We recently shared a preprint presenting a very original investigation. During my Phd, I developed an interest for the Transtheoretical model to promote physical activity. If this model was over-studied in US or UK, the French sport psychology academic community did not explore it.

We (with @aj_romain) performed a cross-cultural validation of Processes of change questionnaire. We quantified the efficacy of Transtheoretical (TTM) based interventions in an awesome and collective project (d = 0.31, 95% CI [0.24, 0.37]). Then, we explored the moderator effects of TTM theoretical constructs in a meta-analysis and concluded that “no significant differences were found between personalized TTM-based interventions based on SOCs and non-personalized TTM based interventions”. However, TTM-based interventions implementing self-efficacy, decisional balance and processes of change constructs were more effective. Finally, we published a state of art about TTM and physical activity (Is there something beyond stages of change in the transtheoretical model?). We suggested that the processes of change should be targeted in priority for future TTM based intervention, and used to personalize a future interventions by targeting POCs with the lowest pre-intervention levels.

Consequently, J. Lapointe, (highly motivated) Msc student, developed a reproducible POC personalized TTM-based intervention. This intervention combined online training sessions and counseling. All details are available here. It was a terrific challenge because most of previous TTM-based interventions were not presented with a relevant level of details.

A set of single case experimental studies with a multiple baseline ABA’ design were carried-out. Physical activity was measured with a GENEactiv accelerometer and an agenda. Furthermore, TTM online questionnaires were weekly sent to participants (only for A-B phases).

As you can see below, we could visually examine the temporal patterns of TTM constructs before and during a behavior change intervention. We also performed piecewise linear models to analyze the intervention effects on physical activity behaviors (i.e., accelerometer and self-reported data). Findings were relatively different for each outcome. 6/7 participants increased their self-reported physical activity level. However, device measured PA of 5 participants was not significantly higher during B and A2 phases. Finally, a minimum of targeted 3/5 processes of change increased among all participants during our intervention. Don’t hesitate to comment this work. There are an important set of methodological weaknesses/ future challenge.