HYPOLEPTINAEMIA OBSERVED IN ELITE FEMALE GYMNASTS DOES NOT AFFECT SKELETAL BONE MINERAL DENSITY

Abstract

Leptin that is almost produced by fat is supposed to be responsible for the symptoms of hormonal disturbances occurring in anorexia athletica. Despite some discrepancies published in the literature serum leptin level is usually positively associated with bone mineral density (BMD) in females. PURPOSE To determine if hypoleptinaemia occurring in elite gymnasts could affect bone health in these subjects. METHODS Leptin levels were determined using ELISA in 36 elite female gymnasts (EG: 13.4 ± 1.7 yrs training 18.1 ± 3.3 hrs/week) and 20 controls (C: 12.5 ±1.6 yrs exercising no more than 3.5 ± 2.9 hrs/week). Body composition and BMD at the whole body (WB) and lumbar spine (LS) were measured using Dual Energy X-ray Absorptiometry. Maturation of each subject was assessed following the Tanner' stages criteria. Quantitative Ultrasound Velocity (SOS) and Broadband Ultrasound Attenuation (BUA) were measured through the calcaneum. Comparisons between groups were made using the Mann- Whitney U test. Further analysis was done using Spearman-Rank correlation. RESULTS There was no difference between groups for age, height, weight, bone mass index and lean tissue mass. Mean breast stage of maturation was B3. None of EG had reached puberty whereas 4 C had undergone menarche. As expected in such a population, EG had significantly lower fat mass (14.4 ± 2.8 vs. 22.7 ± 5.3 \%, P < 0.001) and leptin level (2.16 ± 1.6 vs. 4.27 ± 2.7 μg/L, P < 0.001) than C. LSBMD was significantly higher in EG (0.941 ± 0.39 vs. 0.793 ± 0.141 g/cm2, P < 0.05). There was no difference for WBBMD, SOS and BUA in spite of a trend for higher values in EG. Leptin correlated positively with fat mass (rho=0.44, p = 0.0007), and negatively with the weekly duration of physical activity (rho=−0.37, p = 0.005). CONCLUSION Hypoleptinaemia observed in the gymnasts does not affect BMD. Gymnastic training that is known to have osteogenic effect is able to counterbalance the deleterious effect usually encountered in such hormonal disturbed subjects. %