Does the Plan Fit? The Effectiveness of Combining Implementation Intentions and Regulatory Fit for Increasing Physical Activity and Decreasing Sedentary Behaviour

Abstract

The purpose of this study was to examine the effectiveness of combining implementation intentions (II) and regulatory fit in the context of two important health goals: increasing leisure time physical activity and decreasing leisure time sedentary behaviour. Implementation intentions specify exactly how, when, and where a behaviour will occur and can be an effective method of increasing goal enactment. Regulatory fit occurs when a goal or strategy used to achieve the goal matches an individual’s regulatory orientation. University students (N = 180) were randomly assigned to a goal (increase activity/decrease screen time) and an experimental condition (II/non-II). Participants formed a goal to increase their physical activity or decrease their screen time over the following four weeks according to their random assignment. Participants’ commitment to their goal was monitored over the course of the study. The II group also formed a detailed plan regarding how they would accomplish their goal. Regulatory fit was determined based on group assignment and score on the regulatory focus questionnaire. Physical activity and screen time were assessed with self-report questionnaires. Follow-up occurred online four weeks after baseline. Data were analyzed separately by goal type using linear regressions to examine the effects of regulatory fit, experimental condition, and goal commitment on the behaviour variables. The regulatory fit manipulation was not successful. Among those with the physical activity goal, no significant effects emerged for the experimental variables. Among those with the screen time goal and in the fit, II group, stronger goal commitment tended to be associated with increased participation in moderate physical activity, β = .17, t(22) = .94, p = .36. Also, participants who set II for the screen time goal and were committed to this goal tended to report less screen time than participants with lower goal commitment (β = -.40, t(69) = -2.05, p = .05). Findings provide preliminary insight into the effectiveness of II and the importance of goal commitment in interventions aiming to reduce sedentary behaviour.