Effects of ageing and regular aerobic exercise on endothelial fibrinolytic capacity in humans

Negative Influence of Insufficient Sleep on Endothelial Vasodilator and Fibrinolytic Function in Hypertensive Adults

[Figure: see text].

Does exercise training improve the function of vascular smooth muscle? A systematic review and meta-analysis

We aimed to determine the effects of exercise training on the function of vascular smooth muscle cells. PubMed and Web of Science about the effects of exercise training on vascular smooth muscle cells were searched up to August 2020. The effect sizes were estimated in terms of the standardized mean difference. The number of studies included was thirty-five overall. Exercise training had positive effects on vascular smooth muscle cells function in participants older than 40. Effect sizes for HIGH intensity and MIX were positive but small, and also when training duration was longer than 12 weeks. We concluded that vascular smooth muscle cells response can be promoted by exercise training. Vigorous aerobic exercise and mixture training modality were the best ways to promote the dilation response of vascular smooth muscle cells. Additionally, the significant improvement induced by exercise training only occurred when training lasted for longer than 12 weeks.

Overview of the Assessment of Endothelial Function in Humans

The endothelium is recognized to play an important role in various physiological functions including vascular tone, permeability, anticoagulation, and angiogenesis. Endothelial dysfunction is increasingly recognized to contribute to pathophysiology of many disease states, and depending on the disease stimuli, mechanisms underlying the endothelial dysfunction may be markedly different. As such, numerous techniques to measure different aspects of endothelial dysfunction have been developed and refined as available technology improves. Current available reviews on quantifying endothelial dysfunction generally concentrate on a single aspect of endothelial function, although diseases may affect more than one aspect of endothelial function. Here, we aim to provide an overview on the techniques available for the assessment of the different aspects of endothelial function in humans, human tissues or cells, namely vascular tone modulation, permeability, anticoagulation and fibrinolysis, and the use of endothelial biomarkers as predictors of outcomes.

Association between coronary atherosclerotic burden and all-cause mortality among patients undergoing exercise versus pharmacologic stress-rest SPECT myocardial perfusion imaging

BACKGROUND AND AIMS

Patients with suspected coronary artery disease who undergo stress SPECT myocardial perfusion imaging (MPI) and require pharmacologic stress are at substantially increased mortality risk compared to those who can exercise. However, the mechanisms underlying this increased risk are not well delineated. To test whether increased atherosclerotic burden accounts for this increased risk, we assessed the association between coronary artery calcium (CAC) scores and mortality risk among patients undergoing exercise versus pharmacologic SPECT MPI.

METHODS

We assessed all-cause mortality in 2,151 patients, followed for 12.2 ± 3.4 years, after undergoing stress-rest SPECT-MPI and CAC scanning within 3 months of each other. Patients were divided according to their mode of stress testing (exercise or pharmacologic). We further employed propensity analysis to create a subgroup of exercise and pharmacologic subgroups with comparable age, symptoms, and coronary risk factors.

RESULTS

Despite greater age and worse clinical profiles, pharmacologic and exercise patients had similar CAC scores. However, the hazard ratio (95% CI) for mortality was substantially greater among pharmacologic patients: 2.39 (1.83-3.10). For each level of CAC abnormality, pharmacologic patients had >2-fold increased risk adjusted hazard ratio for all-mortality risk (p < 0.05 for each CAC level). Among propensity-matched exercise versus pharmacologic patients, the same findings were observed.

CONCLUSIONS

Among patients referred for stress-rest SPECT-MPI and CAC scoring, pharmacologic patients have substantially increased mortality risk compared to exercise patients, despite having comparable levels of coronary atherosclerosis.

Effects of circulating extracellular microvesicles from spinal cord-injured adults on endothelial cell function

People with spinal cord injury (SCI) have three- to four-fold greater risk of cardiovascular disease (CVD) compared with those without SCI. Although circulating extracellular microvesicles are key effectors of vascular health and disease, how their functional phenotype might be altered with SCI is unknown. The aim of the present study was to determine the effects of microvesicles isolated from SCI adults on endothelial cell inflammation and oxidative stress as well as endothelial nitric oxide (NO) synthase (eNOS) activation and tissue-type plasminogen activator (t-PA) expression. Eighteen young and middle-aged adults were studied: 10 uninjured (7M/3F; age: 39 ± 3 years) and 8 cervical level spinal cord injured (SCI; 7M/1F; 46 ± 4 years; cervical injury: C3: n=1; C5: n=4; C6: n=3). Circulating microvesicles were isolated, enumerated and collected from plasma by flow cytometry. Human umbilical vein endothelial cells (HUVECs) were cultured and treated with microvesicles from either the uninjured or SCI adults. Microvesicles from SCI adults did not affect cellular markers or mediators of inflammation and oxidative stress. However, microvesicles from the SCI adults significantly blunted eNOS activation, NO bioavailability and t-PA production. Intercellular expression of phosphorylated eNOS at Ser1177 and Thr495 sites, specifically, were ∼65% lower and ∼85% higher, respectively, in cells treated with microvesicles from SCI compared with uninjured adults. Decreased eNOS activity and NO production as well as impaired t-PA bioavailability renders the vascular endothelium highly susceptible to atherosclerosis and thrombosis. Thus, circulating microvesicles may contribute to the increased risk of vascular disease and thrombotic events associated with SCI.

Associations Among Self-reported Physical Activity, Coronary Artery Calcium Scores, and Mortality Risk in Older Adults

Objective

To assess whether self-reported physical activity during daily life reduces the mortality risk associated with atherosclerotic burden, as measured by coronary artery calcium (CAC) scanning.

Methods

We assessed 2318 patients aged 65 to 84 years who underwent CAC scanning from August 31, 1998, through November 16, 2016, and had daily life physical activity assessed by a single-item question that was used to divide patients by low, moderate, and high physical activity levels. Patients were followed for a mean ± SD of 10.6±4.9 years for the occurrence of all-cause mortality.

Results

The results indicated a graded relationship between the magnitude of CAC abnormality and mortality and an inverse relationship between physical activity and mortality. Of patients with low CAC scores (0-99), those with low, moderate, and high physical activity levels had similarly low mortality rates. Of patients with high CAC scores (≥400), however, there was a stepwise increase in mortality with decreasing physical activity. Patients with CAC scores of 400 or greater but reporting high physical activity had a mortality rate that was similar vs that observed in patients with CAC scores of only 0 to 99 and low physical activity (19.9 vs 16.3 per 1000 person-years; P=.60).

Conclusion

Combining CAC score with self-reported physical activity level provides a synergistic means for predicting clinical risk in older patients, with high physical activity level substantially attenuating the mortality risk associated with elevated CAC scores. Moreover, the useful prognostic information afforded by just a single-item physical activity questionnaire supports current initiatives to make such assessments into a "fifth vital sign."

Microparticle Responses to Aerobic Exercise and Meal Consumption in Healthy Men

PURPOSE

Microparticles (MP) are shed extracellular vesicles that express the prothrombotic tissue factor (TF). Aerobic exercise may reduce MP count and TF expression. This study investigated the impact of acute running or rest followed by standardized meal consumption on MP phenotypes and TF expression.

METHODS

Fifteen males (age, 22.9 ± 3.3 yr; body mass, 81.9 ± 11.4 kg; V˙O2max, 54.9 ± 6.5 mL·kg·min; mean ± SD) completed 1 h of running (70% V˙O2max) or rest at 9:00 AM and consumed a standardized meal (1170 kcal, 43% CHO, 17% PRO, 40% fat) at 10:45 AM. Venous blood samples were taken at 9:00 AM, 10:00 AM, and 11:30 AM. The MP concentration, diameter, phenotypes, and TF expression were assessed using nanoparticle tracking analysis and flow cytometry.

RESULTS

Nanoparticle tracking analysis identified no changes in MP concentration or diameter in response to time or trial. Flow cytometry revealed total MP count increased from 9:00 AM to 10:00 AM (1.62 ± 2.28 to 1.74 ± 2.61 × 10 L, P = 0.016, effect size (η) = 0.105), but was unaffected by trial. TF platelet-derived MP % reduced from 9:00 AM to 10:00 AM (44.0% ± 21.2% to 21.5% ± 9.3%, P = 0.001, η = 0.582) after exercise only (control, 36.8% ± 18.2% to 34.9% ± 11.9%; P = 0.972). TF neutrophil-derived MP percentage reduced from 9:00 AM to 11:30 AM (42.3% ± 17.2% to 25.1% ± 14.9%; P = 0.048, η = 0.801) in the exercise trial only (control, 28.5% ± 15.7% to 32.2% ± 9.6%; P = 0.508).

CONCLUSIONS

Running induced a significant reduction in %TF platelet and neutrophil MP, suggesting a transient reduction in cardiovascular risk via reduced TF-stimulated thrombosis. This requires further investigation over longer periods in cardiovascular disease populations.

Receptor GP IIb/IIIa as an Indicator of Risk in Vascular Events

Type 2 diabetes causes a significant risk of cardiovascular diseases, leading to 70% of deaths in patients with diabetes. The effective treatment of diabetes significantly reduces the risk of requiring the involvement of specialists from various fields of medicine. This research aimed to assess the risk of cardiovascular events based on selected biochemical parameters (glycoprotein [GP] IIb/IIIa, von Willebrand factor [vWf], fibrinogen) and their changes in response to physical exercise. The research group consisted of 52 patients with type 2 diabetes with micro- or macro-angiopathy at a mean age of 63.80 years (8.79). The control group consisted of 50 healthy volunteers (17 women and 33 men) at a mean age of 51.16 years (6.39). All the patients consented to have their venous blood tested to measure complete blood counts. Activated GP IIb/IIIa receptors were labeled and analyzed by flow cytometry. Mean values of vWF factor were higher when compared with the control group (196.59% [80.32%] vs 148.06% [90.34%], respectively). The GP IIb/IIIa receptor expression was much higher in test patients than in the control group (3.91% [2.91%] vs 2.79% [2.51%]). Physical exercise had a positive influence on GP IIb/IIIa receptor expression and vWF, decreasing their baseline percentage values.

Blood lipid profile and body composition in a pediatric population with different levels of physical activity

Background

Associations between physical activity and lipid/lipoprotein levels and body composition among pediatric populations are not completely consistent in the literature. Accordingly, the aim of this study was to analyze lipid and lipoprotein profiles and body composition among children and adolescents differentiated according to their level of physical activity.

Methods

The study sample consisted of 69 participants that ranged from 6 to 17 years of age. Objective measures of physical activity were obtained over 7 days with accelerometers. Total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL) and triglycerides (TG) were measured from a fasting blood sample. High-risk values for these lipids/lipoproteins were determined using age- and sex-specific thresholds. Body composition estimates were obtained using a foot-to-foot bioelectrical impedance analysis.

Results

Almost half (47.8%) of the participants did not meet daily moderate-to-vigorous intensity physical activity (MVPA) recommendations. This group had lower free fat mass (by 5.51%), muscle mass content (by 5.17%), and a higher risk for abnormal HDL level (OR = 4.19) and excessive body fat content (OR = 3.05).

Conclusions

Participants who met daily recommended MVPA were found to have more favorable HDL and body fat levels compared to those who did not meet these recommendations.

Effects of moderate and vigorous physical activity on fitness and body composition

Current physical activity (PA) guidelines indicate that moderate-intensity (MPA) and vigorous intensity (VPA) PA provide similar benefits when total volume is equal. The present study examined the associations of MPA and VPA with body composition and cardiorespiratory fitness in free-living young adults. A total of 197 young adults (52.8 % male) were followed over a period of 15 months. Body composition was assessed via dual X-ray absorptiometry and time spent in various PA intensities was determined with a multi-sensor device every 3 months. Cardiorespiratory fitness was assessed with a graded exercise test at baseline and 15-months follow-up. Change in VPA was positively associated with cardiorespiratory fitness while MPA had beneficial associations with percent body fat. In overweight/obese participants the association with VO2peak was similar for MVPA bouts and VPA. Even though MPA and VPA have positive associations with overall health, their associations on key health parameters differ.

The impact of age on vascular smooth muscle function in humans

AIM

Advanced age is associated with vascular endothelial dysfunction, characterized by reductions in the endothelium-dependent vasodilation of the conduit and resistance arteries, in part, from decreased nitric oxide bioavailability. Although vascular smooth muscle function (SMF), assessed by responsiveness to an exogenous nitric oxide donor, is typically reported to be intact, many of these studies are limited by a small sample size. Therefore, the purpose of this meta-analysis is to systematically review and determine whether vascular SMF is different between older versus young healthy individuals.

DESIGN

We conducted a systematic search of MEDLINE, Cochrane and Scopus, since their inceptions until January 2014, for articles evaluating SMF in the brachial artery and/or resistance arteries (BASMF and RASMF, respectively), as assessed by the endothelium-independent vasodilator response to exogenous nitric oxide donors in older (≥60 years) and young (<30 years) groups of healthy individuals. Meta-analyses were performed to compare the mean difference in BASMF and the standardized mean difference in RASMF between older and young groups. Subgroup analyses were performed to identify sources of heterogeneity.

RESULTS

Fifteen studies assessing BASMF and 20 studies assessing RASMF were included, comprising 550 older and 516 young healthy individuals. After data pooling, BASMF and RASMF were lower in older compared with the young groups (mean difference = -1.89%, P = 0.04; standardized mean difference = -0.46, P = 0.0008, respectively). Significant heterogeneity was observed in the BASMF (I2 = 74%, P < 0.00001) and the RASMF (I2 = 57%, P = 0.0008) meta-analyses. Subgroup analyses revealed that studies with (predominantly) men showed similar SMF responses between the older and the young groups.

CONCLUSION

On the basis of the current published studies, vascular SMF is reduced in conduit and resistance arteries of otherwise healthy older individuals, particularly in women.

Microvascular Dilator Function in Athletes: A Systematic Review and Meta-analysis

PURPOSE

Despite the growing research interest in vascular adaptations to exercise training over the last few decades, it remains unclear whether microvascular function in healthy subjects can be further improved by regular training. Herein, we sought to systematically review the literature and determine whether microvascular dilator function is greater in athletes compared to age-matched healthy untrained subjects.

METHODS

We conducted a systematic search of MEDLINE, Cochrane, EMBASE, and Web of Science since their inceptions until October 2013 for articles evaluating indices of primarily microvascular endothelium-dependent or endothelium-independent dilation (MVEDD and MVEID, respectively) in athletes. A meta-analysis was performed to determine the standardized mean difference (SMD) in MVEDD and MVEID between athletes and age-matched controls. Subgroup analyses were used to study potential moderating factors.

RESULTS

Thirty-six studies were selected after systematic review, comprising 521 athletes (506 endurance-trained and 15 endurance- and strength-trained) and 496 age-matched control subjects. After data pooling, athletes presented higher MVEDD (31 studies; SMD, 0.47; P < 0.00001) and MVEID (14 studies; SMD, 0.51; P < 0.00001) compared with the control subjects. Similar results were observed in young (younger than 40 yr) and master (older than 55 yr) athletes when analyzed separately.

CONCLUSION

Both young and master athletes present enhanced microvascular function compared with age-matched untrained but otherwise healthy subjects. These data provide evidence of a positive association between exercise training and microvascular function in the absence of known underlying cardiovascular disease.

Cellular and molecular biology of aging endothelial cells

Cardiovascular disease (CVD) is the leading cause of death in the United States and aging is a major risk factor for CVD development. One of the major age-related arterial phenotypes thought to be responsible for the development of CVD in older adults is endothelial dysfunction. Endothelial function is modulated by traditional CVD risk factors in young adults, but advancing age is independently associated with the development of vascular endothelial dysfunction. This endothelial dysfunction results from a reduction in nitric oxide bioavailability downstream of endothelial oxidative stress and inflammation that can be further modulated by traditional CVD risk factors in older adults. Greater endothelial oxidative stress with aging is a result of augmented production from the intracellular enzymes NADPH oxidase and uncoupled eNOS, as well as from mitochondrial respiration in the absence of appropriate increases in antioxidant defenses as regulated by relevant transcription factors, such as FOXO. Interestingly, it appears that NFkB, a critical inflammatory transcription factor, is sensitive to this age-related endothelial redox change and its activation induces transcription of pro-inflammatory cytokines that can further suppress endothelial function, thus creating a vicious feed-forward cycle. This review will discuss the two macro-mechanistic processes, oxidative stress and inflammation, that contribute to endothelial dysfunction with advancing age as well as the cellular and molecular events that lead to the vicious cycle of inflammation and oxidative stress in the aged endothelium. Other potential mediators of this pro-inflammatory endothelial phenotype are increases in immune or senescent cells in the vasculature. Of note, genomic instability, telomere dysfunction or DNA damage has been shown to trigger cell senescence via the p53/p21 pathway and result in increased inflammatory signaling in arteries from older adults. This review will discuss the current state of knowledge regarding the emerging concepts of senescence and genomic instability as mechanisms underlying oxidative stress and inflammation in the aged endothelium. Lastly, energy sensitive/stress resistance pathways (SIRT-1, AMPK, mTOR) are altered in endothelial cells and/or arteries with aging and these pathways may modulate endothelial function via key oxidative stress and inflammation-related transcription factors. This review will also discuss what is known about the role of "energy sensing" longevity pathways in modulating endothelial function with advancing age. With the growing population of older adults, elucidating the cellular and molecular mechanisms of endothelial dysfunction with age is critical to establishing appropriate and measured strategies to utilize pharmacological and lifestyle interventions aimed at alleviating CVD risk. This article is part of a Special Issue entitled "SI: CV Aging".

Effect of obesity on acute hemostatic responses to live-fire training drills

The objective of this study was to evaluate the impact of obesity and firefighting activities on coagulation and fibrinolytic activity in relatively young, apparently healthy firefighters. Firefighters performed simulated firefighting activities for 18 minutes in a live-fire training structure. Blood samples were obtained at baseline, before firefighting, and within a few minutes of completing the activity. Nearly all markers of coagulation and fibrinolytic activity increased immediately after firefighting with an overall shift toward a procoagulatory profile. Obese firefighters exhibited lower levels of tissue plasminogen activator activity (0.98 vs 0.63 IU/ml) and higher levels of plasminogen activator inhibitor-1 activity (2.2 vs 4.5 ng/ml) at baseline compared with normal-weight firefighters, suggesting that fibrinolytic activity was lower in obese firefighters. There were few interactions between body mass index and firefighting activity, thus our findings suggest that obese firefighters did not exhibit a greater procoagulatory response to live firefighting compared with normal-weight firefighters. Acute live firefighting produced increases in both fibrinolytic and coagulatory responses; although obesity was associated with a reduced fibrinolytic profile at baseline, the changes produced by acute firefighting were similar in obese and nonobese firefighters.

Influence of dietary saturated fat intake on endothelial fibrinolytic capacity in adults

Approximately 50% of middle-aged and older adults in the United States regularly consume a diet high in saturated fat. High dietary saturated fat intake has been linked to promote atherothrombotic vascular disease. We tested the hypothesis that endothelial fibrinolytic function is diminished in middle-aged and older adults who habitually consume a diet high in saturated fat. Twenty-four healthy, sedentary middle-aged, and older adults (54 to 71 years) were studied: 10 (8 men and 2 women) with a dietary saturated fat intake <10% (lower saturated fat) of total calories and 14 (9 men and 5 women) with a dietary saturated fat intake ≥10% of total calories (high saturated fat). Net endothelial release of tissue-type plasminogen activator (t-PA), the primary activator of fibrinolysis, was determined, in vivo, in response to intrabrachial infusions of bradykinin (12.5 to 50.0 ng/100 ml tissue/min) and sodium nitroprusside (1.0 to 4.0 μg/100 ml tissue/min). Capacity of the endothelium to release t-PA in response to bradykinin was ∼30% less (p <0.05) in the high (from -0.7 ± 0.6 to 36.9 ± 3.3 ng/100 ml tissue/min) compared with the lower (from -0.3 ± 0.3 to 53.4 ± 7.8 ng/100 ml tissue/min) dietary saturated fat group. Moreover, total amount of t-PA released was significantly less (∼30%) (201 ± 22 vs 274 ± 29 ng/100 ml tissue) in the adults who reported consuming a diet high in saturated fat. These results indicate that the capacity of the endothelium to release t-PA is lower in middle-aged and older adults who habitually consume a diet high in saturated fat. In conclusion, endothelial fibrinolytic dysfunction may underlie the increased atherothrombotic disease risk with a diet high in saturated fat.

Edward F. Adolph Distinguished Lecture: The remarkable anti-aging effects of aerobic exercise on systemic arteries

Cardiovascular diseases (CVD) remain the leading cause of morbidity and mortality in modern societies, and advancing age is the major risk factor for CVD. Arterial dysfunction, characterized by large elastic artery stiffening and endothelial dysfunction, is the key event leading to age-associated CVD. Our work shows that regular aerobic exercise inhibits large elastic artery stiffening with aging (optimizes arterial compliance) and preserves endothelial function. Importantly, among previously sedentary late middle-aged and older adults, aerobic exercise improves arterial stiffness and enhances endothelial function in most groups and, therefore, also can be considered a treatment for age-associated arterial dysfunction. The mechanisms by which regular aerobic exercise destiffens large elastic arteries are incompletely understood, but existing evidence suggests that reductions in oxidative stress associated with decreases in both adventitial collagen (fibrosis) and advanced glycation end-products (structural protein cross-linking molecules), play a key role. Aerobic exercise preserves endothelial function with aging by maintaining nitric oxide bioavailability via suppression of excessive superoxide-associated oxidative stress, and by inhibiting the development of chronic low-grade vascular inflammation. Recent work from our laboratory supports the novel hypothesis that aerobic exercise may exert these beneficial effects by directly inducing protection to aging arteries against multiple adverse factors to which they are chronically exposed. Regular aerobic exercise should be viewed as a "first line" strategy for prevention and treatment of arterial aging and a vital component of a contemporary public health approach for reducing the projected increase in population CVD burden.

Human tissue-type plasminogen activator

Tissue-type plasminogen activator (t-PA ) plays an important role in the removal of intravascular fibrin deposits and has several physiological roles and pathological activities in the brain. Its production by many other cell types suggests that t-PA has additional functions outside the vascular and central nervous system. Activity of t-PA is regulated at the level of its gene transcription, its mRNA stability and translation, its storage and regulated release, its interaction with cofactors that enhance its activity, its inhibition by inhibitors such as plasminogen activator inhibitor type 1 or neuroserpin, and its removal by clearance receptors. Gene transcription of t-PA is modulated by a large number of hormones, growth factors, cytokines or drugs and t-PA gene responses may be tissue-specific. The aim of this review is to summarise current knowledge on t-PA function and regulation of its pericellular activity, with an emphasis on regulation of its gene expression.

Age and aerobic training status effects on plasma and skeletal muscle tPA and PAI-1

INTRODUCTION

Reductions in fibrinolytic potential occur with both aging and physical inactivity and are associated with an increased cardiovascular disease risk. Plasmin, the enzyme responsible for the enzymatic degradation of fibrin clots, is activated by tissue plasminogen activator (tPA), while plasminogen activator inhibitor-1 (PAI-1) inhibits its activation. Currently, fibrinolysis research focuses almost exclusively on changes within the plasma. However, tPA and PAI-1 are expressed by human skeletal muscle (SM). Currently, no studies have focused on changes in SM fibrinolytic activity with regard to aging and aerobic fitness.

PURPOSE

The purpose of this study was to cross-sectionally evaluate effects of age and aerobic fitness on tPA and PAI-1 expressions and activity in SM.

METHODS

Twenty-six male subjects were categorized into the following groups: (1) young aerobically trained (n = 8); (2) older aerobically trained (n = 6); (3) young aerobically untrained (n = 7); and (4) older aerobically untrained (n = 5). Muscle biopsies were obtained from each subject. SM tPA activity was assessed using gel zymography and SM tPA and PAI-1 expressions were assessed using RT-PCR.

RESULTS

Trained subjects had higher SM tPA activity compared to untrained (25.3 ± 2.4 × 10(3) vs. 21.5 ± 5.6 × 10(3) pixels, respectively; p = 0.03) with no effect observed for age. VO2 max and SM tPA activity were also significantly correlated (r = 0.42; p < 0.04). SM tPA expression was higher in older participants, but no effect of fitness level was observed. No differences were observed for PAI-1 expression in SM.

CONCLUSIONS

Higher levels of aerobic fitness are associated with increased fibrinolytic activity in SM.

Effects of physical activity on endothelial progenitor cells (EPCs)

Physical activity has a therapeutic role in cardiovascular disease (CVD), through its beneficial effects on endothelial function and cardiovascular system. Circulating endothelial progenitor cells (EPCs) are bone marrow (BM) derived cells that represent a novel therapeutic target in CVD patients, because of their ability to home to sites of ischemic injury and repair the damaged vessels. Several studies show that physical activity results in a significant increase in circulating EPCs, and, in particular, there are some evidence of the beneficial exercise-induced effects on EPCs activity in CVD settings, including coronary artery disease (CAD), heart failure (HF), and peripheral artery disease (PAD). The aim of this paper is to review the current evidence about the beneficial effects of physical exercise on endothelial function and EPCs levels and activity in both healthy subjects and patients with CVD.

Effects of a single bout of walking exercise on blood coagulation parameters in obese women

Obesity is associated with increased prevalence of thromboembolic events. We aimed to investigate whether obese women might benefit from vigorous aerobic exercise. Forty-two overweight and obese women performed a 30-min walking exercise test (treadmill ergometer) at an intensity of 70% of individual peak oxygen uptake. Blood samples were collected before and immediately after exercise. Thrombelastometry and platelet function measurements were performed on whole blood. Standard coagulation times, thrombin generation curves, markers of thrombin generation, fibrinolytic parameters, plasma levels of pro- and anticoagulatory factors, and microparticle procoagulant activity were determined in platelet-poor plasma samples. Thrombelastometry revealed a significant prolongation of clot formation time ( P = 0.037) and a significant deceleration of fibrin build up (alpha angle, P = 0.034) after exercise. Calibrated automated thrombography revealed a significant exercise-induced decrease in endogenous thrombin potential ( P = 0.039). Moreover, thrombin formation stopped earlier postexercise, reflected in shortened StartTail ( P = 0.046). Significantly elevated tissue-plasminogen activator levels ( P = 0.001) indicate an exercise-induced activation of the fibrinolytic system. White blood cell count increased significantly from pre- to postexercise ( P = 0.045), indicating a mild exercise-induced leukocytosis. The results of this study demonstrate that vigorous aerobic exercise might be a suitable tool to protect obese women from thrombotic events. We show that a single bout of vigorous aerobic exercise is clearly associated with an activation of the fibrinolytic system and a decreased readiness of the postexercise samples to form a clot and to generate thrombin, the pivotal enzyme of hemostasis.

Self-reported habitual short sleep duration is associated with endothelial fibrinolytic dysfunction in men: a preliminary report

STUDY OBJECTIVES

Habitual short sleep duration is associated with increased cardiovascular disease morbidity and mortality resulting from atherothrombotic events. The mechanisms responsible for this heightened cardiovascular risk are not fully understood. The capacity of the endothelium to release tissue-type plasminogen activator (t-PA), the primary activator of the fibrinolytic system, is a key endogenous defense mechanism against intravascular fibrin deposition and thrombosis. We tested the hypothesis that endothelial t-PA release is impaired in adults who sleep less than 7 h/night compared with adults who sleep between 7 and 9 h/night.

DESIGN

THIRTY ADULT MEN WERE STRATIFIED BASED ON AVERAGE NIGHTLY HABITUAL SLEEP DURATION: 15 with normal sleep duration (age: 55 ± 2 years; sleep duration: 7.6 h/night) and 15 with short sleep duration (56 ± 2 years; 6.1 h/night). Net endothelial release of t-PA was determined, in vivo, in response to intra-brachial infusions of bradykinin (12.5-50.0 ng/100 mL tissue/min) and sodium nitroprusside (1.0-4.0 μg/100 mL tissue/min).

MEASUREMENTS AND RESULTS

Net endothelial t-PA release to bradykinin was significantly lower (∼25%) in the short (from 0.4 ± 0.8 to 41.5 ± 4.3 ng/100 mL tissue/min) compared with the normal (0.4 ± 0.5 to 64.9 ± 6.7 ng/100 mL/tissue/min) sleep duration group. Furthermore, there was an inverse relation between average nightly sleep duration and peak t-PA release to bradykinin (r = 0.36, P < 0.05).

CONCLUSIONS

Endothelial t-PA release is impaired in adults who report short habitual sleep duration. Impaired endothelial fibrinolytic function may underlie the increased atherothrombotic risk associated with chronic short sleep.

Aging is associated with a proapoptotic endothelial progenitor cell phenotype

The aim of this study was to determine if aging is associated with enhanced endothelial progenitor cell (EPC) sensitivity to apoptosis. Cells with phenotypic EPC characteristics were isolated from healthy, nonobese young (age 25 ± 1 years) and older (61 ± 1 years) men. Intracellular active caspase-3 concentrations in response to staurosporine stimulation were approximately 35% higher (p < 0.05) in EPCs from older (3.15 ± 0.29 pg/ml) compared with young (2.33 ± 0.24 pg/ml) men. Protein expression of Akt, p70 S6-kinase and Bcl-2 was markedly lower (approx. 35, 75 and 60%, respectively, all p < 0.05) in EPCs from older compared with young men, whereas there were no age-related differences in either 14-3-3ε or Bax expression. Additionally, EPC telomerase activity was 57% lower (p < 0.05) in older (0.18 ± 0.11 AU) versus young (0.43 ± 0.11 AU) men. These results indicate that aging is associated with a proapoptotic EPC phenotype characterized by decreased expression of key antiapoptotic proteins associated with the PI-3-kinase signaling pathway and reduced telomerase activity. These age-related changes likely contribute, in part, to the diminished ability of EPCs to resist an apoptotic stimulus in older men. Increased susceptibility to apoptosis may contribute to the numerical and functional impairments observed in EPCs with aging.

The effect of physical exercise on endothelial function

Endothelium is essential for maintenance of health of the vessel wall and for the local regulation of vascular tone and structure and haemostasis. Regular physical exercise, which is known to promote a favourable cardiovascular state, may improve endothelial function via several mechanisms. Indeed, it augments blood flow and laminar shear stress, resulting in increased nitric oxide production and bioavailability. In this regard, the beneficial effects of training on endothelial function can be mediated in a number of ways, including synthesis of molecular mediators, changes in neurohormonal release and oxidant/antioxidant balance. On the other hand, physical exercise can also elicit systemic molecular pathways connected with angiogenesis and chronic anti-inflammatory action with consequent modification of the endothelial function. However, its benefit depends on the type and intensity of training performed. While strenuous exercise increases oxidative metabolism and produces a pro-oxidant environment, only regular moderate physical activity promotes an antioxidant state and preserves endothelial function. Thus, exercise may have a beneficial effect on the development of cardiovascular disease through preserving endothelial function.

Clinical Assessment of Endothelial Function

The endothelium is crucial in the maintenance of normal vascular function and disturbance of this balance is a key early event in the development of vascular disease. A wide range of techniques currently exists for assessment of endothelial function in both the coronary and the peripheral vasculature. Many of these in vivo tests have concentrated on measuring nitric oxide bioavailability, however more recently methods for measuring other vascular parameters, such as tissue-plasminogen activator release, have been used. Furthermore indirect systemic measurements of endothelial function and endothelial progenitor cells have been investigated. These methods have given great insights into the pathophysiology of atherosclerosis and have aided in the development of a number of antiatherosclerotic therapies. Importantly the methods used to date for assessing endothelial function in vivo are accurate, reproducible and correlate with the future risk of cardiovascular events. The development of new techniques and the constant refinement of established techniques suggest that many more insights are to be gained from clinical assessment of endothelial function.

Coagulation and fibrinolysis are in balance after moderate exercise in middle-aged participants

Increased age is associated with a higher risk of thrombotic events. The aim of this study was to investigate the age-related changes in hemostasis before and after moderate exercise controlled by individual anaerobic threshold as recommended for rehabilitation training. In this study, 24 young (25 +/- 1 years) and 24 middle-aged healthy nonsmokers (48 +/- 1 years) underwent an individualized exercise test with 80% of individual anaerobic threshold (young individuals: 127 +/- 6 W; middle-aged individuals: 128 +/- 5 W; values are expressed as mean +/- standard error of mean) for 60 minutes. The blood samples were collected before and after the exercise. The age-related higher (P < or = .05) levels could be detected in factors II, VII, VIII, IX, XI, XII, prothrombin fragment 1+2, in tissue plasminogen activator antigen and activity, as well as in plasminogen. The relative exercise-induced increases in these parameters were similar in both groups, although beginning at a higher level for those in the middle-aged group.A statistically enhanced increase after exercise in the middle-aged group could be shown in prothrombin fragment 1+2 (young individuals: 98 +/- 6 to 102 +/- 6 pmol/L; middle-aged individuals: 138 +/- 7 to 156 +/- 8 pmol/L) and in thrombin-antithrombin complex (young individuals: 2.2 +/- 0.1 to 3.1 +/- 0.2 microg/L; middle-aged individuals: 2.4 +/- 0.3 to 3.9 +/- 0.6 microg/L); the latter only showing a tendency. The data show the age-related changes with a rise in blood coagulation and fibrinolysis in a healthy middle-aged group compared with younger participants. Moderate exercise leads to comparably relative increases in hemostatic parameters but starting at higher levels. However, the exercise-induced thrombin generation (prothrombin fragment 1+2) is enhanced in the middle-aged participants in comparison with younger participants, but may be compensated by a sufficient fibrinolysis, and therefore the hemostatic system remains in balance.

Long-term secondary prevention programs after cardiac rehabilitation for the reduction of future cardiovascular events: focus on regular physical activity

Cardiac rehabilitation/secondary prevention programs are recognized as integral to the comprehensive care of patients with coronary heart disease, and as such are recommended in most contemporary clinical practice guidelines. The interventions are aimed at reducing disability, optimizing cardiovascular risk reduction by drug therapy and promoting healthy behavior. Healthy lifestyle habits must be recognized as capable of substantially reducing the risk for cardiovascular events in patients with coronary heart disease. This review highlights the recommended components of cardiac rehabilitation/secondary prevention programs, with special emphasis on regular physical activity.

Endogenous tissue plasminogen activator and risk of recurrent cardiac events after an acute coronary syndrome in the MIRACL study

OBJECTIVE

To examine the relationship of baseline tissue plasminogen activator (t-PA) to early cardiovascular risk after an acute coronary syndrome, and the effect of intensive statin therapy.

METHODS

We measured plasma t-PA in 2860 of the 3086 (93%) subjects in the MIRACL study, an international randomized trial of atorvastatin 80mg daily versus placebo in patients with acute coronary syndromes. The relationship of t-PA to death, non-fatal acute myocardial infarction, cardiac arrest, or worsening angina over 16 weeks was assessed by Cox Proportional Hazards. D-dimer was measured in a random sample of 395 subjects.

RESULTS

Higher baseline t-PA was significantly related to the risk of recurrent events (HR=1.25, p=0.0014). This relationship was unaffected by adjustment for age, sex, troponin, hsCRP, and lipids (HR=1.17, p=0.029), but was attenuated by adjustment including body mass index and smoking (HR=1.14, p=0.08). D-dimer and t-PA concentrations were not related. Atorvastatin reduced the risk of recurrent events, but did not affect t-PA or D-dimer concentrations or the relationship of t-PA to outcomes.

CONCLUSION

In patients with acute coronary syndromes, increasing t-PA concentration was related to a higher early risk of recurrent events, paradoxically reflecting impaired endogenous fibrinolysis. This relationship is due in part to the association of t-PA with age, body mass index and smoking. Although statins lower the risk of recurrent events after acute coronary syndromes, it is unlikely that this benefit is achieved through thrombolytic and fibrinolytic pathways.

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.

Internet-delivered behavior change program increases physical activity and improves cardiometabolic disease risk factors in sedentary adults: results of a randomized controlled trial

OBJECTIVES

To determine whether the Active Living Every Day (ALED-I) internet-delivered theory-based physical activity (PA) behavior change program increases PA and improves cardiometabolic disease risk factors (CDRF) in sedentary overweight adults.

METHODS

The study was a randomized control trial that took place in southern Wyoming and northern Colorado from 2005-2007. Thirty-two men and women (21-65 years) were randomized to a 16-week ALED-I intervention (n=14; age=41.4+/-3.7 years; BMI=32.3+/-1.3 kg/m(2)) or a delayed intent-to-treat control condition (n=18; age=49.4+/-1.7 years; BMI=30.6+/-0.8 kg/m(2)). At baseline and post-intervention, PA by pedometer and CDRFs were measured.

RESULTS

Both groups had similar baseline PA levels. ALED-I increased PA by an average of 1384 steps/day (p=0.03) compared to 816 steps/day (p=0.14) for the control group. Waist circumference (100.6+/-2.4 vs. 96.6+/-2.7 cm) and Coronary Risk Ratio (5.1+/-0.3 vs. 4.7+/-0.3) decreased in the ALED-I group and did not change in the control group (99.2+/-2.2 vs.99.8+/-2.1 cm) and (3.7+/-0.1 vs. 3.7+/-0.1), respectively.

CONCLUSIONS

The internet-delivered ALED program increased PA and improved some CDRFs in sedentary overweight/obese adults. To our knowledge, this is the first efficacy trial of the internet-delivered ALED program. Further studies are warranted due to the reach and cost-effectiveness of internet-delivered PA programs.

Physically Active Lifestyle Enhances Vagal-Cardiac Function but Not Central Autonomic Neural Interaction in Elderly Humans

The cause of the age-related impairment of arterial baroreflex function remains ill-defined; moreover, it is unknown whether this impairment results from aging per se or from an inactive lifestyle associated with aging. In this study, we sought to: 1) determine whether elderly individuals who maintained an active lifestyle had an enhanced carotid baroreflex function as compared with their sedentary counterparts; and 2) determine whether this difference was due in part to altered function of the arterial baroreceptor and/or altered central modulation. Eight healthy, sedentary (SED, 68 ± 2 yr) and eight physically active (ACT, 68 ± 1 yr) elderly men with peak O2 consumption 25.5 ± 1.2 vs 35.7 ± 2.4 ml/min/kg (P < 0.01), respectively, were assessed with carotid baroreceptor (CBR) function using 5s pulses of neck pressure or suction (ranging from +40 to −80 Torr) delivered to the carotid sinus region at rest and during lower body negative pressure (LBNP) of −15 and −40 Torr. Changes in heart rate (HR) and mean arterial pressure (MAP) were assessed for CBR-HR and CBR-MAP gains, respectively. Overall CBR-HR gains in a range of ∼ 120 mmHg of carotid sinus pressure were greater (P < 0.01) in ACT than SED at rest and during LBNP. The derived peak CBR-HR slopes between ACT and SED at rest were −0.32 ± 0.07 vs −0.11 ± 0.02 bpm/mmHg (P = 0.007), respectively. However, there was no statistical difference (P = 0.37) in CBR-MAP gains between the groups. Neither CBR-MAP (P = 0.08) nor CBR-HR (P = 0.41) gain was augmented by LBNP in the elderly. Conclusion: Active lifestyle enhances the CBR-HR reflex sensitivity as a result of the improved vagal-cardiac function in elderly people. Aging is associated with an absence of central autonomic interaction in the control of blood pressure regardless of physical fitness.

Metabolic syndrome and endothelial fibrinolytic capacity in obese adults

The metabolic syndrome (MetS) often accompanies obesity and contributes to the increased risk of atherothrombotic events with increased body fatness. Indeed, the risks for coronary artery disease and acute vascular events are greater with obesity combined with MetS compared with obesity alone. Endothelial release of tissue-type plasminogen activator (t-PA) is a key defense mechanism against thrombosis and has been shown to be impaired with obesity. The aim of the present study was to determine whether the presence of MetS exacerbates endothelial fibrinolytic dysfunction in obese adults. Net endothelial release of t-PA was determined in vivo in response to intrabrachial infusions of bradykinin and sodium nitroprusside in 47 sedentary adults: 15 normal weight (age 57 +/- 2 yr; body mass index 22.9 +/- 0.5 kg/m(2)), 14 obese but otherwise healthy (55 +/- 1 yr; 29.4 +/- 0.3 kg/m(2)), and 18 obese with MetS (55 +/- 2 yr; 32.3 +/- 1 kg/m(2)). MetS was established according to National Cholesterol Education Program ATP III criteria. Net release of t-PA antigen to bradykinin was approximately 50% lower (P < 0.01) in the obese (from 2.5 +/- 1.9 to 37.1 +/- 5.3 ng.100 ml tissue(-1).min(-1)) and obese with MetS (from 0.4 +/- 0.8 to 32.5 +/- 3.8 ng.100 ml tissue(-1).min(-1)) compared with normal-weight (from 0.9 +/- 1.0 to 74.3 +/- 8.1 ng.100 ml tissue(-1).min(-1)) subjects. However, there were no significant differences in the capacity of the endothelium to release t-PA in the obese and obese with MetS adults. These results indicate that the presence of the MetS does not worsen the obesity-related endothelial fibrinolytic dysfunction.

Age-related effects of regular physical activity on hemostatic factors in men

BACKGROUND

Age-related changes in blood coagulation and fibrinolytic factors are associated with an increase in risk of thrombotic events. The purpose of this study was to assess the effects of age, regular aerobic exercise and detraining on blood coagulation and fibrinolytic factors in men.

METHODS

Initially, 41 sedentary and 42 physically active men (20-64 years) were analyzed for plasma levels of coagulation and fibrinolytic factors. Twelve sedentary men were then subjected to 16-week aerobic exercise training and subsequent 2-week detraining. Their blood samples taken at rest were assayed for activity levels of prothrombin, coagulation factor (F) V, VII, VIII, IX, X, XI and XIII, antithrombin III, protein C and plasminogen, and for antigen levels of fibrinogen, prothrombin fragment 1 + 2 (F1 + 2), FIX, protein C, tissue-type plasminogen activator (tPA), plasminogen activator inhibitor 1 (PAI-1) and tPA/PAI-1 complex.

RESULTS

Plasma levels of most coagulation factors, particularly for fibrinogen and FIX antigens as well as FXIII activity significantly increased with aging in sedentary men, while that tendency disappeared in physically active men. By the exercise training, plasma antigen and/or activity levels of most blood coagulation factors except for prothrombin and FIX decreased. These training-effects, however, disappeared after detraining, and in some cases even rebounded to higher levels than those of pre-training. Plasma antigen levels of tPA, PAI-1 and tPA/PAI-1 complex decreased with the training and remained low even after detraining.

CONCLUSION

Regular aerobic exercises give complex effects on expression of hemostatic factors, overall favoring the hemostatic balance to less thrombotic, partly cancelling out the age effects.

Fibrinolytic markers and vasodilatory capacity following acute exercise among men of differing training status

We evaluated the effect of differing physical activity patterns on fibrinolysis and vasodilatory capacity using a cross-sectional design with 16 endurance-trained (ET) (mean+/-SE) (28+/-6 years), 14 resistance-trained (RT) (28+/-7 years), and 10 untrained (UT) (26+/-7 years) men. t-PA and PAI-1 activity and t-PA antigen were measured before and after a maximal treadmill test (VO2peak). Vasodilatory capacity was assessed using strain-gauge plethysmography on the forearm following reactive hyperemia (RH) before and after the treadmill test. The ET group had a smaller body mass index (BMI) (22.8+/-0.5 ET, 26.4+/-0.4 RT, 25.1+/-0.8 UT kg m(-2)) (P<0.05) and a greater VO2peak (57+/-1 ET, 42+/-2 RT, 45+/-2 UT mL min(-1) kg(-1)) (P<0.05). Peak vasodilatory capacity (29.7+/-2 ET, 32.0+/-2 RT, 27.4+/-2 UT mL min(-1) 100 mL of tissue) was similar between groups before and after exercise. Area under the curve for forearm blood flow was greater following acute exercise (212 vs. 122, P<0.05), again with no differences between groups. t-PA activity and antigen increased following maximal exercise in all groups (P<0.0001), with no group differences. PAI-1 activity decreased the least in RT after exercise (70% decrease vs. 86% ET and 82% UT; P<0.05). The change in t-PA activity with exercise was not related to exercise-induced change in overall vasodilatory capacity. These findings demonstrate that in healthy young men different physical activity patterns do not appear to impact the exercise-induced changes in fibrinolysis or vasodilatory capacity.

Endothelin-1 Vasoconstrictor Tone Increases With Age in Healthy Men But Can Be Reduced by Regular Aerobic Exercise

Increased endothelin-1–mediated vasoconstrictor tone has been linked to the etiology of a number of pathologies associated with human aging, including hypertension, congestive heart failure, and coronary artery disease. However, it is currently unclear whether aging, per se, is associated with enhanced endothelin-1 system activity. We hypothesized that endothelin-1 vasoconstrictor activity is greater in healthy older compared with young men and that regular aerobic exercise is an effective intervention for reducing endothelin-1 vasoconstrictor tone in older previously sedentary men. Forearm blood flow (plethysmography) responses to intra-arterial infusion of endothelin-1 (5 pmol/min; for 20 minutes) and selective (BQ-123; 100 nmol/min; for 60 minutes) and nonselective (BQ-123+BQ-788; 100 nmol/min; for 60 minutes) endothelin-1 receptor blockade were determined in 28 healthy, sedentary men: 13 younger (age: 27±1 years) and 15 older (age: 62±2 years). The vasoconstrictor response to endothelin-1 was significantly blunted (≈65%) in the older versus younger men. In response to BQ-123, resting forearm blood flow increased (≈20%; P <0.05) in the older but not in the younger men. The addition of BQ-788 to BQ-123 did not significantly affect the blood flow responses to BQ-123 in either group. Eight of the 15 older sedentary men completed a 3-month aerobic exercise intervention. After the intervention, the vasoconstrictor response to endothelin-1 was markedly increased (225%; P <0.05), whereas BQ-123 resulted in modest vasoconstriction in the previously sedentary older men. These results demonstrate that endothelin-1–mediated vasoconstrictor tone increases with age in healthy men but can be alleviated with regular aerobic exercise.

Aging, exercise, and endothelial progenitor cell clonogenic and migratory capacity in men

Numerical and functional impairment of circulating endothelial progenitor cells (EPCs) is thought to contribute to vascular aging and the associated increase in cardiovascular risk. We tested the following hypotheses: 1) EPC clonogenic and migratory capacity decrease progressively with age in healthy, sedentary adult men; and 2) regular aerobic exercise will improve EPC clonogenic and migratory capacity in previously sedentary middle-aged and older men. Peripheral blood samples were collected from 46 healthy sedentary men: 10 young (26 +/- 1 yr), 15 middle-aged (47 +/- 1 yr), and 21 older (63 +/- 1 yr). Mononuclear cells were isolated and preplated for 2 days, and nonadherent cells were further cultured for 7 days to determine EPC colony-forming units. Migratory activity of EPCs was determined using a modified Boyden chamber. Ten sedentary middle-aged and older men (59 +/- 3 yr) were studied before and after a 3-mo aerobic exercise intervention. The number of EPC colony-forming units was approximately 75% lower (P < 0.01) in middle-aged (12 +/- 3) and older (8 +/- 2) compared with young (40 +/- 7) men. There was no difference in colony count between middle-aged and older men. EPC migration (fluorescent units) was significantly reduced in older (453 +/- 72) compared with young (813 +/- 114) and middle-aged (760 +/- 114) men. The exercise intervention increased (P < 0.05) both EPC colony-forming units (10 +/- 3 to 22 +/- 5) and migratory activity (683 +/- 96 to 1,022 +/- 123) in previously sedentary middle-aged and older men. These results provide further evidence that aging adversely affects EPC function. Regular aerobic-endurance exercise, however, is an effective lifestyle intervention strategy for improving EPC clonogenic and migratory capacity in middle-aged and older healthy men.

Exercise, cognition and Alzheimer's disease: More is not necessarily better

Regional hypoperfusion, associated with a reduction in cerebral metabolism, is a hallmark of Alzheimer's disease (AD) and contributes to cognitive decline. Cerebral perfusion and hence cognition can be enhanced by exercise. The present review describes first how the effects of exercise on cerebral perfusion in AD are mediated by nitric oxide (NO) and tissue-type plasminogen activator, the release of which is regulated by NO. A conclusion of clinical relevance is that exercise may not be beneficial for the cognitive functioning of all people with dementia if cardiovascular risk factors are present. The extent to which cardiovascular risk factors play a role in the selection of older people with dementia in clinical studies will be addressed in the second part of the review in which the effects of exercise on cognition are presented. Only eight relevant studies were found in the literature, emphasizing the paucity of studies in this field. Positive effects of exercise on cognition were reported in seven studies, including two that excluded and two that included patients with cardiovascular risk factors. These findings suggest that cardiovascular risk factors do not necessarily undo the beneficial effects of exercise on cognition in cognitively impaired people. Further research is called for, in view of the limitations of the clinical studies reviewed here.

The physiological response of ankle systolic blood pressure and ankle to brachial index after maximal exercise in athletes is dependent on age

The development of sports activities in the over forties has increased the number of middle-aged patients performing heavy-load exercise. The normal response of ankle systolic blood pressure (ASBP) and ankle to brachial index (ABI) to intense exercise is known in young athletes, but little is known for other age groups. Three groups of 21 athletes: <20 (G1), 20-40 (G2), and >40 (G3) years old, respectively, were studied. ASBP and brachial systolic blood pressure (BSBP) were measured simultaneously before and after an incremental maximal cycle ergometer test. Rest ABI was higher in G3 compared to G1 (P<0.001: ANOVA, Bonferroni). Compared to respective resting values, BSBP, at 1 min of recovery, was increased for the three groups of age (P<0.001) whereas ASBP was unchanged for G1 and G2, and significantly increased for G3 (P<0.001). ASBP was significantly higher in G3 than in G1 and G2, ABI was lower in G1 and G2 compared to G3: 0.70+/-0.11, 0.76+/-0.09 and 0.91+/-0.14, respectively. This age-related ABI increase is consistent with the impaired vasodilator capacity observed in aging normal subjects but not with the decrease observed in ABI resting values in epidemiological studies. ABI is higher in older than in younger athletes at rest and after exercise. In aging athletes, aiming to detect mild to moderate arterial lesions, it is likely that normal limits defined in young athletes are not valid.

Endothelial t-PA release is impaired in overweight and obese adults but can be improved with regular aerobic exercise

Endothelial release of tissue-type plasminogen activator (t-PA) regulates fibrinolysis and is considered to be a primary endogenous defense mechanism against thrombosis. Adiposity is associated with an increased risk of atherothrombotic events. We determined the influence of overweight and obesity on the capacity of the vascular endothelium to release t-PA and the effects of regular aerobic exercise on endothelial t-PA release in previously sedentary overweight and obese adults. First, we studied 66 sedentary adults: 28 normal-weight (BMI < 25 kg/m2); 22 overweight (BMI > or = 25 and < 30 kg/m2); and 16 obese (BMI > or = 30 kg/m2). Net endothelial t-PA release was determined in vivo in response to intrabrachial infusions of bradykinin (BK) and sodium nitroprusside. Second, we studied 17 overweight and obese adults who completed a 3-mo aerobic exercise intervention. Net release of t-PA in response to BK was approximately 45% lower (P < 0.01) in overweight (from 0.1 +/- 0.4 to 41.7 +/- 4.9 ng x 100 ml tissue(-1) x min(-1)) and obese (-0.1 +/- 0.6 to 47.7 +/- 5.2 ng x 100 ml tissue(-1) x min(-1)) compared with normal-weight (0.1 +/- 0.8 to 77.5 +/- 6.7 ng x 100 ml tissue(-1) x min(-1)) adults. There was no difference in t-PA release between the overweight and obese groups. Exercise training significantly increased t-PA release capacity in overweight and obese adults (from -0.3 +/- 0.5 to 37.1 +/- 4.9 ng x 100 ml tissue(-1) x min(-1) before training vs. 1.0 +/- 0.9 to 65.4 +/- 6.3 ng x 100 ml tissue(-1) x min(-1) after training) to levels comparable with those of their normal-weight peers. These results indicate that overweight and obesity are associated with profound endothelial fibrinolytic dysfunction. Importantly, however, regular aerobic exercise can increase the capacity of the endothelium to release t-PA in this at-risk population.

Epidemiological evidence for the role of physical activity in reducing risk of type 2 diabetes and cardiovascular disease

Epidemiological studies suggest that physically active individuals have a 30-50% lower risk of developing type 2 diabetes than do sedentary persons and that physical activity confers a similar risk reduction for coronary heart disease. Risk reductions are observed with as little as 30 min of moderate-intensity activity per day. Protective mechanisms of physical activity include the regulation of body weight; the reduction of insulin resistance, hypertension, atherogenic dyslipidemia, and inflammation; and the enhancement of insulin sensitivity, glycemic control, and fibrinolytic and endothelial function. Public health initiatives promoting moderate increases in physical activity may offer the best balance between efficacy and feasibility to improve metabolic and cardiovascular health in largely sedentary populations.

Endothelial dysfunction occurs in peripheral circulation patients with acute and stable coronary artery disease

Atherosclerosis is a diffuse, systemic process. In addition, acute coronary syndromes (ACS) are associated with inflammatory marker elevations that are hypothesized to affect the function of nonculprit coronary as well as peripheral vessels. We investigated whether femoral vascular reactivity and/or fibrinolytic capacity are impaired in ACS patients over and above any dysfunction associated with stable coronary artery disease. Patients undergoing diagnostic coronary angiography (n = 42 total, 14 patients/group) were recruited into three groups as follows: 1) stable coronary syndromes (SAP group), 2) ACS as defined by rest angina with ECG changes and troponin rise (ACS group), and 3) angiographically normal coronary arteries (control group). After diagnostic coronary angiography, femoral artery endothelial and smooth muscle function were assessed by infusing acetylcholine (ACh) and nitroglycerin (GTN), and tissue-type plasminogen activator (t-PA) release across the femoral circulation was measured as the difference between arterial and venous concentrations before and after ACh and GTN stimulation. There were no significant differences between groups in relevant baseline characteristics apart from significantly higher C-reactive protein levels and reduced net t-PA release in the ACS group at baseline (P < 0.05). The ACS and SAP groups had equivalent angiographic severity of coronary artery disease. Endothelium-dependent dilatation was significantly higher in control individuals (14.9 +/- 9.1%; P < 0.001) compared with either stable patients (2.3 +/- 8.1%) or those with unstable syndromes (2.6 +/- 8.9%, who were similar to each other; P = not significant). Although baseline t-PA release was impaired in the ACS patients (0.09 +/- 0.06 compared with 0.39 +/- 0.33 and 0.49 +/- 0.56 ng/ml; P = 0.03), stimulation of t-PA release by ACh and GTN occurred only in the control subjects and not in the ACS or SAP patients. Coronary artery disease is associated with impaired endothelium-dependent dilatation and impaired stimulation of t-PA release in the systemic circulation. These aspects of endothelial dysfunction, however, were equally severe in acute and chronic coronary syndrome patients.

Estrogen receptor-alpha thymidine and adenine repeat polymorphism and endothelial fibrinolytic regulation in postmenopausal women

OBJECTIVE

We hypothesized that the capacity of the endothelium to release tissue-type plasminogen activator is blunted in postmenopausal women with long (TA)(n) repeat alleles (> or = 18 repeats).

STUDY DESIGN

Forty-two healthy postmenopausal women were studied: 10 women with short allele genotypes (both alleles, <18 repeats; age, 59 +/- 2 years), 8 women with long allele genotypes (both alleles, > or = 18 repeats; age, 59 +/- 3 years), and 24 women with mixed allele genotypes (1 short and 1 long allele; age, 56 +/- 1 years). Net endothelial tissue-type plasminogen activator release was determined in response to intra-arterial bradykinin and sodium nitroprusside.

RESULTS

Tissue-type plasminogen activator release in response to bradykinin was highest in homozygotes for the short allele. The total amount of tissue-type plasminogen activator antigen that was released was significantly higher (>55%) in the short (452 +/- 68 ng/100 mL tissue) compared with the mixed (248 +/- 27 ng/100 mL tissue) and long allele (290 +/- 53 ng/100 mL tissue) groups.

CONCLUSION

Our results demonstrate that the long (TA)n dinucleotide repeat allele is associated with blunted endothelial tissue-type plasminogen activator release in healthy postmenopausal women.

Changes in cardiorespiratory fitness and coronary heart disease risk factors following 24 wk of moderate- or high-intensity exercise of equal energy cost

This study was designed to investigate the effect of exercise intensity on cardiorespiratory fitness and coronary heart disease risk factors. Maximum oxygen consumption (Vo(2 max)), lipid, lipoprotein, and fibrinogen concentrations were measured in 64 previously sedentary men before random allocation to a nonexercise control group, a moderate-intensity exercise group (three 400-kcal sessions per week at 60% of Vo(2 max)), or a high-intensity exercise group (three 400-kcal sessions per week at 80% of Vo(2 max)). Subjects were instructed to maintain their normal dietary habits, and training heart rates were represcribed after monthly fitness tests. Forty-two men finished the study. After 24 wk, Vo(2 max) increased by 0.38 +/- 0.14 l/min in the moderate-intensity group and by 0.55 +/- 0.27 l/min in the high-intensity group. Repeated-measures analysis of variance identified a significant interaction between monthly Vo(2 max) score and exercise group (F = 3.37, P < 0.05), indicating that Vo(2 max) responded differently to moderate- and high-intensity exercise. Trend analysis showed that total cholesterol, low-density lipoprotein cholesterol, non-high-density lipoprotein cholesterol, and fibrinogen concentrations changed favorably across control, moderate-intensity, and high-intensity groups. However, significant changes in total cholesterol (-0.55 +/- 0.81 mmol/l), low-density lipoprotein cholesterol (-0.52 +/- 0.80 mmol/l), and non-high-density lipoprotein cholesterol (-0.54 +/- 0.86 mmol/l) were only observed in the high-intensity group (all P < 0.05 vs. controls). These data suggest that high-intensity training is more effective in improving cardiorespiratory fitness than moderate-intensity training of equal energy cost. These data also suggest that changes in coronary heart disease risk factors are influenced by exercise intensity.

Regulation of Hemostasis by the Sympathetic Nervous System: Any Contribution to Coronary Artery Disease?

Within the last two decades, hemostasis factors have emerged as 'new' risk factors for coronary artery disease. Historical studies on the physiology of the sympathetic nervous system (SNS) attributed accelerated blood clotting to the components of the fight-flight response. Although this has not been demonstrated, exaggerated clotting related to SNS hyperactivity might confer an increased arterial thrombotic risk. This review outlines the effects of sympathetic activation as mimicked by adrenergic infusions and as elicited by mental stress and physical exercise, and the molecular mechanisms involved. A selective review of the pertinent literature was undertaken. Sympathetic activation provokes a simultaneous increase in molecules of both the coagulation and fibrinolysis pathways within minutes, resulting in net hypercoagulability as a part of normal human physiology. Catecholamines and adrenergic receptors interact to mediate hemostatic changes. Exaggerated procoagulant changes in individuals with a preexistent atherosclerotic disease, in those experiencing ongoing stressful life circumstances and in the physically untrained might confer a thrombotic threat with sympathetic activation. Initial evidence suggests that nonselective β-adrenergic blockade may attenuate clotting acceleration upon SNS activation. Prospective studies are needed to demonstrate whether exaggerated clotting as elicited by the SNS is associated with an increased risk of cardiovascular morbidity and mortality. If confirmed, intervention studies targeted at reducing this risk, for example with drugs, psychotherapy (including stress management) and regular physical exercise, would be warranted.

Effects of exercise training on vascular function in obese children

OBJECTIVES

Atherosclerosis is a disease that begins in childhood; endothelial dysfunction is its earliest detectable manifestation, and primary prevention strategies are likely to be most effective if instituted early. The aim of this study was to characterize the impact of obesity on vascular function in young children and to determine whether an exercise program improves abnormalities in vascular function.

STUDY DESIGN

The influence of 8 weeks of exercise training was examined in 14 obese subjects, 8.9 +/- 0.4 years of age, with the use of a randomized crossover protocol. Conduit vessel endothelial function was assessed by means of high-resolution ultrasound and flow-mediated dilation of the brachial artery (FMD).

RESULTS

Exercise training did not change subcutaneous fat mass, body weight, or body mass index. FMD in the obese group was significantly impaired relative to matched control subjects at entry (6.00% +/- 0.69% to 12.32% +/- 3.14%, P <.0001). FMD significantly improved with exercise training (7.35% +/- 0.99%, P <.05) in the obese group.

CONCLUSIONS

Conduit vessel FMD, a validated surrogate measure of early atherosclerosis, was impaired in obese children but improved as a result of exercise training. This study supports the value of an exercise program in the treatment of obese children in a primary prevention setting.

Effects of short-term exercise training on plasminogen activator inhibitor (PAI-1)

PURPOSE

To observe the effects of exercise training on plasminogen activator inhibitor, type-1 (PAI-1), tissue plasminogen activator (tPA), and associated metabolic variables in sedentary men and women.

METHODS

A randomized, controlled experimental design was used to examine the influence of 10 d of moderate-intensity exercise training on measures of fibrinolysis. Sixteen men and 16 women between the ages of 50 and 70 yr were randomly assigned to exercise (EX) and control groups (CON) that were balanced for gender and hormone replacement therapy. Blood samples were collected on days 1, 2, 11, and 12 for measurement of plasma PAI-1, tPA, insulin, glucose, and triglyceride. Subjects in EX performed 50 min of treadmill walking at an intensity corresponding to 65% of heart rate reserve each day for 10 consecutive days.

RESULTS

There were no significant changes in PAI-1, tPA, or associated metabolic variables between EX and CON during the intervention period. Within EX subjects, those with higher body fatness had a significant decrease in insulin and triglyceride compared with those with lower body fatness. However, no changes in fibrinolytic measures were observed within these subgroups.

CONCLUSIONS

Short-term exercise training does not change PAI-1 levels in normal, asymptomatic men and women. In addition, modest decreases in insulin and triglyceride in individuals with elevated body fatness do not result in changes in PAI-1 after short-term training. It appears likely that decreases in PAI-1 with exercise training require decreases in adiposity and/or marked changes in metabolic variables.

Endothelial release of tissue-type plasminogen activator in the human forearm: role of nitric oxide

Release of tissue-type plasminogen activator (t-PA) from the vascular endothelium is paramount to endogenous thrombolysis potential. In addition to its vasodilator effects, nitric oxide (NO) has important antithrombotic properties, such as inhibition of platelet aggregation. It is currently not clear whether NO influences the capacity of the endothelium to release t-PA. The authors determined whether net endothelial t-PA release is regulated, at least in part, by NO. Endothelial t-PA release was determined, in vivo, in response to intrabrachial infusions of bradykinin (12.5-50.0 ng.100 mL tissue-1.min-1) in the presence and absence of the NO synthase inhibitor, NG-monomethyl-l-arginine (l-NMMA; 5 mg/min) in 12 healthy men. Net release of t-PA across the forearm vascular bed was calculated as the product of arteriovenous concentration gradient and forearm plasma flow. The vasodilator response to bradykinin was significantly blunted ( approximately 30%) with l-NMMA. Although there was no effect of l-NMMA on basal t-PA release, acute release of t-PA to bradykinin was higher (P < 0.01) after (from -0.2 +/- 0.5 to 105.2 +/- 9.4 ng.100 mL tissue-1.min-1) versus before (from -0.4 +/- 0.7 to 48.7 +/- 7.3 ng.100 mL tissue-1.min-1) the administration of l-NMMA. Thus, in the absence of NO endothelial t-PA release was enhanced. These results suggest a potential regulatory influence of NO on bradykinin induced endothelial t-PA release.