The effect of mere-measurement of cognitions on physical activity behavior: a randomized controlled trial among overweight and obese individuals

Background: The promotion of physical activity among an overweight/obese population is an important challenge for clinical practitioners and researchers. In this regard, completing a questionnaire on cognitions could be a simple and easy strategy to increase levels of physical activity. Thus, the aim of the present study was to test the effect of completing a questionnaire based on the Theory of Planned Behavior (TPB) on the level of physical activity. Methods: Overall, 452 overweight/obese adults were recruited and randomized to the experimental or control group. At baseline, participants completed a questionnaire on cognitions regarding their participation in leisure-time physical activity (experimental condition) versus a questionnaire on fruit and vegetable consumption (control condition). The questionnaires assessed the TPB variables that are beliefs, attitude, norm, perception of control, intention and a few additional variables from other theories. At three-month follow-up, leisure-time physical activity was self-reported by means of a short questionnaire. An analysis of covariance with baseline physical activity level as covariate was used to verify the effect of the intervention. Results: At follow-up, 373 participants completed the leisure-time physical activity questionnaire. The statistical analysis showed that physical activity participation was greater among participants in the experimental condition than those in the control condition (F(1,370) = 6.85, p = .009, d = 0.20). Conclusions: Findings indicate that completing a TPB questionnaire has a significant positive impact on subsequent participation in physical activity. Consequently, asking individuals to complete such a questionnaire is a simple, inexpensive and easy strategy to increase the level of physical activity among overweight/obese adults.