The onset of puberty and the availability of sex steroids in female gymnasts.

Plasma levels of gonadotropins, (sex) steroids, SHBG bound fractions of 17β-estradiol (E2) and testosterone (T), and sex-hormone-binding globulin (SHBG) were compared at the onset of puberty in female gymnasts (n = 7) and two groups of schoolgirls with similar anthropometric characteristics. Ten schoolgirls were matched to the gymnasts on the basis of a sum of skinfolds and the waist/hip ratio, while 12 other girls were selected on the basis of the stature and bicristal breadth of the female gymnasts. All girls were in the second stage of breast development (M2) and were classified as being in the first stage (M1) 6 months earlier. When female gymnasts were compared to nonathletic schoolgirls with similar physical characteristics at the same stage of early puberty, the former had significantly lower levels of plasma luteinizing hormone (LH), total and available E2, and T. In conclusion, female gymnasts have significantly lower LH, E2, and T plasma levels than nonathletic schoolgirls in early puberty. The E2 and T plasma levels in early female gymnasts are not related to the individual physical characteristics, i.e., fat mass, short stature, or small bicristal breadth. © 1993 Wiley-Liss, Inc.