An Innovative Assessment of Endogenous Estrogen Activity in Persons With Different Habits of Exercise
Final rept. 1 Sep 1997-30 Aug 2002
UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES
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Evidence exists that women exercising have lower estrogen levels than sedentary women. These lower estrogen levels may be the mechanism behind their reduced breast cancer risk. Previous studies included athletes with high exercise levels, and estrogen measurements were based on a few serum samples from different times during a menstrual cycle. This study included identical female twins who were discordant for moderate exercise. Estradiol was measured on a daily basis from saliva samples collected during a complete menstrual cycle. Screening interviews were initially conducted to determine eligibility and attempts were made to contact 304 pairs reaching 272. Of these, 56 were initially eligible however 18 declined to participate, 2 later became ineligible due to menopausal related reasons, and three only completed questionnaires. Samples proved to be un-useable for 5 pairs and another 4 pairs had an anovular cycle. Thus, results of estradiol and progesterone assays from 24 pairs with ovular cycles are provided. An index of activity level based on regular exercise as well as daily activities was developed from the daily logs. Preliminary results, based on these pairs indicated that average E2 during luteal phase was slightly higher 7 in the inactive member of the twin pair, while follicular phase E2 was unchanged. Average progesterone levels were slightly higher in the active member. Final results will incorporate dietary data in the analysis and control for confounding factors using multivariate analysis. Several publications are being planned.
- Medicine and Medical Research
- Stress Physiology