Correlates of exercise motivation and behavior in a population-based sample of endometrial cancer survivors: an application of the Theory of Planned Behavior

BACKGROUND Despite evidence of the benefits of exercise in cancer survivors, exercise participation rates tend to decline after treatments. Few studies have examined the determinants of exercise in less common cancer sites. In this study, we examined medical, demographic, and social cognitive correlates of exercise in endometrial cancer survivors using the Theory of Planned Behavior (TPB). METHODS A mailed survey was completed by 354 endometrial cancer survivors (1 to 10 years postdiagnosis) residing in Alberta, Canada. The study was cross-sectional. Exercise behavior was assessed using the Godin Leisure Time Exercise Questionnaire and the TPB constructs were assessed with standard self-report scales. Multiple regression analyses were used to determine the independent associations of the TPB constructs with intention and behavior. RESULTS Chi-square analyses indicated that marital status (p = .003), income level (p = .013), and body mass index (BMI) (p = .020) were associated with exercise. The TPB explained 34.1% of the variance in exercise behavior with intention (beta = .38, p < .001) and self-efficacy (beta = .18, p = .029) being independent correlates. For intention, 38.3% of the variance was explained by the TPB with self-efficacy (beta = .34, p < .001) and affective attitude (beta = .30, p < .001) being the independent correlates. The TPB mediated the associations of marital status and BMI with exercise but not income level. Age and BMI moderated the associations of the TPB with intention and behavior. CONCLUSION The TPB may be a useful framework for understanding exercise in endometrial cancer survivors. Exercise behavior change interventions based on the TPB should be tested in this growing population.