JMIR Publications

ABSTRACT

Background:

Wearable activity trackers in combination with supportive resources have the potential to influence adolescents’ physical activity levels. Examining the mediating pathways through which these interventions work can inform which mediators to target in future studies.

Objective:

To examine the impact of the Raising Awareness of Physical Activity (RAW-PA) intervention on potential mediators of behaviour change post-intervention, and whether these mediated the intervention effects on physical activity and sedentary time at 6-months follow-up.

Methods:

RAW-PA was a 12-week intervention, grounded in Social Cognitive Theory and Behavioural Choice Theory, aimed at increasing physical activity among inactive adolescents through combining a wearable activity tracker with digital resources (n=159 complete cases). The targeted potential mediators included self-efficacy, peer support, family support, teacher support, self-regulation strategies, barriers, and enjoyment. Outcomes included sedentary time, light- and moderate- to vigorous-intensity physical activity. A series of mixed linear models were used to estimate intervention effects on physical activity and sedentary behaviour at follow-up and on potential mediators post-intervention, and test whether there were indirect effects of the intervention on physical activity and sedentary behaviour via mediators.

Results:

Adolescents in the intervention group (n=75) engaged in higher sedentary time and lower light-intensity at 6-month follow-up compared to the controls (n=84). There were no intervention effects for moderate- to vigorous-intensity physical activity. The intervention group perceived more barriers to physical activity than the control group at 6-months follow-up (mean adjusted difference=1.77 [95% CI: 0.19,3.34], P=.03). However, there were no evidence of mediation effects for any outcomes.

Conclusions:

RAW-PA did not beneficially impact hypothesised mediators in these inactive adolescents, despite strategies being designed to target these. Future studies should consider different strategies to target theoretically informed potential mediators - this is crucial information for designing successful wearable activity trackers interventions. Clinical Trial: The trial is registered with the Australian and New Zealand Clinical Trials Registry: ACTRN12616000899448.