In people with signs of metabolic syndrome, including high blood pressure, high triglycerides, high cholesterol, elevated blood glucose and obesity, physical activity appears to reduce a marker for inflammation which has been linked to heart disease, according to a new study in the Nov. 16, 2004 issue of the Journal of the American College of Cardiology.
“We were surprised by the large effect of fitness level on C-reactive protein in subjects with the metabolic syndrome,” said Doron Aronson, M.D., at the Rambam Medical Center in Haifa, Israel. “Our study emphasizes the importance of physical activity in improving the proinflammatory state associated with the metabolic syndrome,” Dr. Aronson said.
An elevated C-reactive protein level in the blood is a possible indication of a low-grade inflammatory process in blood vessels. People with the metabolic syndrome are at higher risk of heart and vascular disease, and this protein has been shown to provide additional prognostic information on the subsequent risk of cardiovascular events in these patients.
Although this study did not measure heart disease events, Dr. Aronson said being fit appeared to reduce the levels of C-reactive protein even more than medications usually do.
“Drugs such as statins and thiazolidinediones have been used to lower C-reactive protein, resulting in 15 to 25 percent decreases in C-reactive protein. Note that subjects in the upper fitness level have C-reactive protein levels that are about 50 percent lower than subjects in the lowest fitness level,” he said. “Our study does not address the effect of fitness on cardiovascular outcomes. However, it is logical to assume that the reduction in C-reactive protein that follows the improvement in fitness level, in addition to the improvement in lipid profile and other cardiovascular risk factors, should lead to a reduction in cardiovascular events.”
Physical fitness was assessed in 1,640 subjects using a treadmill test. Among participants diagnosed as having the metabolic syndrome, the average C-reactive protein level was 4.62 milligrams per liter in those in the bottom quartile of fitness versus 2.20 mg/l in those in the highest fitness quartile. Among healthy participants, the lowest fitness quartile had an average C-reactive protein level of 1.48 mg/l versus 0.93 mg/l in the highest fitness quartile.
“Our study shows that fitness is an important determinant of C-reactive protein levels in subjects with the metabolic syndrome. Subjects with the metabolic syndrome who maintain a high fitness level have markedly lower C-reactive protein concentrations compared to those with low fitness level. Therefore, improving fitness level is a simple and effective way to lower C-reactive protein,” Dr. Aronson said.
He urged physicians to apply these findings in clinical practice.
“Based on our results, the management of patients with the metabolic syndrome should start with lifestyle changes — particularly with an effort to increase activity level,” he said.
Nathan D. Wong, Ph.D., F.A.C.C., at the University of California in Irvine, who was not connected with this study, noted that the strong inverse relationship between fitness and C-reactive protein levels holds whether someone has a fairly low risk of cardiovascular disease, has some metabolic abnormalities or has been diagnosed with the metabolic syndrome.
“This is a very good paper. It emphasizes the importance of a moderate or high level of physical fitness in possibly maintaining low inflammatory burden, thus beneficially affecting cardiovascular risk,” Dr. Wong said.
The American College of Cardiology, a 31,000-member nonprofit professional medical society and teaching institution, is dedicated to fostering optimal cardiovascular care and disease prevention through professional education, promotion of research, leadership in the development of standards and guidelines, and the formulation of health care policy.