Commitment Matters in Sustainable Digital Health Interventions: Understanding Continued Use of Mobile Fitness Apps for Physical Activity Promotion

The lack of continuance use of fitness apps causes persistent concern. This paper endeavors to examine the impact of initial use on the continuance use of fitness apps by incorporating theories on commitment and investment. A fitness app-based online running event and a two-stage field survey were conducted. A total of 162 participants’ app usage data and survey responses were collected and tested using structural equation modeling. The findings revealed that initial use increases users’ affective commitment and continuance commitment to fitness apps, which promotes continuance use in the subsequent period. The continuance use of fitness apps then enhances users’ physical exercise performance. Additionally, this study confirmed the strengthening moderation effect of users’ social network size, indicating that a larger social network amplifies the positive influence of continuance commitment on continuance use. These findings contribute to sustainable health promotion by explaining how sustained engagement with digital exercise tools can support active lifestyles and well-being.