An Innovative Assessment of Endogenous Estrogen Activity in Persons with Different Habits of Exercise
Abstract
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 includes identical female twins who are discordant for moderate exercise. Estradiol is measured on a daily basis from saliva samples collected during a complete menstrual cycle. Procedures and questionnaires have been developed; enrollment of eligible pairs and laboratory assays are ongoing. Screening interviews have been conducted with 299 pairs. Of these, 56 were initially eligible; however 10 declined to participate and 2 later became ineligible due to menopausal related reasons. Samples proved to be unusable for 3 pairs. Thus, sample collection is currently completed or underway for 39 pairs. Estradiol and progesterone assays have been completed for 29 pairs. Preliminary results, based on these pairs indicated that E2 during luteal phase was significantly higher in the inactive member of the twin pair, while follicular phase E2 was unchanged. During the no-cost extension, we will finish sample collection from about 5 more pairs of twins, complete hormonal assays including daily progesterone, incorporate dietary data in the analysis and control for confounding factors using multivariate analysis. Several publications are being planned.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2001
- Accession Number
- ADA405015
Entities
People
- Ann S Hamilton
Organizations
- University of Southern California