The aim of our study is to develop a physical activity program based on behavioral change models for children and to investigate the effectiveness of the physical activity program we have developed for children attending primary school. There is a limited number of studies in the literature on exercise habits in children, and there is no evidence on which model will provide better results when integrated into school or training programs. Although behavioral modification-based physical activity programs for children have been established and their effectiveness has been investigated in many different countries, there are limited randomized controlled studies on this subject. Currently, there are no randomized control studies on the topic in Turkey.

Our study will be the first study in which a school-based physical activity program based on behavioral change models in Turkish children is developed and its effectiveness is investigated. We believe that our study will contribute to the development of new models and protocols to improve the health of children in Turkey and the world and to provide behavior change methods that are research-based to combat physical inactivity.

The COVID-19 pandemic, which started in 2019, has negatively affected the lives of all humanity in many ways, especially with the decrease in physical activity. Due to quarantines, schools continued their educational activities online for a long time. While physical inactivity in children was a serious problem even in the pre-pandemic period, the restrictions imposed due to pandemic conditions had a catastrophic effect on the physical inactivity levels of children. It has been reported that children reach the recommended physical activity levels while they are at school. Studies show that the habits we have acquired since childhood are most likely habits that we can have for a lifetime.

The effectiveness of behavior change theories and models has been proven in studies conducted to gain exercise habits in various age groups. In the literature, many theories such as Self-Determination Theory (SDT), Transtheoretical Model, Planned Behavior Theory, and Social Cognitive Theory have been used to help children gain exercise habits. In a cross-sectional study involving 462 children aged 7-11, the effectiveness of the SDT model on children's physical activity motivation was examined. The results showed that there is a positive relationship between children's motivation based on activity enjoyment and satisfaction and physical activity scores. It has been reported that applications based on theory are promising for future interventions aimed at increasing physical activity levels in children.

However, there is a limited number of studies in the literature to gain exercise habits in children, and there is no evidence that which model will provide better results. In a postgraduate thesis done in Turkey in 2021, online exercise training based on behavior change theories and strategies was applied to gain exercise habits in children. They reported limited evidence that they obtained Although very few children participated in the study due to restrictions during the COVID-19 pandemic, they reported limited evidence that children achieved positive changes in health behavior.

For these reasons, the planning of our study is to develop a physical activity program based on behavioral change models for children and to investigate the effectiveness of the physical activity program we have developed in children attending primary school.

Inclusion Criteria:

• Voluntarily wanting to join the program
• Not having any chronic diseases
• Be able to read and write
• To have the cognitive skills to understand and answer the questionnaire
• To be a student at primary or secondary school.

Exclusion Criteria:

• Having a vision or hearing problem
• Have a diagnosis of chronic cardiac, neurological, or rheumatic disease
• Doing regular exercise/sports for the last 6 months