Relationship of selected body composition and training variables to 17 B-estradiol in eumenorrheic runners

Although the relationships among body composition, training, and physical characteristics and 17 B-estradiol (estradiol) have been described in active amenorrheic women, little is known about these relationships in eumenorrheic women. This study examined the relationship between selected body composition and training variables, physical characteristics, maximal oxygen consumption (VO2max), luteinizing hormone (LH) and estradiol in eumenorrheic runners. Fifteen women (25.8 +/- 0.8 years) running 19.8 +/- 1.8 miles per week were studied during the midluteal phase of the menstrual cycle. Estradiol and LH were determined by radioimmunoassay. Body composition was measured by hydrostatic weighing. Age, Ponderal Index, and menstrual cycle length (days) were inversely related to estradiol (r = -0.56, r = -0.55, r = -0.52, respectively, p less than 0.05). A significant relationship (R2 = 0.91; p less than 0.05) was found among age, menstrual cycle length, LH (mIU/ml), VO2max (ml/kg/min), weight training (hr/wk), miles run per week, height (cm), additional aerobic training (hr/wk), relative body fat (%), and Ponderal Index and estradiol (pg/ml). These data suggest the midluteal concentration of estradiol in moderately trained eumenorrheic runners is the result of a complex interaction of many factors.