EFFECTS OF CALORIC RESTRICTION COMBINED WITH MODERATE AEROBIC EXERCISE ON CIRCULATING ESTROGENS AND IGF-1 IN PREMENOPAUSAL WOMEN Nancy Williams, Ann Albert, Thomas Parrott, Heather Leidy, Brian Frye, Meredith Snook, Kristin Duke, Erica Richard, and Jackie Gardner Department of Kinesiology and Noll Laboratory, Penn State University, University Park, PA E-mail: niw1@psu.edu The purpose of this study was to examine potential mechanisms relating to the role of physical activity in the reduction of the risk of breast cancer by testing whether moderate aerobic exercise can reduce the levels of two hormonal biomarkers, circulating estrogens and insulin-like growth factor I (IGF-I). The study used a prospective, randomized design to test the effects of a moderate exercise program (4X/wk; 4 months) combined with moderate dietary restriction. Previously sedentary, eumenorrheic women aged 25-40 years were assigned to exercise (exercise 4X/wk; dietary restriction) or light conditioning (exercise 2X/wk; no dietary restriction) groups and studied for a total of six menstrual cycles, i.e., 2 control followed by 4 cycles with training and dietary restriction. Compliance was 3.8 and 1.8 workouts per week for exercise and light conditioning, respectively. Thus far, 23 exercise and 9 light conditioning subjects have completed the study. The light conditioning group exhibited a trend toward a decrease in percent body fat of -3.1% (P< 0.072), but no significant changes in body weight or BMI. The exercising group experienced significant declines in both body weight (-6.2%) and percent body fat (-15.7% of initial percent fat), fat mass (-20.6%) and in BMI (-6.8%). Both groups significantly increased their aerobic capacity. Serum measurements of IGF-1 (ng/ml) at Pre, Mid, and Post time study points showed no significant differences and no significant interaction (ANOVA) with the exercise and diet intervention, regardless of group. Values were 238±23, 205±29, and 230 ± 24 ng/ml (means ± sem) for light conditioning, and 211±12, 205±16, and 203±13 ng/ml for exercising subjects at Pre, Mid, and Post time points, respectively. Serum measurements (n=10) of estradiol and estrone, obtained across the second control menstrual cycle and the fourth exercise menstrual cycle, showed no significant change with the intervention in either group. Values for estradiol were 78.8±8.5 and 79.6±10.2, and 88.2±5.1 and 83.3±6.2 pg/ml for light conditioning and exercising groups at Control 2 and Exercise 4. Values for estrone were 58.7±5.9 and 56.7±5.2 pg/ml for the exercising group (light conditioning values not available) at Control 2 and Exercise 4. Preliminary results of this ongoing study indicate that exercise combined with diet that is sufficient to produce significant increases in aerobic capacity and substantial decreases in body weight and percent body fat is not adequate to reduce circulating estrogen, estrone, and IGF-1. Therefore, these positive lifestyle changes do not appear to reduce breast cancer risk, as indicated by these specific circulating biomarkers. Original work supported by the U.S. Army Medical Research and Materiel Command under DAMD17- 01-1-0361 and current work supported by DAMD17-01-1-0360. Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.