Caroline Eckert

What is the title of your thesis?

Structured Physical Activity and Health in Danish Primary School Children: Dose-Response and Differential Effects of the FIT FIRST 10 Intervention.

At which department and/or research unit did you complete your PhD?

Department of Sports Science and Clinical Biomechanics, Sport and Health Sciences Research Unit.

Who was your principal supervisor?

Professor Peter Krustrup.

What question did you aim to answer with your thesis?

How are participation in organized sports and a school-based multisport initiative associated with the physical health and well-being of Danish schoolchildren?

What did you find?

Children who participated in organised sports generally had better physical fitness and a more positive physical self-perception. Associations with cardiometabolic health and quality of life were less clear. As the study was cross-sectional, the results cannot establish cause and effect.

In the four-month intervention study, approximately 1.5 FIT FIRST 10 sessions per week resulted in small improvements in body composition and handgrip strength, but not in cardiorespiratory fitness. Three weekly sessions provided no additional benefits, highlighting the importance of realistic dosage and effective implementation in schools.

The effects also varied between groups. Boys with two Danish-born parents showed some cardiometabolic improvements, while girls with no or one Danish-born parent experienced improvements in psychological well-being. The findings were selective and should be confirmed in future studies.

How did you do it?

The thesis is based on data from more than 1,000 children at 27 Danish schools.

First, I investigated associations between participation in organised sports, physical fitness, health and well-being. I then evaluated the FIT FIRST 10 intervention in a randomised controlled trial, in which school classes received different weekly doses of the intervention (1.5 or 3 sessions per week) or regular physical education (the control group). 

The children underwent physical and health assessments and completed questionnaires on well-being and physical self-perception.

How can your research be applied (in the clinic, society, etc.)?

The results can help schools and decision-makers plan realistic and feasible physical activity initiatives.

They show that more sessions per week do not necessarily lead to greater health benefits under real-world conditions, and that a higher planned dose does not necessarily produce a greater effect if it is difficult to implement in practice.

At the same time, initiatives should be continuously evaluated across different groups of children to ensure that they promote health without exacerbating existing inequalities.