Although the positive effects of implementing physical activity interventions for kids are well documented, the majority of evidence to date is based on short-term tests of effectiveness conducted in well-supervised environments and usually do not include an extensive cohort, let alone the entire population of children.

Now, a natural experiment – introducing the Healthy Lifestyle Intervention in Slovenian primary schools – has offered the SLOfit research group the chance to study the effectiveness of this population-specific, longitudinal physical activity intervention in a real environment. In an article published in the prestigious scientific journal Obesity they showed the effect of this intervention on body mass index (BMI) among children aged 6 to 14 years. During the 2010/11 and 2017/18 school years at 216 Slovenian schools with more than 34,000 participating pupils, a nationwide intervention was conducted to increase physical fitness, and the researchers compared its results with the same number of pupils and schools where there was no such intervention.

The programme offered children from the first to sixth grade of primary school (age 6-11 years) two additional hours of physical education and three for children from the seventh to ninth grade (age 12-15 years). These additional hours were not part of the compulsory timetables, but were organised immediately after regular classes. The intervention was open to all children at the individual school, and was organised as an elective subject conducted by physical education teachers. The teachers had to ensure the programme offered at least 12 different sports for every three grade years, with priority being given to the three most prominent sports in the local environment. They also needed to raise awareness among pupils and their parents about healthy and energy-balanced diet, limiting the consumption of snacks and sweetened drinks and promoting a varied diet and other healthy life habits.

And what did the results show? That the BMI in the intervention group was without doubt lower, irrespective of how long the participation lasted or how high the starting BMI was.

Of course the difference in BMI increased more over the duration of the programme, with the greatest effects noticeable after three to four years of participation, and these effects were consistently higher in overweight children.

“The results of the Healthy Lifestyle intervention confirmed that the introduction of 2-3 additional hours of physical education per week provides sufficient high-intensity physical activity for a rebalancing of the expenditure and intake of energy, and significantly reverses the worrying trend of increasing obesity among children which we are once again witnessing after the years of corona virus restrictions. Our research team therefore pointed out a solution to the very critical situation, and it is up to the political decision-makers to show how much they care about the future of our young generations,” noted while presenting the results the co-author of the research, Dr Gregor Starc, head of the national Sports Education Card, which is part of the SLOfit monitoring and surveillance system established at the UL Faculty of Sport.

“Only sufficiently intensive and regular physical activity can supply sufficiently strong impulses to trigger processes in the body that are key to positive changes. For this reason, programmes such as Healthy Lifestyle should be the foundation of any education and health policy,” adds Dr Maroje Sorić, lead author of the research and member of the SLOfit research group.

The authors of the research entitled “Effectiveness of a population-scaled, school-based physical activity intervention for the prevention of childhood obesity” are: Dr Gregor Starc, Dr Maroje Sorić, Dr Gregor Jurak and Dr Shawnda A. Morrison, all members of the SLOfit research group at the Faculty of Sport of the University of Ljubljana, and Dr Petra Jurić of the Faculty of Kinesiology at the University of Zagreb.

The research is published in March 2023 in the print version of the journal Obesity, which is published by The Obesity Society (TOS, www.obesity.org), the leading association of scientists and health workers working to understand and eliminate the obesity epidemic and its harmful effects on health, the economy and society.

And how is the significance of this research viewed by other leading researchers in this field who were not involved? 

Francisco B. Ortega, head of the PROFITH group at the University of Granada

“This is truly unique research due to numerous facts.

1) It is based on the entire population of children.

2) It has been conducted in a real environment, and the selected intervention programme Healthy Lifestyle can be transferred to the local, regional or national level, if the policymakers are open to it. Another good example of this is the legally required one-hour daily sports classes in primary schools in Hungary.

3) Important too is the fact that the Healthy Lifestyle programme has been conducted over a very long time, which allows us for the first time to see the long-term effects of such physical movement interventions.

We should therefore acknowledge the exceptional work of the authors, and I believe that this study will have a major impact on further research and even more so on society.”

Justin J. Lang, epidemiologist at the Public Health Agency of Canada

“Slovenia is one of the leading countries in the fight against obesity in children. In this research the authors have shown and proven how important it is for sports education to be placed in the curriculum over the entire education vertical at the same level as, say, mathematics, languages and other major school subjects. For by ensuring the conditions for a healthy and active lifestyle in children and adolescents we will not just reduce the risk of obesity, we will also improve cognitive processes, so children will shine in other academic fields. Schools therefore demonstrably represent an important, if not vital, environment for the fight against childhood obesity, which begins with well planned and targeted policies that lead to greater physical movement literacy. Slovenia has mapped a path to effective solutions for the fulfilment of which the decision-makers need to follow up with concrete measures.”