This Guest Blog is the first in a series of blogs highlighting success stories – where exercise was implemented and made a difference. As part of the BJSM initiative in ‘implementation’ we invite readers to submit success stories – and we will solicit them too!
Cardiorespiratory fitness and cardiovascular disease risk factors in children: effects of a two-year school-based daily physical activity intervention was my PhD study – at the Norwegian School of Sport Sciences, Department of Sports Medicine, Oslo, Norway.
Professors Lars Bo Andersen and Sigmund Anderssen were my mentors for this 2-year, school-based, controlled intervention carried out in two towns in the western parts of Norway.
Here is a brief overview of our investigation:
- To investigate the effects of a school-based intervention, involving 60 minutes of daily physical activity over two school years, on CRF and CVD risk factors in nine-year-old children.
- To describe CRF levels and CVD risk factor levels in rural nine-year old children
- To examine the association between CRF and clustering of CVD risk factors in these children.
A total of 256 rural Norwegian children participated in this controlled intervention study. Intervention-school children carried out 60-minute physical activity over two school years. Control-school children had the regular curriculum-defined amount of physical activity in school, i.e. 45 minutes twice weekly. Peak oxygen uptake was directly measured during a continuous progressive treadmill protocol where the children ran until exhaustion. A blood sample was taken from each child for analyses of glucose, insulin, total cholesterol, high-density-lipoprotein cholesterol and triglyceride. Also body mass, height, systolic and diastolic blood pressure and waist and hip circumference were measured.
The intervention resulted in a significant greater beneficial development in peak oxygen uptake, systolic and diastolic blood pressure, total cholesterol to high-density lipoprotein cholesterol ratio and triglyceride in intervention-school children than in control-school children. No significant differences in changes were observed in waist circumference, body mass index and the homeostasis model assessment for insulin resistance between the two groups. Furthermore, the intervention, primarily carried out at moderate intensity, showed that those children in the I-school with the least favorable starting point experienced the most beneficial effect of the intervention. The cross-sectional data suggested that low CRF, and low CRF and high fatness combined were highly associated with clustered CVD risk.
This two-year school-based teacher-led 60-minute daily PA intervention resulted in a significant greater beneficial development in SBP, DBP, TC:HDL ratio, TG and VO2peak in the I-school children than in the C-school children. No significant differences in changes were observed in WC, BMI and HOMA-IR between the two groups.
A daily school-based physical activity intervention can significantly increase children’s CRF levels and beneficially modify their CVD risk profile if the intervention is sufficiently long, includes substantial daily physical activity, and if the physical activity is planned and organized by expert physical education teachers. Therefore, daily physical activity should be given due consideration in the design of school policies.
EPILOGUE (what happened after the intervention period was over in 2007 ?)
The daily physical activity intervention program was established as part of the school curriculum for all participating children from the I-school, thus the physical activity was mandatory.
However, an important question is: What will happen to the physical activity in the I-school after the physical activity-project is completed? The I-school, Trudvang School in Sogndal, Norway, based on their experience in the Sogndal school-intervention study, has decided to continue its commitment to the physical activity program, and expand the program to all students.
The program consists of 30 minutes of daily teacher-led physical activity. Trudvang School considers the 30 minutes of daily physical activity as a subject with the same status and financial resources as the traditional subjects. Additionally, the children are given the possibility of a minimum of 30 minutes of daily free play in recess. At Trudvang School, there is no conflict between PE and physical activity. The former is a subject with defined goals which teachers and pupils work together to accomplish, while the latter has a public health perspective. For both PE and physical activity, trained PE teachers are responsible for the planning and organizing of lessons, and they also lead the physical activity lessons together with classroom teachers when appropriate. In this way, the students receive physical activity lessons of high quality. According to Trudvang School, all obstacles have now been overcome, and daily physical activity is a natural part of the school day. According to the principal (Bjarte Ramstad), Trudvang school will never return to the “traditional” weekly 2 X 45 minutes PE ! Schools are coming from different parts of Norway to learn from Trudvang school. This week 8 schools from the Hardanger area (close to Bergen) came to visit (and learn).
I believe that the school setting is an ideal environment for population-based physical activity interventions. In most countries, schools exist in all municipalities, and most children and adolescents, from the age of six to 16, spend most of their day in school. Hence, the school setting may be the only means in society to reach a large number of children from all socio-economic backgrounds. In my opinion, the two best school interventions carried out so far is:
1) Reed et al. Action Schools! BC: A school-based physical activity intervention designed to decrease cardiovascular disease risk factors in children. Prev Med. 2008: 46(6): 525–531.
2) Kriemler et al. Effect of school based physical activity programme (KISS) on fitness and adiposity in primary schoolchildren: cluster randomised controlled trial. BMJ. 2010: 340(c785).
Related BJSM Articles
Nettlefold, L, McKay HA, Warburton DER, McGuire KA, Bredin SSD, and Naylor PJ. 2011. The challenge of low physical activity during the school day: at recess, lunch and inphysical education. BJSM ;45:813-819 Published Online First: 9 March 2010.
Nicola D Ridgers, ND, Timperio, A, Crawford D, and Salmon J. 2011. Five-year changes in school recess and lunchtime and the contribution to children’s dailyphysical activity. BJSM, Published Online First: 19 May 2011