High Intensity Endurance Workouts Could Damage Your Heart

by DailyHealthPost Editorial

high intensity endurance workout

Is your exercise routine causing serious damage to your heart?


A recent article in The New York Times shed light on some recent studies that have discovered the dangerous issue of heart scarring in older men with extensive experience in high-intensity exercise.

Their mistake?


Over-exerting their heart to the point that scars developed and heightened their risk of fibrosis.

exhaustion from training

Long, Hard Training

The original study published in the Journal of Applied Physiology examined a group of incredibly fit older men.

These healthy men were between the ages of 26 and 67, all of whom had participated in high-endurance training for a significant portion of their adult life, either as a part of an Olympic or national distance running or rowing team or as a participant in over 100 marathons.


Based on that description, it sounds like these should be some of the healthiest, heartiest men in the nation.

However, the study performed a new method of magnetic resonance imaging in order to detect signs of scarring in the heart that could lead to fibrosis.

Although none of the athletes had full-blown fibrosis, at least half of the older men had some level of heart scarring, indicating that fibrosis was likely to develop.


If fibrosis develops, it can cause irregular heart functions and even heart failure, a problem that you wouldn’t expect for these men.

James O'Keefe MD — Cardiovascular Damage From Extreme Endurance Exercise

Can You Predict It?

Since heart scarring seemed to most often appear in the men who had undergone the longest, hardest training, the study concluded that lifelong cardio performed at such a high level of intensity increases your risk of severe heart damage.


Unfortunately, researchers are not yet able to determine at what point cardio exercise becomes dangerous. However, the study clearly shows that the more marathons or races you participate in, the greater your risk of heart scarring.

In order to corroborate the findings of the first study, a second study was conducted with a goal of recreating the stress of marathon training on rats. At the end of the study, almost every single rat had extensive scarring on its heart as well as some structural changes. Clearly, high-endurance training can pose a serious threat to your health if it isn’t performed with some moderation!

Protecting Yourself

The good news is that unless you are a high performance athlete or marathon runner, this danger most likely will never affect you. However, there is a lesson to be learned from these studies. Too much of a good thing has the potential to actually affect you negatively!


The best response to this study for the average athlete is to listen to your body, practice moderation to some extent and avoid overtraining. This certainly isn’t an excuse to not engage in cardio workouts, because you can’t achieve complete health without regular cardio. 20-30 minutes of cardio a day shouldn’t cause this type of heart scarring, so you can safely continue your regular routine.

What do you do for a cardio workout? What steps do you take to keep your heart healthy? Share your thoughts in the comments below!