Bone Mineralization in Rhythmic Gymnasts before Puberty: No Longitudinal Associations with Adipocytokine and Ghrelin Levels

Abstract

Aim: Relationships between change of bone mineral density (BMD) and baseline adipocytokine and ghrelin levels over 12 months in prepubertal rhythmic gymnasts (RG) and age-matched untrained controls (UC) were studied. Methods: Adipocytokine, ghrelin, body composition, BMD and bone age values were measured in RG (8.0 ± 0.6 years; n = 33) and UC (8.2 ± 0.6 years; n = 35). Results: Increases in BMD and body composition parameters were seen in both groups as a result of the 12-month study period. Adiponectin increased and ghrelin decreased in both groups, leptin increased only in UC. Measured bone age, body composition and hormone values did not predict increases in BMD values in RG. The variables that were associated with increases in whole-body (ΔWB) and femoral neck (ΔFN) BMD values were fat mass and fat-free mass together in UC. Ghrelin and adiponectin were the most important hormonal predictors of ΔWB BMD and ΔFN BMD values in UC, respectively. In RG, adiponectin and ghrelin levels did not predict increases in measured BMD values. Conclusion: Body composition parameters and hormone levels did not predict normal growth in measured BMD values as a result of the 12-month study period in RG. However, leptin together with specific body composition variables was associated with an increase in ΔWB BMD value in UC.