Motivational Composition in Digitally Supported and Conventional Prevention Programs: A Three-Wave Study Based on Self-Determination Theory

Background Digital health interventions offer potential solutions to accessibility barriers in occupational prevention programs, yet their impact on motivational quality remains underexplored. Self-Determination Theory (SDT) posits that autonomous motivation - driven by personal values rather than external pressures - is critical for sustained health behavior change. This study compared motivational composition between digitally supported and conventional prevention programs within the German Pension Insurance system and examined whether autonomous motivation predicts program attendance. Methods In a longitudinal quasi-experimental study, 163 employed adults (mean age 51.7 years, 69% female) participated in either a digitally supported prevention program (n = 96; 14-day inpatient stay plus 6-month digital aftercare) or a conventional RV Fit program (n = 67; four-phase in-person format over 24 weeks). Motivational composition was assessed using the Behavioral Regulation in Exercise Questionnaire-2 (BREQ-2) to calculate the Relative Autonomy Index (RAI) at baseline, 12 weeks, and 24 weeks. Self-reported program attendance was measured at 12 and 24 weeks. Repeated measures ANCOVA examined group differences in motivational trajectories controlling for age and gender. Multiple linear regression analyses tested whether autonomous motivation predicted attendance. Results A significant time-group interaction emerged (F(2,316) = 4.51, p=.012, η²=.028), indicating divergent motivational trajectories. The digitally supported group showed continuous decline in RAI from baseline (M = 13.37) through 12 weeks (M = 12.13) to 24 weeks (M = 11.82). The conventional group showed initial increase to 12 weeks (M = 13.77) followed by decline to 24 weeks (M = 12.68). Despite lower motivational quality, the digitally supported group reported significantly higher attendance at both 12 weeks (10.27 vs. 7.92 weeks, p=.001) and 24 weeks (18.75 vs. 13.56 weeks, p<.001). Autonomous motivation did not significantly predict attendance in either model; group assignment was the strongest predictor. Conclusions While digitally supported prevention programs achieved higher participation rates, they were associated with declining autonomous motivation compared to conventional formats. These findings suggest that structural advantages of digital delivery do not automatically translate to sustained motivational quality. Digital health platforms should be explicitly designed to support basic psychological needs - particularly relatedness and competence - to ensure increased reach translates into long-term behavior change effectiveness. Trial Registration : The study was pre-registered with the German Clinical Trials Register on February 12 2021 (Registration number: DRKS00022550).