Endorphin Junkies Beware: Too Much Cardio Scars the Heart

by Fitness Editor Paula Jager, CSCS Owner of Crossfit Jaguar

too much cardio

The majority of Americans do not get anywhere close to enough exercise so the idea of “too much cardio” may seem ridiculous at first.

Technological “advancements” and gadgets that supposedly make our lives “easier” have come with a price–decreased physical activity and a host of related health problems.

On the opposite end of the spectrum, some exercise aficionados tend to overdo it thinking more is better.

Physical exercise may not be a drug but it does possess the addictive nature and traits of a powerful pharmacologic agent.  As with any chemical agent that affects biological systems, a safe upper dose limit exists beyond which the adverse effects may outweigh the benefits.

I am not undermining the importance of physical exercise with this sobering statement that yes, you can in fact overdo it in the exercise department, especially when it comes to too much cardio!

People that partake in moderate to vigorous physical exercise on a regular basis are much healthier than their sedentary counterparts.

Extreme exercise, however, is actually counterproductive to great cardiovascular health.

If you are exercising correctly and efficiently there’s no need to workout for more than 30-60 min at a time.

It’s important to get your heart pumping with the right type of metabolic conditioning which will improve the amount of blood oxygen, release endorphins, stimulate your immune system and increase staying power.

But there is a point of diminishing returns to these benefits and research is piling up that continuing that cardio session too long–beyond 60 minutes per day can cause more harm than good.

How?  Read on …

  • Shall we say catabolic state?  Excessive cardio spells breakdown and not in a good way.
  • Excess cortisol is released which not only contributes to more catabolism but chronic disease.  It never ceases to amaze me how many endurance athletes have thyroid problems.
  • Repetitive strain injuries and injuries that won’t heal with continued over exercising.
  • Lowered defenses i.e. weakened immune system. Endurance athletes with chronic respiratory infections are a prime example.
  • Insomnia.

too much cardio

If that’s not bad enough, what does too much cardio do to your heart? You’re obviously exercising to improve its function and adopting lifestyle factors that won’t have you dropping dead of a heart attack, but an excess can be a serious blow to your heart’s health.

How Too Much Cardio Kills

Research done on marathon runners and other endurance athletes who regularly partake in too much cardio show the following characteristics including scarring of the heart muscle.

To some they may be the epitome of fitness and the ultimate show of endurance but the extreme stress on their heart comes with a very high price. . .

  • Extended vigorous exercise such as that performed during a marathon or similar event raises your risk of cardiovascular disease by 7 fold.
  • Long-distance training in general leads to high levels of inflammation and the damage continues long after the race is over.
  • Research has revealed diffuse scarring of the heart muscle along with structural changes after several years of excessive training.
  • Studies show long-term endurance athletes suffer from diminished function of the right ventricle.
  • Increased blood levels of cardiac enzymes–markers for heart injury.
  • Atrial fibrillation (rhythm abnormalities).

Although most people reading this article are not exercising enough it’s still important to understand the dangers of excessive traditional cardio.  Since most of us are not elite level endurance athletes what does this mean for us?  It certainly shouldn’t be used to avoid exercising at all. Exercise is absolutely necessary for health & fitness just not excessive amounts of it.

How Much is Too Much Cardio?

Push your body hard enough for a challenge while allowing adequate time for recovery and repair.  Move like traditional man with short burst of high intensity activities but not long distance running, biking and swimming such as required for endurance events.

Even an hour or more more on the gym’s cardio machines is not a wise idea.

Exercise to feel better, look better and perform better. It will aid in keeping your weight in check, help you to sleep more soundly and give you a better outlook–the reasons are many and most of us will not run into the problem of exerting ourselves excessively.

If you are a high level endurance athlete or think 5 marathons a year is a reasonable goal you may want to seriously reconsider how you train.  Bullet proof your heart through short burst of exertion followed by periods of rest or recovery intervals. Heart attacks never happen because your heart lacks endurance rather they typically happen during times of stress when your heart needs more energy and pumping capacity but doesn’t have it.

For further reading on the subject check out these links:





About the Author

paula jagerPaula Jager CSCS and Level 1 CrossFit and CF Nutrition Certified is the owner of CrossFit Jaguar.  Her exercise and nutrition programs yield life changing results.

You can connect with her on Facebook by clicking here.




Comments (32)

  1. Kelly Burns Lieber via Facebook July 13, 2014 at 3:40 pm

    It’s our crazy culture of excess. If a mile is good thirty must be better, right? Um, no.

  2. Does it though or is it how a body fed on modern foods performs in such circumstances? It would be interesting to see if people on a traditional diet are as affected by prolonged cardiovascular exercise. Stressing an already poorly functioning body is clearly going to cause problems so its no surprise that many athletes glugging away at the energy drinks and high carb diets are going to suffer. It is very common in traditional cultures to walk/run down a kill that has been poisoned, sometimes for many miles so we’re clearly up to the task. Personally I would say this issue is similar to the rise in sun-related skin cancer. It is not the sun but the diet of the person exposed to the sun that’s the problem.

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  4. Great article! Thanks! And partly why I no longer do big cardio sessions. I believe in natural, functional movement, not slogging your guts out doing crazy cardio and lifting massive weights which causes so much damage to the body. I’m the fittest and healthiest I’ve been, and I do hardly any cardio, no big weights sessions, just natural movements like climbing, crawling, etc etc. I love it and so does my body. No injuries, no sickness, no burn-out. I also eat clean/paleo/primal and that also plays a role in my overall health.
    Thanks for providing info so people can start to learn about the negative effects of excessive cardio on their bodies.

  5. The problem isn’t excessive cardio; it is overtraining that causes these heart problems. All the studies out there are on people who are completely out of shape and that smoke and don’t exercise. The marathoners who have heart attacks have been overtraining for years leading up to them. Or you have the unhealthy beginner trying to run a marathon as a goal, but should be walking instead of running at all. If you have two 35 year old people that run a mile together, one person’s heart rate can be 110 beats per minute, while the other person’s heart rate is 175 beats per minute. The person at 175 beats per minute, SHOULD NEVER RUN until they walk, swim, bike at a lower heart rate and build their aerobic base. There are so many benefits to low intensity aerobic training. Not saying 15 hours a week, but an hour 5 days a week, below your anaerobic threshold is amazing for your heart, your body, your energy, and your fat burning ability for the next 24 hours. It is a shame that when everyone refers to cardio, they just generalize that all cardio is bad. You shouldn’t be sore after workouts, and if your knees hurt you shouldn’t be running until you first correct that problem.
    There is a major problem with the people who are cardio junkies and working out excessively on the machines in your local gym; if we strapped a heart rate monitor on them, 90+% of them would be overtraining, causing all the problems mentioned in this article. I would even guess that 90% of the pro endurance athletes are overtraining also. The racing requirements nowadays, make athletes qualify in too many races to get in the big race. But there is the other side to the story that is never mentioned. Low intensity training is highly beneficial!

    I also think more intense interval training is great for people who are in great shape. Lifting heavy weights with great form is amazing. Crossfit type workouts are great for people who can handle it.

  6. I agree with the article. After years of high intensity cardio I’ve discovered that I can swim at a gentle pace and walk at a steep incline on a thread mill with 80% of the benefit and 80% less damage to my joints and apparently less risk to my heart. And I can continue to do so for the rest of my life. I’ve too many runners sidelined in their 40’s and 50’s.

  7. I’d argue that your points remain unsupported.

    Your “sources” are written by yourself, uninformed news services, and a guy trying to sell his book. There are equally as many studies that will show you that too much heavy lifting is a detriment to your health.


    Yes, I understand the article says occupational. But what is the difference really behind it doing crossfit for 2hrs a day?

    I am not bashing CrossFit, I just believe their are unsupported claims in your writing.

  8. Hrh Ronnie Cruz Bernardo via Facebook June 18, 2013 at 5:50 pm

    The west should learn from the east when it comes to exercise, they think extensive work out and gym are the way to go, a proper brisk walking give the same amount of exercise than running without injuries, a Qi-kung a very simple movement exercise will make you all sweat compared to a gym work out, a macrobiotic exercise is also a balanced exercise which is a very essential that we often neglect: http://bridgetoselfhealing.blogspot.com/2013/05/stretching-essential-exercise.html

    • I don’t even try to persuade my friends to quit cardio. One of them is a soldier and runes for distance every day. In his free time he also goes running whenever he can. The other one is even worse cardio maniac :-) Nonetheless, to me it’s very impressive, how long and far they can run.

  9. Lindsey Buhl via Facebook June 18, 2013 at 1:52 pm

    Don’t worry I usually save my hour of cardio for after my hour of lifting ;) I think it’s impossible to keep up as recommendations change! First we aren’t doing enough, then we’re doing too much… My goal is every marathon in moderation! Haha l

    • 2 hours in the gym? Hmmm, after your heavy lift you could combine some lighter weights/cardio for a little 10-15 min circuit blast. Very effective and you gain an hour:)

  10. So is one marathon a year okay? I don’t want to be putting all this work in running everyday to be healthy when it’s doing the opposite. I consider myself a long distance runner. 6 miles on an average day…. Like one really long run a month.

    • I wouldn’t go for more than one a year and I wouldn’t run everyday. Less is often more. I would also do some biking/rowing to balance the stress of running all the time. And definitely take off a period of the year off from running and focus solely on strength for about 3 months. In other words, periodize your training around the marathon.

      • Thank you. I will give it a try :) I’m starting to slowly realize less really is more. During my last marathon training I was afraid to take some days off due to a minor injury, but ended up doing so…. I was surprised at how much better I ran from resting vs pushing myself. Seems like a no brainer, but at the time I really had this mentality to keep going faster & harder…

  11. Thank you so much for bringing this out to discussion. I am a recovering exercise/bulimarexic post 15 yrs. I taught aerobics and other classes for 16 yrs and was a hard core about all of it. My wake up call was losing my Dad to cancer at age 58. He was never sick a day and always working and puttering and just a very positive person. That changed a lot of things for me and I began to question my obsession with “health and fitness”. My husband’s uncle, an avid runner, dropped dead of a massive heart attack at 51, which caused further concern, and I noticed a lot of my exercise buddies had some serious chronic injuries and illness. When I realized that I was not in balance or in control, I gave up this obsession for moderation, as the Bible clearly states, even about “physical exertion”. I have been free of the negative thoughts that kept me doing counterproductive things for a long time now, but I do have a “leaky” heart, as diagnosed by my doctor and I have some other health issues that I am becoming aware of now. I am positive that I did damage during those years, but God is gracious and I am beginning to heal with some of the new ways of caring for my body. Thanks again for reminding us that more is not always better, even when it seems to sound logical and benign.

  12. I run/walk about 2.5 miles about 3 times a week. I do a few 5k races and a half marathon each year. Do you think by doing this one bigger race a year would have negative effects? Or does that story speak more to people who run hard each time they run for longer distances and do full marathons frequently? Thanks..

    • @Teresa–no, I don’t think that is excessive at all. And yes I was speaking more in terms of “people who run hard. . . marathons frequently”. Keep up the physical activity that you enjoy, adding in some interval and strength training for even better performance!

    • It’s all over the internet. Check the links provided at the end of the article, Mercola.com has a couple excellent articles on the subject along with Mark’s Daily Apple or just Google “excessive endurance exercise and heart damage” and look for the more reputable sources and ones that you trust.

  13. I’m 52, female, eat a mostly primal diet, and in good health (knock-on-wood). I’m training for a 10K. I just ran my first 5K and my goal is to do a 10K. I’m not a “runner” by any stretch of the imagination, and I don’t see myself continuing at this pace after I’ve accomplished my 10K in Sept. I prefer to walk/jog and ride my bike with strength training at the gym and that’s what I’ll go back to once I’ve done the 10K. It’s just always something I’ve wanted to do and decided this was the year. To build up to a 10K I’ll be running 4x a week, until Sept. 21, at a distance of 2miles to 9 miles by the end of training. I know that the 9 miles will take me well over an hour to complete – if I can even run that far, might have to walk part of the way. From your article it sounds like what I’m doing isn’t necessarily a good thing? I’m aware of the pitfalls of over-exercising but was thinking that since this is only a short term goal for me and not something I plan to do past the 10K, it wouldn’t be such a bag thing? Any thoughts you have on my plan would be greatly appreciated and thanks for all the great articles!

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