Self-determination theory and motivational interviewing in web-based physical activity promotion: long-term effects

Abstract

Background This study assessed the long term effects of I Move, a web-based computer tailored physical activity (PA) intervention, based on self-determination theory (SDT) and motivational interviewing (MI). Methods A randomized controlled trial (n = 3165) was conducted, comparing three research conditions: 1) I Move; 2) an existing web-based computer tailored PA intervention, based on traditional health behavioral theories; 3) a control condition. PA behavior was assessed through self-report at baseline, 6 and 12 months. Intervention effects were evaluated using multilevel linear regression analyses. Findings At 12 months from baseline, I Move significantly increased weekly minutes of moderate to vigorous PA (ES = .13) compared to the control group, while the more traditional intervention did not achieve a significant effect on this outcome. The traditional intervention significantly increased weekly days with ≥ 30 minutes PA (ES = .11) compared to the control group, while I Move did not significantly influence this outcome. Discussion The results suggest that web-based computer tailored PA interventions might best include elements based on both SDT/MI and traditional health behavioral theories.