Accepted for/Published in: JMIR Research Protocols
Date Submitted: Jun 17, 2025
Date Accepted: Nov 27, 2025
A just-in-time adaptive intervention to promote walking behavior and reduce stationary time in physically inactive adults: Protocol for the Walking with JITAIs study
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 manuscript outlines the application architecture and protocol for the pilot “Walking with JITAIs” study, which employs a JITAI approach to improve walking behavior—duration, speed, and distance—and reduce stationary time, defined as idle sitting or standing.
Methods:
The 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 (e.g., home, work, park, gym), weather conditions (e.g., precipitation, wind speed, humidity), and receptiveness. The protocol involves a pre-intervention assessment of demographics, behavior change constructs, anthropometrics, and resting vital signs; a two-week observation period to establish walking behavior and stationary time baselines; a two-week just-in-time learning period to evaluate receptiveness to untailored prompts at all applicable times; the two-week JITAI intervention phase; and a post-intervention 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 “Walking with JITAIs” architecture development began in Spring 2021 and concluded in Fall 2022. Participant recruitment and enrollment began in Fall 2022. Upon completion of the analyses, the results of this study are expected to be submitted for publication.
Conclusions:
Distinctively, the “Walking with JITAIs” just-in-time learning period aims to train the Learner based on user receptiveness within contexts by sending interventions whenever a participant meets the pre-determined thresholds regardless of the likelihood that the user will be receptive to the notification to prune out non-opportune or “non-actionable” times. This approach may allow for greater customization during the JITAI period. Clinical Trial: NA
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