The independent effects of exercise and estrogen on lipids and lipoproteins in postmenopausal women.

OBJECTIVE

To assess the effects of a moderate exercise program with and without oral estrogen replacement on levels of lipids and lipoproteins in postmenopausal women.

METHODS

One hundred one postmenopausal women were randomized into four groups: control or sedentary (N = 20), exercise alone (N = 25), estrogen replacement using 0.625 mg conjugated equine estrogen (N = 28), and exercise supplemented with conjugated equine estrogen (N = 28). The exercise groups were placed on a moderate exercise program. Following baseline testing, each group returned at 3 and 6 months for cardiorespiratory fitness testing and serum lipid and lipoprotein profiles.

RESULTS

We found a significant decrease in systolic blood pressure (P < .05) in all treatment groups. The maximum oxygen uptake increased by 9.0 and 7.8% in the exercise and conjugated equine estrogen/exercise groups, respectively, compared to the other groups (P < .05). These responses were seen at both 3 and 6 months. Total exercise time (time spent on the treadmill until exhaustion during testing) significantly increased in the exercise group by 21% (P < .01). Exercise alone was associated with significant decreases in total cholesterol (5.2%, P < .05), triglycerides (2%, P < .05), and low-density lipoprotein (LDL) cholesterol (10%, P < .01), and a significant increase in the high-density lipoprotein (HDL) cholesterol-LDL ratio (17.2%, P < .01). Significant changes were noted in these values, as well as increases in HDL cholesterol (16 and 14.8%; P < .01) and apolipoprotein A1 (25.6 and 26.5%; P < .001) in the conjugated equine estrogen and conjugated equine estrogen/exercise groups, respectively. However, there were no differences in the changes observed in the conjugated equine estrogen groups with versus without exercise. No direct correlation was seen between measures of exercise performance and the changes seen in lipids and lipoproteins.

CONCLUSIONS

Estrogen therapy alone had the greatest beneficial effect on lipids and lipoproteins. Exercise alone resulted in a significant reduction in cholesterol, triglycerides, and LDL cholesterol, and an increase in the HDL-LDL ratio. However, combined conjugated equine estrogen and exercise did not demonstrate an added improvement in lipid metabolism. Physical fitness levels increased in the exercise groups, but not in the control group or the estrogen-alone treated women.