title: Physical activity and sex hormone levels in estradiol- and placebo-treated postmenopausal women.
abstract: OBJECTIVE
  Postmenopausal changes in the hormonal milieu in women with or without hormone therapy are hypothesized to be the pathway for a number of menopause-associated modifications in physiology and disease risk. Physical activity may modify these changes in women's hormone profiles. The crucial yet complex relationship between physical activity and physiologic and pharmacologic sex hormone levels in postmenopausal women has not been investigated sufficiently.
  
  
  METHODS
  Using structured recall, physical activity was assessed longitudinally during a period of 2 years in 194 postmenopausal women (90 randomized to 1 mg 17β-estradiol treatment daily and 104 randomized to placebo) in the Estrogen in the Prevention of Atherosclerosis Trial. The levels of physical activity were correlated with the serum sex hormone and the serum hormone-binding globulin levels in each treatment group.
  
  
  RESULTS
  Among the placebo-treated women, total energy expenditure was positively associated with sex hormone-binding globulin (SHBG; P < 0.001) and inversely associated with testosterones (total, bioavailable, or free) and androstenedione (P < 0.001 for all), as well as with estradiol (P = 0.02). In estradiol-treated women, estradiol levels were inversely associated with total energy expenditure (P = 0.002) and weekly hours spent in moderate or more vigorous physical activity (P = 0.001).
  
  
  CONCLUSIONS
  Physical activity is associated with lower serum levels of estradiol in both hormone therapy-treated and untreated women. In placebo-treated women only, physical activity is associated with reduced androgen levels and elevated SHBG levels.
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. fchoudhu@usc.edu
authors.forename: Farzana
authors.initials: F
authors.lastname: Choudhury
authors.forename: Leslie
authors.initials: L
authors.lastname: Bernstein
authors.forename: Howard N
authors.initials: HN
authors.lastname: Hodis
authors.forename: Frank Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Mack
mesh_terms: D000368:Aged; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D004958:Estradiol / Q000097:blood / Q000502:physiology / Q000627:therapeutic use*; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology*; D017698:Postmenopause / Q000097:blood / Q000187:drug effects* / Q000502:physiology; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood / Q000502:physiology
chemical_list: D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol