By Ed Susman , Contributing Writer, MedPage Today
Reviewed by Zalman S. Agus, MD; Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
There is a significant inverse relationship between self-reported vigorous-intensity physical activity and elevated levels of C-reactive protein.
LOS ANGELES -- Individuals who vigorously exercise significantly reduce the odds that they will have high levels of C-reactive protein -- a marker of inflammation in the body, researchers reported here.
If a person exercised vigorously less than 500 MET (metabolic equivalents) per week, there was a 27% reduction in the odds of having elevated C-reactive protein levels (odds ratio [OR] 0.72, 95% CI 0.59-0.88, P=0.002) when compared with non-exercisers, said lead author Michael Richardson, BSH, a graduate assistant at Brooks College of Health at the University of North Florida in Jacksonville.
In his poster presentation at the annual meeting of the World Congress on Insulin Resistance, Richardson also noted that if a person did 500 METs or more per week, the risk reduction was 33% (OR 0.67, 95% CI 0.53-0.84, P=0.001).
"Our findings suggest that a significant inverse dose-response relationship exists between self-reported volumes of vigorous intensity exercise and elevated C-reactive protein," he told MedPage Today. "These results also suggest this relationship is independent of visceral adiposity, a known mediator in the relationship between physical activity and C-reactive protein. The protective inverse association was independent of several metabolic risk factors."
"Vigorous intensity physical activity, even among those with central adiposity, reduced the odds ratio of falling into the high levels of C-reactive protein," Richardson explained. "Even people who exercised vigorously that did not reach the recommended levels also showed lower odds ratio for being in the high C-reactive protein level when compared with individuals who did not exercise vigorously during the week."
He said that vigorous intensity varies from one person to another and can be just walking to the mailbox for some people, and playing basketball or running a road race for others.
Richardson and colleagues scrutinized the 1999-2006 National Health and Nutrition Examination Survey (NHANES) database, which lists physical activities, and used that data to calculate vigorous intensity physical activity for the study.
The researchers focused on a sample of 6,242 people in the national survey. They found that the risk of having an elevated C-reactive protein level was significantly higher with increasing age; with being a non-Hispanic black; with being a current smoker; with having elevated -- 160 mg/dL or greater -- low-density lipoprotein cholesterol; and being diabetic.
Richardson said that with higher levels of adiposity, however, a person needs to achieve vigorous intensity exercise levels to have an impact on C-reactive protein. Adiposity, he noted, creates its own inflammatory process that cannot be overcome by just moderate exercise.
"We have seen that vigorous exercise is helpful in patients, but getting them to achieve that level for a length of time can be challenging," said Deborah Evans, a clinical exercise specialist at the Alaska Native Medical Center & Southcentral Foundation, Anchorage. "There is little emphasis on exercise in treatment regimens and I think that needs to increase."
"Future studies should examine the associations among objectively measured vigorous intensity exercise and elevated C-reactive protein levels," Richardson suggested.