Measurement of physical activity and sedentary behavior in breast cancer survivors

Physical activity has numerous physical, mental, and psychosocial bene ts for cancer survivors, such as a reduction in the risk of mobility disability, depression, and anxiety, and improved patient quality of life.1,2 In addition, higher levels of physical activity are associated with reduced cancerspeci c and all-causes mortality as well as cancerspeci c outcomes including reduced risk of cancer progression and recurrence and new primary cancers.3-5 However, fewer than one-third of cancer survivors are meeting government and cancerspeci c recommendations of 150 minutes a week of moderate to vigorous physical activity (MPVA; ≥3 metabolic equivalents [METs]).6,7 Growing evidence also demonstrates a signi cant association between higher levels of sedentary behavior and many deleterious health eŽects after cancer, including an increased risk for decreased physical functioning and development of other chronic diseases such as cardiovascular disease or diabetes.8 Distinct from physical activity, sedentary behavior is de ned as any waking activity resulting in low levels of energy expenditure (≤1.5 METs) while in a seated or reclined position.9 Increased sedentary behavior, even when controlling for moderate and vigorous physical activity (MVPA), is associated with poor quality of life and increased all-cause mortality in cancer survivors.10,11 Given the associations