The Effect of Aerobic Training on C-Reactive Protein in Postmenopausal Women

Abstract

C-reactive protein (CRP), a marker of systemic inflammation, has been reported to be an independent predictor of cardiovascular disease in both women and men. Though a number of epidemiology studies suggest that individuals who exercise regularly have lower CRP than sedentary individuals, there is a paucity of intervention studies that have examined the role of exercise in reducing CRP. PURPOSE: To examine changes in CRP across different doses of aerobic exercise in sedentary post-menopausal women. METHODS: Of the 464 randomized overweight/obese sedentary postmenopausal women (DREW study), 421 participants (91%) completed the study and had available plasma for baseline and follow-up CRP measurement. This sub-set of participants were randomly assigned to a non-exercise control group (n = 96), or 1 of 3 exercise groups; energy expenditure of 4 kcal/kg/min (n = 143), 8 kcal/kg/min (n = 87) or 12 kcal/kg/ min (n = 95). The intervention period was six months in duration. RESULTS: The mean participant age was 57 ± 6 years, 45% of the participants were using hormone replacement therapy (HRT) and 64% of the participants were Caucasian. As a group CRP was elevated as demonstrated by the mean group baseline CRP of 5.6 ± 5.5 mg/dL, median CRP of 4.0 mg/dL (IQR: 1.8, 7.6) and 72% of the participants with a CRP > 2.0 mg/dL. Baseline mean CRP values were similar across randomization groups at 6.0 ± 5.8, 5.3 ± 5.3, 6.5 ± 6.1 and 5.0 ± 4.8 mg/dL for control group, 4, 8& 12 Kcal/ kg/min groups, respectively. Using general linear modeling adjusted for age, baseline value, ethnicity and HRT use, there was no difference in follow-up CRP values across groups for either the mean or geometric mean values. Non-parametric analyses showed similar results as there were no group differences at follow-up. CONCLUSIONS: We conclude that 6-months of aerobic exercise training did not reduce CRP in this population of sedentary postmenopausal woman. It needs to be noted that this study was not specifically designed to examine CRP and exercise. Supported by NIH grants HL66262 and HL071900, and Life Fitness for equipment.