Cardiorespiratory fitness and C-reactive protein among a tri-ethnic sample of women

Reference Value for C-Reactive Protein and Its Distribution Pattern in Thai Adults

BACKGROUND

To set a reference value for high-sensitivity C-reactive protein (hs-CRP) in a healthy Thai population and study the effect of time, gender and age on that value.

METHODS AND RESULTS

Three hundred and sixty-four subjects, aged between 18 and 74 years, comprising 185 men and 279 women, were studied. Another 10 healthy subjects, aged between 18 and 54 years, were recruited for the study of circadian variation in hs-CRP over the days of the week and the months of a year. The reference value for the Thai adults in the present study was 1.8 mg/L, range 0.2-7.9 mg/L. There was no significant difference in the hs-CRP concentration because of region, time, gender or age (p>0.05), nor was the value affected by time.

CONCLUSION

The determination of hs-CRP can be performed at any time and the hs-CRP value determined by this study can be used as the reference for Thai adults.

Relationship between physical fitness and lifestyle behaviour in healthy young men

BACKGROUND

There is substantial knowledge about the inverse association of physical fitness and CVD risk factors and CVD mortality. However, physical fitness per se might be influenced by lifestyle conditions such as physical training, smoking and drinking habits.

HYPOTHESIS

We evaluated the relationship between physical fitness, physical activity, endurance training, smoking and drinking habits and blood pressure, lipids and leukocytes as surrogate cardiovascular risk markers in a large-scale cross-sectional study of healthy young men.

STUDY DESIGN AND METHODS

A total of 6748 healthy young men were selected during their primary flight medical examination for military flying duties. Physical fitness was assessed by achieved physical working capacity at a heart rate of 170 beats per min (PWC170) during cycle ergometry. Parameters such as physical activity, endurance sports, smoking of cigarettes and drinking of alcoholic beverages were assessed by means of standardized questionnaires. Systolic and diastolic blood pressures were measured manually. Fasting cholesterol and triglycerides as well as white blood counts were obtained.

RESULTS

Physical activity itself was not related to significant differences in the tested variables, whereas good physical fitness showed a significant association with improved blood pressure and blood lipids (P<0.001) with no detectable threshold. This effect was independent of endurance training, smoking and drinking. Whereas drinking was associated with elevated systolic blood pressure, smoking was associated with markedly increased triglycerides as well as with elevated leukocytes.

CONCLUSION

Physical fitness is associated with improved blood pressure and blood lipids. This effect is independent of participating mainly in endurance or nonendurance sports, of physical activity per se, and it does not depend on smoking and drinking habits. Smoking itself revealed relevant higher inflammation independent of fitness.

Sedentary lifestyles, physical activity, and cardiovascular disease: from research to practice

More than 60% of the world's population is not physically active at levels that promote health. In concert with other behavioral risk factors for cardiovascular disease (CVD), sedentary lifestyles exact a heavy medical and economic toll on individuals and societies. Physical activity lowers all-cause mortality, reduces several risk factors for cardiovascular disease, and is a category 2 intervention that can halve cardiovascular disease risk. The benefits extend across a wide spectrum of structured as well as lifestyle physical activity levels. Models and programs aimed at translating physical activity's promise in cardiovascular prevention have been assessed, but results have been generally disappointing. A pragmatic strategy based on the "stages of change" or transtheoretical model can be effective. It incorporates self efficacy and individual initiatives, both crucial ingredients necessary to surmount the inevitable hurdles on the path towards physically active lifestyles.

Association between leisure time physical activity and markers of chronic inflammation related to coronary heart disease

BACKGROUND

Some markers of chronic inflammation have been recognized as predictors of cardiovascular risk in apparently healthy subjects and in patients with coronary heart disease (CHD). High sensitivity C-reactive protein (CRP) appears to be the most useful marker in clinical settings. Several studies reported associations between inflammatory markers and other cardiovascular risk factors, such as age, obesity, cholesterol levels, the presence of diabetes mellitus, physical activity, social level and smoking habits. We focussed on the association between C-reactive protein, serum amyloid A (SAA), fibrinogen and leisure time physical activity (LTPA).

METHODS

This report deals with the results observed in a sub-sample of the BELSTRESS study. 892 male subjects, free from clinical CHD and major ECG abnormalities, working in the same environment, aged 35-59 years, were selected. A questionnaire was used to estimate the level of leisure time physical activity. Associations between CRP, SAA, fibrinogen and leisure time physical activity were evaluated through univariate and multivariate methods. Subjects taking statins or other lipid lowering medication were excluded from the study.

RESULTS

Regular leisure time physical activity is associated with reductions of several cardiovascular risk factors, such as body mass index (BMI), waist hip ratio and the lipid profile. Smokers and low educated subjects had a lower physical activity status. Age adjustment did not alter the means of inflammatory parameters according to the levels of leisure time physical activity. After correction for personal characteristics (BMI, current smoking status, educational level, presence of diabetes and alcohol consumption) no significant relation was found between leisure time physical activity and levels of inflammatory markers. The differences of CRP and fibrinogen according to the level of physical activity, found in bivariate analysis, seem to be explained by linked differences in BMI, or related to current smoking habits. Leisure time physical activity, as reported in this study, is not significantly related to C-reactive protein, serum amyloid A or fibrinogen levels, after correction for other cardiovascular risk factors.

CONCLUSION

These data indicate that leisure time physical activity, as reported in our study, is not an independent predictor of C-reactive protein, serum amyloid A or fibrinogen levels. Possible interactions of physical activity and other cardiovascular risk factors might explain the (indirect) relation we found in the bivariate analysis.

C-Reactive protein is inversely related to physical fitness in middle-aged subjects

INTRODUCTION

Physical fitness has a protective effect with regard to the risk of developing coronary disease or diabetes. C-reactive protein (CRP) levels are directly related to increased risk of coronary disease and diabetes. However, data on the association between physical fitness and CRP are sparse.

METHODS

Physical fitness was assessed in a population-based cross-sectional study (n = 892; age 50 +/- 9 years) using the Bruce treadmill protocol. CRP was measured using a high-sensitivity assay.

RESULTS

Geometric mean CRP levels were calculated across quartiles of physical fitness after adjustment for age, gender, body mass index, smoking habit, presence of diabetes and hypertension, HDL cholesterol and triglyceride levels, and use of hormone replacement therapy, statins, and aspirin. CRP levels decreased with increasing quartiles of fitness (P for trend <0.0001). When used as a continuous variable in a stepwise linear regression model, the geometric mean of CRP decreased by 0.061 mg/L (95% confidence interval (CI) 0.034-0.089 mg/L) for each 1 unit increase in metabolic equivalents (METs). Multivariate logistic regression models showed that compared to subjects in the lowest fitness quintile, subjects in the highest fitness quintile had significantly lower adjusted odds of having a high-risk (>3 mg/L) CRP level (OR 0.53; 95% CI 0.39-0.71, P = 0.007).

CONCLUSION

CRP concentration decreases continuously with increasing levels of physical fitness. The health-related salutary effects of physical fitness may be mediated, in part, through an antiinflammatory mechanism.

C-reactive protein genotypes affect baseline, but not exercise training-induced changes, in C-reactive protein levels

OBJECTIVE

The goal of this study is to determine whether C-reactive protein (CRP) gene variants affect baseline and training-induced changes in plasma CRP levels.

METHODS AND RESULTS

Sixty-three sedentary men and women aged 50 to 75 years old underwent baseline testing (Vomax, body composition, CRP levels). They repeated these tests after 24 weeks of exercise training while on a low-fat diet. The CRP +219G/A variant significantly associated with CRP levels before and after training after accounting for the effects of demographic and biological variables. CRP -732A/G genotype was significantly related on a univariate basis to CRP levels after training. The CRP +29T/A variant did not affect CRP levels before or after training. In regression analyses, the +219 and -732 variants each had significant effects on CRP levels before and after training. Subjects homozygous for the common A/G -732/+219 haplotype exhibited the highest CRP levels, and having the rare allele at either site was associated with significantly lower CRP levels. CRP levels decreased significantly with training (-0.38+/-0.18 mg/L; P=0.03). However, none of the CRP variants was associated with the training-induced CRP changes.

CONCLUSIONS

CRP +219G/A and -732A/G genotypes and haplotypes and exercise training appear to modulate CRP levels. However, training-induced CRP reductions appear to be independent of genotype at these loci.

C-reactive protein as a screening test for cardiovascular risk in a multiethnic population

BACKGROUND

Small increases in the inflammatory marker C-reactive protein (CRP) are predictive of vascular events among asymptomatic individuals. There are few data supporting the use of CRP as a risk marker among nonwhite individuals.

METHODS AND RESULTS

1250 adults of South Asian, Chinese, European, and Aboriginal ancestry were randomly sampled from 4 communities in Canada. Participants provided fasting blood samples for CRP, glucose, lipids, and coagulation factors, and they had undergone a carotid B-mode ultrasound. Cardiovascular disease was determined by history and electrocardiogram. The age- and sex-adjusted mean CRP was 3.74 mg/L (standard error, 0.14) among Aboriginals, 2.59 mg/L (0.12) among South Asians, and 1.18 mg/L (0.13) among Chinese compared with 2.06 mg/L (0.12) among Europeans (overall P<0.0001). Differences in the CRP concentration between ethnic groups were substantially diminished, but not abolished, after adjustment for metabolic factors. CRP was independently associated with CVD after adjusting for the Framingham risk factors, atherosclerosis, anthropometric measurements, and ethnicity (OR=1.03 for a 0.1-increase in CRP; P=0.02).

CONCLUSIONS

CRP varies substantially between people of different ethnic origin and is influenced by their differences in metabolic factors. Prospective validation of CRP as a risk predictor for cardiovascular disease among nonwhite ethnic groups is required.

C-reactive protein levels among women of various ethnic groups living in the United States (from the Women's Health Study)

The distribution of C-reactive protein (CRP) levels was compared among 24,455 white, 475 black, 357 Asian, and 254 Hispanic women, all of whom are participants in the Women's Health Study. Median CRP levels were significantly higher among black women (2.96 mg/L, interquartile range [IQR] 1.19 to 5.86) than among their white (2.02 mg/L, IQR 0.81 to 4.37), Hispanic (2.06 mg/L, IQR 0.88 to 4.88), and Asian (1.12 mg/L, IQR 0.48 to 2.25) counterparts. As expected, women taking hormone replacement therapy had higher baseline CRP levels than women not taking hormone replacement therapy. No differences in low-density lipoprotein cholesterol or total cholesterol levels were observed between ethnic groups. In multivariate regression models, body mass index was a significant (p <0.001) predictor of elevated CRP concentrations among all race/ethnic groups, and control for body mass index substantially attenuated the differences noted in CRP levels across race/ethnic groups, particularly among black women. Control for all measured modifiable risk factors for cardiovascular disease did not entirely explain CRP differences. Among these women, the distribution of CRP levels varied significantly between the various race/ethnic groups.

Low cardiorespiratory fitness is associated with elevated C-reactive protein levels in women with type 2 diabetes

OBJECTIVE

The purpose of this study was to examine differences in novel markers of cardiovascular disease (CVD) in women with type 2 diabetes stratified according to cardiorespiratory fitness.

RESEARCH DESIGN AND METHODS

A total of 28 women (mean age 57 +/- 6 years) with type 2 diabetes who were free from overt CVD were placed into low cardiorespiratory fitness (LCF) or average cardiorespiratory fitness (ACF) groups based on a graded exercise test to exhaustion. A group of eight women without type 2 diabetes were also examined and served as healthy control subjects. The median VO(2peak) value was used as a cutoff for group determination. We assessed both conventional CVD risk factors, including blood pressure, BMI, and lipid profile, as well as novel CVD risk factors, such as left ventricular filling dynamics, arterial stiffness, fasting insulin, and C-reactive protein (CRP).

RESULTS

VO(2peak) values were 69 +/- 14 and 91 +/- 24% of predicted values for sedentary age-matched healthy individuals in the LCF and ACF groups, respectively. BMI was significantly greater in the LCF group (P < 0.05); however, no differences were observed in age, lipid profile, or resting hemodynamics. CRP was 3.3-fold higher in the LCF group (6.3 +/- 41. vs. 1.9 +/- 1.7 mg/l, P < 0.05), whereas other novel markers of CVD were not significantly different between the groups. Significant negative relationships were observed between VO(2peak) and both CRP (r = -0.49) and the homeostasis model assessment index (r = -0.48) (P < 0.05).

CONCLUSIONS

The novel finding of this investigation is that low cardiorespiratory fitness is associated with elevated CRP and reduced fasting glucose control in women with type 2 diabetes.

Distribution and correlates of C-reactive protein concentrations among adult US women

BACKGROUND

Understanding the distribution of C-reactive protein (CRP) concentration among adult women in the US helps to establish the magnitude of women at increased risk for cardiovascular disease.

METHODS

We examined the distribution and correlates of CRP, using data from 2205 women >or=20 years of age from the National Health and Nutrition Examination Survey 1999-2000. CRP was measured with a high-sensitivity latex-enhanced turbidimetric assay.

RESULTS

CRP concentration ranged from 0.1 to 296.0 mg/L (median, 2.7 mg/L). After exclusion of women with a CRP concentration >10 mg/L, the median was 2.2 mg/L. Approximately 25.7% of women, representing approximately 26.8 million women, did not report using hormone replacement therapy and had a CRP concentration >3.0 to 10 mg/L, a category considered to indicate high risk for cardiovascular disease. Multiple linear regression analysis included age, race or ethnicity, education, smoking status, total cholesterol concentration, triglyceride concentration, systolic blood pressure, waist circumference, and concentrations of glucose, insulin, c-peptide, and glycated hemoglobin. CRP concentration varied by race or ethnicity (Mexican American > white) and hormone replacement therapy (users > nonusers). In addition, significant and independent associations existed between CRP and waist circumference, total cholesterol and triglyceride concentrations, and systolic blood pressure but not age, smoking status, alcohol use, insulin concentration, glycated hemoglobin, and c-peptide concentration.

CONCLUSION

Large numbers of US women have an increased concentration of CRP.

The interleukin-6 promoter polymorphism is associated with elevated leukocyte, lymphocyte, and monocyte counts and reduced physical fitness in young healthy smokers

Smoking and interleukin-6 are important factors in driving inflammation. This study assessed the relationship between smoking, interleukin-6 genotype, physical fitness, and peripheral blood count in healthy young men. For this interleukin-6 promoter polymorphism -174 genotype-phenotype association study 1,929 healthy German male aviators recruited at the central German Air Force Institute of Aviation Medicine were stratified by smoking habits. Cardiovascular fitness was expressed as maximal physical working capacity (PWCmax) in watts per kilogram body weight as assessed by maximal exercise testing by cycle ergometry up to physical exhaustion. Smokers had higher leukocyte and lymphocyte counts than nonsmokers and lower PWCmax. In the overall study population the C allele of the interleukin-6 polymorphism was weakly associated with elevated leukocytes and lymphocytes; in nonsmokers the interleukin-6 polymorphism was not associated with altered phenotypes, but in smokers the interleukin-6 C allele was associated with higher leukocytes, lymphocytes, and monocytes and with lower PWCmax. Smoking is thus associated with elevated leukocytes and lymphocytes and with reduced physical fitness. Gene carriers with the interleukin-6 C allele may suffer particularly from cigarette smoking.

Vascular inflammation: a role in vascular disease in hypertension?

PURPOSE OF REVIEW

In this review, we summarize the more recent clinical evidence highlighting the importance of vascular inflammation in terms of clinical risk prediction, and the mechanisms mediating the upregulation of inflammatory mediators in cardiovascular disease and hypertension.

RECENT FINDINGS

Markers of inflammation have been shown to be upregulated in different forms of cardiovascular disease, and to correlate with vascular risk. Atherosclerosis is characterized by chronic inflammation of the vascular wall. The I-kappaB/nuclear factor-kappaB system is considered a major intracellular inflammatory pathway, mediating most of the vascular inflammatory responses. Increasing evidence indicates that hypertension, through the vasoactive peptides angiotensin and endothelin-1, promotes and accelerates the atherosclerotic process via inflammatory mechanisms. In animal and human studies proinflammatory properties of angiotensin II have been demonstrated in large conduit and small arteries, in the kidney as well as in the heart. The angiotensin II receptors involved in the inflammatory process and the interaction between angiotensin II and nitric oxide in mediating vascular inflammation have been identified. In addition, recent advances concerning the role of endothelin-1 as another important mediator of chronic inflammation in the vascular wall has been documented, and the relationship between endothelin-1 and angiotensin II on vascular inflammation demonstrated.

SUMMARY

Inflammatory mechanisms are important participants in the pathophysiology of hypertension and cardiovascular disease. The identification of useful markers of inflammation, of new therapeutic targets to interfere with these mechanisms, and the evaluation of the efficacy of antiinflammatory treatments will allow progress in our ability to combat cardiovascular disease and the complications of hypertension.

Physical activity, body fat, and serum C-reactive protein in postmenopausal women with and without hormone replacement

The objective was to determine whether higher physical activity is associated with lower serum C-reactive protein (CRP), independent of oral hormone replacement therapy (HRT) status and body fatness, in 133 postmenopausal women using a cross-sectional exploratory design at a university research laboratory. The subjects were 133 postmenopausal women, age 50-73 years, with no evidence of coronary artery disease or diabetes. The main outcome measures were: serum CRP, physical activity as measured by Stanford 7-day activity recall, body fat (both total and regional) as measured by dual energy X-ray absorptiometry (DXA), and anthropometry (waist and hip circumference). Secondary outcome measures included fasting plasma glucose and insulin as well as fasting serum triglycerides, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Higher physical activity energy expenditures were significantly associated with lower serum CRP levels (r = -0.18, P = 0.041), independent of oral HRT use, age, smoking behavior, alcohol consumption, aspirin use, and statin use. However, in the complete multivariate model, which included body fat, older ages (P = 0.047), greater trunk fat masses (P < 0.001), any oral HRT use (P < 0.001), and unopposed oral estrogen use (P = 0.012) were the sole independent predictors of higher serum CRP levels. The complete multivariate model accounted for 58% of the variance in serum CRP. We conclude that the association between higher physical activity and lower serum CRP levels is dependent on the lower body fat of the more active women, yet independent of oral HRT use. Future intervention trials should determine whether diet- and exercise-related reductions in body fat may be effective ways to diminish the proinflammatory effects of oral HRT in postmenopausal women.