Just-in-Time Adaptive Intervention to Promote Walking Behavior and Reduce Stationary Time in Physically Inactive Adults: Protocol for the Walking With JITAIs Study
Date
2026-01-07
Journal Title
Journal ISSN
Volume Title
Publisher
JMIR Research Protocols
Abstract
Background: A Just-in-Time Adaptive Intervention (JITAI) recognizes the dynamic nature of individuals’ states and contexts, predicts support needs, and sends tailored support at more opportune, actionable times.
Objective: This paper outlines the application architecture and protocol for the pilot “Walking With Just-in-Time Adaptive Interventions” (WWJ) study, which uses a JITAI approach to improve walking behavior—duration, speed, and distance—and
reduce stationary time, defined as idle sitting or standing.
Methods: This study targets 20 adults who are physically inactive and leverages the Apple Watch to deliver fully automated tailored intervention notifications to “walk faster,” “walk longer,” or “stand up and move around” based on real-time data and
contextual factors, including time-of-day activity patterns, geographic locations (eg, home, work, park, and gymnasium), weather conditions (eg, precipitation, wind speed, and humidity), and receptiveness. The protocol involves a preintervention assessment
of demographics, behavior change constructs, anthropometrics, and resting vital signs; a 2-week observation period to establish walking behavior and stationary time baselines; a 2-week just-in-time learning period to evaluate receptiveness to untailored
prompts at all applicable times; the 2-week JITAI intervention phase; and a postintervention assessment. Feasibility will be evaluated through protocol fidelity, participant adherence, Apple Watch wear-time compliance, user burden, acceptability ratings,
and perceptions of benefits and preferences.
Results: The WWJ architecture development began in spring 2021 and concluded in fall 2022. Participant recruitment and enrollment began in fall 2022. A total of 18 participants were recruited. Upon completion of the analyses, the results of this study
are expected to be submitted for publication.
Conclusions: Distinctively, the WWJ just-in-time learning period aims to train the learner based on user receptiveness within contexts by sending interventions whenever a participant meets the predetermined thresholds regardless of the likelihood that the
user will be receptive to the notification to prune out non opportune or “nonactionable” times. This approach may allow for greater customization during the JITAI period.
Description
©Cora J Firkin, Ajith Vemuri, Tanvir Rahman, Barry Bodt, Elizabeth Orsega-Smith, Keith Decker, Gregory M Dominick. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 07.Jan.2026. This is an open-access article
distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in JMIR
This article was originally published in JMIR Research Protocols. The version of record is available at: https://doi.org/10.2196/79022
Keywords
Apple Watch (19), behavior change (387), feasibility (516), iPhone (5), just-in-time adaptive intervention (50), physical activity (1127), wearable (258), mobile phone (3695)
Citation
"Firkin C, Vemuri A, Rahman T, Bodt B, Orsega-Smith E, Decker K, Dominick G Just-in-Time Adaptive Intervention to Promote Walking Behavior and Reduce Stationary Time in Physically Inactive Adults: Protocol for the Walking With JITAIs Study JMIR Res Protoc 2026;15:e79022 URL: https://www.researchprotocols.org/2026/1/e79022 DOI: https://doi.org/10.2196/79022 "