Long-term estrogen replacement therapy is associated with improved exercise capacity in postmenopausal women without known coronary artery disease

Background Short-term estrogen administration improves vasodilation and has been shown to improve exercise capacity. However, it is unknown whether long-term estrogen replacement therapy is associated with improved exercise capacity in postmenopausal women without known coronary artery disease. Methods and Results We studied 248 postmenopausal women without known coronary artery disease (mean age 63.5 years); 158 (64%) were current or past hormone replacement therapy (HRT) users and 108 (44%) were current users of HRT. Attributes potentially affecting exercise capacity and cardiac risk factors were carefully measured. These included duration of estrogen replacement therapy, all variables in the Framingham risk index, physical activity level, body mass index, waist-to-hip ratio, presence of osteoporosis, and family history of heart disease. We measured maximal oxygen uptake (M(V) over doto(2)) and anaerobic threshold as objective markers of exercise capacity. The relation between exercise capacity and use of HRT was analyzed with the use of logistic regression, controlling for confounding variables. We found that fitness, as measured by M(V) over doto(2) and anaerobic threshold, was significantly greater in women who had used HRT currently or in the past compared with women who had never used HRT. This difference in fitness was not confounded by age or physical activity level. Conclusions Estrogen replacement therapy is associated with increased exercise capacity as measured by M(V) over doto2 and anaerobic threshold in postmenopausal women without coronary artery disease. This finding is consistent with the beneficial effect of short-term estrogen administration on improved endothelium-dependent and endothelium-independent vasodilation.