Revisiting the Transtheoretical Model for Physical Activity: A Large-Scale Cross-Sectional Study on Japanese-Speaking Adults.

Background: The Transtheoretical Model (TTM) has been the basis of health promotion programs, which are, for example, used to tailor behavioral interventions according to the stages of change. Empirical studies have shown that the TTM effectively describes the processes of behavioral adaptation to acquire healthier lifestyles; however, it has been argued that TTM-based interventions are not superior to non-TTM-based interventions for promoting physical activity (PA). Evidence has also highlighted some inconsistencies with theoretical assumptions, especially regarding how each process-of-change strategy emerges across the stages.

Purpose: Therefore, we investigated (a) how well the TTM describes the distributional characteristics of PA levels as well as other relevant variables (e.g., process of change, self-efficacy) across stages, and (b) how predictive the TTM variables are of PA levels within each stage.

Methods: We analyzed data from 20,573 Japanese-speaking adults who completed online questionnaires on PA and TTM variables.

Results: The results replicated previous findings that stage membership is associated with PA, the process of change, decisional balance, and self-efficacy, albeit with inconclusive evidence of temptations. Regression analyses revealed that some processes of change (self-reevaluation, reinforcement management, and self-liberation) were more predictive of PA in pre-active stages than in post-action stages; self-efficacy was predictive of PA only in the maintenance stage but not in the other stages.

Conclusions: Overall, the data support the theoretical assumptions of the TTM, but the stage specificity of the active processes may not always be consistent with the theory.