Since sedentary time is related to various health outcomes and is already highly prevalent in childhood and adolescence, effective strategies are needed to tackle this health problem. Children and adolescents spend the majority of the day in a classroom while sitting at a desk. Therefore, the classroom is an important setting for implementing specific strategies to reduce sedentary time.

One of the strategies that gained more attention during the past years is replacing traditional desks and chairs with standing desks.

This project evaluates the implementation of standing desks in primary and secondary schools via a clustered randomized controlled trial using an intervention and control condition. Effects on sedentary time during in class, sedentary activities during leisure time, breaks in sedentary time, and related determinants (secondary outcomes) are evaluated.

Next to effect evaluation, it is also equally important to evaluate how teachers and pupils perceive this change in the classroom environment. Both groups need to be positive in order to obtain the adoption and sustainability. Therefore, focus groups with pupils and interviews with teachers are conducted, with a specific focus on the perceived barriers. Moreover, the process evaluation is conducted quantitatively as well by using questionnaires in pupils and teachers.

The project results will lead to recommendations on how to broadly implement standing desks into primary and secondary schools.

Inclusion Criteria:

• Healthy pupils of primary schools (5th grade) and secondary schools (10th grade)