Arterial intima-media thickness: site-specific associations with HRT and habitual exercise

Vascular Aging: Assessment and Intervention

Vascular aging represents a collection of structural and functional changes in a blood vessel with advancing age, including increased stiffness, vascular wall remodeling, loss of angiogenic ability, and endothelium-dependent vasodilation dysfunction. These age-related alterations may occur earlier in those who are at risk for or have cardiovascular diseases, therefore, are defined as early or premature vascular aging. Vascular aging contributes independently to cardio-cerebral vascular diseases (CCVDs). Thus, early diagnosis and interventions targeting vascular aging are of paramount importance in the delay or prevention of CCVDs. Here, we review the direct assessment of vascular aging by examining parameters that reflect changes in structure, function, or their compliance with age including arterial wall thickness and lumen diameter, endothelium-dependent vasodilation, arterial stiffness as well as indirect assessment through pathological studies of biomarkers including endothelial progenitor cell, lymphocytic telomeres, advanced glycation end-products, and C-reactive protein. Further, we evaluate how different types of interventions including lifestyle mediation, such as caloric restriction and salt intake, and treatments for hypertension, diabetes, and hyperlipidemia affect age-related vascular changes. As a single parameter or intervention targets only a certain vascular physiological change, it is recommended to use multiple parameters to evaluate and design intervention approaches accordingly to prevent systemic vascular aging in clinical practices or population-based studies.

Aerobic Versus Resistance Training Effects on Ventricular-Arterial Coupling and Vascular Function in the STRRIDE-AT/RT Trial

Background: The goal was studying the differential effects of aerobic training (AT) vs. resistance training (RT) on cardiac and peripheral arterial capacity on cardiopulmonary (CP) and peripheral vascular (PV) function in sedentary and obese adults.

Methods: In a prospective randomized controlled trial, we studied the effects of 6 months of AT vs. RT in 21 subjects. Testing included cardiac and vascular ultrasoundography and serial CP for ventricular-arterial coupling (Ees/Ea), strain-based variables, brachial artery flow-mediated dilation (BAFMD), and peak VO₂ (pVO_2; mL/kg/min) and peak O₂-pulse (O₂p; mL/beat).

Results: Within the AT group (n = 11), there were significant increases in rVO₂ of 4.2 mL/kg/min (SD 0.93) (p = 0.001); O₂p of 1.9 mL/beat (SD 1.3) (p = 0.008) and the brachial artery post-hyperemia peak diameter 0.18 mm (SD 0.08) (p = 0.05). Within the RT group (n = 10) there was a significant increase in left ventricular end diastolic volume 7.0 mL (SD 9.8; p = 0.05) and percent flow-mediated dilation (1.8%) (SD 0.47) (p = 0.004). Comparing the AT and RT groups, post exercise, rVO₂ 2.97, (SD 1.22), (p = 0.03), O₂p 0.01 (SD 1.3), (p = 0.01), peak hyperemic blood flow volume (1.77 mL) (SD 140.69) (p = 0.009), were higher in AT, but LVEDP 115 mL (SD 7.0) (p = 0.05) and Ees/Ea 0.68 mmHg/ml (SD 0.60) p = 0.03 were higher in RT.

Discussion: The differential effects of AT and RT in this hypothesis generating study have important implications for exercise modality and clinical endpoints.

The Impact of High-Intensity Interval Training Versus Moderate-Intensity Continuous Training on Carotid Intima-Media Thickness and Ankle-Brachial Index in Middle-Aged Women

Objective:

Obesity has been linked to cardiovascular risk factors characterized by endothelial dysfunction and arterial wall thickening. Regular exercise training is recognized as a powerful tool to improve endothelial function and cardiovascular risk profile, but it is unknown which of high-intensity interval training or moderate-intensity continuous training is the best exercise.

Materials and Methods:

A total of 33 inactive and overweight women aged 40–50 years old and body mass index >27 kg/m² were randomized to high-intensity interval training, moderate-intensity continuous training, or control. The exercise intervention consisted of 12 weeks of training and three supervised sessions per week. The moderate-intensity group was trained continuously for 47 min at 60–70% of maximal heart rate. High-intensity interval training consisted of four interval bouts of 4 min at 85%–95% of maximal heart rate with 3 min breaks at 50%–60% of maximal heart rate between the intervals. For all analyses, statistical significance was assigned at P < 0.05.

Results:

According to our findings, while carotid intima-media thickness decreased in both training groups, this reduction was not statistically significant. In the high-intensity training group, the right ankle-brachial index increased significantly (P = 0.007).

Conclusion:

Twelve weeks of exercise training, especially in high-intensity interval training, have led to improving lipid profiles and endothelial function, it can be said that regular and prolonged exercise can probably be a preventive factor in cardiovascular disease in overweight women.

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.

Effects of acute dietary nitrate supplementation on aortic blood pressures and pulse wave characteristics in post-menopausal women

PURPOSE

Consumption of nitrate-rich beetroot juice can lower blood pressure in peripheral as well as central arteries and may exert additional hemodynamic benefits (e.g. reduced aortic wave reflections). The specific influence of nitrate supplementation on arterial pressures and aortic wave properties in postmenopausal women, a group that experiences accelerated increases in these variables with age, is unknown. Accordingly, the primary aim of this study was to determine the effect of consuming nitrate-rich beetroot juice on resting brachial and aortic blood pressures (BP) and pulse wave characteristics in a group of healthy postmenopausal women, in comparison to a true (nitrate-free beetroot juice) placebo.

METHODS

Brachial (oscillometric cuff) and radial (SphygmoCor) pressures and derived-aortic waveforms were measured during supine rest in thirteen healthy postmenopausal women (63 ± 1 yr) before and 100 min after consumption of 140 ml of either nitrate-rich (9.7 mmol, 0.6 gm NO₃^-) or nitrate-depleted beetroot juice on randomized visits approximately 10 days apart (cross-over design). Ten young premenopausal women (22 ± 1 yr) served as a reference (non-supplemented) cohort.

RESULTS

Brachial and derived-aortic variables showed the expected age-associated differences in these women (all p < 0.05). In post-menopausal women, nitrate supplementation reduced (p < 0.05 vs. placebo visit) brachial systolic BP (BR_nitrate -4.9 ± 2.1 mmHg vs BR_placebo +1.1 ± 1.8 mmHg), brachial mean BP (BR_nitrate -4.1 ± 1.7 mmHg vs BR_placebo +0.9 ± 1.3 mmHg), aortic systolic BP (BR_nitrate -6.3 ± 2.0 mmHg vs BR_placebo +0.5 ± 1.7 mmHg) and aortic mean BP (BR_nitrate -4.1 ± 1.7 mmHg vs BR_placebo +0.9 ± 1.3 mmHg), and increased pulse pressure amplification (BR_nitrate +4.6 ± 2.0% vs BR_placebo +0.7 ± 2.5%, p = 0.04), but did not alter aortic pulse wave velocity or any other derived-aortic variables (e.g., augmentation pressure or index).

CONCLUSIONS

Dietary nitrate supplementation favorably modifies aortic systolic and mean blood pressure under resting conditions in healthy postmenopausal women. Acute supplementation of nitrate does not, however, appear to restore indices of aortic stiffness in this group. Future work should evaluate chronic, long-term effects of this non-pharmacological supplement.

Oral Glucose Tolerance Test Glucose Peak Time Is Most Predictive of Prediabetes and Hepatic Steatosis in Obese Girls

Obese adolescent girls are at increased risk for type 2 diabetes, characterized by defects in insulin secretion and action. We sought to determine if later glucose peak timing (>30 minutes), 1-hour glucose >155 mg/dl, or monophasic pattern of glucose excursion during an oral glucose tolerance test (OGTT) reflect a worse cardiometabolic risk profile. Post-pubertal overweight/obese adolescent girls without diabetes were studied (N = 88; age, 15.2 ± 0.2 years; body mass index percentile, 97.7 ± 0.5). All participants completed an OGTT and body composition measures. Thirty-two girls had a four-phase hyperinsulinemic euglycemic clamp with isotope tracers, vascular imaging, and muscle mitochondrial assessments. Participants were categorized by glucose peak timing (≤30 min = early; >30 min = late), 1-hour glucose concentration (±155 mg/dL) and glucose pattern (monophasic, biphasic). Girls with a late (N = 54) vs earlier peak (n = 34) timing had higher peak glucose (P < 0.001) and insulin (P = 0.023), HbA1c (P = 0.021); prevalence of hepatic steatosis (62% vs 26%; P = 0.003) and lower oral disposition index (P < 0.001) and glucagon-like peptide-1 response (P = 0.037). When classified by 1-hour glucose, group differences were similar to peak timing, but minimal when classified by glucose pattern. In the >155 mg/dL group only, peripheral insulin sensitivity and fasting free fatty acids were worse. A later glucose peak or >155 mg/dL 1-hour glucose predicts metabolic disease risk in obese adolescent girls. This may defect incretin effects and first phase insulin response, and muscle and adipose insulin resistance.

Oral Glucose Tolerance Test Glucose Peak Time Is Most Predictive of Prediabetes and Hepatic Steatosis in Obese Girls

Obese adolescent girls are at increased risk for type 2 diabetes, characterized by defects in insulin secretion and action. We sought to determine if later glucose peak timing (>30 minutes), 1-hour glucose >155 mg/dl, or monophasic pattern of glucose excursion during an oral glucose tolerance test (OGTT) reflect a worse cardiometabolic risk profile. Post-pubertal overweight/obese adolescent girls without diabetes were studied (N = 88; age, 15.2 ± 0.2 years; body mass index percentile, 97.7 ± 0.5). All participants completed an OGTT and body composition measures. Thirty-two girls had a four-phase hyperinsulinemic euglycemic clamp with isotope tracers, vascular imaging, and muscle mitochondrial assessments. Participants were categorized by glucose peak timing (≤30 min = early; >30 min = late), 1-hour glucose concentration (±155 mg/dL) and glucose pattern (monophasic, biphasic). Girls with a late (N = 54) vs earlier peak (n = 34) timing had higher peak glucose (P < 0.001) and insulin (P = 0.023), HbA1c (P = 0.021); prevalence of hepatic steatosis (62% vs 26%; P = 0.003) and lower oral disposition index (P < 0.001) and glucagon-like peptide-1 response (P = 0.037). When classified by 1-hour glucose, group differences were similar to peak timing, but minimal when classified by glucose pattern. In the >155 mg/dL group only, peripheral insulin sensitivity and fasting free fatty acids were worse. A later glucose peak or >155 mg/dL 1-hour glucose predicts metabolic disease risk in obese adolescent girls. This may defect incretin effects and first phase insulin response, and muscle and adipose insulin resistance.

Assessment of Cardiovascular Risk in Natural and Surgical Menopause

BACKGROUND

Menopause is associated with increased cardiovascular disease (CVD) risk. Arterial stiffness, a biomarker of vascular aging, increases the risk for CVD.

AIMS AND OBJECTIVES

The study was aimed to determine whether menopause is associated with arterial stiffness amongst natural and surgical menopausal women.

MATERIALS AND METHODS

We conducted a cross-sectional study amongst natural postmenopausal women, with Surgical menopause and Premenopausal. Arterial stiffness was measured by Periscopy TM. Large artery stiffness may be an important mechanism by which hysterectomy increases the risk of cardiovascular disease in postmenopausal women.

RESULTS

Carotid femoral pulse wave velocity (cfPWV) and Brachial Ankle Pulse wave velocity (baPWV) were significantly higher in surgical and natural menopause compared to women with Premenopausal group.

Vascular Function and Structure in Veteran Athletes after Myocardial Infarction

PURPOSE

Although athletes demonstrate lower cardiovascular risk and superior vascular function compared with sedentary peers, they are not exempted from cardiac events (i.e., myocardial infarction [MI]). The presence of an MI is associated with increased cardiovascular risk and impaired vascular function. We tested the hypothesis that lifelong exercise training in post-MI athletes, similar as in healthy controls, is associated with a superior peripheral vascular function and structure compared with a sedentary lifestyle in post-MI individuals.

METHODS

We included 18 veteran athletes (ATH) (>20 yr) and 18 sedentary controls (SED). To understand the effect of lifelong exercise training after MI, we included 20 veteran post-MI athletes (ATH + MI) and 19 sedentary post-MI controls (SED + MI). Participants underwent comprehensive assessment using vascular ultrasound (vascular stiffness, intima-media thickness, and endothelium (in)dependent mediated dilatation). Lifetime risk score was calculated for a 30-yr risk prediction of cardiovascular disease mortality of the participants.

RESULTS

ATH demonstrated a lower vascular stiffness and smaller femoral intima-media thickness compared with SED. Vascular function and structure did not differ between ATH + MI and SED + MI. ATH (4.0% ± 5.1%) and ATH + MI (6.1% ± 3.7%) had a significantly better lifetime risk score compared with their sedentary peers (SED: 6.9% ± 3.7% and SED + MI: 9.3% ± 4.8%). ATH + MI had no secondary events versus two recurrent MI and six elective percutaneous coronary interventions within SED + MI (P < 0.05).

CONCLUSION

Although veteran post-MI athletes did not have a superior peripheral vascular function and structure compared with their sedentary post-MI peers, benefits of lifelong exercise training in veteran post-MI athletes relate to a better cardiovascular risk profile and lower occurrence of secondary events.

Vascular Adaptation to Exercise in Humans: Role of Hemodynamic Stimuli

On the 400th anniversary of Harvey's Lumleian lectures, this review focuses on "hemodynamic" forces associated with the movement of blood through arteries in humans and the functional and structural adaptations that result from repeated episodic exposure to such stimuli. The late 20th century discovery that endothelial cells modify arterial tone via paracrine transduction provoked studies exploring the direct mechanical effects of blood flow and pressure on vascular function and adaptation in vivo. In this review, we address the impact of distinct hemodynamic signals that occur in response to exercise, the interrelationships between these signals, the nature of the adaptive responses that manifest under different physiological conditions, and the implications for human health. Exercise modifies blood flow, luminal shear stress, arterial pressure, and tangential wall stress, all of which can transduce changes in arterial function, diameter, and wall thickness. There are important clinical implications of the adaptation that occurs as a consequence of repeated hemodynamic stimulation associated with exercise training in humans, including impacts on atherosclerotic risk in conduit arteries, the control of blood pressure in resistance vessels, oxygen delivery and diffusion, and microvascular health. Exercise training studies have demonstrated that direct hemodynamic impacts on the health of the artery wall contribute to the well-established decrease in cardiovascular risk attributed to physical activity.

Obese adolescents with polycystic ovarian syndrome have elevated cardiovascular disease risk markers

Women with polycystic ovarian syndrome (PCOS) have evidence of subclinical cardiovascular disease (CVD). However, insulin resistance, an important factor in the development of CVD in adults, is common in adolescents with PCOS, yet data in adolescents are limited. Therefore, we sought to measure insulin resistance and CVD markers in obese youth with and without PCOS. Thirty-six PCOS and 17 non-PCOS adolescent girls who were obese, sedentary, and non-hypertensive were recruited from clinics located within the Children's Hospital Colorado. Following 3 days of controlled diet and restricted exercise, fasting plasma samples were obtained prior to a hyperinsulinemic euglycemic clamp. PCOS girls were more insulin resistant than controls (glucose infusion rate 5.24±1.86 mg/kg/min vs 9.10±2.69; p<0.001). Girls with PCOS had blood pressure in the normal range, but had greater carotid intima-media thickness (cIMT) (0.49±0.07 mm vs 0.44±0.06; p=0.038), beta stiffness index (5.1±1.3 U vs 4.4±0.9; p=0.037), and reduced arterial compliance (1.95±0.47 mm²/mmHg × 10^-1 vs 2.13±0.43; p=0.047). PCOS girls had a normal mean lipid profile, yet had a more atherogenic lipoprotein cholesterol distribution and had persistent elevations of free fatty acids despite hyperinsulinemia (68±28 μmol/mL vs 41±10; p=0.001), both potential contributors to CVD. Free fatty acid concentrations correlated best with all CVD markers. In summary, adolescent girls with PCOS have greater cIMT and stiffer arteries than girls without PCOS, perhaps related to altered lipid metabolism, even when clinical measures of blood pressure and cholesterol profiles are 'normal'. Therefore, management of adolescent PCOS should include assessment of CVD risk factor development.

Habitual aerobic exercise is associated with smaller femoral artery intima–media thickness with age in healthy men and women

BACKGROUND

Femoral artery intima-media thickness (IMT), an independent predictor of atherosclerotic disease risk, increases with age in sedentary adults. It is not known whether regular aerobic exercise modulates femoral IMT with ageing.

METHODS AND RESULTS

Study 1: Femoral IMT was measured in 173 sedentary, moderately active, and endurance-trained young (20-39 years), middle-aged (40-59 years) and older (60-79 years) men. IMT increased with age in all activity groups (P<0.001). However, IMT was 20-27% smaller in age-matched, endurance-trained compared with sedentary men (P<0.001), and the age-associated increase in IMT was 33% smaller in endurance-trained compared with sedentary men (+0.32 versus +0.45 mm). There was a trend for the IMT to be smaller in moderately active compared with sedentary older men, and the age-associated increase in IMT was 37% smaller in moderately active than sedentary men (+0.28 mm). Study 2: Among 74 premenopausal and postmenopausal sedentary or endurance-trained women, IMT was higher (P<0.001) in postmenopausal compared with premenopausal women regardless of activity status. However, IMT was 15% smaller in endurance-trained compared with sedentary postmenopausal women (P<0.001), and the premenopausal to postmenopausal difference in IMT was approximately 45% smaller in endurance-trained compared with sedentary women (+0.13 versus +0.23 mm).

CONCLUSIONS

Femoral IMT increases with age even in habitually exercising adults. However, the age-associated increase and absolute level of IMT are smaller in middle-aged and older adults who perform regular aerobic-endurance exercise, and may contribute to their lower incidence of atherosclerotic disease.

[Short-term impact of an ambulatory cardiac rehabilitation program on arterial rigidity]

BACKGROUND

If the positive impact of cardiac rehabilitation on metabolic profile and exercise tolerance is well documented in the literature, very few studies evaluated the impact of these rehabilitation programs on arterial rigidity.

PURPOSE

The main objective of this study was to determine if a short and intense 4-week cardiac rehabilitation program could yield a positive impact on arterial rigidity.

METHOD

A cohort study was performed on Leopold Bellan Foundation. All patients referred for cardiac rehabilitation program after an acute event (surgery, technical gesture or acute decompensate heart failure) were included in this study. Our CR program consists of four sessions per week for five weeks (total of 20 sessions) and includes both exercise and health and nutrition education sessions. In addition to clinical and therapeutic data collection, biochemical analysis for carbohydrate and lipid metabolism and exercise capacity measurements, carotid femoral pulse wave velocity (PWV) were measured in a quiet room in the morning of their first and last day prior to any exercise.

RESULTS

One hundred and ninety-eight cardiac patients have participated in this study, of which 79% were male, mean age 60 ± 10, 50 (25%) were diabetic, 103 (52%) were hypertensive, 60 (30%) were current smokers, 98 (50%) had dyslipidemia, and 140 (71%) were referred for cardiac rehabilitation after acute coronary syndrome. Arterial stiffness is defined by a VPWV value greater or equal to 10. At the beginning, 59% of our patients have rigid arteries. After 20 sessions of cardiac rehabilitation, this number is significantly reduced to 51% (P=0.12). Patients with arterial stiffness have accumulated more major cardiovascular risk factors, and have had less exercise capacity than others. However they benefit similarly from the cardiovascular rehabilitation program.

CONCLUSION

In the present study, we observed that arterial stiffness, as reflected by the PWV, tends to decrease after short-term ambulatory cardiac rehabilitation program.

Vascular Aging across the Menopause Transition in Healthy Women

Vascular aging, featuring endothelial dysfunction and large artery stiffening, is a major risk factor for developing cardiovascular disease (CVD). In women, vascular aging appears to be accelerated during the menopause transition, particularly around the late perimenopausal period, presumably related to declines in ovarian function and estrogen levels. The mechanisms underlying endothelial dysfunction and large artery stiffening with the menopause transition are not completely understood. Oxidative stress and the proinflammatory cytokine tumor necrosis factor-α contribute to endothelial dysfunction and large artery stiffening in estrogen-deficient postmenopausal women. Habitual endurance exercise attenuates the age-related increase in large artery stiffness in estrogen-deficient postmenopausal women and can reverse arterial stiffening to premenopausal levels in estrogen-replete postmenopausal women. In contrast, estrogen status appears to play a key permissive role in the adaptive response of the endothelium to habitual endurance exercise in that endothelial improvements are absent in estrogen-deficient women but present in estrogen-replete women. We review here the current state of knowledge on the biological defects underlying vascular aging across the menopause transition, with particular focus on potential mechanisms, the role of habitual exercise in preserving vascular health, and key areas for future research.

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.

Influence of chronic exercise on carotid atherosclerosis in marathon runners

OBJECTIVES

The effect of habitual, high-intensity exercise training on the progression of atherosclerosis is unclear. We assessed indices of vascular health (central systolic blood pressure (SBP) and arterial stiffness as well as carotid intima-medial thickness (cIMT)) in addition to cardiovascular risk factors of trained runners versus their untrained spouses or partners to evaluate the impact of exercise on the development of carotid atherosclerosis.

SETTING

field study at Boston Marathon.

PARTICIPANTS

42 qualifiers (mean age±SD: 46±13 years, 21 women) for the 2012 Boston Marathon and their sedentary domestic controls (46±12 years, n=21 women).

OUTCOMES

We measured medical and running history, vital signs, anthropometrics, blood lipids, C reactive protein (CRP), 10 years Framingham risk, central arterial stiffness and SBP and cIMT.

RESULTS

Multiple cardiovascular risk factors, including CRP, non-high-density lipoprotein cholesterol, triglycerides, heart rate, body weight and body mass index (all p<0.05), were reduced in the runners. The left and right cIMT, as well as central SBP, were not different between the two groups (all p>0.31) and were associated with age (all r≥0.41; p<0.01) and Framingham risk score (all r≥0.44; p<0.01) independent of exercise group (all p>0.08 for interactions). The amplification of the central pressure waveform (augmentation pressure at heart rate 75 bpm) was also not different between the two groups (p=0.07) but was related to age (p<0.01) and group (p=0.02) in a multiple linear regression model.

CONCLUSIONS

Habitual endurance exercise improves the cardiovascular risk profile, but does not reduce the magnitude of carotid atherosclerosis associated with age and cardiovascular risk factors.

Long-term effect of different physical activity levels on subclinical atherosclerosis in middle-aged men: a 25-year prospective study

BACKGROUND

The purpose of the study was to investigate the influence of lifetime physical activity (PA) on selected indices of atherosclerosis in longitudinal observation of middle-aged men.

METHODS

The subject of the study was a cohort of 101 men (mean age 59,7 ± 9,0 years), free of cardiovascular symptoms and treatment, participating in follow-up examinations in the years 1985/90-2011/12. Self-report PA was assessed by interviewer-administered Seven-Day PA Recall and Historical PA questionnaire. Subclinical atherosclerosis was measured by assessing the coronary artery calcification (CAC) according to Agatston's method using multi-slice computed tomography; the carotid intima-media thickness (IMT) using high-resolution B-mode ultrasound; and the reactive hyperemia index (RHI) using peripheral arterial tonometry (EndoPAT2000). The participants were initially divided into three groups according to tertiles of exercise-related energy expenditure (EE) in kcal/week at baseline, i.e. <2050 (low-to-moderate; n = 33), 2050-3840 (high; n = 34), >3840 (very high; n = 34).

RESULTS

The low-to-moderate, high and very high PA groups were comparable in terms of age and atherosclerosis risk factors at baseline. No linear relationship was found between PA and CAC, IMT and RHI. Men who maintained low-to-moderate (n = 26), high (n = 21) and very high (n = 15) PA level had the mean CAC of 286.1 ± 361.9, 10.7 ± 28.9, and 106.1 ± 278.3 (p<0.001 for low-to moderate vs high; p<0.05 for low-to-moderate vs very high); the mean IMT of 0.751 ± 0.19 mm, 0,641 ± 0.26 mm, and 0.750 ± 0.60 mm (p>0.05); and the mean RHI of 1.69 ± 0.4, 2.00 ± 0.4, and 2.13 ± 0.5 (p for trend = 0.050), respectively. No cases of CAC>400, IMT ≥ 0.9 and RHI<1.67 were noted only among men with maintained high PA level. At final examination men with high and very high PA had more favorable cardiometabolic profile than men with lower PA.

CONCLUSIONS

Maintaining regular high PA level through young and middle adulthood may protect against atherosclerosis as measured by CAC, IMT and RHI.

Association of fitness with vascular intima-media thickness and elasticity in adolescence

OBJECTIVES

Vascular intima-media thickness (IMT) and elasticity are surrogate markers of atherosclerosis. Data on the effect of cardiorespiratory fitness on these measures of vascular health in adolescence are scarce. The aim was to examine the association of fitness with aortic and carotid artery IMT and elasticity in adolescents.

METHODS

Aortic (n = 449) and carotid (n = 467) IMT and elasticity were measured ultrasonographically in 17-year-old adolescents participating in a prospective, longitudinal atherosclerosis prevention study (Special Turku Coronary Risk Factor Intervention Project). Distensibility and Young's elastic modulus (YEM) were used as measures of arterial elasticity. Cardiorespiratory fitness (maximum oxygen uptake, mL/kg/min) was measured with a maximal cycle ergometer test. Data on fitness were available for 341 of adolescents with aortic and 355 with carotid ultrasound measures.

RESULTS

Fitness was inversely associated with aortic IMT (β[SE] = -0.0029[0.0013]; P = .031) and YEM (β[SE] = -0.012[0.0053]; P = .025) after adjusting for gender, physical activity, high-density lipoprotein/total cholesterol, triglycerides, high-sensitivity C-reactive protein, homeostasis model of assessment-insulin resistance, BMI, systolic blood pressure, and smoking. Risk of having low aortic distensibility (≤10th percentile) decreased with increasing fitness (odds ratio = 0.89, 95% confidence interval 0.82-0.98); P = .014). The increase in aortic IMT and YEM between ages 11 and 17 years was smaller in adolescents who were fit at age 17 compared with adolescents who had the lowest fitness level (P for IMT = .015, P for YEM = .0072). Fitness was not associated with carotid IMT or elasticity. Lifestyle counseling given in the Special Turku Coronary Risk Factor Intervention Project was not associated with fitness.

CONCLUSIONS

Fitness was favorably associated with aortic IMT and elasticity in adolescents. No association of fitness with the respective carotid indices was found. These data suggest that fitness in part enhances vascular health in healthy adolescents.

Hysterectomy is associated with large artery stiffening in estrogen-deficient postmenopausal women

OBJECTIVE

Hysterectomy, with or without oophorectomy, is associated with increased cardiovascular disease (CVD) risk due, in part, to an adverse CVD risk factor profile. Large artery stiffening, a biomarker of vascular aging, increases the risk for CVD. We determined whether hysterectomy with or without bilateral oophorectomy (BLO) is associated with arterial stiffening in healthy postmenopausal women.

METHODS

We conducted a cross-sectional study including estrogen-deficient postmenopausal women who had a hysterectomy with ovarian preservation (n = 24; mean ± SE age, 59 ± 1 y) or with BLO (n = 21; 58 ± 2 y) and had no hysterectomy/no BLO (n = 58; 58 ± 1 y). Arterial stiffness (arterial compliance and β stiffness index) was measured by ultrasonography of the carotid artery.

RESULTS

Carotid artery compliance was lower in women with hysterectomy alone and in women with hysterectomy with BLO compared with women with no hysterectomy (0.66 ± 0.03 and 0.71 ± 0.06 vs 0.89 ± 0.03 mm/mm Hg × 10, respectively, both P < 0.05). There were no differences in traditional CVD risk factors (ie, adiposity, blood pressure and fasted lipids and lipoproteins, glucose, and insulin) between the groups. After adjustment for age, menopause duration, previous menopausal hormone therapy duration, parity, waist-to-hip ratio, systolic blood pressure, and sex hormone-binding globulin, hysterectomy status remained a significant predictor of arterial compliance.

CONCLUSIONS

These results indicate that hysterectomy status (with or without BLO) is associated with greater arterial stiffening in estrogen-deficient postmenopausal women. The greater arterial stiffening with hysterectomy was not related to an adverse CVD risk profile. Large artery stiffening may be an important mechanism by which hysterectomy increases the risk of CVD in postmenopausal women.

A prospective randomized longitudinal study involving 6 months of endurance or resistance exercise. Conduit artery adaptation in humans

Abstract  This randomized trial evaluated the impact of different exercise training modalities on the function and size of conduit arteries in healthy volunteers. Young (27 ± 5 years) healthy male subjects were randomized to undertake 6 months of either endurance training (ET; n = 10) or resistance training (RT; n = 13). High-resolution ultrasound was used to determine brachial, femoral and carotid artery diameter and wall thickness (IMT) and femoral and brachial flow-mediated dilatation (FMD) and glyceryl trinitrate (GTN)-mediated dilatation. Improvements in peak oxygen uptake occurred with ET (from 3.6 ± 0.7 to 3.8 ± 0.6 l min(-1), P = 0.024) but not RT. Upper body muscular strength increased following RT (from 57.8 ± 17.7 to 69.0 ± 19.5 kg, P < 0.001), but not ET. Both groups exhibited increases in lean body mass (ET, 1.4 ± 1.8 kg and RT, 2.3 ± 1.3 kg, P < 0.05). Resistance training increased brachial artery resting diameter (from 3.8 ± 0.5 to 4.1 ± 0.4 mm, P < 0.05), peak FMD diameter (+0.2 ± 0.2 mm, P < 0.05) and GTN-mediated diameter (+0.3 ± 0.3 mm, P < 0.01), as well as brachial FMD (from 5.1 ± 2.2 to 7.0 ± 3.9%, P < 0.05). No improvements in any brachial parameters were observed following ET. Conversely, ET increased femoral artery resting diameter (from 6.2 ± 0.7 to 6.4 ± 0.6 mm, P < 0.05), peak FMD diameter (+0.4 ± 0.4 mm, P < 0.05) and GTN-induced diameter (+0.3 ± 0.3 mm, P < 0.05), as well as femoral FMD-to-GTN ratio (from 0.6 ± 0.3 to 1.1 ± 0.8, P < 0.05). Resistance training did not induce changes in femoral artery parameters. Carotid artery IMT decreased in response to both forms of training. These findings indicate that 6 months of supervised exercise training induced changes in brachial and femoral artery size and function and decreased carotid artery IMT. These impacts of both RT and ET would be expected to translate to decreased cardiovascular risk.

Vascular adaptations induced by 6 weeks WBV resistance exercise training

BACKGROUND

The impact of whole-body vibration (WBV) upon the cardiovascular system is receiving increasing attention. Despite numerous studies addressing the acute cardiovascular effects of WBV training, very little is known regarding long-term adaptations in healthy humans.

METHODS

A 6-week training study, with a 70 days follow-up was designed to compare resistive exercise with or without super-imposed whole-body vibrations. Arterial diameter, intima media thickness and flow-mediated dilation (FMD) were assessed by ultrasonography in the superficial femoral artery (SFA), the brachial (BA) and the carotid arteries (CA).

RESULTS

SFA resting diameter was increased from 6·22 mm (SD = 0·69 mm) at baseline to 6·52 mm (SD = 0·74 mm) at the end of the training period (P = 0·03) with no difference between groups (P = 0·48). Arterial wall thickness was significantly reduced by 4·3% (SD = 11%) in the CA only (P = 0·04). FMD was not affected by any of the interventions and in any of the investigated arteries.

CONCLUSION

To the best of our knowledge, this has been the first study to show that the superposition of vibration upon conventional resistance exercise does not have a specific effect upon long-term vascular adaptation in asymptomatic humans. Our findings seem to be at variance with the findings observed in a bed-rest setting. One possible explanation could be that the independently saturable effects of flow-mediated versus acceleration-related endothelial shear stresses on arterial structure and function differ between ambulatory and bed-rest conditions.

Tetrahydrobiopterin improves endothelial function and decreases arterial stiffness in estrogen-deficient postmenopausal women

The mechanisms mediating arterial stiffening with aging and menopause are not completely understood. We determined whether administration of tetrahydrobiopterin (BH(4)), a critical cofactor for endothelial nitric oxide synthase to produce nitric oxide, would increase vascular endothelial-dependent vasodilatory tone and decrease arterial stiffness in estrogen-deficient postmenopausal women. Additionally, we examined whether the beneficial effects of estrogen on vascular function were possibly related to BH(4). Arterial stiffness (carotid artery compliance) and endothelial-dependent vasodilation [brachial artery flow-mediated dilation (FMD)] were measured in postmenopausal (n = 24; 57 ± 1 yr, mean ± SE) and eumenorrheic premenopausal (n = 9; 33 ± 2 yr) women before and 3 h after the oral administration of BH(4). Subsequently, in postmenopausal women, vascular testing (before and after BH(4)) was repeated following randomization to either 2 days of transdermal estradiol or placebo. Baseline carotid artery compliance and brachial artery FMD were lower in postmenopausal than in premenopausal women (P < 0.0001). BH(4) administration increased carotid artery compliance (0.61 ± 0.05 to 0.73 ± 0.04 mm(2)·mmHg(-1)·10(-1) vs. baseline, P < 0.0001) and brachial artery FMD (P < 0.001) in postmenopausal women but had no effect in premenopausal women (P = 0.62). Carotid artery compliance (0.59 ± 0.05 to 0.78 ± 0.06 mm(2)·mmHg(-1)·10(-1), P < 0.001) and FMD increased in postmenopausal women in response to estradiol (P = 0.02) but were not further improved with the coadministration of BH(4), possibly because estrogen increased BH(4) bioavailability. Carotid artery compliance and FMD increased with BH(4) in the placebo group (P = 0.02). Although speculative, these results suggest that reduced vascular BH(4) may be an important contributor to arterial stiffening in estrogen-deficient postmenopausal women, related in part to reduced endothelial-dependent vasodilatory tone.

Impact of exercise training on arterial wall thickness in humans

Thickening of the carotid artery wall has been adopted as a surrogate marker of pre-clinical atherosclerosis, which is strongly related to increased cardiovascular risk. The cardioprotective effects of exercise training, including direct effects on vascular function and lumen dimension, have been consistently reported in asymptomatic subjects and those with cardiovascular risk factors and diseases. In the present review, we summarize evidence pertaining to the impact of exercise and physical activity on arterial wall remodelling of the carotid artery and peripheral arteries in the upper and lower limbs. We consider the potential role of exercise intensity, duration and modality in the context of putative mechanisms involved in wall remodelling, including haemodynamic forces. Finally, we discuss the impact of exercise training in terms of primary prevention of wall thickening in healthy subjects and remodelling of arteries in subjects with existing cardiovascular disease and risk factors.

Vascular health in the ageing athlete

The demographics of ageing are changing dramatically such that there will be many more older adults in the near future. This setting is projected to produce a new 'boomer-driven' epidemic of physiological dysfunction, disability and risk of chronic degenerative disorders, including cardiovascular diseases. Standing out against this dreary biomedical forecast are Masters athletes, a group of middle-aged and older adults who engage in regular vigorous physical training and competitive sport. Compared with their sedentary/less active (untrained) peers, Masters athletes who perform endurance training-based activities demonstrate a more favourable arterial function-structure phenotype, including lower large elastic artery stiffness, enhanced vascular endothelial function and less arterial wall hypertrophy. As such, they may represent an exemplary model of healthy or 'successful' vascular ageing. In contrast, Masters athletes engaged primarily/exclusively in intensive resistance training exhibit less favourable arterial function-structure than their endurance-trained peers and, in some instances, untrained adults. These different arterial properties are probably explained in large part by the different intravascular mechanical forces generated during endurance versus resistance exercise-related training activities. The more favourable arterial function-structure profile of Masters endurance athletes may contribute to their low risk of clinical cardiovascular diseases.

Effects of physical activity on cardiovascular disease

Much attention has been directed toward lifestyle modifications as effective means of reducing cardiovascular disease risk. In particular, physical activity has been heavily studied because of its well-known effects on metabolic syndrome, insulin sensitivity, cardiovascular disease risk, and all-cause mortality. However, data regarding the effects of exercise on various stages of the atherosclerosis pathway remain conflicting. The investigators review previously published reports for recent observational and interventional trials investigating the effects of physical activity on markers of (or causal factors for) atherosclerotic burden and vascular disease, including serum lipoproteins, systemic inflammation, thrombosis, coronary artery calcium, and carotid intima-media thickness. In conclusion, the data show a correlation between physical activity and triglyceride reduction, apolipoprotein B reduction, high-density lipoprotein increase, change in low-density lipoprotein particle size, increase in tissue plasminogen activator activity, and decrease in coronary artery calcium. Further research is needed to elucidate the effect of physical activity on inflammatory markers and intima-media thickness.

Exercise-mediated changes in conduit artery wall thickness in humans: role of shear stress

Episodic increases in shear stress have been proposed as a mechanism that induces training-induced adaptation in arterial wall remodeling in humans. To address this hypothesis in humans, we examined bilateral brachial artery wall thickness using high-resolution ultrasound in healthy men across an 8-wk period of bilateral handgrip training. Unilaterally, shear rate was attenuated by cuff inflation around the forearm to 60 mmHg. Grip strength, forearm volume, and girth improved similarly between the limbs. Acute bouts of handgrip exercise increased shear rate ( P < 0.005) in the noncuffed limb, whereas cuff inflation successfully decreased exercise-induced increases in shear. Brachial blood pressure responses similarly increased during exercise in both the cuffed and noncuffed limbs. Handgrip training had no effect on baseline brachial artery diameter, blood flow, or shear rate but significantly decreased brachial artery wall thickness after 6 and 8 wk (ANOVA, P < 0.001) and wall-to-lumen ratio after week 8 (ANOVA, P = 0.005). The magnitude of decrease in brachial artery wall thickness and wall-to-lumen ratio after exercise training was similar in the noncuffed and cuffed arms. These results suggest that exercise-induced changes in shear rate are not obligatory for arterial wall remodeling during a period of 8 wk of exercise training in healthy humans.

Sex-based differences in vascular function

Cardiovascular disease is the leading cause of morbidity and mortality for both men and women in the USA. However, there are differences between the sexes in age-dependent onset, severity, symptoms and outcomes. Basic research into the causes of sex-dependent differences in cardiovascular disease is ongoing and includes investigation into genetic variation in expression and distribution of receptors for the sex steroids; specificity of natural and synthetic ligands that activate the sex steroid receptors; and intracellular mechanisms that are activated by the receptors in all components of the vessel wall and blood elements, which integrate to regulate vascular tone, vascular repair and remodeling in health and disease. In this era of personalized medicine, basic research into mechanisms of sex differences in vascular function will result in improved prevention, detection and treatment of cardiovascular disease in both men and women.

The Impact of Exercise Training on Conduit Artery Wall Thickness and Remodeling in Chronic Heart Failure Patients

Exercise training is an important adjunct to medical therapy in chronic heart failure, but the extent to which exercise impacts on conduit artery remodeling is unknown. The aim of this study was to evaluate the impact of aerobic and resistance exercise training modalities on arterial remodeling in patients with chronic heart failure. We randomized 36 untrained subjects with chronic heart failure to resistance training (58.8±3.5 years), aerobic training (61.3±2.8 years), or an untrained control group (64.4±2.4 years). Peak oxygen consumption during cycle ergometry increased after 12 weeks in both the resistance and aerobic training ( P <0.001) groups, but not in controls, whereas leg strength only increased after resistance training ( P <0.05). Brachial artery wall thickness decreased in the resistance training group (475±10 versus 443±13 μm; P <0.01), whereas no changes were apparent in the aerobic or control groups. Brachial diameter increased by ≈6% and ≈5% in the aerobic training and resistance training groups ( P <0.01), with no change evident in the control group. The wall:lumen ratio consequently declined in the resistance training group at 12 weeks (0.121±0.004 versus 0.107±0.004; P <0.01) and increased in the control group (0.111±0.006 versus 0.121±0.009; P <0.05). No wall:lumen change was evident in the aerobic training group. Our findings suggest that exercise has a systemic impact on remodeling of conduit arteries in humans and that resistance exercise training may be advantageous in subjects with chronic heart failure in this regard.

Exercise and vascular adaptation in asymptomatic humans

Beneficial effects of exercise training on the vasculature have been consistently reported in subjects with cardiovascular risk factors or disease, whereas studies in apparently healthy subjects have been less uniform. In this review, we examine evidence pertaining to the impact of exercise training on conduit and resistance vessel function and structure in asymptomatic subjects. Studies of arterial function in vivo have mainly focused on the endothelial nitric oxide dilator system, which has generally been shown to improve following training. Some evidence suggests that the magnitude of benefit depends upon the intensity or volume of training and the relative impact of exercise on upregulation of dilator pathways versus effects of inflammation and/or oxidation. Favourable effects of training on autonomic balance, baroreflex function and brainstem modulation of sympathetic control have been reported, but there is also evidence that basal vasoconstrictor tone increases as a result of training such that improvements in intrinsic vasodilator function and arterial remodelling are counterbalanced at rest. Studies of compliance suggest increases in both the arterial and the venous sides of the circulation, particularly in older subjects. In terms of mechanisms, shear stress appears to be a key signal to improvement in vascular function, whilst increases in pulse pressure and associated haemodynamics during bouts of exercise may transduce vascular adaptation, even in vascular beds which are distant from the active muscle. Different exercise modalities are associated with idiosyncratic patterns of blood flow and shear stress, and this may have some impact on the magnitude of exercise training effects on arterial function and remodelling. Other studies support the theory that that there may be different time course effects of training on specific vasodilator and constrictor pathways. A new era of understanding of the direct impacts of exercise and training on the vasculature is evolving, and future studies will benefit greatly from technological advances which allow direct characterization of arterial function and structure.

The Role of Endothelial Dysfunction on Development and Progression of Atherosclerosis and Methods to Assess Vascular Function and Structure

The endothelium was originally thought to be just a semipermeable barrier between the vessel wall and the bloodstream, but today we now realize that it is actually a highly active autocrine, paracrine, and endocrine organ. Researchers have also begun to realize that the endothelium plays a key role in the development of atherosclerosis as well as other diseases. This increased recognition has resulted in considerable effort by both researchers and clinicians to develop accurate and reliable methods to measure and track changes in both vascular structure and function. In addition, research interest has focused on various cardiovascular risk factors (eg, age, gender, obesity, physical inactivity) and the effect they have on vascular structure and function. In this review, the authors discuss different research and clinical methods to assess vascular structure and function as well as the effect of various cardiovascular risk factors on the endothelium and the vascular system. They also discuss the ability to modify vascular structure and function through various lifestyle modifications such as weight loss and exercise.

Age-associated elongation of the ascending aorta in adults

OBJECTIVES

To determine whether human aorta lengthens with aging and to evaluate the impact of the hypothesized aortic elongation on pulse wave velocity (PWV) measurements.

BACKGROUND

Although it is generally thought that the aorta becomes tortuous with aging, there has been no systematic study to date in healthy adults to determine if this is so. Such age-related aortic elongation may be a confounding factor for the PWV measurement in elderly people.

METHODS

Arterial lengths were computed by the 3-dimensional transverse magnetic resonance image arterial tracing of the aorta and carotid and iliac arteries in 256 apparently healthy adults (age 19 to 79 years).

RESULTS

The ascending aorta was greater with advancing age (r = 0.72), whereas the lengths of the descending aorta and carotid and iliac arteries were not associated with age. The elongation of the ascending aorta was associated with the corresponding increases in aortic PWV (beta = 0.50) and brachial/aortic pulse pressure ratio (beta = 0.24), which is an index of pulse wave amplification. The straight distance between carotid and femoral sites (car-fem), the most popular arterial length measurement, overestimated the aortic length measured with the magnetic resonance image by approximately 25%. The most accurate arterial length estimation was the distance obtained by subtracting carotid length from the car-fem, with <5% difference from the magnetic resonance image-measured length. Because the ascending aorta was omitted or subtracted from the length estimation in PWV, the impact of age-related elongation of the aorta on PWV was small.

CONCLUSIONS

The aorta lengthens with age, even in healthy humans, due primarily to the elongation of the ascending aorta. Age-related aortic elongation has little impact on PWV measurements, as the ascending aorta, which undergoes lengthening with age, is not included in the arterial length measurements.

Influence of arterial wave reflection on carotid blood pressure and intima-media thickness in older endurance trained men and women with pre-hypertension

Increased carotid intima-media thickness (IMT) with aging is a significant predictor of mortality. Older endurance trained (ET) individuals have lower carotid artery stiffness but similar carotid IMT when compared to sedentary (SED) age-matched peers. The purpose of this study was to examine the contribution of arterial wave reflections to carotid hemodynamics and IMT in older ET and SED with pre-hypertension. Subjects consisted of endurance-trained master athletes and age-matched sedentary controls (mean age 67 years). Carotid artery Beta-stiffness index and IMT was assessed with ultrasonography. Carotid pressure and augmented pressure from wave reflections (obtained from pulse contour analysis) was measured with applanation tonometry. Carotid systolic blood pressure (SBP) and IMT were not different between groups (P>0.05). Carotid stiffness was significantly lower in ET versus SED (7.3 +/- 0.8 versus 9.9 +/- 0.6, P<0.05). Augmented pressure was significantly greater in ET versus SED (17.7 +/- 1.6 versus 13.3 +/- 1.5 mmHg, P<0.05). When adjusting for differences in resting heart rate, there were no group differences in augmented pressure. In conclusion, older ET persons with pre-hypertension have reduced carotid artery stiffness, but similar carotid SBP and carotid IMT when compared to SED. The lack of change in carotid SBP and IMT in older ET may be related to the inability of chronic exercise training to reduce bradycardia-related augmented pressure from wave reflections with aging.

Postural changes may influence popliteal atherosclerosis by modifying local circumferential wall tension

Atherosclerosis of peripheral arteries typically affects vessels of the lower limbs, suggesting that local hemodynamic stimuli play a role in this process. Our study evaluated the effects of body postural changes on carotid and popliteal blood pressure, circumferential wall tension (CWT) and arterial strain, and investigated the relationship between such hemodynamic parameters and intima-media thickness (IMT) of these arteries. One hundred seventeen nondiabetic, nonhypertensive, nonsmoker subjects (48 men and 69 women) were enrolled and had their blood pressure measured in the arm and calf in supine and orthostatic positions. Echo-doppler analysis evaluated the common carotid and popliteal arteries after blood pressure measurements, while CWT was calculated according to Laplace's law. The results showed that changing from supine to orthostatic posture increased blood pressure and CWT in popliteal but not in carotid arteries. Partial correlation analysis adjusted for age and body mass index revealed no major relationship between IMT of the studied vessels and local blood pressure or arterial strain. Conversely, supine and orthostatic CWT exhibited comparable correlation coefficients with carotid IMT, while orthostatic CWT displayed a stronger relationship with popliteal IMT than with supine CWT. These results were confirmed by multiple linear regression analysis that included age, sex, body mass index, lipid fractions and glucose as independent variables. Overall, our results indicate that orthostatic CWT is a stronger hemodynamic predictor of popliteal IMT than supine CWT, suggesting that erectile posture may be a potential risk factor for popliteal atherosclerosis because it increases the local hemodynamic burden. (Hypertens Res 2008; 31: 2059-2064).

Maximal and submaximal aerobic fitness in postmenopausal women: influence of hormone-replacement therapy

The purpose of this study was to examine whether maximal and submaximal aerobic fitness parameters (peak oxygen consumption and ventilatory threshold, respectively) are affected by hormone-replacement therapy (HRT) in moderately active postmenopausal women. Forty healthy, active, postmenopausal women (21 taking HRT, mean age 62 ± 5 years; 19 not taking HRT, mean age 62 ± 7 years) met the peak oxygen consumption criteria during a cycle ergometer test (15 W ramp) and achieved volitional fatigue. Breath-by-breath measurement was used to determine peak oxygen consumption and to estimate ventilatory threshold. There were no differences in characteristics (age, body mass, height, body mass index, leisure-time physical activity) between the non-HRT and HRT groups, nor were there any differences in responses to maximal exercise, with an observed peak oxygen consumption (mL·kg–1·min–1) of 22.9 ± 3.8 in the non-HRT group and 22.0 ± 4.7 in the HRT group. There was also no difference in submaximal aerobic capacity, with ventilatory threshold values (mL·kg–1·min–1) of 16.7 ± 3.4 in the non-HRT group and 15.6 ± 3.2 in the HRT group. In a sample of healthy moderately active postmenopausal women, there was no difference in maximal or submaximal aerobic fitness parameters beteen the HRT and non-HRT groups.

Post menopausal hormones and measures of subclinical atherosclerosis: the multi-ethnic study of atherosclerosis

OBJECTIVE

To evaluate whether post menopausal hormones are associated with atherosclerosis.

METHODS

We studied the relation of hormone use to coronary calcification and carotid intima-media thickness in a cross-sectional sample of 3245 post menopausal women, of whom 1620 had used hormones for various periods. Adjusted associations with three measures of hormone use (ever use, duration, and type of hormone) were estimated by multivariable regression.

RESULTS

The prevalence of coronary calcification was only 4 percentage points lower in women who had ever used hormones than in women who had not (40% versus 44%), and was not monotonically related to longer use: <2 years: 38%; 2-6 years: 36%; 6-13 years: 41%; >13 years: 48%. Similarly, duration of hormone use did not show a monotonic dose-response relation with the calcium score. Mean differences in carotid intima-media thickness according to categories of years of hormone use and type of hormone ranged from -0.10 mm to +0.08 mm, with no consistent patterns. Most adjusted associations were weak and sometimes contrary to our expectation.

CONCLUSIONS

We did not find meaningful associations between hormone use and subclinical atherosclerosis-neither to support benefit or harm, nor to support the prevailing theory of "healthy user" bias (namely, inverse associations due to residual confounding).

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.

Vascular actions of estrogens: functional implications

The impact of estrogen exposure in preventing or treating cardiovascular disease is controversial. But it is clear that estrogen has important effects on vascular physiology and pathophysiology, with potential therapeutic implications. Therefore, the goal of this review is to summarize, using an integrated approach, current knowledge of the vascular effects of estrogen, both in humans and in experimental animals. Aspects of estrogen synthesis and receptors, as well as general mechanisms of estrogenic action are reviewed with an emphasis on issues particularly relevant to the vascular system. Recent understanding of the impact of estrogen on mitochondrial function suggests that the longer lifespan of women compared with men may depend in part on the ability of estrogen to decrease production of reactive oxygen species in mitochondria. Mechanisms by which estrogen increases endothelial vasodilator function, promotes angiogenesis, and modulates autonomic function are summarized. Key aspects of the relevant pathophysiology of inflammation, atherosclerosis, stroke, migraine, and thrombosis are reviewed concerning current knowledge of estrogenic effects. A number of emerging concepts are addressed throughout. These include the importance of estrogenic formulation and route of administration and the impact of genetic polymorphisms, either in estrogen receptors or in enzymes responsible for estrogen metabolism, on responsiveness to hormone treatment. The importance of local metabolism of estrogenic precursors and the impact of timing for initiation of treatment and its duration are also considered. Although consensus opinions are emphasized, controversial views are presented to stimulate future research.

Hormone therapy is associated with preserved smooth muscle structure and dilation in the arterial vasculature of the leg in older women

Long-term hormone therapy (HT) is associated with reduced intima-medial thickness (IMT), an established risk factor for atherosclerotic disease, in the femoral artery of healthy older women relative to age-matched non-hormone users. However, the influence of continuous, long-term HT on the relation between age, IMT, and smooth muscle dilation has not been investigated in the popliteal artery, an artery prone to stiffening and calcification. In the present study, popliteal artery IMT and smooth muscle dilation (the increase in diameter to sublingual nitroglycerin, NTG) were assessed with Doppler ultrasound in young (Y: n=16; age 23+/-1 [mean+/-S.E.M.]), older non-HT (O non-HT: n=14; age 69+/-1), and older HT (O HT: n=8; age 67+/-1) healthy women. The approximately 0.5 mm increase in resting diameter observed in older non-HT women relative to young women was absent in older HT women, as was the age-related increase in IMT (Y: 0.52+/-0.02 mm; O non-HT: 0.63+/-0.02 mm; O HT: 0.56+/-0.02 mm; p<0.05 for age and hormone comparisons). NTG dilation (percent change above rest) was similarly attenuated in older non-HT women (Y: 8.6+/-1%; O non-HT: 3.0+/-0.7%; O HT: 7.4+/-1.7%; p<0.05 for age and hormone comparisons), and NTG dilation was inversely related to IMT (p<0.01). Collectively, these results suggest that long-term, continuous HT may alleviate the detrimental effects of aging on both structural changes and smooth muscle dilation of the popliteal artery in healthy women.

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).

Xanthine oxidase does not contribute to impaired peripheral conduit artery endothelium-dependent dilatation with ageing

Vascular oxidative stress is the key mechanism involved in the age-related decline in endothelium-dependent dilatation (EDD). We tested the hypothesis that xanthine oxidase (XO), a major vascular source of reactive oxygen species, contributes to the impairment in EDD with ageing. At baseline, brachial artery flow-mediated dilatation (FMD) was 55% lower in older (n = 9, 64 +/- 2 years, 8M/1F, mean +/- S.E.M.) versus young (n = 9, 26 +/- 1 years, 8M/1F) healthy adults (3.41 +/- 0.44 versus 7.53 +/- 0.67%, P < 0.001), whereas endothelium-independent dilatation (EID; sublingual nitroglycerin) did not differ between groups. Plasma oxidized low-density lipoprotein (oxi-LDL), a measure of systemic oxidative stress, was greater at baseline in the older subjects (58.3 +/- 5.9 versus 46.8 +/- 2.4 U l(-1), P < 0.05) and inversely correlated with baseline FMD (r = - 0.54; P < 0.05). Acute administration of allopurinol, a competitive inhibitor of XO, reduced plasma uric acid concentrations similarly in both groups (P < 0.001), but did not affect FMD, EID, or oxi-LDL in either group. Vascular endothelial protein expression of XO (immunofluorescence) was not different in antecubital venous cells from the young and older subjects (0.56 +/- 0.12 versus 0.68 +/- 0.19 XO intensity/human umbilical vein endothelial cell intensity, P = 0.49). We conclude that XO does not contribute to oxidative stress-associated reductions in peripheral conduit artery EDD with ageing in humans, possibly due to an absence of age-associated up-regulation of endothelial XO.

Lack of age-related decreases in basal whole leg blood flow in resistance-trained men

Reductions in basal leg blood flow have been implicated in the pathogenesis of metabolic syndrome and functional impairment in humans. We tested the hypothesis that reductions in basal whole leg blood flow with age are either absent or attenuated in those who perform regular strength training. A total of 104 normotensive men aged 20-34 yr (young) and 35-65 yr (middle aged), who were either sedentary or resistance trained, were studied. Mean and diastolic blood pressures were higher (P < 0.05-0.001) in the middle-aged compared with the young men, but there were no significant differences between the sedentary and resistance-trained groups. In the sedentary group, basal whole leg blood flow (duplex Doppler ultrasound) and vascular conductance were lower ( approximately 30 and approximately 38%, respectively; P < 0.01) in the middle-aged compared with the young men. There were no such age-related differences in the resistance-trained group. In the young men, basal whole leg blood flow and vascular conductance were not different between the two activity groups, but, in the middle-aged men, they were higher ( approximately 35 and approximately 36%, respectively; P < 0.01) in the resistance-trained men than in the sedentary men. When blood flow and vascular conductance were expressed relative to the leg muscle mass, the results were essentially the same. We concluded that the age-related reduction in basal whole leg blood flow is absent in resistance-trained men. These results suggest that resistance training may favorably influence leg perfusion in aging humans, independent of its impact on leg muscle mass.

Collateral damage: cardiovascular consequences of chronic sympathetic activation with human aging

Adult aging in humans is associated with marked and sustained increases in sympathetic nervous system (SNS) activity to several peripheral tissues, including the heart, the gut-liver circulation, and skeletal muscle. This chronic activation of the peripheral SNS likely is, at least in part, a primary response of the central nervous system to stimulate thermogenesis to prevent further fat storage in the face of increasing adiposity with aging. However, as has been proposed in obesity hypertension, this tonic activation of the peripheral SNS has a number of adverse secondary cardiovascular consequences. These include chronic reductions in leg blood flow and vascular conductance, increased tonic support of arterial blood pressure, reduced limb and systemic α-adrenergic vasoconstrictor responsiveness, impaired baroreflex buffering, large conduit artery hypertrophy, and decreased vascular and cardiac responsiveness to β-adrenergic stimulation. These effects of chronic age-associated SNS activation on the structure and function of the cardiovascular system, in turn, may have important implications for the maintenance of physiological function and homeostasis, as well as the risk of developing clinical cardiovascular and metabolic diseases in middle-aged and older adults.

The Role of Exercise in the Treatment of Cardiovascular Disease Associated with Type 2 Diabetes Mellitus

The role of exercise training in the prevention and treatment of type 2 diabetes mellitus has been studied extensively over the past two decades. Although the primary treatment aim for patients with type 2 diabetes is metabolic control, the morbidity and mortality associated with the disease is more a function of cardiovascular disease. As exercise is associated with favourable reductions in the risk for cardiovascular disease in other high-risk populations, here we explore the role of exercise in the treatment of cardiovascular maladaptations associated with type 2 diabetes. The cardiovascular adaptation to type 2 diabetes is characterised by hypertrophy, stiffening and loss of functional reserve. Clinically, the cardiovascular adaptations to the diabetic state are associated with an increased risk for cardiovascular disease. Functionally, these adaptations have been shown to contribute to a reduced exercise capacity, which may explain the reduced cardiovascular fitness observed in this population. Exercise training is associated with improved exercise capacity in various populations, including type 2 diabetes. Several structural and functional adaptations within the cardiovascular system following exercise training could explain these findings, such as reductions in ventricular and vascular structural hypertrophy and compliance coupled with increased functional reserve. Although these cardiovascular adaptations to aerobic exercise training have been well documented in older populations with similar decrements in cardiovascular fitness and function, they have yet to be examined in patients with type 2 diabetes. For this reason, we contend that exercise training may be an excellent therapeutic adjunct in the treatment of diabetic cardiovascular disease.