Low-intensity exercise can lower men’s chances of developing heart disease by reducing levels of C-reactive protein (CRP), according to researchers in Finland and Baton Rouge, La.
CRP is a marker of inflammation. Inflammation in the lining of the arteries has been linked with increased plaque build-up that blocks the blood vessels and causes heart disease.
“Regular, low-intensity physical exercise, such as walking four to five times a week, reduced blood level of CRP and improved the function of the cells lining blood vessels. This was especially true in men who are genetically susceptible to cardiovascular disease,” says Rainer Rauramaa, M.D., professor of exercise and medicine at the Kuopio Research Institute of Exercise Medicine and the University of Kuopio in Finland.
This data came from the DNASCO (DNA Polymorphism and Carotid Atherosclerosis) study, a six-year, controlled, randomized trial on the effects of both low-intensity exercise and genetic factors on atherosclerosis and its risk factors.
The DNASCO study used a random population sample of 128 men aged 50 to 60 years identified through the national population registry in Kuopio, Finland. Men were divided into two groups and followed for five years. Those allocated to the exercise group were prescribed an individual training program of mostly aerobic exercise. Men in a reference group were given the choice of whether or not to engage in exercise.
“In practical terms, the exercise level corresponded to brisk walking,” Rauramaa says. “Our recommendation was to exercise four to five times a week for 30 to 60 minutes. In some societies, this might even be considered a moderate level of exercise.”
A measurement of plaque buildup in neck arteries was taken every six months. Markers of inflammation such as CRP and fibrinogen levels, as well as traditional heart disease risk factors such as blood pressure, cholesterol levels, and overall fitness were checked annually. The group’s compliance rate was 91 percent, and the net increase of their ventilatory aerobic threshold (vAT) was 19 percent. This measurement is an indicator of fitness levels based on cardiorespiratory rates, and was obtained by observing the exchange of respiratory gases (oxygen and carbon dioxide) and ventilation during exercise. Low cardiorespiratory fitness is a risk factor for heart disease.
Men in the exercise group showed a 16 percent reduction in CRP, compared with a 2 percent reduction in the reference group. Further, at the end of the study, men in the exercise group who carried an atherogenic PAI -1 genotype – which makes them particularly susceptible to cardiovascular disease – showed a 49 percent reduction in CRP, compared with a 1 percent decrease among their cohorts in the reference group.
The atherogenic PAI-1 genotype is associated with increased levels of plasminogen activator inhibitors, which impairs the dissolving of blood clots. The inability to dissolve clots increases the risk of heart disease.
“Genetic factors explain about 30 percent of the variation in fitness levels,” says Rauramaa. “Fitness can be increased by another 30 percent with regular physical exercise. Regular exercise also affects the atherosclerotic process at various stages; however, much more research – controlled randomized trials – is needed.”
The research team continues to analyze and report the data collected in the DNASCO study. In addition, the Kuopio Research Institute of Exercise Medicine currently has a similar clinical trial under way in men and women up to 75 years of age. Other researchers are: Sari B. Väisänen, Ph.D.; Timo A. Lakka, M.D.; Ilkka M. Penttilä, M.D.; Tuomo Rankinen, Ph.D.; and Claude Bouchard, Ph.D.
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Abstract 3855
NR01-1356 (SS2001/Rauramaa)