Aim of the thesis
The aim of the ”Physical Activity among Norwegian Children Study” was to perform a study that was going to give us knowledge about physical activity level, activity patterns and aerobic fitness in a nationally representative sample of 9- and 15-year-olds. The study was initialized and funded by the Norwegian Directorate of Health.  

 

A total of 2299 children and adolescents participated in the study. The participation rate was high; 89% among the 9-year-olds and 74% among the 15-year-olds. Physical activity was assessed objectively by accelerometry, and the participants wore the accelerometer for four consecutive days. Aerobic fitness was measured directly through a maximum exercise test on a cycle ergometer. Anthropometric variables like height, body mass and waist circumference was also measured. The data collection started in March 2005 and was completed in October 2006.

 

Physical activity level
This is the first study in Norway assessing physical activity objectively and aerobic fitness directly in a large population-based sample of children and youth. The results revealed that boys have a higher physical activity level than girls at both 9- and 15-years. The activity level appears to decline when going from childhood through adolescence as 9-year-olds had a physical activity level that was 46% higher than the 15-year-olds. Both 9- and 15-year-olds had a higher physical activity level during week days than during weekends.

 

The Norwegian physical activity recommendations for children and youth state that there should be a minimum of 60 min of physical activity of at least moderate intensity every day. Whilst four out of five children met current physical activity guidelines, only half of the adolescents did. Nine-year-old children had significantly higher mean physical activity levels in spring than in winter and fall. In the two latter seasons, physical activity levels were especially low after school hours and on weekends. No associations were found between mean physical activity level and season among the 15-year-olds.

 

Changes in physical activity level and body composition
The results from the 9-year-olds in Oslo have been compared with data from the European Youth Heart Study that was carried out in Oslo in year 1999-2000. Nine-year-olds in 2005 had a significantly higher physical activity level than 9-year-olds in 1999-2000. The difference was approximately 6%. This might be a result of the emphasis of the beneficial effects of physical activity over the last years. 

 

In the same time period it was observed an increase of 9-year-olds classified as overweight and obesity, but the increase was not statistically significant. Between 1999-2000 and 2005 no changes were observed for mean BMI, while a significant increase was observed in waist circumference indicating increased adiposity.

 

Aerobic fitness
This study has also included measures of the participants’ aerobic fitness. Mean values for peak oxygen uptake were the following: 9-year old boys, 48.2±7.1 ml/min/kg; 9-year old girls, 42.9±6.7 ml/min/kg; 15-year old girls, 41.1±6.0 ml/min/kg; 15-year old boys, 51.9±8.0 ml/min/kg. The aerobic fitness showed high interindividual variability. In each sex and age group, the 10% with highest peak oxygen uptake had approximately two times higher aerobic fitness compared with the 10% of participants with the lowest peak oxygen uptake.

 

Elin Kolle (1.11.1977) is born in Sandnes. She obtained her Bachelors degree in physical activity and health from Sogn og Fjordane University College, NSSS and Queensland University of Technology, Brisbane, Australia. She completed her Master’s degree in physical activity and health from NSSS. Elin started her PhD in 2005, and has been supervised by   Professor Sigmund A. Anderssen and Professor Lars Bo Andersen .

 

Evaluation committee
Leder:  Professor Elisabet Børsheim, Norwegian School of Sport Sciences
1. Opponent:  Professor Chris Riddoch, University of Bath, England
2. Opponent:  Programme Leader Ulf Ekelund, MRC Epidemiology Unit, Cambridge, England

 

Programme
10.15 – 11.00 Trial lecture: “The relative importance of physical activity and body weight (Body Mass Index) for preventing cardiovascular disease.”

13.00 – 16.00 Dissertation

 

Both the trial lecture and the dissertation are open for the audience. 

 

Welcome!