Matched or nonmatched interventions based on the transtheoretical model to promote physical activity. A meta-analysis of randomized controlled trials

The aim of this study was to examine whether the efficacy of transtheoretical model (TTM)–based interventions on physical activity (PA) varied according to the following criteria: (1) interventions targeted the actual stages of change (SOCs) or did not; (2) participants were selected according to their SOC or were not; and (3) its theoretical constructs (decisional balance, temptation, self-efficacy, processes of change). Thirty-three randomized controlled trials assessing TTM-based interventions promoting PA in adults were systematically identified. The between-group heterogeneity statistic (Qb) did not reveal any differential efficacy either in interventions targeting the actual SOC compared with those that did not (Qb = 1.28, p = 0.22) or in interventions selecting participants according to their SOC compared with those that did not (Qb = 0.01, p = 0.91). TTM-based interventions enhanced PA behavior whether they targeted the actual SOC (Cohen's d = 0.36; 95% confidence interval (CI): 0.22–0.49)) or not (d = 0.23; 95% CI: 0.09–0.38) and whether they selected their participants according to their SOC (d = 0.33; 95% CI: 0.13–0.53) or not (d = 0.32; 95% CI: 0.19–0.44). The moderators of the efficacy of TTM-based interventions were the number of theoretical constructs used to tailor the intervention (Qb = 8.82, p = 0.003), the use of self-efficacy (Qb =6.09, p = 0.01), and the processes of change (Qb = 3.51, p = 0.06). TTM-based interventions significantly improved PA behavior, and their efficacy was not moderated by SOC but by the TTM theoretical constructs