Bone growth in pubertal girls : cross-sectional and longitudinal investigation of the association of sex hormones, physical activity, body composition, and muscle strength with bone mass and geometry

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dc.contributor.author Wang, Qingju
dc.date.accessioned 2008-01-09T13:00:23Z
dc.date.available 2008-01-09T13:00:23Z
dc.date.issued 2005
dc.identifier.isbn 951-39-2273-1
dc.identifier.uri http://urn.fi/URN:ISBN:951-39-2273-1
dc.identifier.uri http://hdl.handle.net/123456789/13488
dc.description.abstract Strong bones are essential to overall health and quality of life. Optimizing peak bone mass during growth is a key strategy in preventing fragility fractures in later life. Understanding the biological process of bone growth and its regulators assumes the greatest importance in realizing this strategy. This study aimed to investigate bone growth in terms of bone size, bone mineral content (BMC) and volumetric mineral density (vBMD) and its relationship with sex hormones, physical activity (PA), body composition and muscle strength in pubertal girls. A total of 258 healthy girls aged 10-13 years were included in the 2-years observational study at baseline. The PA level was assessed using a questionnaire. Body composition and BMC were assessed by dual-energy x-ray absorptiometry. Bone geometry and vBMD at the distal radius (DR) and tibial shaft (TS) were measured by peripheral quantitative computed tomography. Muscle strength of elbow flexors and knee extensors was determined by a dynamometer. Sex hormones were assessed by fluoroimmunoassay. The results showed that the timing of peak growth velocity of BMC lags behind that of bone size by more than 6 months in pubertal girls. This growth asynchrony resulted in vBMD of DR (the metaphyseal trabecular bone site) decreasing slightly from prepuberty up to 1 year before menarche. The cross-sectional area (CSA) of marrow cavity at TS (the diaphyseal cortical bone site) did not change prior to menarche but decreased thereafter. 17?-Estradiol (E2) was not correlated with total bone CSA, but was positively correlated with cortical CSA and cortical thickness (Cth) at TS. On the other hand, testosterone (T) was positively correlated with total bone CSA, but not with cortical CSA and Cth. PA level was positively associated with BMC in early pubertal girls. Total body FM correlated significantly higher with leg BMC than with arm BMC. BMC of arm and leg was highly correlated with muscle strength of elbow flexors and knee extensors, respectively. However, BMC per unit of muscle strength was significantly higher in leg than in arm. The observational study suggests that in pubertal girls, the growth of bone size precedes that of bone mass, and this phenomenon may responsible for the elevated fracture risk during pubertal growth spurt. E2 might be important to counteract this transitory elevated fracture risk, because it makes bone stronger by inhibiting bone resorption and even promoting bone formation at the endocortical surface. E2 may also interact with mechanical loading to facilitate bone mass accretion during pubertal growth. In addition, muscle strength together with body composition may play an important role in determining bone mass. en
dc.description.abstract Wangin tutkimuksen mukaan murrosikäisillä tytöillä luun koon kasvu tapahtuu aiemmin kuin luun massan kasvu. Tämä saattaa selittää muissa tutkimuksissa todetun murtumariskin lisääntymisen kasvukirin aikana. Estradiolin merkitys luun lujuudelle korostuu tässä kehitysvaiheessa, koska se hillitsee luun resorptiota ja mahdollisesti jopa lisää luun endokortikaalista muodostusta. Estradiolin luumassaa lisäävä vaikutus saattaa edellyttää sopivaa mekaanista rasitusta. – Myös lihasvoimalla ja kehon koostumuksella näyttää olevan merkitystä luun lujuuden kehitykselle kehon painoa kantavissa luissa, Wang lisää. Wang tarkasteli tutkimuksessaan luun kasvun koon, mineraalimäärän (BMC) ja volymetrisen mineraalitiheyden (vBMD) yhteyttä sukuhormonituotantoon, fyysiseen aktiivisuuteen, kehon koostumukseen ja lihasvoimaan 10–13 -vuotiailla tytöillä. Hän seurasi tyttöjen kasvua ja kehitystä toistuvin mittauksin kahden vuoden ajan. Fyysistä aktiivisuutta Wang määritteli kyselylomakkeen avulla ja kehon koostumusta ja BMC:tä röntgenabsorptiomenetelmällä. fi
dc.language.iso eng
dc.publisher University of Jyväskylä
dc.relation.ispartofseries Studies in sport, physical education and health;110
dc.relation.isversionof ISBN 951-39-2352-5
dc.title Bone growth in pubertal girls : cross-sectional and longitudinal investigation of the association of sex hormones, physical activity, body composition, and muscle strength with bone mass and geometry
dc.type Diss. fi
dc.identifier.urn URN:ISBN:951-39-2273-1
dc.type.dcmitype Text en
dc.type.ontasot Väitöskirja fi
dc.type.ontasot Doctoral dissertation en
dc.contributor.tiedekunta Liikuntatieteellinen tiedekunta fi
dc.contributor.tiedekunta Faculty of Sport and Health Sciences en
dc.contributor.yliopisto University of Jyväskylä en
dc.contributor.yliopisto Jyväskylän yliopisto fi

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