JMIR Publications

ABSTRACT

Background:

Background:

Physical inactivity is a major modifiable risk factor for cancer. Although cancer typically manifests later in life, early childhood presents a critical window for prevention. Many children and families do not meet Canadian physical activity guidelines. Just-In-Time Adaptive Interventions (JITAIs) offer a scalable, personalized approach to promote physical activity in real time.

Objective:

Objectives: 1) To examine the recruitment, retention, engagement, acceptability of delivering the 10-week Movement for Active Families smartphone-based JITAI targeting parental support for child physical activity; and 2) to assess preliminary efficacy in improving children’s physical activity and key parental support constructs.

Methods:

Methods:

A single-arm pre–post study enrolled families with children aged 8–12 years who did not meet Canadian physical activity guidelines. The intervention delivered weekly tailored content and prompts based on child physical activity and parental support behaviours. Study outcomes included recruitment, retention, app engagement, child’s physical activity, and parent-reported psychosocial constructs related to physical activity support (behaviour, attitudes, capability, opportunity, regulation, identity, and habit).

Results:

Results:

Of 49 enrolled families, 75.5% (n=37) completed the intervention. Over 85% reported high acceptability. Engagement metrics revealed that participants completed 86% (M=25, SD=7.8) of possible lessons and spent 97.53 (SD= 53.45) minutes on the app. Children’s MVPA increased from 56.4 to 64.8 minutes/day (p < .05, d = 0.37). Significant improvements were observed in parental support behaviour, behavioural regulation, identity, and habit.

Conclusions:

Conclusions:

This family-based JITAI is feasible, well-received, and shows early promise for promoting child physical activity. Future trials should explore optimization and long-term impact.