The intermittent group students performed an intermittent teaching unit twice a week for eight weeks aimed at promoting healthy physical activity habits. Specifically, the last 15 minutes of each lesson were used. The rest of lessons' time other contents were worked on with no relation to any health physical activity habit (i.e., acrosport, badminton, basketball, volleyball, soccer and athletics).

The control group students also carried out two Physical Education lessons a week during the intervention period. During these lessons, contents of handball, basketball, alternative sports and traditional games were developed. However, this group did not wear physical activity activity wristbands or receive any behavior modification specific strategy developed in the intermittent group.

The intermittent group students performed an intermittent teaching unit twice a week for eight weeks aimed at promoting healthy physical activity habits. Specifically, the last 15 minutes of each lesson were used. The rest of lessons' time other contents were worked on with no relation to any health physical activity habit (i.e., acrosport, badminton, basketball, volleyball, soccer and athletics).

The Physical Education teacher autonomy-support was assessed through the Spanish version of the Multi-Dimensional Perceived Autonomy Support Scale for Physical Education (MD-PASS-PA). It consists of 15 items (five items per factor) that assessed organizational, procedural, and cognitive autonomy support. The items were preceded by the statement "My Physical Education teacher...". The Spanish version of MD-PASS-PA has shown adequate psychometric properties among adolescents.

Students' perceptions of autonomy, competence, and relatedness satisfaction in Physical Education and physical exercise were assessed using the Spanish version of the Basic Psychological Needs in Exercise Scale (BPNES). It consists of 12 items (four items per factor) that assessed autonomy, competence and relatedness. The items were preceded by the statement "When I do physical activity…". The Spanish version of BPNES has shown adequate psychometric properties among adolescents.

Participants' self-determined motivation toward Physical Education was measured by the Spanish version of the Revised Perceived Locus of Causality Scale (PLOC-R). It consists of of 23 items spread over six dimensions (four items each except external regulation) that measure intrinsic motivation, amotivation, integrated, identified, introjected, and external regulation. This questionnaire was preceded by the statement "I participate in Physical Education lessons…". The autonomous (i.e., averaging intrinsic, integrated, and identified regulation) and controlled (i.e., averaging introjected and external) motivations were also calculated. The Spanish version of the PLOC-R has shown adequate psychometric properties among adolescents.