Little effect of long-term, self-monitored exercise on serum lipid levels in middle-aged women.

To study the effect of long-term, self-monitored exercise on physical fitness and serum lipid levels of middle-aged, nonsmoking females, a controlled study was conducted in 33 sedentary Swiss women. Seventeen women were randomly allocated to jog 2h/wk for 4 months on an individually prescribed and heart rate controlled base, whereas 16 women served as controls. Although leisure-time physical activity increased significantly in exercisers compared to controls, the average running distance of 10.9 km/wk was somewhat less than expected. The "net decrease" (4-month change in exercisers minus 4-month change in controls) in the sum of four skin-folds was -4.85 mm (p < 0.05). Four-month changes in serum lipids were generally small and nonsignificant. For example, the net decrease in total triglycerides was -0.2 mmol/l (p = 0.13). Correlational analyses revealed significant associations between changes in the waist-hip ratio and changes in total cholesterol (total-C) or the HDL/total-C ratio (r = 0.44, p < 0.01 and r = -0.29, p < 0.05, respectively). An increase in endurance capacity was associated with an increase in the HDL2-subfraction and in the ratio of HDL/total-C (r = 0.46, p < 0.05 and r = 0.52, p < 0.01). Multivariate linear regression analyses confirmed a change in endurance capacity as the statistically strongest positive predictor of changes in HDL, HDL2 and the HDL/total-C ratio. However, women who used oral contraceptives did not show any favourable lipid changes despite a considerable improvement in endurance capacity. The present training study in healthy, habitually sedentary middle-aged women was not able to show the same beneficial changes in serum HDL concentration as seen in male counterparts, when analyzed according to the principle of intention-to-treat. Exploratory analyses revealed that a too low jogging activity as well as a confounding effect of oral contraceptive use may partially account for the lack of significant changes in serum lipid levels after training.