The Role of Exercise Self-Efficacy in Exercise Participation Among Women With Persistent Fatigue After Breast Cancer: A Mixed-Methods Study

Objective Survivors of breast cancer with persistent cancer-related fatigue (CRF) report less exercise participation compared with survivors of breast cancer without CRF. Although CRF predicts other domains of self-efficacy among survivors, the effect of CRF on exercise self-efficacy (ESE)-an important predictor of exercise participation-has not been quantified. This study examined the relationship between CRF, ESE, and exercise participation and explored the lived experience of engaging in exercise among survivors of breast cancer with persistent CRF. Methods Fifty-eight survivors of breast cancer (3.7 [SD = 2.4] years after primary treatment) self-reported CRF, ESE, and exercise participation (hours of moderate-intensity exercise per week). Regression and mediation analyses were conducted. Survivors who reported clinically significant CRF and weekly exercise were purposively sampled for 1-on-1 interviews (N = 11). Thematic analysis was performed across participants and within higher versus lower ESE subsets. Results Greater CRF predicted lower ESE (beta = -0.32) and less exercise participation (beta = -0.08). ESE mediated the relationship between CRF and exercise participation (beta = -0.05, 95% CI = -0.09 to -0.02). Qualitative data showed that survivors of breast cancer with higher ESE perceived exercise as a strategy to manage fatigue, described self-motivation and commitment to exercise, and had multiple sources of support. In contrast, survivors with lower ESE described less initiative to manage fatigue through exercise, greater difficulty staying committed to exercise, and less support. Conclusions Survivors of breast cancer with persistent CRF may experience decreased ESE, which negatively influences exercise participation. Clinicians should screen for or discuss confidence as it relates to exercise and consider tailoring standardized exercise recommendations for this population to optimize ESE. This may facilitate more sustainable exercise participation and improve outcomes. Impact This study highlights the behavioral underpinnings of CRF as a barrier to exercise. Individualized exercise tailored to optimize ESE may facilitate sustainable exercise participation among survivors of breast cancer with CRF. Strategies for clinicians to address ESE are described and future research is suggested. Lay Summary Women with fatigue after breast cancer treatment may have lower confidence about their ability to engage in exercise. Individually tailoring exercise to build confidence as it relates to exercise may result in more consistent exercise and better health-related outcomes.