Innovative Assessment of Endogenous Activity in Persons with Different Habits of Exercise

摘要

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 274 pairs. Of these, 53 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 38 pairs. Estradiol and progesterone assays have been completed for 25 pairs. An additional 30 pairs are being contacted to increase the sample size. Preliminary results, based on the first 15 pairs indicated that E2 during luteal phase was slightly higher in the inactive member of the twin pair, while follicular phase E2 was higher. In Year 4 (no-cost extension), we will continue to screen and enroll twins, complete data entry of questionnaires, conduct hormonal as says, integrate laboratory and questionnaire data sets, and complete analyses of the results.