Introduction
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HEART, ADIPOSITY, SECONDARY
Physical activity (PA) in children and adolescents has not only been consistently associated with physical health (i.e., adiposity, cardiometabolic health, health-related physical fitness (HRPF), bone health, etc.) (Schools serve as environments where millions of children and adolescents, representing diverse socioeconomic backgrounds, cultures, and fitness profiles, coexist for extended periods of time. This makes the school an ideal setting for developing strategies to encourage the adoption of healthy lifestyle habits. Moreover, the American Heart Association recommends that children and adolescents should accumulate at least 30 min of MVPA in the school day (Currently, schools serve as alarming hubs of inactivity and sedentary behavior, necessitating strategies that aim to increase MVPA levels and reduce prolonged sedentary periods during the school day. Traditionally, physical education lessons and recess have been regarded as opportune periods to incorporate PA during the school day. However, such methods have proven ineffective in increasing PA levels, particularly among adolescents (AB involve incorporating short breaks of PA (usually with moderate or vigorous intensity) into academic lessons, excluding physical education (PAL involves integrating PA into lessons in key learning areas other than physical education (e.g., mathematics) (The scarcity of studies and the disparity of results found in secondary education, joined with the observed decline in PA levels during this stage (Thus, this study reports on the methods and rationale of the ACTIVE CLASS study. This randomized controlled trial (RCT) has two main objectives: (i) examines the effect of two active learning intervention (AB and PAL) on PA levels, sedentary time, educational indicators, cognition, and markers of physical and psychological health in secondary education students; (ii) evaluate teachers’ and students’ experiences about the implementation of these the two school-based PA intervention.