Intervention Programme Based on Self-Determination Theory to Promote Extracurricular Physical Activity through Physical Education in Primary School: A Study Protocol.

Low levels of physical activity (PA) are a concern among students, producing negative physical, health and mental consequences. This study aims to present a protocol intervention in physical education (PE) based on self-determination theory (SDT) to enhance students' motivation towards performing PA and increasing their PA levels in their leisure time. This protocol is a convenience study with two allocation arms (intervention group versus control group). SDT-based motivational strategies will be carried out and co-created with PE teachers to increase motivation and out-of-school PA levels. Data collection will be conducted three times: before the intervention, after the intervention (four months after baseline) and at the end of the intervention (retention measurement, seven months after baseline). The measures will assess perceived teacher support for PA, motivation towards PA, intention to be physically active, PA levels, engagement in PE and academic performance. Overall, this intervention programme is expected to increase students' autonomous motivation for PA and their PA levels in their free time. This intervention might encourage teachers to establish strategies and resources to increase their students' adaptive outcomes.