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

Chronic disease and malnutrition biomarkers among unemployed immigrants and Canadian born adults

Background

Immigration status and unemployment may intersect on the health outcomes of men and women. This study aimed to identify intersections between unemployment and immigration in inflammatory, metabolic and nutritional blood markers and assess gender differences.

Methods

We used Canadian Health Measures Survey data on 2493 participants aged 18 to 65. Outcomes were chronic inflammation (high-sensitivity C-reactive protein (hsCRP) and fibrinogen), nutritional (albumin and hemoglobin), and metabolic blood markers (glycosylated hemoglobin, blood glucose, total and high density lipoprotein (HDL) cholesterol). Multivariate linear regressions were used to assess the associations between each biomarker, unemployment and immigrant status, controlling for age, education, province, smoking, physical inactivity and body mass index and testing for multiplicative interactions between unemployment, immigrant status and gender.

Results

Unemployment was associated with higher inflammation (hsCRP and fibrinogen) in Canadian born men; Canadian born employed women showed higher hsCRP values compared with corresponding employed men. Unemployed immigrant women presented the highest values of hsCRP while employed immigrant women had the lowest hsCRP. Unemployment was associated with higher glucose; immigrant status was associated with higher glucose and glycosylated hemoglobin. Unemployed immigrants had significantly lower levels of hemoglobin and albumin than employed immigrants, and Canadian-born citizens regardless of their employment status. Some of these associations were attenuated after adjustment by body mass index, physical inactivity and smoking.

Conclusion

Blood biomarkers unveil intersections among unemployment, immigration and gender. This study provides evidence on biological pathways of unemployment on the likelihood of common chronic diseases, inflammation and potential malnutrition with some increased vulnerabilities in unemployed immigrants, and particularly in unemployed immigrant women.

Pulse wave velocity is lower in trained than in untrained sickle cell trait carriers

BACKGROUND

Sickle cell trait (SCT) is a benign condition of sickle cell disease. Nevertheless, previous reports showed that SCT carriers have increased blood viscosity and decreased vascular reactivity compared to non-SCT carrier. The benefit of regular exercise on vascular function has been well documented in the general population but no study focused on the SCT population.

PURPOSE

The aim of our study was to compare arterial stiffness and blood viscosity between trained and untrained SCT carriers, as well as a group of untrained non-SCT.

METHODS

Arterial stiffness (finger-toe pulse wave velocity) and blood viscosity were evaluated in untrained non-SCT carriers (n = 10), untrained SCT carriers (n = 23) and trained SCT carriers (n = 17) who reported at least 10 hours of physical exercise per week.

RESULTS

Untrained SCT carriers had higher pulse wave velocity (p = 0.032) and blood viscosity (p < 0.001) than their trained counterparts. In addition, untrained SCT carriers had higher blood viscosity (p < 0.001) than the untrained non-SCT group. A positive association was noted between blood viscosity and pulse wave velocity in the whole study population.

CONCLUSION

Our study suggests that regular exercise may be beneficial for the vascular function of SCT carriers.

Dose–Response Association Between Physical Activity and Incident Hypertension

Despite the inverse association between physical activity (PA) and incident hypertension, a comprehensive assessment of the quantitative dose–response association between PA and hypertension has not been reported. We performed a meta-analysis, including dose–response analysis, to quantitatively evaluate this association. We searched PubMed and Embase databases for articles published up to November 1, 2016. Random effects generalized least squares regression models were used to assess the quantitative association between PA and hypertension risk across studies. Restricted cubic splines were used to model the dose–response association. We identified 22 articles (29 studies) investigating the risk of hypertension with leisure-time PA or total PA, including 330 222 individuals and 67 698 incident cases of hypertension. The risk of hypertension was reduced by 6% (relative risk, 0.94; 95% confidence interval, 0.92–0.96) with each 10 metabolic equivalent of task h/wk increment of leisure-time PA. We found no evidence of a nonlinear dose–response association of PA and hypertension ( P nonlinearity =0.094 for leisure-time PA and 0.771 for total PA). With the linear cubic spline model, when compared with inactive individuals, for those who met the guidelines recommended minimum level of moderate PA (10 metabolic equivalent of task h/wk), the risk of hypertension was reduced by 6% (relative risk, 0.94; 95% confidence interval, 0.92–0.97). This meta-analysis suggests that additional benefits for hypertension prevention occur as the amount of PA increases.

Leisure time, occupational and household physical activity, and risk factors for cardiovascular disease in working men and women: the WOLF study

Aims: The aim of the present study was to examine the association of leisure time, occupational and household physical activity, as well as a combination of these (total activity), with four major risk factors for cardiovascular disease. Methods: Cross-sectional data from the Work, Lipids and Fibrinogen (WOLF) study were used. The study population consisted of 10,413 employed persons from two regions in Sweden, 7,168 men and 3,245 women, aged 19 to 70 years. Results: The adjusted prevalence ratio (PR) of having low high density lipoprotein (HDL) cholesterol levels was 0.54 (95% confidence interval (C.I.) 0.46 - 0.65) for men and 0.55 (95% C.I. 0.41 - 0.73) for women who were involved in leisure time physical activity on a regular basis compared with persons with a more sedentary lifestyle. The adjusted PR of having elevated plasma fibrinogen was also significantly lower among those with regular leisure time physical activity. Occupational and household physical activity showed different associations among men and women. Women with high self-perceived household physical activity had an adjusted PR of 1.33 (95% C.I. 1.05 - 1.68) of having low HDL cholesterol levels. Total activity showed strong beneficial associations with several cardiovascular risk factors. Overweight persons seemed to have relatively more benefit from their physical activity with regard to cardiovascular risk factors than leaner persons. Smokers did not have as strong relative decrease in plasma fibrinogen with increasing activity level as non-smokers. Conclusion: Leisure time, as well as total physical activity, was associated inversely with cardiovascular risk factors, particularly HDL cholesterol, in both men and women.

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.

Leisure-time and occupational physical activity in relation to cardiovascular risk factors and eating habits in French adults

Objective

To investigate the relationships of two main physical activity domains (during leisure and at work) with cardiovascular risk factors and eating habits.

Design

Cross-sectional study.

Setting

Preventive medicine centre.

Subjects

In 5478 adults (32% women, aged 20–80 years) who consecutively underwent a standardised health examination, leisure-time physical activity (LTPA; i.e. non-sport leisure and sport activities), occupational physical activity (OPA) and eating habits were assessed by self-administered questionnaires. We analysed sex-specific relationships of LTPA and OPA (in quartiles) with (1) various cardiovascular risk factors and (2) eating habits using analysis of variance and logistic regression, respectively.

Results

In both genders, with and without adjustment for education in addition to age, LTPA was associated negatively with body mass index, body fat, waist circumference, resting heart rate, diastolic blood pressure and triglycerides, and positively associated with high-density lipoprotein cholesterol (all P ≤ 0.005). OPA adjusted for age only was positively associated with most cardiovascular risk factors but these associations were not significant after further adjustment on education (except for waist circumference in women). Age- and education-adjusted LTPA was associated with increased frequency of consumption of fruits (odds ratio (OR) = 2.05, 95% confidence interval (CI) 1.68–2.52 in men; OR = 1.90, 95% CI 1.41–2.05 in women) and vegetables (OR = 1.81, 95% CI 1.48–2.21 in men; OR = 2.22, 95% CI 1.66–2.97 in women).

Conclusions

The data emphasise the favourable associations of LTPA, a modifiable behaviour, with various cardiovascular risk factors and healthy eating habits. The results also suggest that the relationships of OPA with cardiovascular risk factors depend, at least in part, on socio-economic status as reflected by educational level.

The effects of long-term regular exercise on endothelial functions, inflammatory and thrombotic activity in middle-aged, healthy men

As studying with population carrying no classical cardiovascular risk factors seems to be an advantage in isolating effects of regular exercise on endothelial functions, inflammatory and thrombotic activity; the present study was designed to evaluate the clear effects of long-term regular exercise in middle-aged, healthy men. A total of 32 regularly exercising (three times per week, 12.8 ± 6.8 years) men (Group I, mean age = 53.2 ± 6. 1 yrs) and 32 sex- and age-matched sedentary subjects (Group II, mean age = 51.0 ± 7.7 yrs) were involved in the study. All participants were non-smokers and with no history of hypertension and diabetes. During one day preceding tests, the subjects refrained from training and maintained their normal diet. In all subjects, body mass index (BMI), percentage of body fat (% BF) and maximal oxygen uptake (VO2max) were calculated. Serum uric acid, glucose, HbA1c, lipids, high-sensitive C-reactive protein (hs-CRP), fibrinogen levels, white blood cell (WBC) and platelet count were measured. Resting heart rates and blood pressures were recorded and standard exercise stress test was applied using the modified Bruce protocol. Flow-mediated and nitrate-induced dilatation (FMD and NID) of the brachial artery and carotid intima-media thickness (cIMT) were evaluated as markers of endothelial functions and early atherosclerosis. Mean BMI, % BF, systolic and diastolic blood pressures, WBC and platelet count, HbA1c, total and LDL cholesterol, hs-CRP and fibrinogen levels were similar between the groups. Group I had significantly lower serum glucose, uric acid and triglyceride (p < 0.05, p < 0.005 and p < 0.05, respectively) and higher HDL cholesterol levels (p < 0.0001) than in Group II. FMD values were significantly higher in Group I than in Group II (p < 0.005) while there were no significant differences in NID and cIMT measures between the groups. VO2max and cIMT showed a negative correlation in Group I (r = -0.463, p < 0.0001). Negative correlations also existed between VO2max and fibrinogen levels in both Group I and II (r = -0.355, p < 0.05 and r = -0.436, p < 0.05, respectively). These results are concordant with the concept of favorable effects of regular physical exercise on cardiovascular health based on enhancement of endothelial functions even in subjects who have low cardiovascular risk profile. Key PointsThe present study results suggest that regular exercise is effective on endothelial functions even in subjects who have low risk for cardiovascular disease.Therefore, regular exercise is feasible in improving endothelial functions independently from cardiovascular risk profile.

Effects of exercise training on pathological cardiac hypertrophy related gene expression and apoptosis

This study determined whether exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial and apoptosis-associated genes. We used spontaneously hypertensive rats (n=15, non-exercise SHR), exercise-trained SHR (n=15, treadmill exercise for 12 weeks), and sedentary Wistar-Kyoto (WKY) rats (n=15). Exercise-trained SHR expressed adaptive changes such as reduced body weight, heart rate, blood pressures, left ventricle wall thickness, lipid profiles, and homocysteine level. The mRNA expression of angiotensin converting enzyme, endothelin-1, and brain natriuretic peptides in the heart was lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR, whereas mRNA expression of caveolin-3 and eNOS in the heart was higher. Bcl-2 protein was higher in the exercise-trained SHR than in the WKY and the non-exercise SHR. In contrast, Bax protein levels were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. Furthermore, the levels of the active forms of caspase-3 (20 kDa) were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. These findings suggest that exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial genes and that it interferes with a signal transduction pathway of apoptosis secondary to the pathological cardiac hypertrophy.

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.

Established and recently identified coronary heart disease risk factors in young people: the influence of physical activity and physical fitness

Epidemiological studies have identified several risk factors for coronary heart disease (CHD), many of which are present in young people. [For the purpose of this review, the phrase "young people" embraces both children and adolescents.] One such risk factor is hypertension. In adults, exercise is thought to have a positive effect on blood pressure levels; however, findings are inconclusive for young people. Despite its association with CHD, obesity is on the increase in Western society's young population; prevention and intervention during early years is needed. An active lifestyle is considered to have a beneficial effect on body fatness. Lipoprotein profiles are directly associated with CHD status. In adults, there is some evidence that physical activity and/or fitness have a favourable effect on lipoprotein levels. Although information regarding the younger population is more ambiguous, it tends to concur with these findings. High levels of lipoprotein(a), are considered an independent risk factor for CHD. Relatively little has been written on young people, although some studies have postulated a favourable relationship with physical activity. An inverse relationship between aerobic fitness and CHD has been confirmed in adults; an association is not as easily verified for young people. Physical activity is similarly deemed to have a beneficial effect on health status. A high-fat diet has been linked to CHD in adults, and evidence to date reports similar findings for young people. Smoking increases the risk of CHD and even moderate smoking during youth could have damaging long-term consequences. There is some evidence that smoking is related to physical activity and fitness levels in young people. In adults, high levels of homocyst(e)ine have been associated with CHD. As yet, little has been written on the relationship between physical activity or physical fitness and homocysteine status in young people. High levels of plasma fibrinogen have been linked to CHD. Several studies have explored the relationship between plasma fibrinogen and physical activity and/or fitness in adults, but findings are inconclusive; for young people, the ambiguity is even greater. C-reactive protein is a molecular marker for CHD but, to date, little attention has been given to this aspect, especially amongst young people. The link between high levels of plasminogen activator inhibitor-1 and CHD has been confirmed, although the essence of this relationship is not established. There is a paucity of data on the younger population and the relevance of collating such information is questionable. For the younger population, most research is limited to the established CHD risk factors and further investigations of recently identified CHD risk factors are needed.

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.

Physical fitness and C-reactive protein level in children and young adults: the Columbia University BioMarkers Study

OBJECTIVE

To examine the association of physical fitness with C-reactive protein (CRP) level in children and young adults.

METHODS

Subjects (N = 205) aged 6 to 24 years were enrolled in the Columbia University BioMarkers Study (1994-1998). Physical fitness was assessed using a non-effort-dependent treadmill testing protocol (physical work capacity at heart rate of 170 beats per minute). CRP level was measured using a high-sensitivity assay.

RESULTS

Subjects were 54% female and 65% of Hispanic origin. Mean fitness level was higher in boys than in girls, but CRP levels did not differ by gender. Fitness level was inversely correlated with CRP (r = -0.22). This relationship was significant in boys (r = -0.32) but not in girls (r = -0.15). After multivariate regression adjustment for age, race/ethnicity, body mass index, and family history of early-onset ischemic heart disease, physical fitness remained inversely associated with CRP level in boys (beta = -0.02; standard error = 0.01).

CONCLUSIONS

These findings indicate that physical fitness is inversely related to CRP level in children and that this relationship is more pronounced in boys than in girls.

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.

The effect of high-protein diets on coronary blood flow

Recent research has demonstrated that successful simultaneous treatment of multiple risk factors including cholesterol, triglycerides, homocysteine, lipoprotein (a) [Lp(a)], fibrinogen, antioxidants, endothelial dysfunction, inflammation, infection, and dietary factors can lead to the regression of coronary artery disease and the recovery of viable myocardium. However, preliminary work revealed that a number of individuals enrolled in the original study went on popular high-protein diets in an effort to lose weight. Despite increasing numbers of individuals following high-protein diets, little or no information is currently available regarding the effect of these diets on coronary artery disease and coronary blood flow. Twenty-six people were studied for 1 year by using myocardial perfusion imaging (MPI), echocardiography (ECHO), and serial blood work to evaluate the extent of changes in regional coronary blood flow, regional wall motion abnormalities, and several independent variables known to be important in the development and progression of coronary artery disease. Treatment was based on homocysteine, Lp (a), C-reactive protein (C-RP), triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, and fibrinogen levels. Each variable was independently treated as previously reported. MPI and ECHO were performed at the beginning and end of the study for each individual. The 16 people (treatment group/TG) studied modified their dietary intake as instructed. Ten additional individuals elected a different dietary regimen consisting of a "high-protein" (high protein group/HPG) diet, which they believed would "improve" their overall health. Patients in the TG demonstrated a reduction in each of the independent variables studied with regression in both the extent and severity of coronary artery disease (CAD) as quantitatively measured by MPI. Recovery of viable myocardium was seen in 43.75% of myocardial segments in these patients, documented with both MPI and ECHO evaluations. Individuals in the HPG showed worsening of their independent variables. Most notably, fibrinogen, Lp (a), and C-RP increased by an average of 14%, 106%, and 61% respectively. Progression of the extent and severity of CAD was documented in each of the vascular territories with an overall cumulative progression of 39.7%. The differences between progression and extension of disease in the HPG and the regression of disease in the TG were statistically (p<0.001) significant. Patients following recommended treatment for each of the independent variables were able to regress both the extent and severity of their coronary artery disease (CAD), as well as improve their myocardial wall motion (function) while following the prescribed medical and dietary guidelines. However, individuals receiving the same medical treatment but following a high-protein diet showed a worsening of independent risk factors, in addition to progression of CAD. These results would suggest that high-protein diets may precipitate progression of CAI) through increases in lipid deposition and inflammatory and coagulation pathways.

Plasma viscosity and its biochemical predictors: associations with lifestyle factors in healthy middle-aged men

The association of lifestyle factors and biochemical variables with plasma viscosity was examined in a sample of middle-aged males of high social status. Analyses were performed on a subsample of men that had relevant rheological and biochemical variables determined during a preventive medical assessment conducted between 1992 and 1996. Among 622 subjects (64 smokers), measures of physical activity or predicted VO2max and adiposity (sum of subcutaneous skinfolds) were the lifestyle factors significantly associated with plasma viscosity (both P < 0.001). Among the biochemical variables, serum total protein and plasma fibrinogen concentrations accounted for most of the explained variability in plasma viscosity within subjects (combined adjusted r2 = 65.5%). Logarithm-transformed triglyceride, leukocyte count and serum globulin together contributed an additional 3.0% of the variance in plasma viscosity. Serum total protein, In triglycerides and leukocyte count decreased significantly across higher quartiles of predicted VO2max (all P < 0.0001), with trends towards lower fibrinogen and globulin concentrations (P = 0.054 and P = 0.050, respectively). Higher levels of adiposity were also significantly associated with higher levels of serum total protein (P < 0.0001), globulin (P < 0.0001), fibrinogen (P < 0.01), leukocyte count (P < 0.05), and triglycerides (P < 0.0001). The association of lifestyle factors with the biochemical predictors of plasma viscosity may result directly from a pro-inflammatory state of adipose tissue origin and/or a larger plasma volume related to higher levels of cardiorespiratory fitness. Randomised controlled trials of the effects of regular physical activity of different intensities on plasma viscosity, with reference to body composition, are now required.

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.

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.

Physical activity, cardiorespiratory fitness, and the primary components of blood viscosity

PURPOSE

The relationship of both self-reported leisure time physical activity (LTPA) and predicted maximum oxygen consumption (VO2max) with plasma viscosity and hematocrit (Hct) concentration was examined within a cross-sectional sample of employed middle-aged men.

METHODS

Analyses were performed on a subsample of nonsmoking men who completed a preventive medical assessment between 1992-1996.

RESULTS

Among nonsmokers the mean age-adjusted levels of plasma viscosity (N = 590) and Hct concentration (N = 632) were significantly lower with higher Physical Activity Index (PAI) categories (P = 0.001 and P = 0.01, respectively). Following adjustment for conventional IHD risk factors and blood leukocyte count, a significant inverse relationship remained for Hct (P = 0.044) but not plasma viscosity. Mean age-adjusted plasma viscosity and Hct concentration also showed a significant decrease with higher quartiles of predicted VO2max (mL x kg(-1) x min(-1))(P = < 0.00005 and P = 0.0004, respectively). Following adjustment for all confounding variables mean plasma viscosity and Hct concentration remained significantly lower with higher quartiles of predicted VO2max (mL x kg(-1) x min(-1))(P = < 0.00005 and P = 0.047).

CONCLUSIONS

These data confirm the inverse relationship between LTPA and/or predicted VO2max with plasma viscosity and Hct concentration within nonsmoking middle-aged men of high socioeconomic status.

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.

Exercise stress testing. An overview of current guidelines

Exercise stress testing (ET) is an inexpensive noninvasive tool that provides valuable cardiopulmonary information in healthy and diseased populations. It is most commonly used for diagnosing coronary artery disease (CAD) and developing appropriate exercise prescriptions (EP). With its widespread use and application, it is imperative that safe and appropriate guidelines and procedures are used, as there are a number of risks associated with testing in a population with or suspected of having CAD. The focus should be on the patient's safety: personnel must be properly trained and aware of all emergency procedures, contra-indications for ET and indications for test termination must be strictly adhered to. Three main types of testing are prevalent: submaximal, maximal and maximal utilising gas exchange. The maximal test is most commonly used, and the submaximal is appropriate for hospitalised patients. Gas exchange data is essential when assessing congestive heart failure and timing for heart transplantation. ET is commonly performed using a treadmill or a bicycle ergometer. The treadmill provides a more familiar exercise modality and has been shown to have greater diagnostic sensitivity than the bicycle ergometer; it is, however, more expensive and requires more space in the testing room. The bicycle ergometer is more appropriate for those individuals who are severely obese or have problems with extended periods of walking. Regardless of the modality used, an appropriate exercise protocol should be used. In North America, the Bruce protocol is the most common. However, the Bruce protocol, and others that estimate exercise capacity based on equations, tend to overestimate exercise capacity. They may be too demanding for those with limited exercise capacity, and too long for those with high exercise capacity. For these people, an exercise protocol that reaches maximal capacity in 8 to 12 minutes using smaller increments in workload should be considered. Once completed, the results of ET needs to be correctly interpreted. This includes reviewing the test results while considering the patient's history, medications and indication for the test. ET can also be used to develop an EP for the participant. An EP should take into account the intensity, modality of exercise, frequency and duration, as well as being realistic for the individual and the goals to be achieved. All the information from the test results and the pre-test examination should be presented in a report that also includes the advised EP.

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.

Aerobic and myocardial demands of lawn mowing in patients with coronary artery disease

Lawn mowing approximates 4 to 6 METs and may evoke heart rate and systolic blood pressure responses that approach and exceed those attained during maximal exercise testing. The excessive cardiac demands may be deceptively camouflaged by the moderate aerobic requirements and perceived effort.

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.

Influence of exercise training on blood viscosity in patients with coronary artery disease and impaired left ventricular function

Exercise training has recently become an accepted therapeutic modality in chronic heart failure after myocardial infarction. Because the therapeutic mechanism behind it is controversial and not well understood, we analyzed the influence of exercise training on blood viscosity. Twenty-five patients with chronic heart failure (ejection fraction < 40%) after myocardial infarction were randomly assigned to either an 8-week intensive exercise program at a residential rehabilitation center or 8 weeks of sedentary life at home. Exercise consisted of two 1-hour walking sessions per day and four intensive bicycle ergometer training sessions of 40 minutes at 70% to 80% peak exercise capacity per week. Whole blood viscosity, viscosity at standardized hematocrit of 45% (P45) at high and low shear rates, and plasma viscosity were measured in a Couette-type viscometer before, during, and at the end of the study period. Exercise training, which significantly increased maximal cardiac output and oxygen uptake, did not change plasma viscosity, whole blood viscosity, and P45 significantly. Sedentary controls, however, had a higher whole blood viscosity and P45 after 8 weeks. No statistical difference was found, however, between the two groups. We conclude that blood rheology remains unaffected by exercise training in patients with chronic heart failure. The improvement of blood viscosity remains an interesting therapeutic option for the symptoms of these patients, which must be achieved by methods other than exercise training.

Measurement of fibrinogen in frozen plasma

Several large studies have compared fibrinogen measurements determined over a particular time interval. These assays are subject to difficulties encountered by all laboratories on tests carried out over a period of time such as assay drift. To avoid this problem, plasma can be stored frozen and fibrinogen determined in a large number of samples simultaneously. However, a thorough comparison of measurements carried out in fresh and frozen plasma has not yet been performed. Fibrinogen concentration was therefore determined in fresh plasma samples and then at a later date in the same samples after storage at -70 degrees C. A good correlation was observed between the two measurements, however, bias increased at the higher fibrinogen levels which are most critical in the determination of thrombotic risk. An increase in measurement error as a result of freezing was also observed. These effects may, therefore, be important considerations in future studies of this nature.

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)

Intra-individual variability of fibrinogen levels

Elevated fibrinogen concentrations are recognized as playing an important role in the pathogenesis of atherosclerosis. In the framework of a risk factor survey in 342 middle-aged working men, screened twice over a period of five months, plasma fibrinogen levels were found to be fairly unstable as large discrepancies between both measurements were observed. Due to a substantial proportion of within-person variability, the reliability coefficient was only R = 0.56. Repeatability was highest in higher educated and physically more active men. Our data suggest that the impact of elevated fibrinogen levels on the development of ischemic heart disease and stroke, is likely to be under-estimated.

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, 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.

Regular physical activity and changes in risk factors for coronary heart disease: a nine months prospective study

This study reports the non-acute effects of a long-term training programme of increasing intensity on some cardiovascular risk factors and the interrelation between these risk factors. Twenty sedentary men and 14 sedentary women were trained 3 to 4 times a week for nine months. After 36 weeks all individuals ran a half marathon run. The Wmax, weight, body mass index, systolic and diastolic blood pressure were recorded. The concentrations of fibrinogen, tissue plasminogen activator, plasminogen activator inhibitor, triacylglycerols, total cholesterol, LDL cholesterol, HDL cholesterol and lipoprotein(a) were measured. The training programme induced a median increase in Wmax of 12% in the male group (from 226 to 251.5 Watt) and of 18% in the female group (from 160 to 188.5 Watt). These increases inn Wmax did not correlate with any other property under investigation in this study. Blood pressure was not altered, but body weight and body mass index were significantly decreased in the male group (from 74.6 to 72.2 kg and from 23.1 to 22.0 kg/m2, respectively) at the end of the training programme and decreased non-significantly in the female group (from 63.0 to 60.7 kg and from 21.6 to 21.5 kg/m2, respectively). In the male group total cholesterol, low density lipoprotein cholesterol and triacylglycerols decreased significantly under the influence of the training sessions. Furthermore, in both groups, a great decrease in plasma plasminogen activator inhibitor concentrations was noticed: in men from 22.5.10(3) AU/l to 4.5.10(3) AU/l and in women from 18.7 x 10(3) AU/l to 5.1 x 10(3) AU/l. However, the changes in the lipid and fibrinolytic quantities were not correlated with each other. Initial total cholesterol, LDL cholesterol and triacylglycerol levels correlated significantly with systolic blood pressure, while diastolic pressure was correlated to tissue plasminogen activator. Since tissue plasminogen activator also was significantly related to triacylglycerols, a trias existed between primary risk factors like blood pressure, lipid levels and fibrinolysis. In contrast, the changes in these properties under the influence of physical training were not interrelated. Median serum lipoprotein(a) concentrations were significantly increased in both men and women five days before the half marathon run: from 32 mg/l to 39 mg/l in men, and from 65 mg/l to 125.5 mg/l in women. Concomitantly, median fibrinogen concentrations were significantly elevated in men (from 2.32 g/l to 3.10 g/l) and non-significantly in women (from 2.62 g/l to 2.93 g/l), although no correlation existed between the changes in these properties. In conclusion, the nine months exercise programme increased the aerobic fitness in both men and women as indicated by the Wmax increase. This improvement coincided but was not correlated with beneficial changes in several anthropometric, lipid and fibrinolytic properties. Improvement in the risk factors under investigation was more pronounced in men than in women. The changes in lipid and haemostasis properties did not correlate with each other. The increases in lipoprotein(a) and fibrinogen concentrations, both atherogenic indices, could actually present a normal physiological response to the physical strain of exercise training of increasing workload.

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.

Increased fibrinogen levels in the offspring of hypertensive men. Relation with hyperinsulinemia and the metabolic syndrome

Epidemiological studies have revealed that elevated fibrinogen concentrations are associated with an increased risk of myocardial infarction, stroke, intermittent claudication, and cardiovascular mortality. The manner in which fibrinogen operates in atherogenesis has not yet been elucidated, but genetic control of fibrinogen levels is partially responsible. Fibrinogen frequently acts in concert with hyperlipidemia, diabetes, hypertension, physical inactivity, and age, variables that are influenced by insulin action. Because the offspring of hypertensive men tend to be hyperinsulinemic and insulin resistant from a young age, we hypothesized that their increased fibrinogen levels might reflect decreased insulin action and thus play a role in the metabolic syndrome. We chose 48 adult offspring (mean age, 38.4 years) of 30 fathers who had been treated for hypertension, and the former were matched by age, body mass index, sex, and smoking habits with 37 control subjects. Elevations in fibrinogen concentration (3.63 +/- 0.93 versus 2.87 +/- 0.54 g/L, P < .001) paralleled increases in blood glucose and insulin levels, estimates of insulin resistance, and blood pressure. In the offspring, in contrast to the control group, correlations between fibrinogen and metabolic-syndrome variables (ie, insulin, glucose, and waist and hip circumferences) were found. In stepwise multiple regression analyses, age and smoking habits were entered as variables in both study groups, but postload insulin and high-density lipoprotein cholesterol were entered as variables in the offspring group only. We propose that familial predisposition influences the relationship between insulin concentration and fibrinogen, an effect that may contribute to the clinical importance of the metabolic syndrome.

Effects of different antihypertensive drugs on plasma fibrinogen in hypertensive patients

1. In order to evaluate whether treatment with different antihypertensive drugs would affect plasma fibrinogen levels, 118 mild to moderate essential hypertensive subjects, all males, aged 18 to 65 years, were randomly treated with amlodipine 10 mg, atenolol 100 mg, hydrochlorothiazide 25 mg or lisinopril 20 mg, all given once daily for 8 weeks. 2. Before and after 8 weeks' treatment, blood pressure (BP), heart rate (HR), fibrinogen, total cholesterol (TC), HDL-C, LDL-C, triglycerides (TG), plasma glucose, plasma uric acid, serum creatinine and serum potassium were evaluated. 3. All four medications significantly reduced BP values, although the BP lowering effect of lisinopril, amlodipine and atenolol was significantly greater compared with that of hydrochlorothiazide. 4. Plasma fibrinogen levels were unaffected by atenolol, hydrochlorothiazide and amlodipine, whereas they were significantly decreased by lisinopril (-11.2%, P = 0.002). This fibrinogen lowering effect was more evident in smokers (-17.7%) than in non smokers (-7.4%). 5. Atenolol and amlodipine did not significantly affect plasma lipids, hydrochlorothiazide increased TC, LDL-C and TG and reduced HDL-C; lisinopril increased HDL-C and decreased TC and LDL-C. 6. Hydrochlorothiazide increased plasma glucose and uric acid concentrations, which were unaffected by the other drugs. The diuretic also reduced serum potassium. 7. The results of this study indicate that lisinopril reduces levels of plasma fibrinogen and confirm that different antihypertensive drugs may elicit different metabolic effects, which may variously influence the overall risk profile of the hypertensive patients.

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.

Leisure-time physical activity and other health behaviours: are they related?

Data on the associations between leisure-time physical activity and other health behaviours are conflicting. The National Heart Foundation 1989 Risk Factor Prevalence Survey data were analysed to examine the associations between leisure-time physical activity and other life-style health behaviours in a national representative sample with adjustment for potential confounders. Multivariate stepwise logistic regression analysis using data from 9054 respondents aged 20 to 69 years showed that participation in leisure-time physical activity, even when it was not vigorous, was weakly associated with not smoking, following a special diet and moderate consumption of alcohol; it was inversely associated with obesity. These weak associations could influence health practices at a population level if, as has been hypothesised, the adoption of leisure activity promotes the adoption of other good health practices. Confirmation of earlier findings of cross-sectional associations between activity and other positive health practices justifies future prospective or experimental studies to determine the behavioural response to adoption of leisure-time physical activity.

Fibrinogen: an important risk factor for atherothrombotic diseases

Epidemiological follow-up studies have suggested that fibrinogen is a major, primary cardiovascular risk factor. Cross-sectional results also show associations between fibrinogen and cardiovascular risk factors or diseases. Clinical cohort studies demonstrate that fibrinogen might also be a secondary risk factor. The determinants of the plasma level of fibrinogen in health and disease are known only incompletely. Our understanding of the mechanisms involved in the atherogenic actions of fibrinogen is similarly fragmentary. These might include blood coagulation, blood rheology, platelet aggregation, direct effects on the vascular wall, and the acute phase response. Thus, many questions are yet to be answered. Nevertheless, the data available at present strongly suggest that fibrinogen represents a major, independent cardiovascular risk factor. Fibrinogen should be considered for screening programmes aimed at identifying individuals at risk.