Effects of the route of estrogen administration and exercise on hormonal levels in postmenopausal women

Objective: To examine the effects of exercise on serum estrogens, growth hormone, insulin, cortisol, lactate, and glucose levels in postmenopausal women receiving two routes of administration of estrogen replacement therapy (ERT).

Design: Prospective, randomized, crossover study.

Setting: The general clinical research center of an academic medical center.

Patient(s): Eleven active, postmenopausal women.

Intervention(s): The patients were screened with exercise stress testing, then oral micronized estradiol or transdermal estradiol was administered, followed by two 45-minute submaximal exercise tests. Dietary intake before the tests was standardized.

Main Outcome Measure(s): The study measured maximal heart rate and aerobic power ( ₂max), and serum levels of estradiol (E₂), estrone (E₁), cortisol, growth hormone (GH), insulin, glucose, and lactate.

Result(s): Growth hormone, cortisol, and insulin all changed significantly in response to the 45-minute exercise bouts, but no differences were observed between the oral micronized estradiol and transdermal estradiol responses. E₂ levels increased significantly during the transdermal estradiol 45-minute exercise bout; this change did not occur during the oral estradiol exercise bout. In the transdermal estradiol treatment group, the E₂ levels at +30 and +45 minutes of exercise were elevated compared to the post-exercise levels at −15, 0, and 30 minutes. E₁ was not significantly changed during the 45-minute exercise bouts in either group.

Conclusion(s): During exercise, serum E₂ levels rise significantly higher with transdermal but not oral routes of E₂ administration. However, the elevated levels are not prolonged and normalize by 30 minutes after exercise.