Social-Cognitive Theory Predictors of Exercise Behavior in Endometrial Cancer Survivors

Objective: This study evaluated whether social-cognitive theory (SCT) variables, as measured by questionnaire and ecological momentary assessment (EMA), predicted exercise in endometrial cancer survivors. Method: One hundred posttreatment endometrial cancer survivors received a 6-month home-based exercise intervention. EMAs were conducted by using hand-held computers for 10- to 12-day periods every 2 months. Participants rated morning self-efficacy and positive and negative outcome expectations by using the computer, recorded exercise information in real time and at night, and wore accelerometers. At the midpoint of each assessment period, participants completed SCT questionnaires. Using linear mixed-effects models, the authors tested whether morning SCT variables predicted minutes of exercise that day (Question 1) and whether exercise minutes at time point T-j could be predicted by questionnaire measures of SCT variables from time point Tj-i (Question 2). Results: Morning self-efficacy significantly predicted that day's exercise minutes (p < .0001). Morning positive outcome expectations were also associated with exercise minutes (p = .0003), but the relationship was attenuated when self-efficacy was included in the model (p = .4032). Morning negative outcome expectations were not associated with exercise minutes. Of the questionnaire measures of SCT variables, only exercise self-efficacy predicted exercise at the next time point (p = .003). Conclusions: The consistency of the relationship between self-efficacy and exercise minutes over short (same day) and longer (T-j to Tj-1) time periods provides support for a causal relationship. The strength of the relationship between morning self-efficacy and exercise minutes suggest that real-time interventions that target daily variation in self-efficacy may benefit endometrial cancer survivors' exercise adherence.