title: Effect of exercise on serum estrogens in postmenopausal women: a 12-month randomized clinical trial.
abstract: Elevated circulating estrogens and a sedentary lifestyle increase risk for breast cancer. The effect of exercise on circulating estrogens in sedentary postmenopausal women is unknown. The objective of this study was to examine the effects of a 12-month moderate-intensity exercise intervention on serum estrogens. We randomly assigned 173 sedentary, overweight (body mass index > 24.0 kg/m(2), body fat > 33%), postmenopausal women, ages 50-75 years, not using hormone therapy, living in the Seattle, Washington, area for the next year, and willing to be randomly assigned to an exercise intervention or stretching control group. The exercise intervention included facility and home-based exercise (45 min, 5 days/week moderate intensity sports/recreational exercise). A total of 170 (98.3%) women completed the study with exercisers averaging 171 min/week of exercise. After 3 months, exercisers experienced declines in estrone, estradiol, and free estradiol of 3.8, 7.7, and 8.2%, respectively, versus no change or increased concentrations in controls (P = 0.03, 0.07, and 0.02, respectively). At 12 months, the direction of effect remained the same, although the differences were no longer statistically significant. The effect was limited to women who lost body fat: women whose percentage of body fat [by dual energy x-ray absortiometry (DEXA)] decreased by >/==" BORDER="0">2% had statistically significant (comparing exercisers versus controls) decreases at 12 months of 11.9, 13.7, and 16.7% for serum estrone, estradiol, and free estradiol, respectively. We concluded that a 12-month moderate-intensity exercise intervention in postmenopausal women resulted in significant decreases in serum estrogens. The association between increased physical activity and reduced risk for postmenopausal breast cancer may be partly explained by effects on serum estrogens.
authors.affiliation: Cancer Prevention Research Program, The Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
authors.forename: Shelley S
authors.initials: SS
authors.lastname: Tworoger
authors.forename: Cornelia M
authors.initials: CM
authors.lastname: Ulrich
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yasui
authors.forename: Melinda L
authors.initials: ML
authors.lastname: Irwin
authors.forename: Kumar B
authors.initials: KB
authors.lastname: Rajan
authors.forename: Bess
authors.initials: B
authors.lastname: Sorensen
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Rudolph
authors.forename: Deborah
authors.initials: D
authors.lastname: Bowen
authors.forename: Frank Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: John D
authors.initials: JD
authors.lastname: Potter
authors.forename: Robert S
authors.initials: RS
authors.lastname: Schwartz
mesh_terms: D000368:Aged; D004967:Estrogens / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009765:Obesity / Q000097:blood; D010349:Patient Compliance; D017698:Postmenopause / Q000097:blood*; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism
chemical_list: D004967:Estrogens; D012738:Sex Hormone-Binding Globulin