Adding Planning Strategies to an Experiential and Conceptual Knowledge-Based Intervention: Does it Help to Reduce Sedentary Time?

Objective: The study compared the effects of an "active" control condition addressing conceptual and experiential knowledge about a behavior, with an intervention condition combining conceptual and experiential knowledge together with action planning, coping planning, and behavioral substitution. We targeted a decrease in sedentary time as the primary outcome.

Methods: A preregistered trial [BLINDED] was carried out with 603 participants aged 11-86 years (M = 33.57; 65.2% women), randomly assigned to the "planning + knowledge" condition or the "knowledge" condition. Sedentary time was assessed with ActiGraph wGT3X-BT accelerometers at baseline, 1-week, and 36-week follow-ups. Conceptual knowledge strategies involved information about health consequences and instructions on how to perform behaviors while experiential knowledge was enhanced by participants taking/discussing photographs of their home environment that has been triggering sedentary behavior. Action/coping plans referred to ways to substitute sedentary behavior with bouts of physical activity behaviors. Mixed models were fit.

Results: No significant Time × Condition interaction was found. In the total sample, sedentary time estimated to be around 502.34 minutes/day at baseline, showed a significant linear decline over time (p = .002), by approximately -1.22 minutes per each month elapsing since baseline (-9.76 min/day across 8 months).

Conclusions: The findings suggest that applying behavior change techniques targeting both conceptual and experiential knowledge about antecedents, circumstances and consequences of sedentary behavior may result in a small reduction of sedentary time. Adding action plans, coping planning, and behavioral substitution did not improve the effectiveness of the intervention.