Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
4 Feb

Dear Mark: Chronic Cardio

Dear Mark,

I’m still having a hard time understanding what “chronic high level training” is, exactly. How much is too much? Is there a heart rate zone you guys can give me? A time limit? Am I overthinking this??

Thanks, Charlotte, for posting this question last week. As is so often the case, another MDA reader (hats off to you, Mike OD!) offered great advice. We thought the question was well worth revisiting. First off, let’s investigate the concept of chronic cardio. Intense cardio as we commonly think of it today means long stretches at a sustained heart rate in the 80+% range.

The fact is, our hunter-gatherer ancestors didn’t ramp up their heart rates significantly for over an hour every day, and I don’t think we should either. They walked at a very low level of exertion, burning almost entirely stored fats. Once you get into the zones where less fat is burned and where there’s a big dependency on glucose to fuel muscles, your body goes into a less efficient mode of fuel oxidation. There are biochemical costs associated with this shift. Your muscles and liver can only hold 500-600 grams of precious glycogen (stored glucose) at any one time, which means about 2 hours’ worth for the best trained individuals and less for most people. That means that to come back and work out hard the next day requires at least 600 more grams of carbs every day. That’s just too much glucose and insulin to deal with every day.

I don’t recommend pushing this limit or even approaching it. Why bother? This kind of training (and diet) raises cortisol levels, increases oxidative damage, systemic inflammation, depresses the immune system and decreases fat metabolism. About the only thing good it does is improve cardiac muscle strength – and even then you get too the point of diminishing returns fairly quickly.

As you know, I recommend a different approach that more accurately mirrors what we evolved doing. In those simpler (but not really “good old”), primal times, we spent several hours a day engaged in low level activity. A few times a week, caveman/woman life required brief spurts in high intensity anaerobic mode to run from various predators, hunt down dinner, engage in “play” etc. Each of these modes resulted in its own unique and very positive growth response.

This pattern, for most of us, isn’t easily replicated as a result of our busy lives. Instead, I suggest anywhere from 30 minutes to an hour of low to moderate level aerobic movement such as walking briskly, hiking, cycling, etc. It doesn’t need to be every day, but at least a few times a week is important. The goal during these sessions is to maintain the zone that burns mostly fat. For very fit people, this could be as high as 70-80% of your maximum heart rate, but we’re really talking 60-70% for most people. The benefits of exercising at this zone are numerous and the risks minimal. It’s the ideal level of activity for decreasing body fat, increasing the capillary network, and for lowering blood pressure and reducing risk for degenerative diseases, including heart disease.

Add to this routine a few anaerobic, “interval” workouts once or twice a week. Weight-bearing, anaerobic bursts are the best training for building muscle, and lean muscle mass is critical to health. It also increases your aerobic capacity, natural growth hormone production and insulin sensitivity.

Traditional running sprints are one option, but we presented several others last month for your perusal. Put your all into it for 20-40 seconds and then rest for two minutes or so between “sets.” You can start out with three or four bursts and work your way up to as much as eight. As always, get in some warm up time and stretches afterward. It’s no fun pulling a muscle.

Finally, working all muscle groups through dynamic strength-training sessions (ie: lifting weights) a few times a week helps further build and maintain muscle mass, insulin sensitivity and growth hormone release.

Finally, let me add that I’m not trying to squash anyone’s passion for competing. As a former competitor myself, I totally “get” the drive to compete. Do I think that mode of existence is healthy, particularly in the long run? Not really, but I still understand what brings people to it. I simply want to convey that certain and sometimes significant health compromises are inherent to competition training. If anti-aging, longevity and robust excellent health are your primary goals, high-level training isn’t the best way to achieve them.

Now, for those who aren’t into the competition mission, you have the advantage of making your fitness routine and health about ideal balance. And I’m a true believer in achieving the balance that allows people to live the longest, healthiest lives possible. Thanks for your questions, and keep them coming!

Abraaj Flickr Photo (CC)

Further Reading:

My Weekly Workout Routine

Anaerobic Exercise HGH Link

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You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. for anyone who has made it to the bottom of the comment thread, here’s a great story about what chronic cardio can do to you… with horrifying photos!

    Ruby wrote on August 4th, 2011
  2. I’m curious, Mark, how do you reconcile your vision of “Grok” being a slow-moving, sometimes-sprinter with the persistence hunt? Clearly we were eating meat long before we had weapons and we had to catch it somehow.

    Donnie_O wrote on September 24th, 2011
  3. Hi, Neat post. There’s a problem along with your site in web explorer, could check this? IE still is the market leader and a good component of folks will leave out your wonderful writing due to this problem.

    kettlebell exercises wrote on December 2nd, 2011
  4. This website might be useful if you want to check your heart rate online.

    Just tap the space bar whenever you feel the beat and it will tell you your BPM and calculate your training zone.

    Iyad wrote on January 4th, 2012
  5. I have a question regarding chronic cardio type training.

    I am contemplating a trip to Thailand in the next few months. My cousin and friends went to a Muay Thai training camp and trained with them. The thing is, the training is very intense, and it lasts several hours a day.

    Is there a way to prepare myself for this type of exercise? What can I do to reduce the stress/cortisol response, and keep my body from being depleted and then respiked with insulin?

    Thanks for any help!

    Robert wrote on February 13th, 2012
  6. This is somewhat depressing to me. During the warmer months I like to do a 30 mile ride on both days of the weekend which takes me 1.5 hours per ride. I’ll have to dig out my HRM to see just how much I am pushing myself.

    Nick T wrote on December 19th, 2012
  7. Slaves eat grains.
    Slaves eat carb heavy diets to deal with the amount of work they have to do. Is it any wonder soccer moms and business men are running around like chickens with their heads cut off and chowing down on candy bars and carbs every five minutes?
    Examine your lifestyle: if you are having a hard time getting through your hectic workday without overeating carbohydrates, you are a slave. YOU ACTUALLY NEED TO EAT CARBS, OR YOUR BOSS-MASTER WILL NOT BE HAPPY.

    Lisa Being wrote on August 2nd, 2013
  8. Hi Mark,
    I am 18 years old and have competed in middle distance events the last 2 years (Averaging 30-50km a week), but have recently quit endurance training due to low T levels. I still want to compete in athletics though- so do you think the typical training of a 400 metre runner would be classified as ‘chronic cardio’? Which athletic events do you think are ideal to still enjoy competing and training, albeit without producing too much stress?
    Thanks a lot, I love your blog,


    Jonny S wrote on September 4th, 2013
  9. Why would anyone worry about getting too much exercise if they are having a blast and feeling great? I surf every day. Have been for over twenty years. Sessions average an hour and half in 52 degree water. Air is usually in the forties. When the water gets up into the high fifties and air warms a bit, two and three hour sessions are more frequent. Every other day I do a 10 minute planking routine and on alternate days I do a half hour or so of interval type training on my spin bike. I adjust this upward or downward depending on my energy levels. More hard surfing (my main priority) means backing off on bike and plank and vice versa. I can’t imagine not surfing ( about the most enjoyable/feel great thing in the world to me) to meet some assumed paleo level of activity. I don’t think that’s really what Mark means anyway. I think his advice is a warning for people who are hurting themselves from excessive exercise and encouragement for the sedentary by offering realistic goals

    Clay wrote on January 27th, 2014
  10. Women have been know for better cardio health than men. When you think of the motion and activity performed by women, this may be a factor in better cardio health. Currently this is changing as more women work outside the home. In the past women moved all day long, due to lifting weights, (babies and children) cleaning, cooking, moving things, making beds, doing laundry, (hanging clothing on the line this was great for sun exposure) climbing stairs, walking to market or neighbors, working in the garden. This was interspersed with sitting as they did things such as shucking beans, and the intense sprints of chasing children, and then interspersed with constant weight resistance of keeping a home. Sitting around with the family listening to the radio probably lead to more movement than sitting on the couch watching television.

    I had an uncle, (shuffling Joe), who was a steeplechase runner even participating at the German Olympics in 1936. He kept running most of his life and always remained lean. He had long legs and a short torso, (our family body type). The members of my family who lived into their 90’s and even 100’s followed a Paleo type diet. Thanks for the food for thought.

    Kathleen A wrote on March 8th, 2014
  11. I get what you’re saying Mark- I’m a fan of circuit training, too. But, I noticed that you’re a former marathon runner. How can you disapprove of long bouts of cardio when you’re a marathon runner? I enjoy all forms of exercise, but nothing beats a good, long run every once and a while. Are you saying this is ultimately bad for health?

    L.M.N. wrote on August 6th, 2014

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