Oral estrogen therapy may mitigate the effects of aerobic training on cardiorespiratory fitness in postmenopausal women: a double-blind, randomized clinical pilot study.

Objective: The aim of this study was to evaluate the isolated and associated effects of oral estrogen therapy and aerobic training on cardiorespiratory fitness in postmenopausal women.

Methods: Forty-two hysterectomized healthy postmenopausal women were randomly divided (in a double-blind manner) into four groups: placebo-control (n = 9), estrogen therapy-control (n = 12), placebo-aerobic training (PLA-AT; n = 11), and estrogen therapy-aerobic training (ET-AT; n = 10). The estrogen therapy groups received estradiol valerate (1 mg/day) and the aerobic training groups trained on a cycle ergometer three times per week at moderate intensity. Before and 6 months after the interventions, all women underwent a maximal cardiopulmonary exercise test on a cycle ergometer.

Results: Regardless of hormone therapy, aerobic training increased oxygen uptake at anaerobic threshold (P = 0.001), oxygen uptake at respiratory compensation point (P = 0.043), and oxygen uptake at peak exercise (P = 0.020). The increases at respiratory compensation point and peak exercise were significantly greater in the groups receiving placebo than in the groups receiving estrogen (oxygen uptake at respiratory compensation point: PLA-AT +5.3 [2.8] vs ET-AT +3.0 [2.5] mL kg(-1) min(-1), P = 0.04; oxygen uptake at peak exercise: PLA-AT +5.8 [3.4] vs ET-AT +2.8 [1.4] mL kg(-1) min(-1), P = 0.02).

Conclusions: Oral estrogen therapy may mitigate the cardiorespiratory fitness increase induced by aerobic training in hysterectomized healthy postmenopausal women.