Theory of Planned Behavior: Implications for an email-based physical activity intervention

Objectives: A 3-week Study was conducted to determine the effect of persuasive messages sent via email on psychological constructs associated with Theory of Planned Behavior (TPB) and exercise behavior in sedentary college Students (N = 170). Methods: Participants (105 M; 65 F; 94% Caucasian; 20.2 +/- .9 years) completed the Godin Leisure Time Exercise Questionnaire (GLTEQ) and self-report measures of the TPB. Participants received persuasive messages every other day for 2 weeks. One randomly assigned group received positively framed messages (PFM; n = 57); the other received negatively framed messages (NFM, n = 57); and the control group (CG; n = 56) received none. Participants completed the GLTEQ and TPB questionnaires following the 2-week treatment phase and again 1 week later. Results: ANCOVA results revealed that PFM reported higher exercise behavior levels than both NFNI and CG at follow-up (p < .05) and retention (p < .05). For exercise intention, PFM and NFM reported significantly higher levels than CG at follow-up) <.05), while PFM reported higher levels than NFM and CG at retention (p < .05). Also, pairwise comparisons revealed higher intention levels for NFM compared to CG at retention (p < .05). PFM reported higher levels of affective attitude compared to CG at follow-up (p < .05) and retention (p < .05), while NFM reported higher levels than CG at Follow-up (p < .05). For instrumental attitude, all three groups were statistically different (p < .05) at retention (PFM>NFM, NFM > CG, PFM > CG). Conclusions: Only positively framed persuasive messages sent via email improved exercise behavior. Both types of messages affected attitude, and intention in sedentary young adults. This research provides useful information for creating interventions to enhance exercise adherence. Published by Elsevier Ltd.