Physical activity and sedentary time: associations with fatigue, pain, and depressive symptoms over 4 years post-treatment among breast cancer survivors.

INTRODUCTION: Despite the recommendations for cancer survivors to engage in physical activity (PA), little is known about the effects of both PA and sedentary time (ST) on key health symptoms. This study prospectively examined the lifestyle behaviors of moderate-to-vigorous PA (MVPA) and ST as predictors of depressive symptoms, pain, and fatigue in breast cancer survivors using longitudinal data from early post-treatment to 4-year survivorship. METHODS: Breast cancer survivors (n = 199, mean(SD) age = 55.0(11.0) years) self-reported depressive symptoms, pain, and fatigue, and wore an accelerometer to measure MVPA and ST every 3 months during the first year (times 1 to 5) and 2 and 4 years (times 6 and 8) post-cancer treatment. Linear mixed models were adjusted for personal (e.g., age, BMI, education) and cancer (e.g., stage, time since treatment) variables. RESULTS: MVPA and ST were independent predictors of depressive symptoms, but not fatigue, and only ST was associated with pain over 4 years post-treatment. Higher levels of MVPA were associated with lower scores of depressive symptoms ([Formula: see text] (95%CI): - 0.062 (- 0.092, - 0.031) p < .001), whereas higher levels of ST were associated with higher scores of depressive symptoms ([Formula: see text] (95%CI): 0.023 (0.017, 0.028) p < .001). Higher levels of ST were associated with increased pain level over time ([Formula: see text] (95%CI): 0.017 (0.007, 0.027) p = .001). CONCLUSIONS: Rehabilitation interventions should aim to both increase MVPA and reduce ST to promote health and well-being among breast cancer survivors, in particular during the early post-treatment period.