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Extreme Long Distance Running Has Questionable Impact on Heart

CardioSmart News

Extreme levels of running may harm rather than help the heart, based on a small study of runners participating in a 140-day cross-country race.

Published in the Journal of the American College of Cardiology, this study explored the relationship between extreme long distance running and heart health. While exercise is one of the best ways to protect against heart disease, studies have raised concerns about the effects of extreme levels of exercise on the heart. Some suggest that high levels of exercise may cause or even accelerate heart disease—the No. 1 killer of men and women in the United States. However, few studies have tested this theory, and evidence remains limited on the issue.

To learn more, researchers assessed runners’ heart health before and after a 140-day foot race from California to Maryland, known as the Race Across the USA. During this race, runners covered an average of 26 miles a day, with one rest day weekly. The study included a total of 8 runners with an average age of 45; nearly all were men.

Within 24 hours of the start and end of the race, participants completed imaging tests to measure plaque build-up in the arteries. They also underwent medical exams to review their medical history and assess cardiovascular markers like blood pressure, cholesterol and inflammation.

After the 140-day race, participants’ systolic blood pressure (the top number in a blood pressure reading) decreased on average by 6% and levels of “good” cholesterol (high-density lipoprotein or HDL) increased. Authors also note that no participants developed heart disease during the four-month study period.

However, researchers found that markers of inflammation called c-reactive protein (CRP) significantly increased among runners during the study period. Among the four participants with pre-existing heart disease, plaque build-up significantly increased between the start and end of the race.

Although this study was small, findings suggest that extreme long-distance running is not protective against heart disease in the same way that regular levels of exercise are. Rather, findings support the theory that extreme exercise may actually accelerate the progression of heart disease.

However, it’s important to note that the Race Across the USA is one of the longest running events in the world, which few runners complete. During this race, runners completed nearly one marathon daily for more than four months. Therefore, study findings cannot be generalized to other types of long distance running, which are more common and shorter in length.

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