Application of the theory of planned behavior to understand physical activity intentions and behavior among Korean breast cancer survivors

Purpose: The purpose of this study was to apply the theory of planned behavior (TPB) to understand physical activity intentions and behaviors among Korean breast cancer survivors. Methods: A total of 286 Korean breast cancer survivors (M_age52.3 ± 8.3) completed a self-reported survey administered face to face by a trained interviewer. The survey assessed the physical activity frequency and intensity in a typical week after breast cancer diagnosis, demographic factors, and theory of planned behavior variables including attitude, subjective norm, perceived behavioral control (PBC), planning, and intentions to participate in physical activity. We used structural equation modeling to examine the direct and indirect effects of the TPB variables on physical activity intentions and behavior. Covariates included age, cancer stage, and clinical treatment. Results: Confirmatory factor analyses indicated a satisfactory model fit. We observed direct effects for instrumental attitude (ß = 0.34, p < 0.001), subjective norm (ß = 0.12, p < 0.05), and PBC (ß = 0.57, p < 0.001) on physical activity intentions. PBC (ß =.17, p < 0.01) and physical activity intentions (ß = 0.46, p < 0.01) had direct effects on planning. PBC (ß = 0.28, p < 0.01) and planning (ß = 0.22, p < 0.01) had direct effects on physical activity behavior. Conclusion: The TPB was a useful model for understanding Korean breast cancer survivors’ physical activity intentions and behavior. Interventions that can enhance attitudes, subjective norm, PBC, intention, and planning may facilitate physical activity intentions and behaviors in this population.