Background: Because physical activity may affect risk of certain chronic diseases, we wanted to examine the effects of leisure time physical activity on the metabolic profiles.

Methods: In a population-based cohort study, 5220 men and 5869 women, aged 20 to 49 years at entry, took part in 2 surveys (1979-1980 and 1986-1987) with repeated assessments of self-reported leisure time activity. Measurements of body mass index (measured as the weight in kilograms divided by the square of the height in meters [BMI]) and levels of serum triglyceride, total cholesterol (total C), and high-density lipoprotein cholesterol (HDL-C) were studied in relation to 4 levels of physical activity.

Results: There was a dose-response relationship between serum lipid levels and BMI, and levels of physical activity in both sexes after adjustments for potential confounders. Differences in BMI and serum lipid levels between sedentary and sustained exercising groups were consistently more pronounced after 7 years than at baseline, especially in the oldest age group. Men reporting sustained very hard exercising compared with sedentary men had lower total C concentrations (5.65 mmol/L vs 6.21 mmol/L [218 mg/dL vs 240 mg/dL]), triglyceride levels (1.34 mmol/L vs 1.85 mmol/L [118 mg/dL vs 164 mg/dL] ), total C/HDL-C ratios by 19.0%, and BMI (23.9 kg/m2 vs 25.7 kg/m2), and higher HDL-C levels (1.52 mmol/L vs 1.36 mmol/L [59 mg/dL vs 52 mg/dL]). The combined sustained hard and very hard exercising group of women compared with sedentary women had lower total C concentrations (5.70 mmol/L vs 5.90 mmol/L [220 mg/ dL vs 228 mg/dL]), triglyceride levels (1.03 mmol/L vs 1.18 mmol/L [91 mg/dL vs 104 mg/dL]), total C/HDL-C ratios by 7.5%, BMI (23.1 kg/m2 vs 23.6 kg/m2), and higher HDL-C levels (1.73 mmol/L vs 1.66 mmol/L [67 mg/dL vs 64 mg/ dL]). An increase in leisure time activity over the 7 years improved metabolic profiles, whereas a decrease worsened them in both sexes.

Conclusions: Sustained high levels and change from sedentary to higher levels of physical activity relative to sedentary men and women improved the metabolic risk profiles in both sexes. The differences observed are sufficiently large to have a beneficial effect in the prevention of certain chronic diseases.