Adherence to prescribed exercise time and intensity declines as the exercise program proceeds: findings from women under treatment for breast cancer

Purpose: Adherence to prescribed exercise is a challenge for cancer patients undergoing treatment. The changing pattern of exercise adherence over time cannot be fully understood by an overall measure of adherence. This study was aimed to identify the trajectory of exercise adherence and its predictors for women with breast cancer during their chemotherapy. Methods: Participants were 78 women with breast cancer assigned to the exercise arm of a randomized control trial. Based on the weekly adherence rates in time and intensity, patients were classified as good (>100 %), acceptable (80–100 %), and poor (<80 %) adherents. Data were analyzed using ordinal logistic hierarchical linear modeling. Results: The trajectories for both time and intensity adherence declined significantly. The decline in exercise-time adherence was significantly slower in women who reported higher interest in exercise. Women with higher perceived importance of exercise, early disease stage, and employed were more likely to be classified as good intensity adherents. Poorer weekly adherence for both exercise time and intensity was associated with higher fatigue level for that week. Conclusions: Adherence to exercise adherence in breast cancer patients declined as the dose of exercise prescription increased. Factors influencing overall adherence and adherence trend were identified.