Substantial evidence indicates that motor competence, physical activity, and physical fitness are independently associated with numerous health outcomes. However, only a few studies have empirically investigated the association between all mentioned factors and the mediators that influence them. Understanding the mechanisms associated with improving motor competence, physical activity, and physical fitness is crucial for children and adolescents.

Children spend most of their daytime at school, where they are usually deprived of time for physical activity. The consequences include the decrease in physical fitness, motor competence, and physical activity. The lack of the aforementioned essential components of children’s development and increasing time spent in sedentary behaviours during childhood place importance on developing simple, low cost school-based interventions to increase this performance among children. Moreover, the mediators of behaviour in interventions to promote physical activity among children and adolescents are still undefined.

The aim of this Special Issue is to provide an opportunity to publish high-quality research relating to the promotion of motor competence, physical activity, and physical fitness. We welcome innovative, simple, and feasible interventions (active commuting to/from school, active Physical Education lessons, active school recess, after school programs, health promotion, or an integrated program incorporating all interventions) to improve motor competence, physical activity, and physical fitness in school children. Moreover, we aimed to investigate the possible mediators that contribute to the improvements in performance. We welcome original research and review articles.

Potential topics include but are not limited to the following:

• School-based high-intensity interval training programs
• School-based high-intensity interval training programs and nutrition intervention
• School-based circuit training
• School-based team sport interventions
• Multisport interventions
• Active recess
• Mediation role of motor competence, physical activity and physical fitness in exercise interventions