The Effectiveness of the Transtheoretical Model to Improve Physical Activity in Healthy Adults: A Systematic Review

Background: Despite the known risks of physical inactivity, only 50% of adults meet the recommended guidelines for physical activity (PA). Therefore, numerous interventions have been designed to increase PA across a lifespan. The purpose of this systematic review was to determine the effectiveness of interventions based on the transtheoretical model to improve PA in healthy adults. Methods: Electronic databases (CINAHL, MEDLINE, Psychology & Behavioral Sciences Collection, PsycINFO, Sociological Collection, and SPORTDiscus) were systematically searched from January 2001 to May 2020. Results: A total of 11 randomized pretest-posttest studies were included in this review. Ten studies utilized a subjective measurement of PA, and 3 studies included an objective measure. Five studies demonstrated significant improvements in PA for the transtheoretical model-based intervention groups compared with control/comparison groups; however, 6 studies demonstrated no differences between groups. Conclusion: The findings suggest that there is inconsistent evidence to support the use of interventions based on the transtheoretical model to improve PA in adult populations. Interventions were more successful when materials were delivered via in-person counseling and when study participants were in the precontemplation or contemplation phases at baseline.