In normal postmenopausal women physiologic estrogen replacement therapy fails to improve exercise tolerance: A randomized, double-blind, placebo-controlled, crossover trial

OBJECTIVE: Our purpose was to test whether estrogen replacement therapy could increase exercise tolerance in postmenopausal women. STUDY DESIGN: A randomized, double-blind, placebo-controlled, crossover study in 31 healthy postmenopausal women who received 12 weeks of physiologic estrogen replacement therapy (micronized estradiol, 2 mg/day) and were evaluated with modified Balke exercise treadmill tests. RESULTS: Serum estradiol levels increased significantly during replacement therapy in this cohort of female volunteers with a mean age of 59 years, and resting heart rate was lower in women receiving estrogen replacement (p < 0.05). However, neither the heart rate nor the blood pressure responses to exercise was different, nor was the total exercise time, rate of oxygen uptake, or maximal oxygen uptake increased after estradiol treatment. Similarly, ventilatory parameters were unaffected by estradiol. The slope of the respiratory exchange ratio was slightly but significantly different (p < 0.05) while volunteers received estrogen replacement therapy. CONCLUSION: Estrogen replacement therapy, which achieves serum estradiol concentrations in the physiologic range for 12 weeks, fails to increase exercise tolerance or improve cardiovascular response to exercise in postmenopausal women.