodic acceleration (pGz) prior to whole body ischemia reperfusion injury provides early cardioprotective preconditioning

AIMS

Periodic acceleration (pGz) is a method that applies repetitive sinusoidal head-to-foot motion to the horizontally positioned body. pGz adds pulses to the circulation as a function of frequency, thereby increasing shear stress to the endothelium. Pulsatile shear stress increases release of cardioprotective endothelial-derived nitric oxide prostaglandin E-2 and prostacyclin into the circulation. We investigated whether pGz may be effective as an early preconditioning strategy when applied one hour prior to whole body ischemia reperfusion injury induced by ventricular fibrillation (VF).

MAIN METHODS

Twenty anesthetized and paralyzed male swine were randomized to one hour of pGz and conventional mechanical ventilation [PC] or solely conventional mechanical ventilation [Control] prior to VF and resuscitation. After eight minutes of unsupported VF, cardiopulmonary resuscitation was carried out followed by defibrillation. Hemodynamics, electrocardiogram, echocardiogram, regional blood flows, and markers of global myocardial injury were measured. Protein expression of endothelial-derived nitric oxide synthase (eNOS), phosphorylated eNOS (p-eNOS), serine/threonine kinase Akt total (t-Akt), and phosphorylated (p-Akt) were determined by immunoblotting.

KEY FINDINGS

All animals had spontaneous return of circulation after cardiopulmonary resuscitation (CPR) and defibrillation. Preconditioned animals had less hemodynamically significant arrhythmias, less myocardial stunning, and greater regional blood flows to the brain, heart, kidneys, and ileum than Controls. Troponin I and creatine phosphokinase values in PC were 65% of the values present in Controls. In addition, preconditioned animals had higher protein expression of cardiac eNOS, p-eNOS, t-Akt, and p-Akt than Controls.

SIGNIFICANCE

pGz preconditioning confers early cardioprotection in a model of whole body ischemia reperfusion injury.

Effects of acute resistance exercise on arterial stiffness in young men

Background and Objectives

Increased central arterial stiffness is an emerging risk factor for cardiovascular disease. Acute aerobic exercise reduces arterial stiffness, while acute resistance exercise may increase arterial stiffness, but this is not a universal finding. We tested whether an acute resistance exercise program was associated with an increase in arterial stiffness in healthy young men.

Subjects and Methods

Thirteen healthy subjects were studied under parallel experimental conditions on 2 separate days. The order of experiments was randomized between resistance exercise (8 resistance exercises at 60% of 1 repeated maximal) and sham control (seated rest in the exercise room). Carotid-femoral pulse wave velocity (PWV) and aortic augmentation index as indices of aortic stiffness were measured using applanation tonometry. Measurements were made at baseline before treatments, 20 minutes, and 40 minutes after treatments (resistance exercise and sham control).

Results

There was no difference in resting heart rate or in arterial stiffness between the two experimental conditions at baseline. At 20 minutes after resistance exercise, heart rate, carotid-femoral PWV and augmentation index@75(%) were significantly increased in the resistance exercise group compared with the sham control (p<0.05). Brachial blood pressure, central blood pressure and pulse pressure were not significantly increased after resistance exercise.

Conclusion

An acute resistance exercise program can increase arterial stiffness in young healthy men. Further studies are needed to clarify the effects of long-term resistance training on arterial stiffness.

Involvement of endothelin-1 in habitual exercise-induced increase in arterial compliance

AIM

Habitual aerobic exercise results in a significant increase in central arterial compliance. Endothelin-1 (ET-1) is a potent endothelium-derived vasoconstrictor peptide and could play a role in mediating the habitual aerobic exercise-induced increase in central arterial compliance. The aim of the present study was to examine whether ET-1 is involved in the mechanisms underlying the increase in central arterial compliance with aerobic exercise training.

METHODS

Seven apparently healthy middle-aged and older (60 +/- 3 years) adults underwent systemic endothelin-A/B (ET(A/B))-receptor blockade (500 mg of Tracleer) before and after 12 weeks of aerobic exercise training (70 +/- 1% of maximal heart rate, 44 +/- 2 min day(-1), 4.4 +/- 0.1 days week(-1)).

RESULTS

Basal carotid arterial compliance (via simultaneous B-mode ultrasound and arterial applanation tonometry on the common carotid artery) increased significantly after exercise training. Resting plasma ET-1 concentration decreased significantly after exercise training. Before exercise intervention, carotid arterial compliance increased significantly with the administration of the ET(A/B)-receptor blockade. After training, however, increases in carotid arterial compliance previously observed with the ET(A/B)-receptor blockade before training were abolished.

CONCLUSIONS

Regular aerobic exercise training enhances central arterial compliance in middle-aged and older humans. The increase in arterial compliance was associated with the corresponding reduction in plasma ET-1 concentration as well as the elimination of ET-1-mediated vascular tone. These results suggest that reductions in ET-1 may be an important mechanism underlying the beneficial effect of exercise training on central artery compliance.

Reduction in alpha-adrenergic receptor-mediated vascular tone contributes to improved arterial compliance with endurance training

BACKGROUND

Regular aerobic exercise improves large artery compliance in middle-aged and older humans. However, the underlying mechanisms are unknown. We tested the hypothesis that the improved central arterial compliance with endurance training is mediated by decreased alpha-adrenergic tone and/or increased endothelial function.

METHODS

Seven sedentary healthy adults (60+/-3 years) underwent systemic alpha-adrenergic blockade (phentolamine) and nitric oxide synthase (NOS) inhibition using N(G)-monomethyl-L-arginine in sequence before and after a 3-month moderate endurance training (walk/jog, 4-5 days/week). Phentolamine was given first to isolate the contribution of nitric oxide to arterial compliance by minimizing reflex suppression of sympathetic tone resulting from systemic NOS inhibition as well as to assess the alpha-adrenergic receptor-mediated modulation of arterial compliance.

RESULTS

Baseline arterial compliance (via simultaneous ultrasound and applanation tonometry on the carotid artery) increased 34+/-12% after exercise training (P<0.01). When alpha-adrenergic blockade was performed, arterial compliance increased 37+/-6% (P<0.01) before the exercise training but did not change significantly after the training. Decreases in arterial compliance from the alpha-adrenergic blockade to the subsequent additional NOS blockade were not different before and after exercise training.

CONCLUSION

Our results suggest that the reduction in alpha-adrenergic receptor-mediated vascular tone contributes to the improved central arterial compliance with endurance training.

Habitual exercise and arterial aging

Aging affects the function and structure of arteries and increases the risk of cardiovascular diseases (CVD). In healthy sedentary adults, aging is associated with increased stiffness (reduced compliance) of large elastic arteries; impaired vascular endothelial function, including reductions in endothelium-dependent dilation (EDD), release of tissue-type plasminogen activator (fibrinolytic capacity) and endothelial progenitor cell number and function; increased intima-media wall thickness (IMT); and peripheral vasoconstriction (decreased basal leg blood flow). Habitual physical activity/increased aerobic exercise capacity is associated with reduced risk of CVD. Compared with their sedentary peers, adults who regularly perform aerobic exercise demonstrate smaller or no age-associated increases in large elastic artery stiffness, reductions in vascular endothelial function, and increases in femoral artery IMT. A short-term, moderate-intensity aerobic exercise intervention (brisk daily walking for 12 wk) improves carotid artery compliance and can restore vascular endothelial function in previously sedentary middle-aged and older adults. Reduced oxidative stress may be an important mechanism contributing to these effects. Habitual resistance exercise increases (high-intensity) or does not affect (moderate-intensity) large elastic artery stiffness, and prevents/restores the age-associated reduction in basal leg blood flow independent of changes in leg fat-free mass. Habitual exercise favorably modulates several expressions of arterial aging, thus preserving vascular function and possibly reducing the risk of CVD.

Voluntary running exercise attenuates the progression of endothelial dysfunction and arterial calcification in ovariectomized rats

AIM

Loss of oestrogen synthesis capacity after menopause contributes to increases in arterial stiffness and calcification. Exercise training improves arterial stiffness and calcification. However, the mechanism of exercise training-induced improvement of arterial stiffness and calcification remains unclear.

METHOD

We examined the mechanism by using aortas of sham-operated rats (sham control; SC), ovariectomized rats (OVX control; OC), OVX plus treatment with vitamin D(3) plus nicotine (VDN) rats (OV sedentary; OVSe), which is an animal model of endothelial dysfunction and arterial calcification, and voluntary running wheel exercise for 8 weeks plus OVX plus VDN rats (OV exercise; OVEx).

RESULTS

The arterial tissue calcium and endothelin-1 (ET-1: a vasoconstrictor peptide and a potent regulator of arterial calcification) levels were significantly higher in OVSe rats compared with the SC and OC rats, whereas these levels in the OVEx rats were significantly lower than in the OVSe rats. Additionally, arterial expression of endothelial nitric oxide synthase (eNOS), which is an enzyme that produces nitric oxide (NO: a vasodilator substance), was reduced in OVSe rats. However, exercise training prevented the decrease in eNOS expression. Moreover, there was a significant positive correlation between arterial calcium level and arterial ET-1 level.

CONCLUSION

These findings suggest that exercise training-induced improvement of ET-1 and NO prevents the impairment of endothelial function after menopause in females, and this improvement may result in less arterial calcification.

Alteration of gene expression in rat colon mucosa after exercise

The development of colon cancer is highly influenced by lifestyle factors such as nutrition and physical inactivity. Detailed biological mechanisms are thus far unclear. The purpose of this study was to investigate the effects of regular treadmill exercise on gene expression in rat colon mucosa. For this purpose, 6-week-old male Wistar rats completed a stress-free voluntary treadmill exercise period of 12 weeks. Sedentary rats served as a control group. In the colon mucosa, steady-state mRNA expression levels of approximately 10,000 genes were compared between both groups by micro-array analysis (MWG rat 10K array). A total of 8846 mRNAs were detected above background level. Regular exercise led to a decreased expression of 47 genes at a threshold-factor of 2.0. Three genes were found to be up-regulated in the exercise group. The identified genes encode proteins involved in signal transduction (n=11), transport (n=8), immune system (n=7), cytoskeleton (n=6), protein targeting (n=6), metabolism (n=5), transcription (n=3) and vascularization (n=2). Among the genes regulated by regular exercise, the betaine-homocysteine methyltransferase 2 (BHMT2) seems to be of particular interest. Physical activity may protect against aberrant methylation by repressing the BHMT2 gene and thus contribute to a decreased risk of developing colon cancer. We have also identified vascular endothelial growth factor (VEGF), angiopoietin-2 (ANG-2) and calcium-independent phospholipase a2 (iPL-A2), all of them with markedly reduced transcript levels in the mucosa of active rats. In summary, our experiment presents the first gene expression pattern in rat colon mucosa following regular treadmill activity and represents an important step in understanding the molecular mechanisms responsible for the preventive effect of physical activity on the development of colon cancer.