A sedentary lifestyle can lead to problems with heart health, but people with active lifestyles aren’t immune, according to a new study of longtime endurance runners.
The results did not surprise Dr. Peter McCullough. The cardiologist at Baylor Heart and Vascular Hospital has done several studies related to running and heart disease. He's also run in 54 marathons across the U.S. and in Europe and Asia.
McCullough believes it's hard to beat running for cardiopulmonary fitness. He says it helps with weight maintenance and blood pressure, and runners tend to stay away from smoking and bad dietary habits.
But the study of 50 men, who had run in at least 25 marathons, found that running isn't as protective as they might expect or hope when it comes to heart health. The majority of runners in the study had small-to-large levels of atherosclerosis, fatty deposits that can clog arteries.
"The majority of runners actually do have some cholesterol deposits in their arteries feeding their heart," McCullough said. "They don’t have clean arteries."
McCullough estimates at least 50 percent of what doctors see with atherosclerosis comes through inherited factors.
There have been cardiac studies examining a related issue, sudden death with exercise, McCullough said. With every large race – 50,000 runners or more – there’s typically one death, but the majority of those aren't believed to be related to atherosclerosis or blockages, he said.
Rather, the thinking is excessive exercise leads to scar formation in the heart muscle because of too much stretching of the right atrium and right ventricle – two of the four chambers of the heart, McCullough said.
"That scar formation can be the site of an abnormal electrical rhythm that can spin around the scar, and that can take a patient into a lethal arrhythmia, and they go down like a rock," McCullough said.
The good news: scar formation is reversible. But coronary calcium in the arteries feeding the heart is permanent; it slowly advances over time.
If you keep risk factors like LDL cholesterol, blood pressure and blood sugar in check, you can have coronary calcium and some atherosclerosis and still never have a heart attack, said.
"It’s like rust on the pipes and the water still flows," McCullough said.
McCullough said the "sweet spot" for cardiovascular exercise is 10 to 15 miles a week of running or a combination of running, walking and jogging.
"That could be accomplished in as little as 30 minutes a day of some walking or some aerobic activity several times a week," he said.
To determine the right level of exercise, McCullough recommends seeing a doctor and undergoing a risk assessment of cardiovascular risk factors.
A treadmill test can give a doctor and patient an idea of his or her current level of fitness. A heart scan, called a coronary artery calcium score, can see if there are blockages to the arteries. And for endurance athletes, an MRI shows if the scar formation is occurring.