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“Chronic Cardio”–why too much of a good thing can be bad

By June 4, 2017 No Comments

“Chronic Cardio”.  This is a term I first heard used by Primal Health guru Mark Sisson (  He was a former competitive Ironman triathlete and marathoner who almost wrecked his health with this sort of training combined with eating a Standard American Diet (SAD)  (Check out the links for more info on his experience)

We all know that person.  The man or woman who has been a dedicated runner, cyclist or triathlete for years.  Every morning or afternoon they lace their running shoes up and hit the pavement.  Religiously.  Rain or Shine.  Cold or Heat.  Wind or Calm.  He/She may run 3 miles, 5 miles or however many miles for 45-60 minutes or longer (depending on the person and the training).  It’s a fairly intense workout, usually done at a fairly high intensity level and the individual feels tired afterwards and like they had a “good” workout. The problem is many of these people never really look any different.  Some of these people may be of “normal” weight, but they lack much muscular tone and are sometimes a bit soft around the middle.  Some of these people started out obese and after several dedicated years of running, they are still obese.  Some of these people are more on the thin side but they, of course, remain thin and not very tone.  Of course, there are people who run or bike religiously who do look healthy and fit as well.  Maybe they are a triathlete or a marathon runner.   Oftentimes these people will have health concerns such as irritable bowel syndrome (IBS), frequent colds and viral illnesses, joint pain and even heart issues as they get older (how is that possible??).   If you take these “chronic cardio” habits and mix it with a Standard American Diet it can set the stage for health concerns.

The common theme  with the above scenarios is Chronic Cardio (CC).  CC is intense cardiovascular exercise that is sustained, oftentimes >1 hour, at or around 80% or more of maximum heart rate.  What are the potential consequences of this type of training?  This type of training is hard on the body.  It is a frequent and repetitive stress to the body so it can cause in increase in cortisol (stress hormone) and this can cause all sorts of health issues.   It increases oxidative damage in the body (think of stress in your arteries that can cause hardening–not a good thing) and can contribute to systemic inflammation (inflammation throughout the body).  Systemic inflammation in the body that is chronic is NEVER a good thing whether it is induced by exercise or something like metabolic syndrome or autoimmune disease.  Our hunter-gatherer ancestors did not do this.  It would not have been a smart choice for survival of humans.  When you exercise at this intensity your primarily burn glycogen (so think “sugar” or “carbs”) which means you have to replace this with carbs to sustain this (this is why people “bonk” usually around the 2 hour mark in marathons).  More carbs and insulin burden only contributes to ongoing health concerns.  As I mentioned in my previous post, our body prefers to use body fat for fuel.  This is best accomplished when we keep our activity at a low and steady level.  Our hunter-gatherer ancestors may have covered 5, 10, or more miles in a day on a hunt or gathering food, but it was done at a slow pace.  They conserved their small glycogen stores and used their own body fat as fuel. And if the hunt was unsuccessful, they had to be careful not to exhaust themselves in the process with too high intensity of activity for too long of a time period.  At times they probably had to sprint to either catch prey or run away from danger, but this was brief, short, and relatively infrequent (sprints or brief and intermittent high intensity training is awesome by the way).

“Common Wisdom” is the stuff we, as a society, tend to believe as truth or fact even though there may not be hard evidence to support it.  “Cardio” is typically regarded as the best way to get into shape and lose weight.  Fitness circles and casual conversations discussing weight loss usually involves, “I need to do more cardio.”  Now, I’m all in support of regular doses low-level cardio.  It’s vital for health and it’s in our genes.  We, as humans, are designed to move frequently at a slow pace.  By “low-level” I’m talking about going for a walk, hike, leisurely bike ride, leisurely swim, paddleboarding, an easy jog, etc.  These sort of activities leave you feeling healthy and refreshed and not exhausted.  There are multiple health benefits with this sort of regular activity from cardiovascular and metabolic health to sleep and psychological health.  As I mentioned above, I’m also a big fan of high intensity training, with a caveat—it should only be done infrequently (maybe 1-2 times a week) and it should be short in duration, sometimes less than 10 minutes, and performed only when well rested (I will do a post in the future on the benefits of high intensity training).  As for long-term weight management and health body fat levels, 80-90% of the success is all in what you eat.  Period.  You cannot out exercise a bad diet.   The Primal recipe for success for body composition and heath is: eating in a primal manner, adequate sleep, appropriate exercise (frequent movement at a slow pace, strength training a couple times/week, sprint infrequently) and appropriately managing stress.  Doing “chronic cardio” for an hour or more a day several days a week will not get you to those goals and may even put you at risk for health problems.

I personally experienced the negative side effects of chronic cardio.  A few years back, in my early to mid 30’s, I started training for and running ultramarathons (any race greater than 26.2 miles).  As you can imagine, the training for this was rather intense.  The longest run I completed was a 50 mile trail race that took about 12 hours (on a hilly course in a torrential downpour!).  3-5 days a week I was up by 5 am and running AT LEAST 7-10 miles with a long run on Saturdays (12-20 miles).  On the outside I looked like the picture of health–I was thin and tone (I lifted weights 3 days a week as well) with a bodyfat percentage in the single digits.  I did ok for a while but eventually this type of training caught up with me.  I started to feel fatigued, irritable and just not quite right.  I couldn’t sleep, my resting heart rate was up and I was getting sick with viral illnesses much more frequently than what I ever had.  After a period of denial, I eventually figured out I was exhausted and likely suffering from adrenal fatigue (the adrenal glands are small glands on top the kidneys that produce cortisol, the stress hormone).  I then decided to quit the Chronic Cardio and balance out my life a bit more. After a few weeks of quitting chronic cardio, my sleep was better, my mood less irritable, I could sleep again and I quit getting sick.  I have continued to live the Primal lifestyle since that time and I feel great and rarely get sick.

That’s it for today, thanks for reading.  Please leave any questions or comments below.  Does anyone have a similar experience with Chronic Cardio??

Author Ryan Parnham

Hello and thanks for visiting my site. My name is Ryan Parnham and I'm a 37 year old husband and father of two from central Illinois (hope I haven't bored you yet). The reason I started this site is because I have a passion and desire to live the BEST life possible, and I want to share my thoughts and experiences with other people so they can educate themselves and change things in their lives to live the best life possible as well. I strongly believe that nutrition is one of, if not the biggest, factor in health, vitality and longevity. I feel I have a bit of a unique perspective on things given my professional and personal back ground. I have an undergraduate degree in nursing as well as a master's of science degree in nursing and am a board certified family nurse practitioner from the American Academy of Nurse Practitioners (AANP). I have been in the medical field for over 15 years now

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