Increased sclerostin and preadipocyte factor-1 levels in prepubertal rhythmic gymnasts: associations with bone mineral density, body composition, and adipocytokine values.
CONCLUSIONS
Rhythmic gymnastics as high-impact bone loading sport has positive effects on bone mineralization in prepubertal years. Sclerostin and preadipocyte factor-1 (Pref-1) are hormones that inhibit bone formation. The present study demonstrates that these hormones are higher in gymnasts, and gymnasts present higher bone mineral density (BMD) as compared to controls.


BACKGROUND
Rhythmic gymnasts (RG) start their heavy trainings already in prepuberty and despite of low body fat mass (FM) and hypoleptinemia, their BMD is higher than in non-trained normal girls. The specific role of sclerostin and Pref-1, which are the inhibitors of bone formation, in bone development is not well understood. The impact of sclerostin and Pref-1 levels on BMD, body composition, and adipocytokine values was studied in prepubertal RG and untrained controls (UC).


METHODS
Sixty-four 9-10-year-old girls were divided into RG (n = 32) and UC (n = 32) groups. Bone mineral and body composition values were measured by dual-energy X-ray absorptiometry and bone age by X-ray. Sclerostin, Pref-1, leptin, and adiponectin levels were measured from fasting blood samples.


RESULTS
Sclerostin (RG 19.8 ± 6.3 pmol/l; UC 15.8 ± 5.4 pmol/l) and Pref-1 (RG 1.6 ± 1.0 ng/ml; UC 1.1 ± 0.5 ng/ml) were higher (p < 0.05) in RG compared with UC. Sclerostin was related to adiponectin (r = 0.41; p < 0.05) in UC. No relationship was found between sclerostin and Pref-1 with BMD values in prepubertal RG and age-matched UC groups.


CONCLUSIONS
Sclerostin and Pref-1 levels are higher in RG compared to UC girls. Specific physical activity pattern seen in prepubertal RG has a beneficial effect on bone mineralization despite increased levels of hormones that inhibit bone formation.
Institute of Sport Pedagogy and Coaching Sciences, Faculty of Exercise and Sport Sciences, University of Tartu, Tartu, Estonia. jaak.jurimae@ut.ee.
J
J
Jürimäe
Department of Pediatrics, Faculty of Medicine, University of Tartu, Tartu, Estonia.
V
V
Tillmann
Department of Sciences for Quality of Life, University of Bologna, Bologna, Italy.
A
A
Cicchella
Department of Sciences for Quality of Life, University of Bologna, Bologna, Italy.
C
C
Stefanelli
Institute of Sport Pedagogy and Coaching Sciences, Faculty of Exercise and Sport Sciences, University of Tartu, Tartu, Estonia.
K
K
Võsoberg
Tartu Health Care College, Tartu, Estonia.
A L
AL
Tamm
Institute of Sport Pedagogy and Coaching Sciences, Faculty of Exercise and Sport Sciences, University of Tartu, Tartu, Estonia.
T
T
Jürimäe
D015502:Absorptiometry, Photon / Q000379:methods; D048868:Adaptor Proteins, Signal Transducing; D054392:Adipokines / Q000097:blood; D015415:Biomarkers / Q000097:blood; D001823:Body Composition / Q000502:physiology*; D015519:Bone Density / Q000502:physiology*; D019485:Bone Morphogenetic Proteins / Q000097:blood*; D002135:Calcium-Binding Proteins; D016022:Case-Control Studies; D002648:Child; D005260:Female; D005819:Genetic Markers; D006173:Gymnastics / Q000502:physiology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000097:blood*; D008565:Membrane Proteins / Q000097:blood*; D011627:Puberty / Q000097:blood
D048868:Adaptor Proteins, Signal Transducing; D054392:Adipokines; D015415:Biomarkers; D019485:Bone Morphogenetic Proteins; D002135:Calcium-Binding Proteins; C512941:DLK1 protein, human; D005819:Genetic Markers; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C422903:SOST protein, human
Adiponectin; Bone mineral density; Leptin; Pref-1; Prepubertal athletes; Sclerostin