Associations of objectively assessed physical activity and sedentary time with biomarkers of breast cancer risk in postmenopausal women: findings from NHANES (2003-2006)

Breast Cancer Res Treat. 2011 Nov;130(1):183-94. doi: 10.1007/s10549-011-1559-2. Epub 2011 May 8.


Physical activity reduces the risk of postmenopausal breast cancer through multiple inter-related biologic mechanisms; sedentary time may contribute additionally to this risk. We examined cross-sectional associations of objectively assessed physical activity and sedentary time with established biomarkers of breast cancer risk in a population-based sample of postmenopausal women. Accelerometer, anthropometric and laboratory data were available for 1,024 (n = 443 fasting) postmenopausal women in the U.S. National Health and Nutrition Examination Survey 2003-2006. Associations of quartiles of the accelerometer variables (moderate- to vigorous-intensity activity, light-intensity activity and sedentary time per day; average length of active and sedentary bouts) with the continuous biomarkers were assessed using linear regression models. Following adjustment for potential confounders, including sedentary time, moderate- to vigorous-intensity activity had significant (P < 0.05), inverse associations with all biomarker outcomes (body mass index, waist circumference, C-reactive protein, fasting plasma glucose, fasting insulin and homeostasis model assessment of insulin resistance). Light-intensity activity and sedentary time were significantly associated in fully adjusted models with all biomarkers except fasting glucose. Active bout length was associated with a smaller waist circumference and lower C-reactive protein levels, while sedentary bout length was associated with a higher BMI. The associations of objectively assessed moderate- to vigorous-intensity activity with breast cancer biomarkers are consistent with the established beneficial effects of self-reported exercise on breast cancer risk. Our findings further suggest that light-intensity activity may have a protective effect, and that sedentary time may independently contribute to breast cancer risk.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Biomarkers, Tumor / blood
  • Biomarkers, Tumor / metabolism*
  • Breast Neoplasms / epidemiology*
  • Breast Neoplasms / metabolism*
  • Female
  • Humans
  • Middle Aged
  • Motor Activity*
  • Nutrition Surveys*
  • Postmenopause*
  • Risk
  • Sedentary Behavior*


  • Biomarkers, Tumor