CARROLL, S., C. B. COOKE, and R. J. BUTTERLY. Leisure time physical activity, cardiorespiratory fitness, and plasma fibrinogen concentrations in nonsmoking middle-aged men. Med. Sci. Sports Exerc., Vol. 32, No. 3, pp. 620–626, 2000.
Purpose: The relationship of both leisure time physical activity and predicted maximum oxygen consumption (V̇O2max) 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 (PAI) categories and quartiles of predicted V̇O2max (mL · kg−1 · 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 V̇O2max (mL · kg−1 · 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 V̇O2max (mL · kg−1 · min−1) with fibrinogen concentrations among nonsmoking middle-aged men of similar high social class.
Prospectiveinvestigations have established that high plasma fibrinogen concentrations are predictive of the incidence of ischemic heart disease (IHD) events (17). There is also considerable evidence that higher levels of leisure time physical activity and cardiorespiratory fitness are associated with lowered incidence rates of IHD (5,24). Within British studies, vigorous physical activity has been associated with the lowest risk (33), although moderate levels of physical activity are associated with a decreased risk (39). “Habitual, continuing, and current” physical activity appears essential, suggesting an effect on the acute thrombotic component of IHD (33).
Plasma fibrinogen is the component of the hemostatic system most frequently studied for the effects of physical activity (30). Several, although not all (6,12), cross-sectional studies have shown inverse associations with high levels of overall leisure time physical activity and plasma fibrinogen concentrations (16,19). Other investigations have indicated only vigorous exercise to be associated with lower fibrinogen concentrations in middle-aged (8,25) and elderly men (41).
Aging, smoking, and low social class have also been positively associated with fibrinogen (4,18,21,27) and may confound the relationship between physical activity and fibrinogen (26,27). Limited research has evaluated the relationship between cardiorespiratory fitness and plasma fibrinogen (25,26,32,35,46). Additional epidemiological investigations of physical activity habits, cardiorespiratory fitness, and plasma fibrinogen concentrations are required (15). We have examined the relationship between leisure time physical activity, predicted maximum oxygen consumption (V̇O2max) and plasma fibrinogen concentrations within a cohort of nonsmoking middle-aged men of similar high social class.