Exercise Shown to Keep Inflammation Markers in Check

Source: Tufts University
November 14, 2002 (Reviewed: November 13, 2004)

Staying active is one way to reduce the risk of cardiovascular disease, but exactly how exercise helps control the inflammation that leads to arterial damage is still under review. A study in the journal Epidemiology furthers what scientists know about the effect of exercise on levels of C-reactive protein and other markers used to gauge inflammation.

Measuring effects of exercise

A researcher with the Centers for Disease Control and Prevention analyzed data collected on more than 13,000 adults as part of the third National Health and Nutrition Examination (NHANES III, 1988-1994). He compared reported levels of leisure time activity - graded as 'vigorous,' 'moderate,' 'light,' and 'sedentary' - to levels of C-reactive protein in blood samples collected during the survey.

After controlling for potential confounders, including age, body mass index, smoking status, and serum cholesterol, the researcher found that participants who routinely engaged in vigorous exercise at least three days a week were about half as likely as others in the study to have elevated levels of C-reactive protein (odds ratio=0.53, 95% CI 0.40-0.71). They were also more likely to have elevated serum albumin levels and reduced levels of fibrinogen and lower white blood cell counts.

Potential benefits

The results of this current analysis support earlier findings that regular exercise appears to have a favorable impact on markers used to assess level of inflammation. While this cross-sectional study cannot be used to infer cause and effect, there are several possible explanations to support the findings. Exercise may help control the inflammation process by reducing insulin resistance or improving endothelial function, both factors that may help control the release of substances that trigger an immune response. Exercise could also help control inflammation through a positive effect on body weight, although in the present study, body mass index did not have an appreciable effect on the findings.

What about the walkers?

In this study, significant results were limited to the 5% of participants who exercised vigorously at least 3 times per week. However, more than 30% of the participants fell into the 'moderate activity' level - the steady walkers who worked out at least 5 times a week. While this level of exertion did not produce significant results in this analysis, a positive linear trend was demonstrated with increasing level of exercise, with moderate exercisers showing greater benefit than light exercisers for levels of C-reactive protein (p for trend <0.001), albumin (p for trend 0.006), and fibrinogen (p for trend 0.004).

These results add to earlier research that supports a protective role for physical activity in reducing the inflammation that contributes to cardiovascular disease. More study is needed to determine what kind and how much exercise produces the most benefit.

Source

• Does exercise reduce inflammation? Physical activity and C-reactive protein among US adults. E. Ford, Epidemiology., 2002, vol. 13, pp. 561--568

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