Social Network Intervention in Physical Education Classes Through Social Support to Promote Physical Activity and Reduce Screen Time in Adolescents: A Cluster Randomized Controlled Trial

Physical activity (PA) and screen time (ST) are complex behaviors influenced by social factors such as relationships with family and friends, linked to mechanisms such as social support. This study implemented a segmentation-based social network intervention which is a promising approach to improving health-behaviors in a network. The objective was to determine the effects of a social network intervention through social support from friends and parents on PA and ST among adolescents. A cluster-randomized controlled trial was conducted involving 4 schools, 24 classrooms, with 787 adolescents. A segmentation-based social network intervention was implemented over ten weeks in physical education classes. Two components, ClassI involving friends support and ParentsI involving parents support was included. Follow-up was conducted at week ten post-intervention. A mixed-effects model was used to determine the effectiveness. Network mechanisms of perceived social support from friends most associated with PA and ST were explored. Findings indicated a significant increase of 12.2 daily minutes of PA in the intervention group (95% CI: 1.9 to 22.5, p = .02). Main effects suggest sustainability over time. Social support from friends and parents was significant (p < .001), and homophily was positively associated with PA (p < .05). For ST, a reduction of 56.7 minutes was observed in the intervention group (95% CI: −105.2 to −8.1, p = .02). Main effects indicate that the effectiveness for ST was not sustainable over time. Implementing a social support network intervention from friends and parents within physical education classes is effectively increased daily PA and decreased ST among adolescents.