Bone mineral density acquisition in peripubertal female rhythmic gymnasts is directly associated with plasma IGF1/IGF-binding protein 3 ratio

Abstract

Intense physical activity in peripubertal girls may delay menarche and cause menstrual disorders and estrogen deficiency, particularly in sport disciplines that require strict weight control. It may also have a deleterious effect on bone mass acquisition. The aim of this study was to determine the time-course of bone mass accretion in peripubertal elite female rhythmic gymnasts (FRGs) over a 1-year period, as well as the anthropometric and hormone parameters that could be helpful for predicting bone mineral density (BMD) gain. We conducted a 1-year follow-up study in 29 FRGs (10.7-16.1 years old). Whole body composition and BMD of the whole body, proximal femur, lumbar spine, mid-radius, and skull were measured by dual energy X-ray absorptiometry (DXA). Moreover, baseline growth- and bone metabolism-related hormones such as IGF1, IGF-binding protein 3 (IGFBP3), leptin, and bone markers were measured. BMD increased significantly at all bone sites throughout puberty, particularly between Tanner stages II and IV-V (P=0.025 to P<0.001). The IGF1 level, IGF1/IGFBP3 ratio, and leptin level were higher in late pubertal stages (i.e. IV-V) compared with early stage (i.e. I). In simple and multivariate analyses, only the IGF1/IGFBP3 ratio was strongly correlated with the BMD change at all bone sites (r=0.49, P=0.02 to r=0.77, P<0.0001). This 1-year follow-up study of peripubertal FRGs showed that BMD gain was maximal around Tanner stage III. The plasma IGF1/IGFBP3 ratio was associated with bone mass acquisition in this period, and it may thus serve as a surrogate marker of bone mass gain in this population.