Exercise at high levels increases risk of hardening of the arteries

By Kate Bass, B.Sc.Oct 18 2017

A study comparing exercise patterns and indicators of heart disease over 25-years, has shown that white men who exercise at high levels were 86% more likely to develop plaques in the coronary arteries than men who exercise at lower levels.

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Heart disease is the leading cause of death in the US. Early identification of individuals with increased risk of heart disease is important to allow risk-lowering strategies to be implemented to help prevent future morbidity.

It is generally accepted that the best way to identify patients at increased risk of developing heart disease is by measuring the level of calcium build-up in the arteries supplying blood to the heart— coronary artery calcification.

Since efforts to control coronary artery calcification with medical therapy have not been successful, researchers are keen to determine which factors contribute to the initiation and progression of coronary artery calcification.

One factor that has been investigated is exercise. However, due to controversial study findings, there remains some doubt regarding the association between physical activity and the risk of heart disease.

To try and resolve this issue, researchers at the University of Illinois at Chicago and Kaiser Permanente assessed the presence of coronary artery calcification relative to exercise patterns over 25 years among participants in the multicenter, community-based, longitudinal cohort CARDIA Study. Data from over three thousand individuals aged 18 to 30 years from across the United States were analysed.

Participants reported their level of physical activity at three or more examinations between 1985 and 2011. Based on this information, participants were split into one of three groups: less than 150 minutes of exercise a week; 150 minutes of exercise a week; more than 450 minutes of exercise a week. National guidelines recommend 150 minutes of exercise a week.

The results showed that participants who exercised for more than 450 minutes a week were 27% more likely to have signs of coronary artery calcification by middle age than those who only had <150 minutes of exercise a week.

Furthermore, the researchers discovered that for white men the risk increased to being 86% greater for heavy exercisers compared with low exercisers. The difference was not so marked among white women.

We expected to see that higher levels of physical activity over time would be associated with lower levels of coronary artery calcification. Because the study results show a significantly different level of risk between black and white participants based on long-term exercise trajectories, the data provides rationale for further investigation, especially by race, into the other biological mechanisms for coronary artery calcification risk in people with very high levels of physical activity".

Deepika Laddu, assistant professor of physical therapy in the UIC College of Applied Health Sciences.

It is possible that high levels of exercise may increase coronary artery calcification as a result of the added stress on the coronary arteries. However, further research into the nature of these arterial plaques is needed to determine whether they do indeed increase the risk of heart disease.

It may be that the increase in calcium deposits after prolonged exercise are more stable and thus less likely to rupture and cause a heart attack. Exercise provides many health benefits and there is no need to change exercise patterns on the strength of these findings alone.