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Digital Nudges in New Gym Members: A Randomized Formative Evaluation of Gym Attendance and Behavioral Determinants of Exercise Engagement
ABSTRACT
Background:
Digital nudging strategies are increasingly implemented to promote physical activity, yet evidence from real-world fitness settings remains limited. The early membership period in fitness centers is characterized by high dropout rates, emphasizing the need for formative evaluations that clarify behavioral mechanisms underlying exercise engagement.
Objective:
This study aimed to evaluate the formative impact of WhatsApp-based digital nudges on objectively measured weekly gym visits among new fitness club members and to examine behavioral determinants associated with exercise engagement.
Methods:
A randomized formative evaluation was conducted among 61 new gym members (mean age 29.05 years, SD 8.06; 34.4% female) recruited from two fitness centers. Participants were randomly assigned to an intervention group receiving digital nudges via WhatsApp or to a control group receiving no intervention. Weekly gym visits were obtained from computerized entry records. Self-reported measures included exercise self-efficacy (Self-Efficacy for Exercise Scale), habit strength (Self-Report Habit Index), and exercise adherence (Exercise Adherence Rating Scale). Statistical analyses included descriptive statistics, t tests, analyses of variance, correlation analyses, and multiple regression models.
Results:
Digital nudges did not significantly increase gym attendance, and weekly gym visits declined over time in both groups. However, higher exercise self-efficacy and habit strength were associated with more frequent attendance. Participants attending the gym at least twice weekly demonstrated greater habit strength and self-efficacy. Exercise adherence emerged as the strongest predictor of weekly gym visits.
Conclusions:
Findings from this formative evaluation suggest that external digital prompts alone may be insufficient to sustain exercise participation during early gym membership. Instead, behavioral determinants—particularly exercise adherence, self-efficacy, and habit formation—appear central to engagement. These results provide formative insights for the development and optimization of future digital health interventions targeting long-term physical activity adherence. Clinical Trial: Not applicable.
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