Effects of different doses of physical activity on C-reactive protein among women

Abstract

Elevated C-reactive protein (CRP) is associated with an increased risk of cardiovascular disease. Physical activity has been inversely associated with CRP. However, the clinical trials examining the effect of exercise training have produced conflicting results.

Purpose: The purpose of this study was to examine the influence an exercise training program on CRP in postmenopausal women.

Methods: Sedentary, overweight, or obese postmenopausal women with elevated systolic blood pressure (120-160 mm Hg; n = 464) were randomized into one of four groups: a nonexercise control or one of three aerobic exercise groups; exercise energy expenditure of 4, 8, or 12 kcal·kg(-1)·wk(-1) (KKW) for 6 months at a training intensity of 50% of peak VO2.

Results: Complete data for 421 participants were available, and mean (SD) baseline CRP was 5.7 (5.5) mg·L(-1), with no significant differences across groups. Although VO2 increased in a dose-response manner, there were no significant changes in CRP in any of the exercise intervention groups compared with the control group. Change in fitness was not associated with change in CRP, whereas change in weight was significantly associated with change in CRP.

Conclusions: Despite increasing fitness, 6 months of aerobic exercise training did not improve CRP. However, improvements in CRP were associated with reductions in weight.

Trial registration: ClinicalTrials.gov NCT00011193.

Figures

Figure 1

Participant flow diagram.

Figure 2

The distribution of the change in CRP values in the control and exercise groups. There were no differences in median (IQR) CRP change between any of the groups (p=0.6).

Figure 3

Change in CRP by study group: control, exercise energy expenditure of 4, 8, or 12 kcal/kg/week (KKW). The left set of bars represents findings for all participants and the right set of data represent findings with individuals with changes in CRP > 3 standard deviations from the mean removed. There were no significant changes in CRP in any of the exercise groups compared with the control group in either of the analyses.

Figure 4

Changes in CRP (adjusted for baseline CRP and randomization group) across quartiles of change in weight. * P