title: Physical activity and C-reactive protein levels: the confounding role of body fat.
abstract: BACKGROUND
  This study investigated the relationship between objectively-measured total physical activity (PA), and intensity of PA and high-sensitivity C-reactive protein (CRP) in 211 healthy, middle-age women (43.1±3.0 y). In addition, this study examined the extent to which age, BMI, abdominal circumference, and body fat percentage operated as confounders in these associations.
  
  
  METHODS
  PA was objectively measured for 7 continuous days using accelerometry. Fasting blood samples were taken, from which CRP was measured using a solid phase ELISA. Body mass index (BMI) (kg/m2), abdominal circumference measured at the umbilicus, and body fat percentage using air displacement plethysmography, were assessed.
  
  
  RESULTS
  Total PA (activity counts) was significantly and inversely related to CRP concentrations (F=7.76, P=.006) as was vigorous-intensity PA. After adjusting for differences in body fat percentage, total PA and vigorous-intensity PA were no longer significant predictors of CRP. Abdominal circumference and BMI also tended to weaken the relationship between total or vigorous-intensity PA and CRP but not to the same extent as body fat percentage.
  
  
  CONCLUSIONS
  These findings suggest that higher total and vigorous-intensity PA levels are significantly related to lower CRP levels in healthy, middle-age women; however, this relationship is largely a function of differences in body fat percentage.
authors: Department of Exercise Sciences, Brigham Young University, Provo, UT, USA.
authors: James
authors: J
authors: LeCheminant
authors: Larry
authors: L
authors: Tucker
authors: Kenric
authors: K
authors: Russell