Background: A recent randomized controlled trial found that an intervention focused on developing an exercise habit increased weekly minutes of moderate to vigorous physical activity (MVPA) over 8 wk compared to a control group. The purpose of the current study was to test if changes in habit, as well as other behavioral strategy constructs from the Multi-Process Action Control Test, mediated between group condition and MVPA (self-report and accelerometry). Methods: Inactive new gym members (N = 94) were randomized into control or experimental (habit-building) groups. Results: No construct entirely explained mediation condition (experimental and control) and changes in MVPA measured by accelerometry. Self-report MVPA found affective judgments, behavioral regulation, and preparatory habit to be mediated between group (experimental/control conditions) and changes in behavior (β = 0.36, 95% confidence interval [.05–.78]). Conclusions: Self-reported and objectively measured behavior models demonstrated complete and partial mediation, respectively. New gym members could benefit from successful behavioral enactment by developing constructs to support habit formation.
Kaushal is with the Faculty of Medicine, Montreal Heart Inst., University of Montreal, Montreal, QC, Canada. Rhodes and Meldrum are with the School of Exercise Science, Physical & Health Education, University of Victoria, Victoria, BC, Canada. Spence is with the Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB, Canada.