Is Exercise Bad For Your Heart?

Get-Fit Guy weighs in on the latest research about whether exercise is bad for the heart or body, how much exercise is too much, and how to know if your heart is healthy enough for exercise. Read on to learn more.

Ben Greenfield
5-minute read
Episode #159

As I write this article, I am just 2 days from having crossed the finish line of a hot, humid, and extremely difficult race called “Ironman Hawaii.” For nearly 20 minutes after crossing that finish line, I laid exhausted and short of breath in the medical tent, where I was told that I was experiencing a highly irregular heart rate..


This isn’t the first time I’ve felt my heart rate skip a beat or feel funny during exercise. Recently, in a chapter of a book I wrote entitled Beyond Training, I described how during long workouts leading up to the race, I occasionally experienced a phenomenon called PVC, or Premature Ventricular Contraction, in which the heart’s electrical activity become slightly abnormal during physical exertion.

In extreme endurance athletes such as marathoners and Ironman triathletes, these type of heart issues have even caused death! For example, distance-running legend Micah True – better known for his role as Caballo Blanco in the book Born to Run – died during on a trail run. The cause was cardiomyopathy due to an enlarged heart. True was just one example of seasoned endurance athletes who have experienced sudden fatal cardiac episodes during exercise. Marathoner Ryan Shay and Ironman triathlete Steve Larsen are others, and most recently, professional Ironman triathlete Torbjorn Sindalle was forced into unexpected retirement due to premature wearing of a part of his heart called the bicuspid valve. I list many other such examples in my article Are Endurance Sports Unhealthy?

Of course, the last thing I want to do is scare you away from exercising. After all, in a generally sedentary and increasingly unhealthy and obese society, the last thing most people need to hear is that exercise could kill them! But it is important to at least be aware of the latest research about whether exercise is bad for your heart or body, how much exercise is too much, and how to know if your heart is healthy enough for exercise.

Is Exercise Bad For Your Heart?

This week, a study was released in the Canadian Journal of Cardiology. In the study, a group of recreational marathon runners were observed to undergo significant damage to their heart muscles after a strenuous race.

Now don’t go calling all your marathoning friends or canceling your entry in the local 5K!

Here’s why: These effects were found to be both temporary and reversible. But the researchers warned that these potentially dangerous effects are definitely more widespread in less fit exercisers and that recreational distance runners should be sure to prepare properly for the rigor of something like a marathon. 

The professor who oversaw the study summed it up like this:

"Although no permanent injury was observed in this group of runners, the findings suggest that there may be a minimum fitness level needed beyond which the heart can bounce back from the strain of training and running a long race. Furthermore, these results emphasize the need for proper preparation before recreational distance runners engage in a marathon race.”

So although it may seem obvious, the main takeaway is this: Don’t jump into a hard exercise session or a race for which you’re inadequately prepared! By pushing too far outside your comfort zone, you could indeed put yourself into a situation where exercise could be bad for your heart.


About the Author

Ben Greenfield

Ben Greenfield received bachelor’s and master’s degrees from University of Idaho in sports science and exercise physiology; personal training and strength and conditioning certifications from the National Strength and Conditioning Association (NSCA); a sports nutrition certification from the International Society of Sports Nutrition (ISSN), an advanced bicycle fitting certification from Serotta. He has over 11 years’ experience in coaching professional, collegiate, and recreational athletes from all sports, and as helped hundreds of clients achieve weight loss and fitness success.

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