Associations between pubertal hormones and physical activity levels, and subsequent bone mineral characteristics: a longitudinal study of boys aged 12–18

Abstract

Osteoporoos on märkimisväärne rahvatervise probleem. Haiguse väljakujunemisel on oluline roll esimesel kolmel aastakümnel saavutatud luu tippmassil. Kuna ligi 95% luu tippmassist moodustub lapse- ka noorukieas ning kriitiliseim periood luukoe formeerumise seisukohalt on just murdeiga ehk puberteet, siis on tegurid, mis puberteedi perioodil luukoe juurdekasvu mõjutavad, edaspidise skeletisüsteemi tervise seisukohalt väga olulised. Luukoe moodustumist mõjutavaid tegureid on mitmeid, olulisimateks biokeemilisteks teguriteks on suguhormoonid, kasvuhormoon koos insuliinisarnase kasvufaktor 1 ja vitamiin D, aga ka mitmed adipokiinid nagu leptiin ja adiponektiin. Oluline tegur on ka kehaline aktiivus, mis suurendab luukoe juurdekasvu ja luutihedust läbi mehaanilise koormamise. Sporditeaduste ja füsioteraapia instituudi longitudinaalses uuringus osalesid terved poisid, keda uuriti 12, 13 ja 14 aasta vanuses. Käesoleva doktoritöö raames kutsuti samad uuritavad 18 aasta vanuses järeluuringusse, mille eesmärgiks oli uurida puberteediea testosterooni, leptiini ja adiponektiini suhte ning kehalise aktiivsuse seoseid luutiheduse näitajatega 18 aasta vanuses. Lõpliku uuringugrupi moodustasid 88 noormeest, kellel olid vastavad näitajad mõõdetud kõigil neljal ajahetkel. Leidsime, et testosterooni tase 12 aasta vanuses on positiivselt seotud järgneva 6 aasta kogu keha volumeetrilise luutiheduse tõusuga. Samas on puberteediea leptiini-adiponektiini suhe negatiivselt seotud lülisamba luutiheduse ning lülisamba volümeetrilise luutihedusega 18 aasta vanuses ning ka samade luutiheduse näitajate juurdekasvuga 12ndast 18nda elusaastani. Noormeeste puberteediea suurem üldine kui ka tugeva intensiivsusega kehaline aktiivsus on seotud kõrgema kogu keha ja reieluu kaela luutihedusega 18 aasta vanuses.Osteoporosis is a significant public health problem. Peak bone mass obtained during first three decades plays an important role in the development of the disease. Since almost 95% of the peak bone mass is formed in childhood and adolescence, and the most critical period for the formation of bone tissue is puberty, the factors that affect accumulation of bone mass during puberty are important regarding future skeletal health. There are several factors that affect bone formation. The most important biochemical factors are sex hormones, growth hormone together with insulin-like growth factor 1 and vitamin D, as well as several adipokines such as leptin and adiponectin. One of the most important factors affecting bone density is physical activity, which has effect on bone mass and bone mineral density through mechanical loading. A cohort of healthy boys recruited at the Institute of Sport Sciences and Physiotherapy was followed annually at the age of 12, 13 and 14 years. As part of this dissertation the subjects were asked to come to the follow-up study at the age of 18 years. The main goal of the study was to investigate associations between serum testosterone, leptin to adiponectin ratio and physical activity in puberty and bone mineral characteristics at the age of 18 years. The final study cohort consisted of 88 healthy males who had most complete data set at all 4 study points. We found that serum testosterone concentration at the age of 12 years is positively correlated with subsequent 6-year increase in total body bone mineral apparent density in healthy young males. Leptin to adiponectin ratio in puberty is negatively associated with lumbar spine bone mineral density and lumbar spine bone mineral apparent density at the age of 18 years as well as their increment between 12 and 18 years. Increased total physical activity and vigorous physical activity in puberty is associated with higher total body and femoral neck bone mineral density in healthy young males at the age of 18 years.