Currently accepted at: JMIR Formative Research
Date Submitted: Oct 22, 2025
Open Peer Review Period: Oct 22, 2025 - Dec 17, 2025
Date Accepted: Mar 4, 2026
(closed for review but you can still tweet)
This paper has been accepted and is currently in production.
It will appear shortly on 10.2196/85484
The final accepted version (not copyedited yet) is in this tab.
Evaluating an incentive-based mHealth application for physical activity promotion using the ORBIT Model: A small five-week feasibility study
ABSTRACT
Background:
Physical inactivity remains a public health concern with 42% of women and 34% of men in the United Kingdom (UK), for example, failing to meet moderate-to-vigorous physical activity (MVPA) guidelines. To promote physical activity (PA) at scale, smartphone-based mobile health software applications (mHealth apps) offer a promising solution.
Objective:
To evaluate the feasibility of implementing an mHealth app offering very small (‘micro’) financial incentives (FI) for PA in Leeds, UK.
Methods:
A five-week single-arm proof-of-concept study was conducted with rolling recruitment among Caterpillar Health app users between September 12 and December 12, 2022 (ORBIT model, Phase IIa). Users earned FI in the form of ‘points’, redeemable for consumer rewards (e.g., movie tickets, gym passes), for meeting personalized daily step goals ($0.13 USD per goal achieved; set using data from 5-day baseline) and completing educational quizzes ($0.33 USD per quiz). Descriptive statistics assessed feasibility outcomes (i.e., reach, recruitment, retention, engagement, acceptability) and preliminary effectiveness. Paired-samples t-tests (p<0.05) examined changes in weekly mean daily step count (from baseline) and step goal achievement over five weeks.
Results:
Of 285 app downloads, 46 users consented to participate (recruitment rate: 16.1%). Participants (mean age: 39.9±11.1 years; 71.1% female) had a baseline step count of 5598±2664 steps/day. Twenty-five remained engaged (i.e., completed at least one quiz) at Study Week 5 (retention rate: 54.3%). Acceptability was high, with 75% of respondents (12/16) indicating they would recommend the app. Weekly mean daily step count did not significantly increase from baseline (mean difference±standard deviation: 317±2273, p=0.533). Weekly daily step goal achievement rate (%) decreased from Study Week 1 to 5 (-23.23±22.85, p=0.024).
Conclusions:
Despite lower-than-expected recruitment and no statistically significant PA increase, relatively high engagement and acceptability suggest future pilot testing (ORBIT model, Phase IIb) of a refined intervention (e.g., wider selection of loyalty reward partners) and modified study protocol (e.g., simplified consent process) is warranted. Clinical Trial: ClinicalTrials.gov NCT05294692; https://clinicaltrials.gov/study/NCT05294692
Citation
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Copyright
© The authors. All rights reserved. This is a privileged document currently under peer-review/community review (or an accepted/rejected manuscript). Authors have provided JMIR Publications with an exclusive license to publish this preprint on it's website for review and ahead-of-print citation purposes only. While the final peer-reviewed paper may be licensed under a cc-by license on publication, at this stage authors and publisher expressively prohibit redistribution of this draft paper other than for review purposes.