Hypoleptinemia in female and male elite gymnasts

Elite gymnasts favour low body fat mass as the current aesthetic ideal required for complex movements in this sports discipline. Pubertal development and growth are retarded in juvenile gymnasts. Leptin, the protein product of the ob-gene, is secreted by fat cells. Besides its role in regulation of body weight, leptin also stimulates the reproductive axis. We investigated various serum hormones including leptin, body composition and nutrition in cohorts of female and male elite gymnasts to elucidate if there is a relationship between leptin levels and delayed puberty in elite gymnasts.

Twenty-two female and 18 male elite gymnasts were enrolled in this study. Pubertal stage, various hormonal levels and body composition were determined and nutritional intake was assessed. Leptin was analysed using a specific RIA.

Pubertal development and growth were delayed in the study group, especially in girls. The percentage of body fat was reduced as compared to a normal age-matched population: 14.4% versus 21.9% in girls and 10.4% versus 15.1% in boys. Serum leptin levels were decreased, especially in pubertal girls, and did not show the normal developmental pattern with a steady increase in girls and a peak in boys of pubertal stage 2. In all gymnasts leptin levels correlated with the amount of fat mass (r = 0.6, P = 0.005 in girls; r = 0.44, P = 0.038 in boys). When leptin levels were transformed into standard deviation scores (SDS) it became obvious that the gymnasts, especially pubertal females, had significantly lower values than normal controls of the same sex, pubertal stage and body mass index (BMI): leptin SDS (BMI) = -1.21 and -3.99 in prepubertal and pubertal girls, - 0.94 and -0.91 in prepubertal and pubertal boys, respectively. When leptin SDS were based on % body fat instead of BMI, mean values were still significantly decreased compared to normal controls: -1.05 in girls (P < 0.001) and -0.60 in boys (P = 0. 025).

Adjustment of serum leptin levels in elite gymnasts for gender, pubertal stage and BMI or % body fat reveals inappropriately low values. The reason for this hypoleptinemia is most probably insufficient caloric intake. The data suggest that hypoleptinemia in turn causes delayed puberty and growth in this particular group of athletes.