According to the website MarathonGuide.com, more than 382,000 marathon finishing times were recorded in the United States in 2005. Those who complete marathons are often credited with having high levels of physical prowess. However, recent research claims that regular participation in such events may negatively impact heart health.

Researchers at the Athens Medical School, Hippokration Hospital in Athens, Greece, discovered that men who regularly participate in some high-intensity activities—like marathons—tended to experience stiffness in the large arteries. The information was provided via press release from the American College of Cardiology on March 13, 2010. The researchers measured blood pressure and pulse wave velocity—an indicator of arterial stiffness—in 49 men who regularly trained for marathons and 46 subjects who did not. The scientists found that both measures were higher in the marathoners than the control group. Exercise intensity appeared to correlate with arterial stiffness.

“Our data suggest that exercise may have an inverted U-shape relation with arterial stiffness,” stated lead author Despina Kardara, MD. “In other words, when you do not exercise, you have higher risk of cardiovascular events, but the same also happens when you exercise too much.” Though Kardara and colleagues focused their research on marathon runners, they suggested that other forms of high-intensity endurance exercise might produce similar effects.

“This is important because stiff arteries lead to high blood pressure and can impair the heart, keeping it from performing properly,” added Kardara. “Overall, aortic stiffness is an indicator of cardiovascular disease and hardening of the arteries, and a predictor of heart attack and related death.”

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