THE ONSET OF PUBERTY AND THE AVAILABILITY OF SEX STEROIDS IN FEMALE GYMNASTS

Plasma levels of gonadotropins, (sex) steroids, SHBG bound fractions o f 17beta-estradiol (E2) and testosterone (T), and sex-hormone-binding globulin (SHBG) were compared at the onset of puberty in female gymnas ts (n = 7) and two groups of schoolgirls with similar anthropometric c haracteristics. Ten school-girls were matched to the gymnasts on the b asis of a sum of skinfolds and the waist/hip ratio, while 12 other gir ls were selected on the basis of the stature and bicristal breadth of the female gymnasts. All girls were in the second stage of breast deve lopment (M2) and were classified as being in the first stage (M1) 6 mo nths earlier. When female gymnasts were compared to nonathletic school girls with similar physical characteristics at the same stage of early puberty, the former had significantly lower levels of plasma luteiniz ing hormone (LH), total and available E2, and T. In conclusion, female gymnasts have significantly lower LH, E2, and T plasma levels than no nathletic schoolgirls in early puberty. The E2 and T plasma levels in early female gymnasts are not related to the individual physical chara cteristics, i.e., fat mass, short stature, or small bicristal breadth. (C) 1993 Wiley-Liss, Inc.