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Institute of Sport Pedagogy and Coaching Sciences, Centre of Behavioural and Health Sciences, University of Tartu, Tartu 50090, Estonia
To whom requests for reprints should be addressed at 1 Institute of Sport Pedagogy and Coaching Sciences, University of Tartu, 18. Ülikooli Street, Tartu 50090, Estonia. E-mail: jaakj{at}ut.ee
The aim of the present investigation was to study the influence of plasma insulin-like growth factor1 (IGF-1) and leptin levels on bone mineral mass (BMC) and bone mineral density (BMD) in premenopausal women and the relationship between IGF-1 and leptin levels. Two hundred and four healthy women participated in this study. All participants had a body mass index (BMI) <30 kg/m2 and were matched for their level of mean daily energy expenditure. BMC and BMD were correlated with measured body composition and blood biochemical parameters. No association was observed between BMC and BMD values with measured physical performance characteristics. Leptin had a significant association with BMC (ß = 0.840; P = 0.0001), total BMD (ß = 0.833; P = 0.0001), femoral neck BMD (ß = 0.829; P = 0.0001), and lumbar spine BMD (ß = 0.833; P = 0.0001). However, these associations were no longer independent when adjusted for body fat mass (FM) and trunk fat:leg fat ratio (P > 0.385). IGF-1 was significantly related to BMC (ß = 0.920; P = 0.0001), total BMD (ß = 0.918; P = 0.0001), femoral neck BMD (ß = 0.921; P = 0.0001), and lumbar spine BMD (ß = 0.917; P = 0.0001), but did not remain significant when adjusted for fat free mass (FFM; P > 0.062). In addition, a significant association between IGF-1 and leptin was found (ß = 0.801; P = 0.0001), and it remained significant after controlling for age, FM, FFM, insulin, and fasting insulin resistance index (FIRI), but not when adjusted for BMC and body mass values. In conclusion, it appears that fasting IGF-1 and leptin concentrations have no direct effect on BMC and BMD values. In addition, if there is an important relationship between IGF-1 and leptin, it is mediated or confounded by BMC in premenopausal women.
Key Words: bone mineral mass bone mineral density IGF-1 leptin premenopausal women
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