Long-term protective effects of physical activity and self-control on problematic smartphone use in adolescents: A longitudinal mediation analysis

Adolescents are more likely to experience problematic smartphone use (PSU) due to developmental immaturity. As most previous studies have focused on cross-sectional relationships between PSU, self-control, and physical activity, it is difficult to make valid inferences about their causal relationships and long-term effects. This study aims to investigate the interrelationships between these three variables through a mediation analysis based on a cross-lagged model in a longitudinal design. A total of 2131 participants (Mage = 12.14, SD = 2.29, 51.5% female) were surveyed at three time points with 1-year intervals. Smartphone Addiction Proneness Scale (SAPS) and revised Self-Control Scale were used to assess PSU and self-control respectively. Physical activity was measured with an item questioning frequency of physical activity. Cross-lagged model showed that both self-control and physical activity were negatively and bidirectionally associated with PSU. Self-control had a positive predictive effect on physical activity at the next time point. Additionally, self-control positively predicted subsequent physical activity, which in turn negatively predicted subsequent PSU, indicating a mediating effect of physical activity between self-control and PSU. Self-control and physical activity had a long-term effect on reducing the propensity for PSU. Because of the accessibility and operability of physical activity interventions, the public and policy-makers need to prioritize physical activity as an intervention to prevent PSU in adolescents.