Master i Exercise Physiology and Sport Sciences Tore Christoffersen disputerer for ph.d.-graden i helsevitenskap og vil offentlig forsvare avhandlingen:
”The influence of birth weight, childhood fractures and lifestyle factors on peak bone mass in Norwegian boys and girls between 15-18 years of age. The Tromsø Study, Fit Futures”
Kort sammendrag av avhandlingen:
Osteoporotic fractures in the elderly constitute a major problem worldwide, and the highest incidences of hip fractures ever reported are from the Scandinavian countries including Norway. Fracture risk in old age is determined by bone mass accumulation during growth and subsequent bone loss through adult life. While traditional strategies have focused on the reduction of age-related bone loss and fracture rates among the elderly, attention has recently shifted to the role of peak bone mass (PBM) on bone strength. The basis of bone strength is created during early development and growth, before the achievement of a PBM in the second or early third decade of life. In order to optimize PBM, we need to identify factors that influence bone mass accrual during growth and adolescence.
The main aim of this thesis was to investigate the influence of birth weight and length, childhood fractures and lifestyle factors like physical activity on the accumulation of bone mass among Norwegian adolescents.
The Tromsø Study, Fit Futures is an expansion of the population-based Tromsø Study. In 2010/2011 we invited all first-year upper-secondary school students in Tromsø and surrounding municipalities to a health survey and 508 girls and 530 boys attended. We measured hip and total body bone mineral content (BMC), bone mineral density (BMD) by Dual-energy X-ray absorptiometry (DXA). Weight and height were measured and information about lifestyle was collected through clinical interviews and an electronic self-reporting questionnaire. All fractures in the cohort were retrospectively recorded from the local hospital UNN Tromsø. Information on birth parameters were collected from the Medical Birth Registry of Norway.
Through childhood, fractures were registered among 35% and 31% of boys and girls, respectively. Higher levels of physical activity (PA) in adolescence were associated with increased levels of BMD and BMC, suggesting that participation in PA is of major importance to PBM. Birth weight and length were positively associated with BMC at all measured sites. However, these associations were attenuated when adjusting for change in size and lifestyle factors during adolescence. We could not confirm that childhood fracture is an early marker of skeletal vulnerability as the association between a previous fracture and bone outcomes appeared inconsistently across levels of physical activity and sex.
(Avhandlingen er tilgjengelig for utlån hos Seksjon for utdanningstjenester frem til disputasdato)
Hovedveileder professor Nina Emaus, Institutt for helse- og omsorgsfag, Det helsevitenskapelige fakultet, UiT Norges arktiske universitet
Biveileder forsker Luai Awad Ahmed, Institutt for helse- og omsorgsfag, Det helsevitenskapelige fakultet, UiT Norges arktiske universitet og Institute of Public Health, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, UAE
Professor Peter Nordström, Umeå Universitet, Sverige
Dekan Trine Karlsen, Fakultetet for sykepleie og helsevitenskap, Nord universitet
Førsteamanuensis Kristin Benjaminsen Borch, Institutt for samfunnsmedisin, Det helsevitenskapelige fakultet, UiT Norges arktiske universitet
Prodekan professor Jan Rosenvinge, Det helsevitenskapelige fakultet, UiT Norges arktiske universitet
Prøveforelesning over oppgitt emne holdes kl. 09.15, samme sted: «Måling av fysisk aktivitet – finnes det en gullstandard?»