Prospective examination of objectively-assessed physical activity and sedentary time after breast cancer treatment: Sitting on the crest of the teachable moment

Background: This study prospectively examined patterns of objectively-assessed sedentary time and moderate-to-vigorous physical activity (MVPA) during a one-year period following completion of primary treatment among breast cancer survivors. The potential moderating effect of weight status on sedentary and MVPA time was also examined.

Methods: Breast cancer survivors [N=177; M(SD)age = 54.9 (11.1) years, 85% White/Caucasian; 82% Stage I or II cancer; M(SD)time since treatment = 3.5 (2.4) months] who were recruited into a convenience sample had weight, height, and waist circumference measured and wore Actigraph GT3X accelerometers for one week every three months for one year. Data were analyzed using repeated measures analysis of variance.

Results: Survivors spent nearly 78% of their day sedentary across all time points compared to less than 2% of their day engaged in MVPA. Sedentary time remained fairly stable over 12 months, whereas MVPA levels significantly decreased. Survivors with an overweight body mass index and unhealthy waist-to-height ratio engaged in significantly less MVPA compared to healthy weight survivors, with significant waist-to-height ratio moderator effects for both sedentary and MVPA.

Conclusions: Survivors spent nearly 78% of their day sedentary across all time points compared to less than 2% of their day engaged in MVPA. Sedentary time remained fairly stable over 12 months, whereas MVPA levels significantly decreased. Survivors with an overweight body mass index and unhealthy waist-to-height ratio engaged in significantly less MVPA compared to healthy weight survivors, with significant waist-to-height ratio moderator effects for both sedentary and MVPA.