Bone mineralization in boys during puberty: associations with body composition, physical activity and selected bone and adipose tissue biochemical markers
Date
2016-09-20
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Abstract
Kehaline inaktiivsus ja rasvumine on kujunenud ülemaailmseks probleemiks rahvatervise seisukohalt, omades sealhulgas mõju ka organismi luukoe arengule. Eriti ulatuslik luukoe juurdekasv toimub organismis puberteediperioodi jooksul, mistõttu võib seda perioodi pidada eriti kriitiliseks hilisema luukoe tervise suhtes. Mitmetes uuringutes on leitud, et luukoe arengut mõjutavad keha koostise, kehalise aktiivsuse, kui ka vere biokeemilised näitajad. Seega on oluline uurida, millised faktorid mõjutavad luukoe juurdekasvu just sellel kriitilisel kasvuperioodil. Meile teadaolevalt puuduvad varasemad uuringud luukoe juurdekasvu määramisel, kus hinnatakse erinevate keha koostise, kehalise aktiivsuse ja luukoe ning rasvkoe vere biokeemiliste markerite pikaajalist mõju puberteediealiste poiste luukoe arengule.
Uurimustöö eesmärk ja ülesanded
Antud uurimistöö eesmärgiks oli hinnata erinevate keha koostise, kehalise aktiivsuse ning luu- ja rasvkoe biokeemiliste markerite seoseid luukoe juurdekasvuga erineva keha koostise ja kehalise aktiivsusega puberteediealistel poistel. Lähtuvalt eesmärgist olid ülesanneteks:
1. uurida kehalise aktiivsuse pikemaajalist mõju luutiheduse kasvule puberteediperioodil erineva keha massiga poistel;
2. uurida luukoe ja rasvkoe biokeemiliste markerite seoseid luutihedusega erineva kehalise aktiivsusega varases puberteedieas poistel;
3. uurida luu- ja rasvkoe vere biokeemiliste näitajate ning kehalise aktiivsuse pikemaajalist mõju luutiheduse kasvule poistel puberteediea jooksul.
Uuritavad ja metoodika
Uuringus osales kokku 206 12-14 aastast poissi Tartu linna ning ümbruskonna koolidest. Vaatlusaluseid uuriti kahe aasta jooksul ning mõõtmised toimusid uuringu alguses ning peale 12 ja 24 kuu möödumist. Kõigil uuritavatel määrati keha pikkus ja kehamass ning arvutati kehamassiindeks. Bioloogiline vanus määrati Tanneri metoodikaga. ning luuline vanus käelaba röntgeniga. Keha koostise ja luutiheduse näitajad määrati DXA meetodiga ning kehaline aktiivsus aktseleromeetritega. Samuti määrati veeniverest erinevad luu- ja rasvkoe biokeemilised näitajad.
Järeldused
1. Keha rasvavaba mass omas pikaajalist positiivset mõju poiste luutiheduse suurenemisele puberteediperioodil. Alakaal puberteediperioodi alguses on tervise riskifaktor madalamale luutihedusele hilisemas puberteedieas võrreldes normaalkaaluliste, ülekaalulisete ja rasvunud poistega;
2. Kehaline aktiivsus mõjutab puberteediealistel poistel rasvkoe ja luukoe vere biokeemiliste markerite seost luutihedusega;
3. Luukoe sünteesi ja degradatsiooni biokeemilised näitajad on negatiivselt seotud luutiheduse kasvuga poistel puberteediperioodil. Samuti oli leptiini kontsentratsioon negatiivselt seotud luutiheduse kasvuga puberteediealistel poistel
Physical inactivity and increasing rates of obesity are becoming one of the most serious concerns in public health. Those factors also have the influence on bone accrual during maturation. Puberty is a critical period of bone mineral accrual that may have long-term consequences for bone health in adulthood. It is known that half of the peak bone mass is accumulated during pubertal years. The associations of bone mineral accrual with different body composition, physical activity and blood biochemical variables should be assessed to better monitor bone development during puberty. To our knowledge, there are no longitudinal studies about the influence of body composition, bone and adipose tissue biochemical markers, and objectively measured physical activity on bone mineral accrual in boys during puberty. The general aim of this dissertation was to evaluate possible associations between body composition, physical activity and different biochemical markers of bone and adipose tissue with bone mineral development in pubertal boys with different body mass and physical activity values. The specific purposes of this study were to: 1) investigate longitudinal effect of physical activity on bone mineral parameters in boys with different body mass values during puberty; 2) examine the relationships of bone and adipose tissue biochemical markers with bone mineral parameters in early pubertal boys with different physical activity level; 3) investigate longitudinal effect of bone and adipose tissue biochemical markers and physical activity level on bone mineral parameters in boys during puberty. In total, 206 12-14 year-old boys from different schools in Tartu (Estonia) and its surrounding areas participated in this study. The boys were followed for two years and 3 measurement sessions were performed: at baseline, after 12 and after 24 months. In the first 24-month longitudinal study (Study I), the subjects (n = 206) were divided into underweight (BMI<15.35 kg/m2; n=27), normal weight (BMI≥15.35–21.22 kg/m2; n=133), overweight (BMI≥21.22–26.02 kg/m2; n=22) and obese (BMI>26.02 kg/m2; n=24) groups at the baseline. In the cross-sectional study (Study II), the number of participants was cut to 86 due to lacking data on blood biochemical analysis. The subjects were divided into physically active (moderate-to-vigorous physical activity [MVPA] ≥60 min/day; n=46) and physically non-active (MVPA<60 min/day; n=40) groups. In the second 24-month longitudinal study (Study III), the number of participants was 96, and boys were monitored over 24-month study period. Body height and body mass were measured, and body mass index (BMI; kg/m²) was calculated. Pubertal development was assessed by self-reported questionnaire of pubertal stages according to Tanner classification. A uniaxial accelerometer was used to assess physical activity. Body composition and bone mineral values were assessed using dual-energy X-ray absorptiometry. Serum leptin, adiponectin, osteocalcin and C-terminal telopeptide of type I collagen were also measured. Conclusions: 1) Lean body mass has a positive longitudinal effect on bone mineral values in boys during puberty. Being an early pubertal underweight boy indicates greater chance to have lower bone mineral density during future pubertal development compared to normal weight, overweight and obese boys; 2) Physical activity has an important role in mediating the relationship between bone and adipose tissue biochemical markers and bone mineral values in early pubertal boys; 3) Bone formation and resorption markers are negatively associated with bone mineralization in boys during puberty. Leptin but not adiponectin is inversely associated with bone mineralization in boys during puberty.
Physical inactivity and increasing rates of obesity are becoming one of the most serious concerns in public health. Those factors also have the influence on bone accrual during maturation. Puberty is a critical period of bone mineral accrual that may have long-term consequences for bone health in adulthood. It is known that half of the peak bone mass is accumulated during pubertal years. The associations of bone mineral accrual with different body composition, physical activity and blood biochemical variables should be assessed to better monitor bone development during puberty. To our knowledge, there are no longitudinal studies about the influence of body composition, bone and adipose tissue biochemical markers, and objectively measured physical activity on bone mineral accrual in boys during puberty. The general aim of this dissertation was to evaluate possible associations between body composition, physical activity and different biochemical markers of bone and adipose tissue with bone mineral development in pubertal boys with different body mass and physical activity values. The specific purposes of this study were to: 1) investigate longitudinal effect of physical activity on bone mineral parameters in boys with different body mass values during puberty; 2) examine the relationships of bone and adipose tissue biochemical markers with bone mineral parameters in early pubertal boys with different physical activity level; 3) investigate longitudinal effect of bone and adipose tissue biochemical markers and physical activity level on bone mineral parameters in boys during puberty. In total, 206 12-14 year-old boys from different schools in Tartu (Estonia) and its surrounding areas participated in this study. The boys were followed for two years and 3 measurement sessions were performed: at baseline, after 12 and after 24 months. In the first 24-month longitudinal study (Study I), the subjects (n = 206) were divided into underweight (BMI<15.35 kg/m2; n=27), normal weight (BMI≥15.35–21.22 kg/m2; n=133), overweight (BMI≥21.22–26.02 kg/m2; n=22) and obese (BMI>26.02 kg/m2; n=24) groups at the baseline. In the cross-sectional study (Study II), the number of participants was cut to 86 due to lacking data on blood biochemical analysis. The subjects were divided into physically active (moderate-to-vigorous physical activity [MVPA] ≥60 min/day; n=46) and physically non-active (MVPA<60 min/day; n=40) groups. In the second 24-month longitudinal study (Study III), the number of participants was 96, and boys were monitored over 24-month study period. Body height and body mass were measured, and body mass index (BMI; kg/m²) was calculated. Pubertal development was assessed by self-reported questionnaire of pubertal stages according to Tanner classification. A uniaxial accelerometer was used to assess physical activity. Body composition and bone mineral values were assessed using dual-energy X-ray absorptiometry. Serum leptin, adiponectin, osteocalcin and C-terminal telopeptide of type I collagen were also measured. Conclusions: 1) Lean body mass has a positive longitudinal effect on bone mineral values in boys during puberty. Being an early pubertal underweight boy indicates greater chance to have lower bone mineral density during future pubertal development compared to normal weight, overweight and obese boys; 2) Physical activity has an important role in mediating the relationship between bone and adipose tissue biochemical markers and bone mineral values in early pubertal boys; 3) Bone formation and resorption markers are negatively associated with bone mineralization in boys during puberty. Leptin but not adiponectin is inversely associated with bone mineralization in boys during puberty.
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Keywords
teismelised, poisid, füüsiline aktiivsus, keha koostis, luukude, rasvkude, luutihedus, biomarkerid, teenagers, boys, physical activity, body composition, bone tissue, adipose tissue, bone density, biomarkers