Association of physical activity with reproductive hormones: the Penn Ovarian Aging Study.
BACKGROUND
Physical activity is associated with reduced risk for breast cancer, perhaps through reductions in circulating reproductive hormones (estrogens and androgens). There may also be a role for physical activity in regulating menopausal symptoms. Few studies have examined associations of physical activity on hormone levels. None have examined the potential effect of the menopausal transition on the associations between physical activity and reproductive hormone levels.


METHODS
Data from the Penn Ovarian Aging Study were used for this analysis. Self-reported physical activity was assessed in 391 women up to four times over 10 years and extending across the menopausal transition. Other assessments included reproductive hormones via RIA (estradiol, luteinizing hormone, follicle-stimulating hormone, testosterone, DHEA sulfate), body weight, and height. Multivariate repeated measures regression models were developed to compare reproductive hormone levels within physical activity tertiles, adjusting for age, follow-up time, smoking, and ethnicity.


RESULTS
Activity level was inversely associated with estradiol in the subgroup in the late transition stage. Adjusted means for estradiol were 24.6 and 37.9, a relative difference of 54% in estradiol when comparing highest to lowest activity tertile (P = 0.02). Similarly, in this subgroup, there was an inverse association between physical activity and testosterone levels (means of 11.1 and 15.94 in the highest and lowest tertile, a 47% relative difference; P = 0.01). There were no significant associations of activity with any other reproductive hormone.


CONCLUSIONS
These results identify a particular window of the menopausal transition during which physical activity is associated with reduced estradiol and/or testosterone levels.
Schmitz
Kathryn H
KH
Center for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, 423 Guardian Drive, 921 Blockley Hall, Philadelphia, PA 19104, USA. Schmitz@mail.med.upenn.edu
Lin
Hui
H
Sammel
Mary D
MD
Gracia
Clarissa R
CR
Nelson
Deborah B
DB
Kapoor
Shiv
S
DeBlasis
Tracey L
TL
Freeman
Ellen W
EW
D000328:Adult; D000375:Aging / Q000502:physiology*; D001827:Body Height / Q000502:physiology; D049628:Body Size / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D004958:Estradiol / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005500:Follow-Up Studies; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood; D008593:Menopause / Q000502:physiology*; D008875:Middle Aged; D010053:Ovary / Q000502:physiology*; D011863:Radioimmunoassay; D012907:Smoking / Q000097:blood; D013739:Testosterone / Q000097:blood
D012739:Gonadal Steroid Hormones; D013739:Testosterone; D004958:Estradiol; D019314:Dehydroepiandrosterone Sulfate; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone