Determinants of environmentally related physical activity in adolescents: integration of self-determination and planned behavior theories

BACKGROUND/OBJECTIVE: Eco-friendly behaviors (EFB) represent an important domain at the intersection of health, quality of life, and environmental sustainability. The present study focuses on two related subdomains: PA-related energy-saving behaviors (PA-RESB) and energy-saving behaviors (ESB). More specifically, this study tested an integrated Self-Determination Theory (SDT) and Theory of Planned Behavior (TPB) model to identify the psychological determinants of PA-RESB and ESB among adolescents. METHODS: A cross-sectional sample of 391 Greek adolescents (12-15 years) completed measures of basic psychological need satisfaction (autonomy, competence, relatedness), TPB constructs (attitudes, subjective norms, perceived behavioral control, intentions), and PA-RESB and ESB. Two structural equation models were tested (one for each outcome). RESULTS: In both models, competence had the strongest association with TPB constructs, showing positive associations with attitudes, subjective norms, and perceived behavioral control. Across models, perceived behavioral control and attitudes significantly predicted intention, and intention significantly predicted PA-RESB and ESB. The direct perceived behavioral control→behavior paths were not significant. CONCLUSION: Integrating SDT and TPB helps explain adolescents' eco-friendly behaviors in both physically active and household energy-saving domains. Interventions that strengthen perceived competence and perceived behavioral control may support stronger intentions and greater engagement in PA-RESB and the ESB.