Benefits have been established for regular physical activity (PA) and exercise after breast cancer, but a decline of PA has also been a reported result of breast cancer diagnosis and treatments. The Health Action Process Approach (HAPA) model has been shown to predict various health behaviors, but few studies have tested it at the intrapersonal level. The aim of the present study was to test whether the HAPA constructs that are well confirmed at the interpersonal level also hold at the intrapersonal level in a group of women survivors of breast cancer.
PA behaviors (N = 338) by nine survivors of breast cancer were observed for 6 weeks, and the associations between the HAPA constructs and PA over time were examined. Participants completed a questionnaire with the HAPA constructs related to PA behavior (direct step count and self-reported).
A multilevel model of behavior prediction found that optimistic beliefs about ability to initiate and maintain PA (self-efficacy) were positively related to intentions to be active, and these intentions predicted plans to be active. PA was directly and positively predicted by planning and by confidence in the ability to resume PA after a break.
Self-efficacy and planning are associated with PA behavior within women survivors of breast cancer over time, which was not the case for the outcome expectancies, social support, and action control at this intrapersonal level. A multilevel approach for psychological predictors of PA can be useful in grounding interventions for survivors of breast cancer.