The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Heart of an Athlete: How extreme exercise affects the heart

Posted in

Friday, Feb 08, 2019

We often say that exercise is the best medicine, but can you have too much of a good thing?

Our latest study, published in JAMA Cardiology, takes a closer look at the risk of hardening of the arteries in athletes and whether they can continue their training.

While most of us are in no danger of exercising too much, there is a very real concern about hardening of the arteries for people who exercise at high levels. Marathoners, triathletes and other endurance athletes who workout vigorously most days sometimes develop a buildup of plaque in their coronary arteries.

Known as coronary artery calcification (CAC), this plaque buildup is a known risk factor for heart attack. So the question that has plagued cardiologists is this: Is it safe for these athletes to continue working out at high levels or do they need to scale back their activity? 

Researchers from The Cooper Institute and the Institute for Exercise and Environmental Medicine recently published a study in JAMA Cardiology to examine whether too much physical activity was a significant risk factor for heart disease mortality. The study looked at nearly 22,000 generally healthy middle-aged men who were examined at the Cooper Clinic between 1998 and 2013. All of the men underwent CAC scanning, then were divided into three categories based on their physical activity levels and followed for 10 years. 

“The current study shows no increased risk of mortality in high-volume, high-intensity athletes who have coronary artery calcium,” said Dr. Laura DeFina, CEO and Chief Science Officer for The Cooper Institute. “Certainly, these highly active people should review their cardiovascular disease risk with their primary care doctor or cardiologists, but there is no reason to think they can’t continue exercising at high levels.”

The first important initial finding was that the men with the highest physical activity levels were 11% more likely to have arterial calcification than men who were less active. Their activity level was equivalent of running six miles/day, every day at 10 minutes per mile pace.

The second most important finding was that the most highly active men were at lower risk for all-cause and cardiovascular disease mortality when compared to men who were less active. So while these men may be at increased risk for developing CAC, they are at no greater risk of heart attack. The researchers concluded that these athletes can safely continue with their exercise programs.   

So is there such thing as too much exercise? Current public health guidelines for aerobic activity recommend 150-300 minutes per week at a moderate intensity, or 75-150 minutes per week at a vigorous intensity. The most active men in this study greatly exceeded these recommendations, yet were still at no greater risk of mortality. 

“The question has never been whether exercise is good for you, but whether extreme exercise is bad for you. For the past decade or so, there’s been increasing concern that high-volume, high-intensity exercise could injure the heart. We found that high volumes of exercise are safe, even when coronary calcium levels are high,” said Dr. Benjamin Levine from UT Southwestern Medical Center.

Dr. Levine is a Professor of Internal Medicine and Director of the Institute for Exercise and Environmental Medicine, a collaboration between UT Southwestern and Texas Health Presbyterian Hospital Dallas.

Additionally, overwhelming scientific evidence concludes that regular physical activity decreases the risk of developing and dying from a number of adverse health conditions, including: cardiovascular disease, type 2 diabetes, metabolic syndrome, hypertension, dementia, and some cancers. It is also helpful in managing depression and anxiety, controlling body weight, improving sleep, and decreasing the risk of falls in the elderly. 

It is safe to say that exercise is still the best preventive medicine for living Well. Into the Future. 


DeFina, L., Radford, N., Barlow, C., Willis, B., Leonard, D., Haskell, W.…Levine, B. Association of all-cause and cardiovascular mortality with high levels of physical activity and concurrent coronary artery calcification. Published online January 30, 2019 in JAMA Cardiology. doi:10.1001/jamacardio.2018.4628.   

Listen Now | JAMA Cardiology Audio Interview 


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