Association of leisure-time physical activity on inflammation markers (C-reactive protein, white cell blood count, serum amyloid A, and fibrinogen) in healthy subjects (from the ATTICA study)

Abstract

T the 20th century, many researchers focused their interest on prevention and therapy of cardiovascular diseases. Among the factors that may influence the occurrence of disease is the beneficial effect of physical activity, which has been discussed in several studies.1–3 In addition, recent studies have provided evidence that inflammation plays a role in the pathogenesis of cardiovascular disease.4,5 Several investigators have addressed the association between fitness and the inflammation process,6–9 but the strength of this relation has not been fully investigated. The aim of this study is to evaluate the effect of various levels of leisure-time physical activity on inflammation markers, such as high-sensitivity C-reactive protein (CRP), fibrinogen, amyloid A, and white blood cell (WBC) counts, in a population-based sample of healthy adults. • • • The ATTICA study is a health and nutrition crosssectional survey that was carried out in the province of Attica from 2001 to 2002. A sample of 891 men and 965 women, aged 18 years old, was drawn from the general population, which excluded persons living in institutions, or subjects with mobility problems or who had chronic disease that could restrict their physical activity status (e.g., arthritis). Also, all subjects entered into this study were without any clinical evidence of coronary heart disease, stroke, or any atherosclerotic disease according to a detailed medical history, a physical examination, and electrocardiography as performed by a cardiologist. The stratification was random and based on the age/gender/city distribution of the Attica area (census of 2001). The study’s design anticipated enrolling only 1 participant per household (78% of the selected subjects participated). The number of the participants was determined by power analysis. All participants were interviewed by trained personnel who used a standard questionnaire. Physical activity was defined as any type of nonoccupational physical exercise 1 time per week, during the past year. A self-reported questionnaire was applied that was based on a special questionnaire for the assessment of leisure-time physical activity.10 Physical activity was graded in qualitative terms as follows: light (expended calories 4 kcal/min, i.e., walking slowly, stationary cycling, light stretching, and so forth), moderate (expended calories 4 to 7 kcal/min, i.e., walking briskly, cycling outdoors, swimming with moderate effort, and so forth), and high (expended calories 7 kcal/min, i.e., walking briskly uphill, long distance running, cycling fast or racing, swimming fast crawl, and so forth). The remaining subjects were defined as physically inactive. The duration of physical activity, in years of exercise, was also taken into account. Venous blood samples were collected between 8 and 10 A.M., with patients seated after 12 hours of fasting and avoidance of alcohol. High-sensitivity CRP levels, as well as fibrinogen levels, were measured by BNII Dade Behring Inc. (Leiderbach, Germany) automatic nephelometry. For the determination of plasma fibrinogen, blood was anticoagulated with 3.8% trisodium citrate (9:1 volume/volume) and cooled on ice until centrifugation. The intraand interassay coefficients of variation of fibrinogen did not exceed 9%, total cholesterol 8%). All other biochemical examinations (uric acid, urea, creatinine, total cholesterol, low-density lipoprotein cholesterol, highdensity lipoprotein cholesterol, triglycerides) were measured using a chromatographic enzymatic method with a Technicon RA-1000 automatic analyzer (TexLab Inc., Houston, Texas). Blood pressure at rest was measured with subject sitting comfortably for 5 to 10 minutes and the cuff arm supported at the heart level. Hypertension was defined as systolic blood pressure 140 mm Hg, diastolic blood pressure 90 mm Hg, or the use of any antihypertensive medication. Hypercholesterolemia was defined as total cholesterol levels 220 mg/dl or the use of antilipidemic medication. Diabetes mellitus was defined as a fasting blood sugar 125 mg/dl or the use of antidiabetic medication. The questionnaire given to subjects included the following demographic characteristics: age, gender, financial status (classified as low, moderate, high, and very high), and educational level (as an index of social status) that was measured in years of schooling. DiFrom the Cardiology Clinic, School of Medicine, University of Athens; Hellenic Heart Foundation, Athens, Greece; and Cardiology Division, Georgetown University, Washington, DC. The ATTICA study is funded by research grants from the Hellenic Cardiological Society and the Hellenic Heart Foundation, Athens, Greece. Dr. Panagiotakos’ address is: 48-50 Chiou Str., Glyfada, 165 61, Attica, Greece. E-mail: D.b.Panagiotakos@usa.net. Manuscript received July 29, 2002; revised manuscript received and accepted September 24, 2002.