Physical activity in women receiving chemotherapy for breast cancer: adherence to a walking intervention.

PURPOSE/OBJECTIVES To describe and predict adherence to a physical activity protocol for patients with breast cancer receiving chemotherapy. DESIGN Longitudinal, observational study. SETTING Cancer center in the upper Midwestern region of the United States. SAMPLE 36 patients with breast cancer aged 40-55 years who were receiving adjuvant treatment. METHODS A longitudinal study was conducted within a randomized clinical trial comparing the effects of physical activity versus bisphosphonates on bone mineral density. Participants randomized to physical activity were advised to walk 10,000 steps per day and received initial physical therapy consultation and ongoing motivational interviewing. Multilevel modeling was used to identify variables that predict adherence. MAIN RESEARCH VARIABLES Adherence to the 10,000-step protocol was estimated with total steps and mean steps per day. FINDINGS Thirty-six women were enrolled in the physical activity group; 29 provided step data. The mean total steps per participant for the first six weeks was 280,571 (SD = 111,992), which is 67% of the prescribed steps. Excluding days when no steps were recorded, the mean steps per day for the initial six-week period was 7,363 (SD = 2,421), a 74% adherence rate. A significant linear increase occurred in steps per day after chemotherapy in a treatment cycle (p < 0.0001). Baseline inactivity predicted adherence. CONCLUSIONS Adherence to the walking program was compromised during chemotherapy but improved after chemotherapy completion. IMPLICATIONS FOR NURSING Knowing that chemotherapy predicts adherence to a walking protocol is useful for selecting the type, timing, and intensity of physical activity interventions.