Change in physical activity during a weight management intervention for breast cancer survivors: Association with weight outcomes

OBJECTIVE: The study examined the effects of a group-phone based weight management intervention on change in physical activity as measured via accelerometer and self-report in rural breast cancer survivors. The study also evaluated the role of physical activity on clinically meaningful cut-points for weight loss (baseline to 6 months) and weight loss maintenance (6 to 18 months). METHODS: Participants were breast cancer survivors in a weight management intervention who provided valid weight and accelerometer data (N=142). We categorized participants into four groups based on weight loss ≥10% and weight regain ≥5% at 18 months. RESULTS: Accelerometer-measured moderate-to-vigorous physical activity (MVPA) significantly increased from baseline to 6 months (+46.9 minutes). MVPA declined during maintenance; however remained significantly greater than baseline. Self-reported MVPA followed a similar pattern as accelerometer MVPA, but estimates were significantly higher. Participants in the high loss, low regain group had significantly higher MVPA at all points. CONCLUSIONS: A distance-based weight management intervention for survivors improved physical activity outcomes over 18 months. Self-reported physical activity was substantially higher than accelerometer-measured. Findings highlight the importance of device-based measurement for characterizing the magnitude of physical activity change, as well as the role of physical activity in weight management outcomes.