Personalized Mobile App–Based Messaging and Step Tracking for Improving Walking Behavior in Adults: Randomized Controlled Trial

Background Walking is one of the most effective forms of physical activity; however, maintaining long-term engagement in digital step-counting interventions remains challenging. Objective This study aimed to evaluate the effects of personalized message interventions integrating the Information-Motivation-Behavioral Skills (IMB) model and regulatory focus theory (RFT) on walking behavior. Methods Participants were recruited offline through community advertisements containing a QR code that linked to an online sign-up form and were screened using an online baseline questionnaire by research staff, while all intervention delivery and outcome assessments were conducted via the WalkOn mobile app. A 12-week randomized controlled trial targeting 174 adults in Mapo-gu, Seoul, Korea, was conducted from April 1 to June 22, 2024. Of the 174 randomized participants, 141 (67 in the intervention group and 74 in the control group) engaged in the intervention. Both groups received incentives based on goal achievement and general health information, whereas the intervention group received weekly personalized messages provided by research staff according to midweek step-count performance. Primary outcomes included weekly goal achievement rates for the 25,000-step goal, step-count patterns, and consecutive 2-week goal achievement failure events. Analyses were conducted using generalized estimating equations (GEEs), linear mixed models (LMMs), and Cox proportional hazards models. Results Of the 174 participants randomized, 141 (81%) engaged in the intervention and were included in the analyses (67 intervention; 74 control), while 33 participants did not participate after randomization. The overall 12-week mean goal achievement rate was 87% in the intervention group and 87% in the control group, with no significant difference between the groups (odds ratio [OR] 1.12, 95% CI 0.29-4.37; P=.87). Weekly step-count patterns also showed no significant differences (group × time interaction: estimate=–417; SE 09; P=.31). However, the risk of consecutive 2-week goal achievement failure events was significantly lower in the intervention group (hazard ratio [HR] 0.67, 95% CI 0.52-0.86; P=.002). The intervention group showed an approximately 33% lower likelihood of consecutive 2-week goal achievement failure events than the control group. Conclusions Personalized message interventions did not show significant effects on overall step-count increase but were associated with a reduced risk of consecutive 2-week goal achievement failure events. These findings suggest that personalized messages may play an important role in improving behavior change sustainability and failure resilience. Incorporating personalized messaging strategies may enhance the effectiveness of digital health intervention design. Trial Registration Clinical Research Information Service (CRIS), Republic of Korea KCT0010966; https://tinyurl.com/3jeepxve