C-reactive protein levels according to physical activity and body weight for participants in the coronary health improvement project.

OBJECTIVES To identify whether the Coronary Health Improvement Project (CHIP), an intervention designed to increase physical activity and improve diet, lowers serum C-reactive protein (CRP). The study will also assess whether changes in CRP over the study period are associated with baseline levels of and changes in selected coronary risk factors. METHODS A randomized controlled study design assigned 348 individuals to the intervention or control group with measurements taken at baseline, 6 weeks, and 6 months of body weight, physical activity, and serum CRP levels. Participants attended an intensive 40-hour educational course delivered over a 4-week period, beginning March 2003, in Rockford, IL, USA. RESULTS The intervention significantly increased physical activity and decreased BMI, weight, percent body fat, and saturated fat (P<0.0001). However, the intervention was not significantly associated with a decrease in CRP. Participants in both the intervention and control groups combined showed a decrease in high CRP (>3 mg/L), from 46% at baseline to 38% at 6 weeks and 41% at 6 months. Those with higher BMI at baseline showed a greater increase in CRP over time (P<0.0001), whereas those with higher CRP at baseline showed a greater decrease in CRP over time (P<0.0001). CONCLUSIONS Over 6 week and 6 month follow-up periods, the intervention failed to discriminate changes in CRP. However, the percentage with high CRP did fall, more so for those with lower BMI and higher CRP at baseline. BMI may mediate the influence of physical activity on CRP.