Plasma adipocytokine and ghrelin levels in relation to bone mineral density in prepubertal rhythmic gymnasts

Abstract

The aim of the present study was to investigate possible differences in plasma adipocytokine and ghrelin levels and body composition parameters in prepubertal rhythmic gymnasts (RG) and untrained controls (UC), and to examine the relationships of bone mineral density (BMD) with hormonal status in prepubertal children with different physical activity patterns. Eighty-nine 7- to 9-year-old girls participated in the study (RG, n = 46; UC, n = 43). Body composition and BMD were measured by dual-energy X-ray absorptiometry. Bone maturity was estimated by using a radiograph of the nondominant hand. The measured whole-body, lumbar spine (LS), and femoral neck (FN) BMD values were significantly higher (P < 0.05) in gymnasts than in controls. In addition, RG presented significantly lower and higher values (P < 0.05) for leptin and ghrelin concentrations, respectively, in comparison with UC. No differences were observed for adiponectin levels between the studied groups. No relationships between measured BMD values with leptin and ghrelin were observed even after adjustment for age and fat mass (FM) in RG. Whole-body and LS BMD values were significantly correlated with leptin after controlling for age and FM (r = 0.32, P < 0.05) in UC. Femoral neck BMD remained significantly correlated with ghrelin after adjusting for age and FM (r = -0.4, P < 0.05) in UC. No relationships were found between measured BMD values and adiponectin even after controlling for age and FM values in both groups. In conclusion, although all measured BMD values were significantly higher in RG, plasma adipocytokine and ghrelin concentrations were not directly related to bone mineralization in prepubertal RG in contrast to UC.