The Tromsø Study: Fit Futures: a study of Norwegian adolescents’ lifestyle and bone health

Abstract

Summary Bone mass achievement predicts later fracture risk. This population-based study describes bone mineral density levels (BMD) and associated factors in Norwegian adolescents. Compared with international reference ranges, BMD levels appear higher and physical activity levels are positively associated with BMD.Purpose Norway has one of the highest reported incidences of osteoporotic fractures. Maximization of peak bone mass may prevent later fractures. This population-based study compared BMD levels of Norwegian adolescents with international reference ranges and explored associated factors.Methods All first year upper secondary school students, aged 15-19 years in the Tromsø region were invited to the Fit Futures study in 2010-2011. Over 90% of the invited participants attended, 508 girls and 530 boys. BMD was measured at total hip, femoral neck and total body by dual x-ray absorptiometry.Lifestyle variables were collected by self-administered questionnaires and interviews. All analyses were performed sex stratified, using linear regression models.Results In girls mean BMD (SD) was 1.060 (0.124), 1.066 (0.123) and 1.142 (0.077) g/cm² at the total hip, femoral neck and total body respectively. In boys corresponding values were 1.116 (0.147), 1.103 (0.150) and 1.182 (0.097), with significant higher values than the Lunar pediatric reference at 16 years of age In girls, height and self-reported intensive physical activity of more than four hours a week and early sexual maturation were positively associated with BMD at both femoral sites (p<0.047). Among boys age, height, body mass index, physical activity and alcohol intake were positively (p<0.038), whereas early stages of sexual maturation and smoking was negatively (p<0.047) related to BMD.Conclusions Despite the heavy fracture burden, Norwegian adolescents´ BMD levels are higher than agematched Caucasians. Physical activity is associated with 1 SD increased BMD levels in those involved in competition or hard training.

Changes and tracking of bone mineral density in late adolescence: the Tromsø Study, Fit Futures

“…The underlying mechanisms behind the effects of contraceptives are complex and data on length of use and dosage are lacking. Winter et al reported that late sexual maturation was associated with low aBMD levels in TFF1 [31]. The fact that proportions of sexual maturation categories in our study are comparable with other Norwegian youth cohorts [40] and that the association between late sexual maturation and increased odds for positive deviation in this longitudinal study is consistent suggest that this adverse effect levels out to some extent.…”

“…PA seemed beneficial for TB aBMD, but we found no clear dose-response effect. This may indicate that participants reporting to be in the hard training and competition category at baseline were already at the tail of the z-score distribution as reported by Winther et al [31]. Sustained activity level during follow-up and preservation of high z-score could lead to classification into the reference group no change or downwards drift for these participants.…”

The influence of birth weight and length on bone mineral density and content in adolescence: The Tromsø Study, Fit Futures

“…The Danish study included 119 versus 765 in ours. Furthermore, as bone mass acquisition varies in girls and boys during adolescence [21], our analyses were performed sex stratified in contrast to the study of Jensen et al…”

“…The invited cohort comprised 1117 adolescents and 1038 (508 girls and 530 boys) attended the survey (93%). The cohort characteristics have been described in detail previously [21,22]. The present investigation includes participants aged 15-18 years of age (n = 961).…”

Cross-sectional study of the differences between measured, perceived and desired body size and their relations with self-perceived health in young adults: The Tromsø Study – Fit Futures 2

“…Students in upper secondary school from two municipalities in northern Norway (Tromsø and Balsfjord) were invited to participate in the population-based Tromsø Study youth survey, Fit Futures, which has been described in detail elsewhere [13,14]. …”