Strenuous exercise, plasma fibrinogen, and factor VII activity

Fibrinogen, Coagulation, and Ageing

The World Health Organization estimates that the world's population over 60 years of age will nearly double in the next 30 years. This change imposes increasing demands on health and social services with increased disease burden in older people, hereafter defined as people aged 60 years or more. An older population will have a greater incidence of cardiovascular disease partly due to higher levels of blood fibrinogen, increased levels of some coagulation factors, and increased platelet activity. These factors lead to a hypercoagulable state which can alter haemostasis, causing an imbalance in appropriate coagulation, which plays a crucial role in the development of cardiovascular diseases. These changes in haemostasis are not only affected by age but also by gender and the effects of hormones, or lack thereof in menopause for older females, ethnicity, other comorbidities, medication interactions, and overall health as we age. Another confounding factor is how we measure fibrinogen and coagulation through laboratory and point-of-care testing and how our decision-making on disease and treatment (including anticoagulation) is managed. It is known throughout life that in normal healthy individuals the levels of fibrinogen and coagulation factors change, however, reference intervals to guide diagnosis and management are based on only two life stages, paediatric, and adult ranges. There are no specific diagnostic guidelines based on reference intervals for an older population. How ageing relates to alterations in haemostasis and the impact of the disease will be discussed in this chapter. Along with the effect of anticoagulation, laboratory testing of fibrinogen and coagulation, future directions, and implications will be presented.

Inflammatory markers, D-dimer, pro-thrombotic factors, and physical activity levels in patients with peripheral arterial disease

Men and women with lower extremity peripheral arterial disease (PAD) have reduced physical activity levels compared with persons without PAD. We describe associations between physical activity levels with D-dimer, pro-coagulant factors, and inflammatory markers in patients with PAD. Participants were188 patients with PAD identified from non-invasive vascular laboratories. Physical activity was measured over 7 days with a vertical accelerometer. We measured the ankle brachial index (ABI) and levels of D-dimer, C-reactive protein (CRP), fibrinogen, serum amyloid A (SAA), prothrombin 1.2, t-PA antigen, PAI-1, and the t-PA antigen=PAI-1 ratio. Adjusting for age, sex, race, body mass index, ABI, comorbidities, smoking, total cholesterol=HDL ratio and statin use (for CRP only), we found significant inverse linear associations between physical activity levels and log D-dimer (p 1/4 0.002), log CRP (p < 0.001), fibrinogen (p 1/4 0.014), and log SAA (p 1/4 0.012). There were no significant associations between physical activity levels and other blood factors. In an analysis adjusting for all blood factors simultaneously along with known and potential confounders, log D-dimer was the only blood factor associated significantly with physical activity levels (p 1/4 0.036). Based on these findings, future studies should assess whether interventions to increase physical activity in patients with PAD reduce levels of D-dimer and inflammatory markers.

Diet and haemostatic processes

Diet plays an important role in the primary and secondary prevention of cardiovascular disease. The growing perception that abnormal haemostatic processes of coagulation, platelet aggregation and fibrinolysis contribute to cardiovascular disease aetiology motivated this review on the relationships of diet, specific foods and nutrients with haemostatic function. Functional endpoints that reflect the function and status of some of these processes and which can be measured in dietary trials are identified. The effects of energy intake and expenditure, alcohol, total fat and specific fatty acids, non-starch polysaccharides (dietary fibre), antioxidant nutrients and some foods on a variety of haemostatic markers are reviewed. The results indicate that the prudent low-fat, high-fibre diet and maintenance of ideal body weight recommended to protect against and treat hyperlipidaemia and coronary heart disease will also benefit haemostatic profiles. It is concluded that more research on specific effects is needed for improved recommendations on a population level for prevention of cardiovascular disease.

Role of clotting factors and fibrin structure in predisposition to atherothrombotic disease

Atherothrombotic disease is a multifactorial disorder that develops secondary to a complex gene-environment interaction. The formation of an obstructive thrombus represents the final stage of the atherothrombotic process, and understanding the mechanisms involved in clot formation is essential in order to develop new preventive and therapeutic strategies aimed at decreasing mortality and morbidity from the disease. Studies have demonstrated an important correlation between final clot structure and predisposition to atherothrombotic disease. Both genetic and environmental factors contribute to the final ultrastructure of the clot, which, in turn, influences an individual's risk of the disease. This paper reviews the factors involved in determining clot structure. The role of commonly used therapeutic agents in modulating clot structure will also be discussed.

Cardiovascular disease risk factors in habitual exercisers, lean sedentary men and abdominally obese sedentary men

OBJECTIVE

To investigate whether the favourable cardiovascular disease (CVD) risk factor profile of habitual exercisers is attributable to exercise or leanness.

DESIGN

Cross-sectional study of 113 nonsmoking men aged 30-45 y. CVD risk factors were compared in exercisers (n=39) and sedentary men (n=74), and in subgroups of lean exercisers (n=37), lean sedentary men (n=46) and obese sedentary men (n=28). Waist girth was used to identify lean (<100 cm) and abdominally obese (> or =100 cm) subgroups.

MEASUREMENTS

Blood pressure, physical activity (7-day recall), physical fitness (maximum oxygen consumption) and fasted lipoproteins, apolipoprotein (apo) B, triglycerides, glucose and fibrinogen.

RESULTS

Exercisers were fitter and leaner than sedentary men and had a better CVD risk factor profile. Total cholesterol, LDL-cholesterol and apo B concentrations were lower in lean exercisers than in lean sedentary men, suggesting that exercise influences these risk factors. Indeed, time spent in vigorous activity was the only significant predictor of total cholesterol and LDL-cholesterol in multiple linear regression models. Exercise status had little influence on triglycerides and HDL-cholesterol (HDL-C), and unfavourable levels were only evident among obese sedentary men. Waist girth was the sole predictor of triglycerides and HDL-C, explaining 44 and 31% of the variance, respectively.

CONCLUSIONS

These findings suggest that the CVD risk factor profile of habitual exercisers is attributable to leanness and exercise. Leanness is associated with favourable levels of HDL-C and triglycerides, while exercise is associated with lower levels of total cholesterol, LDL-cholesterol and apo B.

Patterns of inflammation associated with peripheral arterial disease: the InCHIANTI study

OBJECTIVE

To determine whether peripheral arterial disease is associated with high circulating levels of pro-inflammatory cytokines, independent of confounders.

METHODS

Participants were 955 men and women aged 60 years and older representative of the population in 2 Italian communities (107 with peripheral arterial disease). Measurements included the ankle brachial index, comorbidities, total cholesterol and high-density lipoprotein cholesterol (HDL-C) levels, and these inflammatory factors: albumin, alpha-2 macroglobulin, C-reactive protein, fibrinogen, interleukin (IL)-1beta, IL-1 receptor antagonist, IL-6, IL-6 receptor, IL-10, IL-18, tumor necrosis factor alpha, and transforming growth factor beta.

RESULTS

Adjusting for age, sex, body mass index, smoking, comorbidities, HDL-C, and total cholesterol, participants with peripheral arterial disease had higher levels of IL-1 receptor antagonist (147.97 vs 131.24 pg/mL, P = .002), IL-6 (1.65 vs 1.37 pg/mL, P = .026), fibrinogen (362.49 vs 345.50 mg/dL, P = .039), and C-reactive protein (3.18 vs 2.56 mg/dL, P = .043) compared with those without peripheral arterial disease. These associations were attenuated after additional adjustment for physical activity.

CONCLUSION

In a community population, peripheral arterial disease is associated with increased circulating levels of IL-6, IL-1 receptor antagonist, fibrinogen, and C-reactive protein compared to persons without peripheral arterial disease. Further study is needed to determine whether reducing levels of certain inflammatory factors lowers the incidence and progression of peripheral arterial disease.

Differences in leisure-time, household, and work-related physical activity by race, ethnicity, and education

BACKGROUND

Racial and ethnic minority groups have lower levels of leisure-time physical activity (LTPA) than whites, but it is unclear how much of this is explained by differences in socioeconomic status and health.

OBJECTIVE

To examine differences in LTPA, work-related physical activity (WRPA; heavy household chores and strenuous job activities), and total physical activity (TPA) by race, ethnicity, and education.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional analyses of data from the 1992 Health and Retirement Study for a nationally representative cohort of 9,621 community-dwelling adults aged 51-61 years.

MEASUREMENTS

Physical activity scores for LTPA, WRPA, and TPA based upon self-reported frequency of light or vigorous recreational activities, heavy household chores, and strenuous job-related physical activities.

MAIN RESULTS

LTPA was lower for blacks and Hispanics compared to whites, and LTPA steadily declined with lower levels of education. WRPA showed the reverse pattern, being lowest for whites and persons with greater education. Education was far more important than race/ethnicity as a determinant of LTPA and WRPA in multivariate analyses. After adjusting for differences in overall health and physical functioning, mean TPA scores were similar across racial/ethnic and education categories; blacks (beta=1.0; 95% confidence interval [CI], 0.5 to 1.5) and Spanish-speaking Hispanics (beta=1.1; 95% CI, 0.3 to 1.9) had slightly higher levels of TPA than whites (P<.01 and P=.01, respectively).

CONCLUSIONS

Differences in educational attainment and health status accounted for virtually all of the racial and ethnic differences in LTPA. After accounting for WRPA, TPA was similar across race, ethnicity, and education subgroups.

Selected genetic polymorphisms and plasma coagulation factor VII changes with exercise training

We assessed the effects of coagulation factor VII (FVII) gene polymorphisms, lipid-related polymorphisms, and exercise training-induced plasma lipoprotein lipid changes on FVII level changes with exercise training in middle- to older-aged men and women. Forty-six healthy sedentary men and women were stabilized on a low-fat diet and then underwent baseline testing, 6 mo of endurance exercise training, and final testing. Plasma FVII-Ag levels decreased with exercise training (106.7 ± 1.4 vs. 104.2 ± 1.6%, P = 0.005). There were no significant differences in FVII-Ag changes with exercise training between -323 (0/10 bp)/-401 (G/T) haplotype or -402 (G/A) genotype groups. FVII-Ag changes with training were not correlated with changes in plasma lipoprotein lipids. In linear regression analyses, FVII-Ag changes with training remained significant after adjusting for training-induced plasma lipoprotein lipid changes ( P = 0.01). FVII changes with training were associated with apolipoprotein E genotype ( P = 0.012); this relationship was still evident after adjusting for training-induced plasma lipoprotein lipid changes ( P = 0.047). FVII changes with training also were significantly associated with human ATPase binding cassette-1 genotype ( P = 0.018); this relationship persisted after accounting for the effect of the training-induced plasma lipoprotein lipid changes ( P = 0.045). We conclude that plasma FVII-Ag changes with exercise training are more closely related to selected lipid-related genotypes than FVII gene promoter variants.

–455G/A β-fibrinogen gene polymorphism, factor V Leiden, prothrombin G20210A mutation and MTHFR C677T, and placental vascular complications

Hyperfibrinogenaemia is associated with systemic arterial and venous thromboembolism and therefore may contribute to placental vascular disease associated with obstetric complications. The fibrinogen-raising -455G/A beta-fibrinogen gene polymorphism may enhance the physiological increase in fibrinogen levels during pregnancy and thereby predispose to obstetric complications. This retrospective case-control study looked at the association between the beta-fibrinogen gene polymorphism -455G/A, the hereditary thrombophilic markers factor V Leiden, prothrombin G20210A mutation (PGM) and C677T methylene tetrahydrofolate reductase (MTHFR), and obstetric complications associated with placental vascular disease. The study group (n = 247) comprised 147 women (90 Caucasian) who met the clinical criteria and a control group of 100 parous women (90 Caucasian) with no history of obstetric or medical complications. No significant differences were observed in the -455A allelic frequencies of the patient and normal control groups, with (allelic frequencies, 0.156 and 0.178, respectively; P = 0.5716, chi2 test, odds ratio = 1.17, 95% confidence interval = 0.65-2.13) or without (allelic frequencies, 0.129 and 0.170, respectively; P = 0.2077, chi2 test, odds ratio = 1.38, 95% confidence interval = 0.81-2.35) the exclusion of non-Caucasian women. There was an increased prevalence of factor V Leiden among Caucasian patients compared with normal controls (allelic frequencies, 0.056 and 0.017, respectively; P = 0.048, chi2 test, odds ratio = 0.29, 95% confidence interval = 0.05-1.15) but there were no differences in the prevalences of PGM or MTHFR. These data suggest that factor V Leiden is associated with an increased risk of obstetric complications, but that the -455A allele of beta-fibrinogen, PGM and MTHFR do not appear to be implicated.

Exercise-induced changes in coagulation and fibrinolysis in healthy populations and patients with cardiovascular disease

This review highlights the clinical significance of coagulation and fibrinolytic responses, and adaptations in healthy individuals and patients with cardiovascular disease (CVD). Much of the review focuses on indicators of the potential for coagulation and fibrinolysis. The terms 'coagulation potential' and 'fibrinolytic potential' are used frequently, as much of the literature in the area of exercise haemostasis evaluates factors that reflect an increased potential for coagulation, while coagulation per se, may or may not be occurring. Similarly, fibrinolysis is definitively the lysis of inappropriate or excessive blood clot, which may or may not be occurring when the enzymes that stimulate fibrinolysis are activated. Nevertheless, markers of coagulation and fibrinolytic potential are associated with CVD, ischaemic events, and cardiovascular mortality. Additionally, fibrinolytic potential is associated with other established CVD risk factors. Ischaemic events triggered by physical exertion are more likely to occur due to an occlusive thrombus, suggesting the exercise-induced responses related to haemostasis are of clinical significance. The magnitude of increase in coagulation potential, platelet aggregation and fibrinolysis appears to be primarily determined by exercise intensity. Patients with CVD may also have a larger increase in coagulation potential during acute exercise than healthy individuals. Additionally, the magnitude of the fibrinolytic response is largely related to the resting fibrinolytic profile of the individual. In particular, high resting plasminogen activator inhibitor-1 may diminish the magnitude of tissue plasminogen activator response during acute exercise. Therefore, acute responses to exercise may increase the risk of ischaemic event. However, chronic aerobic exercise training may decrease coagulation potential and increase fibrinolytic potential in both healthy individuals and CVD patients. Due to the aforementioned importance of resting fibrinolysis on the fibrinolytic response to exercise, chronic aerobic exercise training may cause favourable adaptations that could contribute to decreased risk for ischaemic event, both at rest and during physical exertion.

Leisure-time physical activity and reduced plasma levels of obesity-related inflammatory markers

OBJECTIVE

This study investigated the relationship between physical activity and the obesity-related inflammatory markers C-reactive protein, interleukin-6, and soluble tumor necrosis factor receptors (sTNF-Rs) 1 and 2. Furthermore, we examined the relationship between physical activity and insulin sensitivity (insulin, C-peptide, and hemoglobin A(1c) levels) and whether inflammatory markers mediate this association.

RESEARCH METHODS AND PROCEDURES

Biomarkers were measured in 405 healthy men and 454 healthy women from two large ongoing prospective studies. Information about physical activity and other variables was assessed by questionnaires.

RESULTS

After adjustment for other predictors of inflammation, physical activity was inversely associated with plasma levels of sTNF-R1, sTNF-R2, interleukin-6, and C-reactive protein (p = 0.07, p = 0.004, p = 0.04, and p = 0.009). After further adjustment for BMI and leptin, as a surrogate for fat mass, most of these associations were no longer significant. Physical activity was also inversely related to insulin and C-peptide levels (p = 0.008 and p < 0.001); however, in contrast to BMI and leptin, levels of inflammatory markers explained only very little of this inverse relationship.

DISCUSSION

These results suggest that frequent physical activity is associated with lower systemic inflammation and improved insulin sensitivity. These associations can partially be explained by a lower degree of obesity in physically active subjects. Although inflammatory markers may mediate obesity-dependent effects of physical activity on inflammatory related diseases such as type 2 diabetes or coronary heart disease, our study suggests that they do not directly account for the beneficial effects of physical activity on insulin resistance.

Inflammatory markers are unrelated to physical activity, performance, and functioning in hemodialysis

OBJECTIVE

To determine the associations among dietary intake and inflammatory cytokines with physical activity, function, and performance in maintenance dialysis patients.

DESIGN

Cross-sectional analysis of cohort study.

SETTING

University-affiliated dialysis units, general clinical research center.

SUBJECTS

Multiethnic cohort of maintenance hemodialysis patients.

MAIN OUTCOME MEASURES

Physical activity by accelerometry; physical performance by gait speed, stair climbing, and chair raising; physical functioning by the Medical Outcomes Study Short Form 36-item questionnaire subscale scores; and maximal and adjusted activity scores of human activity profile.

RESULTS

Levels of inflammatory cytokines were uniformly high. Tumor necrosis factor-alpha was directly correlated with dietary protein and energy intake; no other cytokines were directly or inversely correlated with intake. Dietary intake was associated with physical activity, as expected, and not significantly associated with performance or function (with the exception of gait speed). There were no significant associations among inflammatory cytokines and physical activity, performance, or function.

CONCLUSION

Although dietary intake and inflammation may independently influence traditional proxies of nutritional status, this analysis provides no evidence for a link between cytokines and physical activity, performance, or function in hemodialysis patients. More research is required to understand the role of cytokines in protein energy malnutrition and the mechanisms of wasting and functional decline in the dialysis population.

Inflammatory markers are unrelated to physical activity, performance, and functioning in hemodialysis

OBJECTIVE

To determine the associations among dietary intake and inflammatory cytokines with physical activity, function, and performance in maintenance dialysis patients.

DESIGN

Cross-sectional analysis of cohort study.

SETTING

University-affiliated dialysis units, general clinical research center.

SUBJECTS

Multiethnic cohort of maintenance hemodialysis patients.

MAIN OUTCOME MEASURES

Physical activity by accelerometry; physical performance by gait speed, stair climbing, and chair raising; physical functioning by the Medical Outcomes Study Short Form 36-item questionnaire subscale scores; and maximal and adjusted activity scores of human activity profile.

RESULTS

Levels of inflammatory cytokines were uniformly high. Tumor necrosis factor-alpha was directly correlated with dietary protein and energy intake; no other cytokines were directly or inversely correlated with intake. Dietary intake was associated with physical activity, as expected, and not significantly associated with performance or function (with the exception of gait speed). There were no significant associations among inflammatory cytokines and physical activity, performance, or function.

CONCLUSION

Although dietary intake and inflammation may independently influence traditional proxies of nutritional status, this analysis provides no evidence for a link between cytokines and physical activity, performance, or function in hemodialysis patients. More research is required to understand the role of cytokines in protein energy malnutrition and the mechanisms of wasting and functional decline in the dialysis population.

Relative associations of fitness and fatness to fibrinogen, white blood cell count, uric acid and metabolic syndrome

OBJECTIVE

To examine the relation between fitness and fibrinogen, white blood cell count, uric acid and metabolic syndrome across levels of adiposity in apparently healthy, nonsmoking men.

DESIGN

Cross-sectional study of 4057 men from the Aerobics Center Longitudinal Study examining the age-adjusted resting levels and risk of having a clinically significant elevation of fibrinogen, white blood cell count, uric acid and metabolic syndrome score across nine fitness-body fatness combinations. Fitness categories (low fitness, moderately fit or high fitness) were based on a maximal treadmill test. Body mass index (BMI) <25.0 was classified as normal weight, BMI > or = 25.0 but <30.0 as overweight and BMI > or = 30.0 as obese.

RESULTS

Fitness (inversely) and BMI (directly) were independently related to the age-adjusted values of all four variables (P for trend P<0.0001 for each). For all four variables, the greatest age-adjusted risk of having a clinically relevant value was found in the low fitness-obese category and the lowest age-adjusted risk was found in the high fitness-normal weight group.

CONCLUSION

Fibrinogen, white blood cells, uric acid and metabolic syndrome score are independently related to both fitness (inversely) and fatness (directly). Within levels of fatness, risk for significant elevations in fibrinogen, white blood cells, uric acid and metabolic syndrome score is lower for the higher fitness groups.

Physical activity and hemostatic and inflammatory variables in elderly men

BACKGROUND

Physical activity is associated with lower risk of cardiovascular disease, but the mechanisms are uncertain. Hemostatic and inflammatory markers have been linked with risk of cardiovascular disease. We therefore examined the relationship between physical activity and hemostatic and inflammatory variables.

METHODS AND RESULTS

In 1998 to 2000, 20 years after the initial screening of 7735 men 40 to 59 years old from general practices in 24 British towns, 4252 subjects (77% of available survivors, now 60 to 79 old) attended for reexamination. A fasting blood sample was available in 4088 men. All men on warfarin (n=134) and men with incomplete data on physical activity (n=144) were excluded, leaving 3810 men for analysis. Physical activity showed a significant and inverse dose-response relationship with fibrinogen, plasma and blood viscosity, platelet count, coagulation factors VIII and IX, von Willebrand factor, fibrin D-dimer, tissue plasminogen activator antigen, C-reactive protein, and white cell count, even after adjustment for possible confounders. The effects were similar in men with and without prevalent cardiovascular disease. No relationship was seen with activated partial thromboplastin time, activated protein C resistance, hematocrit, or factor VII. An examination of changes in physical activity between baseline and 20 years later showed that inactive men who took up at least light physical activity had levels of blood variables approaching those who remained at least lightly active. Those who became inactive showed levels more similar to those who remained inactive.

CONCLUSIONS

These data suggest that the benefit of physical activity on cardiovascular disease may be at least partly a result of effects on hemostasis and inflammation.

Effects of acute exercise on hemorheological, endothelial, and platelet markers in patients with chronic heart failure in sinus rhythm

BACKGROUND

Chronic heart failure (CHF) is associated with an increased risk of thrombosis and thromboembolic events, including stroke and venous thromboembolism. which may be related to a prothrombotic or hypercoagulable state. Acute vigorous exercise has been associated with activation of hemostasis, and this risk may well be particularly increased in patients with CHF.

HYPOTHESIS

The study was undertaken to determine whether acute exercise would adversely affect abnormalities of hemorheological (fibrinogen, plasma viscosity, hematocrit), endothelial (von Willebrand factor), and platelet markers (soluble P selectin) in patients with CHF.

METHODS

We studied 22 ambulant outpatients (17 men; mean age 65+/-9 years) with stable CHF (New York Heart Association class II-III and a left ventricular ejection fraction of < or =40%) who were exercised to exhaustion on a treadmill. Results were compared with 20 hospital controls (patients with vascular disease, but free of CHF) and 20 healthy controls.

RESULTS

Baseline von Willebrand factor (p = 0.01) and soluble P-selectin (p = 0.006) levels were significantly elevated in patients with CHF when compared with controls. In the patients with CHF who were exercised, plasma viscosity, fibrinogen, and hematocrit levels increased significantly, both immediately post exercise and at 20 min into the recovery period (repeated measures analysis of variance, all p<0.05). There was a positive correlation between exercise workload and the maximal changes in plasma viscosity in the patients with CHF (Spearman r = 0.5, p = 0.02). Plasma viscosity levels increased with exercise in the hospital control group, although no other exercise-induced changes were noted in this group.

CONCLUSION

The present study indicates that the hemorheological indices. fibrinogen, and hematocrit specifically increase during acute exercise in patients with CHF. Although moderate exercise should be encouraged in patients with CHF, vigorous exercise should probably be avoided in view of its potential prothrombotic effects in this high-risk group of patients.

Exercise and thrombosis

Long-term moderate or strenuous physical activity is associated with a considerable reduction in cardiovascular morbidity and mortality in primary and secondary prevention. Various mechanisms, including changes in lipids, lifestyle habits, and other positive physiologic effects, have been suggested to mediate these beneficial effects. In addition, the hemostatic and fibrinolytic systems appear to play an important role. Fibrinogen has been convincingly shown to be an independent cardiovascular risk factor. Other hemostatic and fibrinolytic parameters that are predictive of coronary events include factor VII, platelet hyperreactivity, plasminogen-activator inhibitor 1 (PAI-1), and tissue-plasminogen activator. The effects of exercise on fibrinogen have been intensively studied. Several randomized controlled trials, various other intervention studies and a large number of population-based cross-sectional studies all found an inverse relationship between measures of sport activity or leisure activity and plasma fibrinogen. The magnitude of the effect reported might be associated with a sizeable reduction in major coronary events. Relatively few data are available on the effects of endurance exercise on markers of the fibrinolytic system, with inconsistent results. Acute exercise leads to a transient activation of the coagulation system, which is accompanied by an increase in the fibrinolytic capacity in healthy subjects. Patients with ischemic heart disease, who cannot increase their fibrinolytic potential, however, may be at considerable risk for acute ischemic events if they are exposed to unaccustomed strenuous physical exertion.

Association between physical activity and markers of inflammation in a healthy elderly population

Higher levels of physical activity are associated with lower risk of cardiovascular disease. There is growing evidence that the development of the atherosclerotic plaque is associated with inflammation. In this study, the authors investigated the cross-sectional association between physical activity and markers of inflammation in a healthy elderly population. Data obtained in 1989-1990 and 1992-1993 from the Cardiovascular Health Study, a cohort of 5,888 men and women aged >/=65 years, were analyzed. Concentrations of the inflammation markers-C-reactive protein, fibrinogen, Factor VIII activity, white blood cells, and albumin-were compared cross-sectionally by quartile of self-reported physical activity. Compared with persons in the lowest quartile, those in the highest quartile of physical activity had 19%, 6%, 4%, and 3% lower concentrations of C-reactive protein, white blood cells, fibrinogen, and Factor VIII activity, respectively, after adjustment for gender, the presence of cardiovascular disease, age, race, smoking, body mass index, diabetes, and hypertension. Multivariate regression models suggested that the association of higher levels of physical activity with lower levels of inflammation markers may be mediated by body mass index and glucose. There was no association between physical activity and albumin. Higher levels of physical activity were associated with lower concentrations of four out of five inflammation markers in this elderly cohort. These data suggest that increased exercise is associated with reduced inflammation. Prospective studies will be required for verification of these findings.

In vitro effects of heparin and tissue factor pathway inhibitor on factor VII assays. possible implications for measurements in vivo after heparin therapy

The coagulant activity of blood coagulation factor VII (FVII:C) can be lowered by changes in lifestyle and by therapeutic intervention, e.g. heparin infusion. The question is, however, whether FVII:C determined ex vivo is a valid measure of the FVII activity in vivo. We measured plasma FVII:C, activated FVII (FVIIa), FVII protein (FVII:Ag), tissue factor pathway inhibitor (TFPI), triglycerides, and free fatty acids (FFA) before and 15 min after infusion of a bolus of unfractionated heparin (50 IU/kg body weight) in 12 healthy subjects. Additionally, we conducted in vitro experiments to investigate the effect of unfractionated heparin and TFPI, which is released from the endothelium by heparin, on FVII:C, FVIIa, and FVII:Ag. Heparin infusion decreased triglycerides and increased FFA and TFPI. This was accompanied by significant reductions in FVIIa, FVII:C and FVII:Ag. In vitro, anti-TFPI antibodies increased FVIIa and FVII:C, and heparin reduced FVIIa. The heparinase Hepzyme was unable to abolish the effect of heparin. There were no in vitro effects on FVII:Ag. We conclude that, due to interference by TFPI and heparin in post-heparin plasma, it is impossible to measure the in vivo FVII activity by means of FVII clotting assays. These assays should therefore not be used to measure the coagulation status of patients in heparin therapy, unless extraordinary precautions are taken to eliminate TFPI and heparin effects ex vivo. The observed effect of heparin on FVII:Ag should be investigated further.

Reduction of factor FVIIa activity during heparin therapy. Evidence for assay interactions with tissue factor pathway inhibitor and antithrombin

Heparin is known to exert its antithrombotic effects by accelerating the effect of antithrombin (AT) and by mobilizing tissue factor pathway inhibitor (TFPI) into the circulation from vascular endothelium. Heparin treatment has been reported to decrease FVIIa activity by 40%; this was suggested as a new antithrombotic action of heparins. The present study was conducted to investigate whether the apparent reduction in FVIIa activity induced by unfractionated heparin (UFH) infusion in vivo is due to interactions between AT and TFPI with the FVIIa assay or due to an actual decrease in FVIIa. Blocking plasma TFPI in affinity purified anti-TFPI IgG caused a 25% increase in plasma FVIIa activity (Staclot VII - rTF, Diagnostica Stago, Aswiéres-sur-Seine, France). In vitro heparinization of plasma caused a dose-dependent decrease in FVIIa (up to 56 +/- 8%) at high heparin concentrations (1.0-5.0 IU/mL UFH), a reduction abolished by Hexadimethine Bromide (HDB) to neutralize heparin-induced activation of AT. Thus, heparin-induced activation of AT is apparently responsible for decreased FVIIa under in vitro conditions. Bolus injection followed by continuous infusion of heparin to healthy volunteers was accompanied by a prompt 50% reduction in FVIIa activity, which was sustained throughout heparin infusion and normalized within 24 hours after discontinuation of treatment. Addition of anti-TFPI IgG to postheparin plasma reversed the heparin-induced reduction in FVIIa by approximately 50%, and combined pretreatment of postheparin plasma with anti-TFPI IgG and HDB brought FVIIa to preheparin levels. The present study shows that the FVIIa assay is sensitive to TFPI and AT, especially during heparin treatment, and thereby indicates that the heparin-induced decrease in FVIIa is affected by interactions between TFPI and AT with the FVIIa assay.

Influence of age and normal plasma fibrinogen levels on flow-mediated dilation in healthy adults

This study examined the effects of age-associated increases in fibrinogen on brachial artery flow-mediated dilation in 30 healthy nonsmokers. The findings demonstrate an inverse association between normal plasma fibrinogen levels and vascular function (r = -0.56, p = 0.001), suggesting elevated plasma fibrinogen may decrease the artery's responsiveness to certain vasodilatory signals, such as shear stress.

Nutritional status influences plasma fibrinogen concentration: evidence from the THUSA survey

Nutritional status and risk factors for chronic diseases, including plasma fibrinogen and its determinants, of Africans in the Northwest Province of South Africa, have been studied in a cross-sectional survey. A representative sample of 1854 "apparently healthy" African men and women volunteers aged 15 years and older was recruited from 37 randomly selected sites throughout the Province and stratified for level of urbanisation. Information was collected using validated and culture-sensitive questionnaires. Fasting blood samples were drawn, and all measurements were done with standardised methodology using appropriate equipment, procedures, and controls. Fibrinogen concentration was measured in citrated plasma with the method of Clauss, using the ACL200 automated system and the international fibrinogen standard. The results revealed a population with a high mean plasma fibrinogen (3.17+/-1.10 g/L for HIV-negative men and 3. 64+/-1.12 g/L for HIV-negative women). Factors known to influence plasma fibrinogen, such as age, gender, smoking habit, and physical activity, were also observed in this population. Young rural men and women had the lowest fibrinogen level. Nasal snuff taking and HIV infection did not influence fibrinogen concentration. Multivariate analyses revealed that lower plasma fibrinogen was associated with low to normal body mass index in women, and with dietary intakes compatible with prudent dietary guidelines in men and women (low intakes of animal protein; trans fatty acids and higher intakes of plant protein; dietary fibre, vitamin E, and iron, and a high dietary P/S ratio). Subjects in the higher quartiles of plasma fibrinogen had significantly lower iron, vitamin E, and vitamin B6 (women) status. Increases in fibrinogen were associated with significant increases in serum lipids. Both under- and overnutrition seem to be associated with high plasma fibrinogen. It is concluded that overall nutritional status, possibly in addition to specific nutrients (and foods), influences plasma fibrinogen.

Exercise and thrombosis

Long-term moderate or strenuous physical activity is associated with a considerable reduction in cardiovascular morbidity and mortality. This article reviews the evidence to suggest that part of the effect is mediated through the effects on thrombogenic factors. Fibrinogen has been convincingly shown to be an independent cardiovascular risk factor. Other hemostatic and fibrinolytic parameters that are predictive of coronary events include factor VII, platelet hyperreactivity, plasminogen activator inhibitor-1, and tissue-plasminogen activator. The effects of exercise on fibrinogen have been studied intensively. One randomized, controlled trial, two other intervention studies and a large number of population-based cross-sectional studies have consistently found an inverse relationship between various measures of sport activity or leisure activity and plasma levels of fibrinogen. The magnitude of the effect might be associated with a sizeable reduction in major coronary events. Relatively few data are available on endurance exercise and markers of the fibrinolytic system. Acute exercise leads to a transient activation of the coagulation system, which is accompanied by an increase in the fibrinolytic capacity in healthy subjects. However, patients with ischemic heart disease, who cannot increase their fibrinolytic potential, may be at considerable risk for acute ischemic events if they are exposed to unaccustomed strenuous physical exertion. It is concluded that physical activity has profound effects on thrombogenic factors and that these mechanisms could contribute to its beneficial cardiovascular effects.

Leisure time physical activity, cardiorespiratory fitness, and plasma fibrinogen concentrations in nonsmoking middle-aged men

PURPOSE

The relationship of both leisure time physical activity and predicted maximum oxygen consumption (VO2max) with plasma fibrinogen concentration was examined within a cohort of employed middle-aged men.

METHODS

Analyses were performed on a subsample of 635 nonsmoking men (46.7 +/- 7.7 yr) who completed a preventive medical assessment between 1992 and 1996.

RESULTS

Among nonsmokers, mean age-adjusted fibrinogen concentration decreased significantly with higher physical activity index (PAL) categories and quartiles of predicted VO2max (mL x kg(-1) x min(-1)) (both P = 0.001). Mean age-adjusted plasma fibrinogen concentrations were significantly different (P < 0.05) between inactive and vigorous PAI groups and extreme quartiles of predicted VO2max (mL x kg(-1) x min(-1)). These relationships were no longer significant after adjustment for the confounding effect of other ischemic heart disease risk factors. Stepwise multiple regression analyses showed that age, sum of skinfolds, and blood leukocyte count were the strongest predictors of plasma fibrinogen concentration.

CONCLUSION

These data do not confirm a significant independent association of both physical activity and predicted VO2max (mL x kg(-1) x min(-1)) with fibrinogen concentrations among nonsmoking middle-aged men of similar high social class.

Lifestyle and hemostatic risk factors for ischemic heart disease : the Caerphilly Study

We have recently shown that fibrin D-dimer, tissue plasminogen activator (tPA) antigen, von Willebrand factor antigen, fibrinogen, plasma viscosity, and white cell count are associated with subsequent ischemic heart disease (IHD) in men aged 49 to 65 years in the Caerphilly Study from South Wales. We now report the contribution of major lifestyle factors to plasma levels of these new risk predictors for IHD. Results were available for up to 2188 men. The contribution of factors associated with lifestyle (smoking, alcohol, body mass index, leisure and work activity, social class, and use of prescribed medicines) to variation in plasma levels of 8 hemostatic variables was examined. All results were adjusted for other lifestyle variables, age, and time of day. Most hemostatic variables increased with age and smoking habit. Increasing levels of alcohol consumption were associated with increases in tPA and plasminogen activator inhibitor (PAI-1) activity and with decreases in fibrinogen and white cell count. tPA, PAI-1, fibrinogen (nephelometric), and viscosity were positively associated with body mass index. Increasing levels of leisure activity were inversely associated with D-dimer, von Willebrand factor, nephelometric fibrinogen, and viscosity. Use of prescribed medicines (a marker for chronic illness) was associated with adverse levels of D-dimer, fibrinogen, plasma viscosity, and white cell count. tPA, PAI-1, and plasma viscosity were associated with blood pressure, cholesterol, and triglycerides but not with lipoprotein(a) or homocysteine. We conclude that several lifestyle factors are associated with hemostatic risk predictors for IHD. Lifestyle modifications may reduce IHD risk partly by altering hemostatic function; large intervention studies are required to test this hypothesis.

Interaction of physical activity and diet: implications for haemostatic factors

Regular moderate intensity physical activity and habitual diet providing no more than one third of energy from fats have been recommended for the prevention of atherosclerotic diseases. The background for these guidelines is the key role of plasma lipids. However, the importance of thrombogenesis in acute myocardial infarction has become obvious during the last decade. Hyperlipidaemia and excess of adipose tissue increase platelet aggregability and blood coagulation, and decrease fibrinolysis. Both regular physical activity and dietary fat reduction decrease blood lipids and body fat thereby diminishing the risk of thrombosis. Currently, data on interactions between physical activity and diet on haemostasis are scarce, and the few studies available have not demonstrated additional effects when these two lifestyle modifications have been combined. This paper is restricted only to studies using controlled randomized design. Regular moderate intensity physical activity as well as diet rich in omega-3 fatty acids decrease platelet aggregability. The effects of regular physical activity on plasma fibrinogen remain contradictory, while the impact of diet is even less clear. Plasminogen activator inhibitor-1, a possible link between insulin resistance syndrome and coronary heart disease, may decrease due to physical training or low fat diet. It can be hypothesized that moderation in physical activity and diet carries a more powerful impact on blood coagulation and fibrinolysis than either lifestyle modification alone. Studies focusing on the interactions of regular moderate physical activity and fat-modified diet are needed in efforts to optimize the preventive actions by lifestyle changes.

Interleukin-6 as a central mediator of cardiovascular risk associated with chronic inflammation, smoking, diabetes, and visceral obesity: down-regulation with essential fatty acids, ethanol and pentoxifylline

Increased plasma levels of fibrinogen and C-reactive protein (CRP), as well as leukocytosis, are now established as risk factors for the thromboembolic complications of vascular disease. Chronic inflammation or infection associated with an acute-phase response--notably, periodontal disease and smoking-induced lung damage--are likewise known to increase cardiovascular risk. A common etiologic factor in these conditions may be interleukin-6 (IL-6), acting on hepatocytes to induce acute-phase reactants that increase blood viscosity and promote thrombus formation. Recent evidence that hypertrophied adipocytes release IL-6, and that hyperglycemia evokes IL-6 production by endothelium, may explain why plasma fibrinogen is increased in visceral obesity and poorly controlled diabetes. IL-6 is released by a range of tissues in response to stimulation by the monocyte-derived cytokines interleukin-1 and tumor necrosis factor; by suppressing production of these cytokines, fish oil, alpha-linolenic acid, and pentoxifylline can reduce IL-6 synthesis. Moderate ethanol consumption, as well as sex-hormone replacement, also appear to inhibit IL-6 production or activity. These practical protective measures may be of particular value to patients with pre-existing atheroma and elevated plasma levels of acute-phase reactants. Since IL-6 plays a crucial physiological role in osteoclast generation and activation, these measures may also aid preservation of bone density.

Fibrinogen and cardiovascular risk

The hypothesis that fibrinogen is closely related to cardiovascular risk has been strengthened through the results of various lines of research, which this review will aim to unravel. Several prospective epidemiological studies convincingly show elevated fibrinogen to represent a major, independent cardiovascular risk factor. Cross-sectional studies strongly associate fibrinogen and conventional cardiovascular risk factors. Clinical cohort studies demonstrate that increased fibrinogen is also a risk factor for the sequelae of cardiovascular disease. Our knowledge about the determinants of the variable plasma level of fibrinogen in health and disease is incomplete. Understanding of the mechanisms that might be involved in the atherothrombogenic action of fibrinogen is also fragmentary. Fibrinogen strongly affects blood coagulation, blood rheology and platelet aggregation. In addition, it has direct effects on the vascular wall and is a prominent acute phase reactant. All of these phenomena might constitute pathophysiological mechanisms involved in the association between fibrinogen and cardiovascular events. Their relative importance is unclear at present. Even though many crucial questions await conclusive answers, little doubt exists that fibrinogen represents a major, independent risk factor.

Associations between central obesity and indexes of hemostatic, carbohydrate and lipid metabolism. Results of a 1-year intervention from the Oslo Diet and Exercise Study

The relationships of central obesity and physical fitness to indexes of hemostatic, lipid and glucose metabolism both at baseline and after 1 year of diet and exercise intervention were examined in 209 sedentary middle-aged men and women with increased coronary risk factor levels. Central obesity was measured as either waist circumference or waist/hip ratio. Maximal oxygen uptake was used as a measure of physical fitness. The cross-sectional results show that there were significant correlations between waist circumference and euglobuline clot lysis time (r = 0.23), factor VII (r = 0.16), glucose and insulin before and after 1 h glucose load (r ranging from 0.32 to 0.50). The 1-year intervention gave the following associations between changes in waist circumference and changes in: euglobuline clot lysis time (r = 0.27), factor VII (r = 0.19), carbohydrate variables and lipids (magnitude of r ranging from 0.19 to 0.43). Also the other indexes of obesity and physical fitness showed significant correlations to indexes of hemostatic, lipid and glucose variables, both cross-sectionally and for changes after the 1-year intervention. The associations between changes in central obesity and changes in indexes of hemostatic, carbohydrate and lipids were generally stronger during 1 year of diet and exercise intervention than those found at baseline. Multiple regression analyses with waist circumference, waist/hip ratio, percent body fat and Vo2 max as independent variables and indexes of hemostatic, carbohydrate and lipid metabolism as dependent variables showed that waist circumference was a significant predictor for indexes of the hemostatic, carbohydrate and lipid metabolism, mostly independent of physical fitness. The cross-sectional and 1-year change results support each other and therefore underscore the importance of abdominal obesity as an important risk factor for cardiovascular disease.

Walking to health

Walking is a rhythmic, dynamic, aerobic activity of large skeletal muscles that confers the multifarious benefits of this with minimal adverse effects. Walking, faster than customary, and regularly in sufficient quantity into the 'training zone' of over 70% of maximal heart rate, develops and sustains physical fitness: the cardiovascular capacity and endurance (stamina) for bodily work and movement in everyday life that also provides reserves for meeting exceptional demands. Muscles of the legs, limb girdle and lower trunk are strengthened and the flexibility of their cardinal joints preserved; posture and carriage may improve. Any amount of walking, and at any pace, expends energy. Hence the potential, long term, of walking for weight control. Dynamic aerobic exercise, as in walking, enhances a multitude of bodily processes that are inherent in skeletal muscle activity, including the metabolism of high density lipoproteins and insulin/glucose dynamics. Walking is also the most common weight-bearing activity, and there are indications at all ages of an increase in related bone strength. The pleasurable and therapeutic, psychological and social dimensions of walking, whilst evident, have been surprisingly little studied. Nor has an economic assessment of the benefits and costs of walking been attempted. Walking is beneficial through engendering improved fitness and/or greater physiological activity and energy turnover. Two main modes of such action are distinguished as: (i) acute, short term effects of the exercise; and (ii) chronic, cumulative adaptations depending on habitual activity over weeks and months. Walking is often included in studies of exercise in relation to disease but it has seldom been specifically tested. There is, nevertheless, growing evidence of gains in the prevention of heart attack and reduction of total death rates, in the treatment of hypertension, intermittent claudication and musculoskeletal disorders, and in rehabilitation after heart attack and in chronic respiratory disease. Walking is the most natural activity and the only sustained dynamic aerobic exercise that is common to everyone except for the seriously disabled or very frail. No special skills or equipment are required. Walking is convenient and may be accommodated in occupational and domestic routines. It is self-regulated in intensity, duration and frequency, and, having a low ground impact, is inherently safe. Unlike so much physical activity, there is little, if any, decline in middle age. It is a year-round, readily repeatable, self-reinforcing, habit-forming activity and the main option for increasing physical activity in sedentary populations. Present levels of walking are often low. Familiar social inequalities may be evident. There are indications of a serious decline of walking in children, though further surveys of their activity, fitness and health are required. The downside relates to the incidence of fatal and non-fatal road casualties, especially among children and old people, and the deteriorating air quality due to traffic fumes which mounting evidence implicates in the several stages of respiratory disease. Walking is ideal as a gentle start-up for the sedentary, including the inactive, immobile elderly, bringing a bonus of independence and social well-being. As general policy, a gradual progression is indicated from slow, to regular pace and on to 30 minutes or more of brisk (i.e. 6.4 km/h) walking on most days. These levels should achieve the major gains of activity and health-related fitness without adverse effects. Alternatively, such targets as this can be suggested for personal motivation, clinical practice, and public health. The average middle-aged person should be able to walk 1.6 km comfortably on the level at 6.4 km/h and on a slope of 1 in 20 at 4.8 km/h, however, many cannot do so because of inactivity-induced unfitness. The physiological threshold of 'comfort' represents 70% of maximum heart rate. (ABSTRACT TRUNCATED)

Leisure-time physical activity but not work-related physical activity is associated with decreased plasma viscosity. Results from a large population sample

BACKGROUND

Regular leisure-time physical activity (LTPA) is inversely associated with coronary heart disease (CHD). This has been mainly explained by its impact on traditional CHD risk factors, but more recently it was also shown to lower fibrinogen, which largely determines plasma viscosity. No data on the effect of work activity (WA) on plasma viscosity have been published.

METHODS AND RESULTS

We studied the relationship between self-reported LTPA or WA and plasma viscosity as well as other CHD risk factors in 3522 men and women age 25 to 64 years. Physical activity was assessed by questionnaire. LTPA was inversely associated with plasma viscosity in both sexes. The unadjusted mean differences in plasma viscosity in men between no activity and the highest activity were 0.024 mPa.s (95% confidence interval [CI], 0.016 to 0.032 mPa.s, P < .001) during winter and 0.024 mPa.s (95% CI, 0.016 to 0.031 mPa.s, P < .001) during summer. After adjustment for age, cholesterol, smoking, blood pressure, body mass index, and years of education, mean differences decreased but still remained substantial and statistically significant (0.010 mPa.s; 95% CI, 0.003 to 0.018 mPa.s [P = .009] for winter activity; and 0.010 mPa.s; 95% CI, 0.002 to 0.017 mPa.s [P = .011] for summer activity). Similar results were found in women. WA showed no appreciable association with plasma viscosity after controlling for the covariates.

CONCLUSIONS

LTPA is inversely associated with plasma viscosity, independent of other risk factors, whereas WA shows no material effect in men and women. Decreased plasma viscosity may represent one mechanism through which LTPA confers a decrease of CHD risk.

Ethnic differences in pre-admission levels of physical activity in patients admitted with myocardial infarction

BACKGROUND

Regular exercise is generally considered to reduce the risk of coronary heart disease. Reduced levels of physical activity in Indo-Asians may partly explain why patients from this ethnic group sustain so many heart attacks.

AIM

To investigate ethnic differences in pre-admission levels of physical activity amongst patients admitted with myocardial infarction and triggers for the acute cardiac event.

DESIGN

Cross-sectional study using standard Baecke questionnaire, which provided a semi-quantitative work score, sport score, leisure score and total activity score of general daily activities, with additional questions on activity at the onset of chest pain.

SETTING

Coronary Care Unit, City Centre Teaching Hospital.

PATIENTS AND RESULTS

We studied 100 consecutive patients (76 males, mean age 62.3 years, S.D. 12.5; 74 caucasians, 26 Indo-Asians) admitted with myocardial infarction. Most patients were engaged in sedentary activities, including lying in bed (25%), sitting (19%), watching television (14%) and sleeping (6%), whilst only 21% of patients were engaged in physical activity at chest pain onset; there were, however, no ethnic differences in activity at chest pain onset. There was a diurnal variation in chest pain onset, with the mode between 08:00 and 10:00 h. As the mean age of Indo-Asians was significantly lower than caucasians in the whole group (56.3 vs. 64.4 years; t-test, P < 0.002), the Baecke questionnaire analysis was confined to only male patients aged < 70 years (n = 56). Indo-Asian patients with myocardial infarction were found to have a significantly lower overall physical activity score (3.78 vs. 5.33; P = 0.003), leisure time physical activity (2.43 vs. 2.74; P < 0.05) and sporting score (0.14 vs. 0.82; P < 0.01) when compared to caucasians, despite a similar mean age and body mass index.

CONCLUSION

The majority of myocardial infarction patients were engaged in sedentary activities at chest pain onset. Although there were no differences between caucasians and Indo-Asians in activity at symptom onset, Indo-Asian patients had a significantly lower overall physical activity score, leisure time physical activity and sporting score compared to caucasians. The lower general physical activity amongst Indo-Asians may in part contribute to the high prevalence of ischaemic heart disease amongst this ethnic group.

Physical activity, fitness, and plasma fibrinogen with reference to fibrinogen genotypes

The relation of daily energy expenditure (EE) and maximal oxygen uptake (VO2max) to plasma fibrinogen with reference to DNA polymorphism was analyzed in a random sample of men (N = 189), age 50-60. Fibrinogen polymorphism was detected using polymerase chain reaction (PCR) and digestion with HindIII and BclI (beta-fibrinogen), and TaqI (alpha-fibrinogen) restriction enzymes. Mean VO2max was 29.4 ml.kg-1.min-1 (95%CI 28.5; 30.2) and mean daily EE was 179 kJ.kg-1.d-1 (173; 186) and were similar in all fibrinogen genotypes. Plasma fibrinogen was 3.26 g.1-1 (3.18; 3.34) and did not associate with fibrinogen polymorphisms. Both EE and VO2max related inversely to fibrinogen level (r = -0.24, P < 0.001). Strongest predictors of plasma fibrinogen were VO2max in TaqI 800 bp homozygotes, and EE together with smoking in TaqI 900 bp homozygotes. The predictive role of VO2max was marginal in the common beta-fibrinogen genotypes, whereas physical activity level explained up to 9% of the variance in the less frequent genotypes. These data suggest that the association of VO2max and EE with plasma fibrinogen varies across the fibrinogen genotypes.

Physical activity, physical fitness, blood pressure, and fibrinogen in the Northern Ireland health and activity survey

STUDY OBJECTIVE

To investigate the relationship between physical activity, physical fitness, blood pressure, and fibrinogen.

DESIGN

This was a cross sectional population study using a two stage probability sample.

SETTING

Northern Ireland.

PARTICIPANTS

A sample of 1600 subjects aged 16-74 years from the population of Northern Ireland.

MAIN OUTCOME MEASURES

Physical activity profile from computer assisted interview using the Allied Dunbar national fitness survey scales. Physical fitness using estimation of VO2 max by extrapolation from submaximal oxygen uptake while walking on a motor driven treadmill. Systolic and diastolic blood pressure measured with a Hawksley random zero sphygmomanometer. Measurement of fibrinogen using the Clauss method.

MAIN RESULTS

There were significant relationships between both current and past activity and blood pressure. These were of a magnitude that would have been clinically significant, but for the fact that, with the exception of the relationship between habitual activity and diastolic pressure (p = 0.03) and past activity and systolic pressure (p = 0.03) in men, they were not sustained after adjustment for the effect of age using analysis of variance. After adjustment for other potentially confounding factors using multiple regression, there was an inverse relationship between systolic blood pressure and past activity in men, so that those with a life-time of participation compared with a life-time of inactivity had a lower systolic blood pressure of 6 mmHg (p < 0.05). There was a highly significant (p < 0.001) inverse association between both systolic and diastolic blood pressure and physical fitness (VO2 max) which was not sustained after adjustment for possible confounding factors. There were relationships between fibrinogen and highest recorded activity (p < 0.001), habitual activity (p < 0.01), and past activity (p < 0.01) in men but no significant relationship in women. The relationship between fibrinogen and activity was no longer sustained after adjustment for possible confounding factors. There was a highly significant (p < 0.001) inverse relationship with physical fitness using VO2 max. This relationship was sustained after adjustment for possible confounding factors in both men (p < 0.05) and women (p < 0.001).

CONCLUSIONS

There was a relationship between physical activity, physical fitness, and blood pressure but the relationship was greatly influenced by age. A reduction of 6 mmHg in systolic blood pressure associated with past activity is of clinical significance and supports the hypothesis that physical activity is of benefit in reducing cardiovascular risk. There was a lower level of fibrinogen in those who were most active but this relationship was not significant after adjustment for possible confounding factors. There was also a lower level of fibrinogen those who were most fit (VO2 max) and this relationship persisted even after adjustment for possible confounding factors.

Exercise in the prevention of atherosclerotic, metabolic and hypertensive diseases: a review

Evidence that physical inactivity and low fitness confer an increased risk of coronary heart disease (CHD) is convincing. There is a graded relationship with the amount of physical activity (or physical fitness), with some evidence that an asymptote is reached in the mid-range. Epidemiological studies have also shown that physically inactive individuals are at greater risk of developing hypertension or non-insulin-dependent diabetes or of experiencing a stroke, but less is known about the nature of these relationships. The effects of exercise on blood pressure, glucose/insulin dynamics and lipoprotein metabolism may contribute to the lower risk of these diseases in people who exercise regularly. Long-term adaptations to regular exercise may result in improved insulin sensitivity and in higher serum concentrations of high-density lipoprotein cholesterol-mediated in part by improved weight regulation. However, the residual effects of individual exercise bouts may, cumulatively, also be important; these "acute' effects may be enhanced when functional capacity is increased through training. More intensive exercise may carry greater benefits in some respects, but it also carries higher risks, for example of orthopaedic injury or triggering of heart attack. Consequently, public health policies should aim to foster a long-lasting commitment to increased levels of frequent, moderate-intensity activity in as many people as possible.

Fibrinogen levels and exercise. Is there a relationship?

Haemostatic disturbances associated with elevated plasma fibrinogen levels have been implicated in coronary heart disease. Changes involving plasma fibrinogen levels have been reported after acute exercise. However, the results reported have sometimes been controversial, due to differences in the populations studied, exercise protocols and testing procedures, and the analytical methods employed for the assessment of plasma fibrinogen levels. The influence of physical training on plasma fibrinogen levels is more controversial and less well known. Cross-sectional studies suggest that regular exercise reduces plasma fibrinogen concentration. However, the influence of training programmes on plasma fibrinogen levels is less well studied and the available data are still poor with conflicting results being reported. This lack of evidence warrants further investigations in order to clarify the exact effects of acute exercise and physical training on plasma fibrinogen levels in normal healthy individuals and patients.

Does walking decrease the risk of cardiovascular disease hospitalizations and death in older adults?

OBJECTIVES

The purpose of this study was to determine whether walking is associated with a reduced risk of cardiovascular disease hospitalization and death in community-dwelling older men and women.

DESIGN

A prospective study, with follow-up time of 4 to 5 years (average 4.2 years).

SETTING

A western Washington health maintenance organization.

PARTICIPANTS

Men and women aged 65 years and older from a random sample of HMO enrollees invited by mail to participate in a health promotion intervention trial (36% accepted the invitation and completed questionnaires). This report is based on 1645 older adults without severe disability and without history of heart disease. Vital status ascertainment was complete (100%), and only 2.6% did not complete the follow-up.

MEASUREMENTS

Reported frequency and duration of walking for exercise, work, errands, pleasure, and hiking in the 2 weeks before baseline were used to classify hours of walking per week. The two main outcomes were: (1) cardiovascular disease hospitalizations with a discharge diagnosis of coronary (ICD-9-CM 410-414) or other cardiovascular diseases (ICD-9-CM 390-409, 415-448) documented by computerized hospitalization records and (2) death. Numerous potential confounding factors were considered, including age, sex, treated high blood pressure, current estrogen use and chronic disease score (ascertained by computerized medical and pharmacy records), and ethnicity, education, income, physical function, self-rated health status, smoking, alcohol intake, and body mass index (ascertained by self-report on the mailed questionnaire).

RESULTS

Walking more than 4 hours/week was associated significantly with a reduced risk of cardiovascular disease hospitalization in both sexes combined compared with walking less than 1 hour/week (age and sex-adjusted relative risk = 0.69; 95% confidence interval, 0.52-0.90). This association was not altered by adjustment for baseline cardiovascular risk factors and indicators of general health status. The association was present in all age groups, among those with and without physical limitations, and also among those who did and did not also participate in more vigorous physical activities. Walking more than 4 hours/week was also associated with a reduced risk of death (age and sex-adjusted relative risk = 0.73; 95% confidence interval, 0.48-1.10), however, this association was substantially diminished by adjustment for cardiovascular risk factors and measures of general health status.

CONCLUSIONS

Walking more than 4 hours/week may reduce the risk of hospitalization for cardiovascular disease events. The association of walking more than 4 hours/week with reduced risk of death may be mediated by effects of walking on other risk factors. These findings provide much stronger evidence than previously available for advising older men and women to embark on or maintain a sustained program of walking to prevent cardiovascular disease events.

Plasma fibrinogen levels and their correlates in 6457 coronary heart disease patients. The Bezafibrate Infarction Prevention (BIP) Study

The association between fibrinogen measured in healthy individuals and subsequent development of ischemic heart disease is well established, but studies reporting fibrinogen levels in coronary heart disease patients are scarce. Plasma fibrinogen was determined for 5729 men and 728 women (aged 45 to 74) with established coronary heart disease, screened for participation in the Bezafibrate Infarction Prevention study, with the following lipid profile at the time of the first screening visit: total serum cholesterol < or = 270 mg/dl, high density lipoprotein cholesterol < or = 45 mg/dl and triglyceride < or = 300 mg/dl. Increased age was associated with augmented plasma fibrinogen values. Age-adjusted fibrinogen levels were higher in women than in men. A direct association was found between mean fibrinogen levels and low density lipoprotein cholesterol. On the other hand, the correlation with high density lipoprotein cholesterol was inverse. Fibrinogen was also associated with body mass index, behavioral variables and severity of coronary heart disease. In a multivariable linear regression analysis performed, risk factors considered explained merely 6 and 4% of fibrinogen variation for men and women, respectively. Therefore, most of the fibrinogen level variability in coronary heart disease patients is accounted for by factors that remain to be established by further research.

Hemostatic concomitants of syndrome X

The elevated risk factors classically associated with Syndrome X do not adequately explain the increased cardiovascular risk linked to insulin resistance. Considerable indirect evidence and more limited direct evidence suggests that increases in certain prognostically significant hemostatic variables--notably plasma fibrinogen, factor VII coagulant activity, and plasminogen activator inhibitor-1 levels--may be concomitants of Syndrome X. Increased platelet aggregability, and a reduced capacity of vascular endothelium for prostacyclin generation, may also be associated with insulin resistance. Large clinical studies, involving quantification of insulin sensitivity and measurement of hemostatic variables, are required to test this hypothesis. It is unlikely that hyperinsulinemia mediates the connections between insulin resistance and hemostatic variables (or indeed other risk factors in Syndrome X). In light of the remarkably broad impact of insulin resistance on cardiovascular risk factors, promotion of optimal insulin sensitivity should assume a central role in preventive cardiology.

Physical exercise and hemostasis

A number of hemostatic changes involving platelets, coagulation and fibrinolysis have been reported after acute physical exercise. Results have sometimes been controversial, due to differences in subjects investigated, type of exercise and methods used for hemostatic evaluation. On the whole, physical exercise has been shown to induce: (1) increases in platelet number and activity, (2) activation of coagulation leading to a slight but significant thrombin generation and (3) activation of fibrinolysis. These changes are short lasting. Less known are hemostatic changes induced by exercise training programs: a few data are available on the effects on platelets and coagulation, whereas studies performed on fibrinolysis show a decrease in plasminogen activator inhibitor-1 levels at rest and an increase in fibrinolytic capacity after training.

Moderate to high intensity conditioning leisure time physical activity and high cardiorespiratory fitness are associated with reduced plasma fibrinogen in eastern Finnish men

A reduction of plasma fibrinogen has been suggested as one mechanism through which physical activity would protect against coronary heart disease (CHD). Therefore, we investigated the association of conditioning leisure time physical activity (CLTPA), assessed quantitatively by a 12-month history, and maximal oxygen uptake (VO2max) with plasma fibrinogen concentration in eastern Finnish men aged 42-60 years. A high mean intensity of CLTPA (standardized multivariate regression coefficient beta -0.059, p = 0.020) and a high maximal oxygen uptake (beta -0.163, p < 0.001) were associated with reduced plasma fibrinogen when adjusting for the strongest covariates. The adjusted relative difference in plasma fibrinogen concentration was 6.6% between men with a mean CLTPA intensity of < 4 and > 8 METs and 9.1% between the extreme quartiles of VO2max (< 2.21 vs > 2.961/min). The association between the mean intensity of CLTPA (p = 0.030 for interaction) and VO2max (p = 0.033) and plasma fibrinogen was stronger for smokers than for non-smokers. These data indicate that a reduction of plasma fibrinogen concentration may be one mechanism through which moderate to high intensity CLTPA and high cardiorespiratory fitness reduce the risk of CHD.

Regular exercise reduces fibrinogen levels: a review of longitudinal studies

Fibrinogen can be considered as a major cardiovascular risk factor. Therefore there is a growing interest in methods to lower its plasma level. This paper is aimed at reviewing the data investigating the effects of regular exercise on plasma fibrinogen levels. Cross-sectional studies strongly suggest that regular exercise will reduce fibrinogen levels, and longitudinal data confirm this. The average decrease achieved by regular endurance exercise over several months is around 0.4 g/l. It can be extrapolated that this corresponds to a substantial decrease in risk of coronary heart disease. It is concluded that regular exercise is the most practicable approach known to date to lower plasma fibrinogen levels.

Exercise, fibrinogen, and other risk factors for ischaemic heart disease. Caerphilly Prospective Heart Disease Study

OBJECTIVE

To examine the associations between physical activity and a wide range of risk factors for ischaemic heart disease including fibrinogen concentration and viscosity.

DESIGN

Cross sectional evidence from the 2398 men aged 50-64 years in the Caerphilly Prospective Heart Disease Study.

METHODS

Validated questionnaires were used to quantify energy expenditure on leisure activities and to grade activities related to occupation. Risk factors for heart disease examined included blood pressure, lipids, fibrinogen, and plasma viscosity. Possible confounding variables included smoking, employment, and prevalent heart disease (angina, previous myocardial infarction, and electrocardiographic evidence of ischaemia).

RESULTS

Fibrinogen concentration was lower by 0.24 g/l and viscosity by 0.026 cP in the third of men who were most active in leisure activities (about 0.25 x 1 SD). A weak positive relation was found with high density lipoprotein cholesterol, but none with total cholesterol or fasting glucose concentrations or blood pressure. Triglyceride concentrations seem to be substantially lower in the most active men, although the evidence for this is not consistent. Work related activity showed relation with the lipid concentration but not with the haemostatic tests.

CONCLUSIONS

Leisure activities of all levels seem to affect haemostatic and lipid factors beneficially. These effects correspond to a difference in the risk of heart disease for an active man and a sedentary man of at least 7% or 8%. Fasting triglyceride concentrations have already been shown to be strongly predictive of heart disease in this cohort of men, and the effect of exercise on this factor is also likely to confer benefit.