The effect of hormone replacement therapy and exercise on cardiovascular disease risk factors in postmenopausal women.
Following menopause, women show an increased risk of heart disease to a level equal that of men. This elevated risk is thought to be due, at least partly, to changes in blood lipid and fibrinogen levels. The purpose of this article is to review the published research on the relationship between both exercise and hormone replacement with regards to common cardiovascular disease (CVD) risk factors and the relative importance of each. Menopause is associated with increased total serum cholesterol, triglycerides and fibrinogen, and a decrease in high density lipoprotein (HDL) cholesterol levels. The major reason for these changes following menopause is believed to be a result of fluctuations in hormonal status, primarily a deficiency in estrogen. Intervention may be justified since estrogen replacement therapy has been shown to decrease the risk of developing CVD and to have a significant impact on many of the CVD risk factors. The results vary from study to study, but generally estrogen replacement has been found to decrease total cholesterol and fibrinogen, while increasing HDL cholesterol and triglycerides. All of these changes, other than the increase in triglycerides, are seen as positive. The addition of progestogen to estrogen may negate some of the beneficial changes of estrogen, most notably the increase in HDL cholesterol levels. However, progestogen has also been reported to offset the increase in triglycerides seen with unopposed estrogen replacement. Thus, there are contradictory effects (both positive and negative) of hormone replacement on CVD risk factors in women. Regular aerobic exercise and resulting improvements in cardiorespiratory fitness have consistently been shown as preventive of CVD. This decreased CVD risk is in part because of the impact of exercise on blood lipids and fibrinogen. Increased aerobic exercise is thought to improve the risk profile, mainly through an increase in HDL cholesterol levels and decreases in triglycerides and fibrinogen. Unfortunately, the majority of research supporting the effects of exercise on CVD risk factors has been done on men. Even when research has included women, very few studies have focused on postmenopausal women. However, the research done on postmenopausal women points to a significantly improved CVD risk factor profile with regular cardiorespiratory exercise.