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

A Case Against Cardio (from a former mileage king)

We all know that we need to exercise to be healthy.

Unfortunately, the popular wisdom of the past 40 years – that we would all be better off doing 45 minutes to an hour a day of intense aerobic activity – has created a generation of overtrained, underfit, immune-compromised exerholics. Hate to say it, but we weren’t meant to aerobicize at the chronic and sustained high intensities that so many people choose to do these days. The results are almost always unimpressive. Ever wonder why years of “Spin” classes, endless treadmill sessions and interminable hours on the “elliptical” have done nothing much to shed those extra pounds and really tone the butt?

Don’t worry. There’s a reason why the current methods fail, and when you understand why, you’ll see that there’s an easier, more effective – and fun – way to burn fat, build or preserve lean muscle and maintain optimal health. The information is all there in the primal DNA blueprint, but in order to get the most from your exercise experience, first you need to understand the way we evolved and then build your exercise program around that blueprint.

Like most people, I used to think that rigorous aerobic activity was one of the main keys to staying healthy – and that the more mileage you could accumulate (at the highest intensity), the better. During my 20+ years as a competitive endurance athlete, I logged tens of thousands of training miles running and on the bike with the assumption that, in addition to becoming fit enough to race successfully at a national class level, I was also doing my cardiovascular system and the rest of my body a big healthy favor.

Being the type A that I am, I read Ken Cooper’s seminal 1968 book Aerobics and celebrated the idea that you got to award yourself “points” for time spent at a high heart rate. The more points, the healthier your cardiovascular system would become. Based on that notion, I should have been one of the healthiest people on the planet.

Unfortunately, I wasn’t – and that same mindset has kept millions of other health-conscious, nirvana-seeking exercisers stuck in a similar rut for almost 40 years. It’s time to get your head out of the sand and take advantage of your true DNA destiny, folks!

The first signal I had that something was wrong was when I developed debilitating osteoarthritis in my ankles…at age 28. This was soon coupled with chronic hip tendonitis and nagging recurrent upper respiratory tract infections. In retrospect, it is clear now that my carbohydrate-fueled high-intensity aerobic lifestyle was promoting a dangerous level of continuous systemic inflammation, was severely suppressing other parts of my immune system and the increased oxidative damage was generally tearing apart my precious muscle and joint tissue.

The stress of high intensity training was also leaving me soaking in my own internal cortisol (stress hormone) bath. It wasn’t so clear to me at the time exactly what was happening – in fact it was quite confusing, since I was doing so much of this so-called “healthy” aerobic exercise – but I had no choice but to give up racing, unable to train at anywhere near the intensity required to stay at an elite level.

To make ends meet…

…I became a “personal trainer” and I refocused my attention on training average “non-athletic” people to achieve reasonable levels of general fitness and health. Of course, we lifted weights as part of the overall plan (and I will go into greater detail on that important aspect of fitness in a later post), but for the aerobic component of their training, I started doing long walks or hikes or easy bike rides with them. My many clients got the benefit of me actually working out right along side them and I got the benefit of 3 to 5 hours a day of very low intensity aerobic work (well, very low for me anyway). It was refreshing and really didn’t take much effort on my part, but I knew I had to be deriving at least some small benefit from those hours.

Since I didn’t have much time left in the week for my own workouts, once or twice a week I would do a very short but very intense workout for my own benefit, usually sprints at the track or “hill repeats” of 2-3 minutes each on the bike. Lo and behold, within a year, my injuries were healing, I was rarely sick and I was even back to occasionally racing – faster than ever. Something “primal” was happening and it made total sense in the context of the DNA blueprint. I was training like my hunter-gatherer ancestors, building my aerobic capacity slowly and steadily without overstressing my adrenals or my immune system, training my body to derive more energy from fats (and not glucose), requiring far fewer carbohydrate calories from my diet, and building muscle with occasional quick bursts of speed and intensity. I was suddenly both fit AND healthy. My Primal Health system was kicking in and it all made perfect sense.

Humans, like all mammals, evolved two primary energy systems that powered the skeletal muscles of our hunter-gatherer ancestors 40,000 years ago and that would keep us all well-powered the same way today, if we weren’t so bent on circumventing them with our ill-fated (literally) lifestyle choices.

The first energy system relied heavily on the slow burning of fats to create ATP (the universal energy currency), keeping us fueled while we were at rest or sleeping, yet also allowing for continuous or intermittent low levels of aerobic activity (think of our ancestors walking across the savannah for hours foraging for roots, shoots, berries, grubs, insects and the occasional small animal). It makes sense. Fats are very efficient fuels that are stored easily in the fat cells and burn easily and cleanly when lots of oxygen is present (as when we are breathing normally). Even if there’s no food in the immediate area, a well-trained fat-burning hunter-gatherer could continue walking and foraging for days without compromising his or her health or efficiency.

The second major energy system we developed through evolution was the ATP-PC system, which allowed for intense loads of work to be done in very brief bursts (think of our hunter-gatherer ancestors sprinting to the safety of a tree to avoid being eaten by a lion). Both ATP and phosphocreatine (PC) are always sitting right there within the muscle cells, with the former providing a quick burst of energy and the latter replenishing the former as it depletes. Together, they are the highest octane fuel we have, but it doesn’t last long. In fact, it’s ATP-PC and adrenaline that allow the little old lady to lift the front end of the Ford Fairlane off her husband when the jack fails. Unfortunately, the muscles can only store about 10-20 seconds worth of this precious fuel to complete life-or-death tasks. If our ancestors survived that quick sprint to safety, however, their ATP and PC reserves were filled again within a minute or two, making available another 10-20 second slot of intensity.

Furthermore, that brief burst of intense energy sparked a small “growth spurt” in the muscle, making it even stronger for the next encounter with the next lion – a true survival adaptation.

(Note: While our energy systems are actually quite complex, varied and interrelated, I have simplified things here to make it easier to “digest”.)

Bottom line: Fats and ATP-PC were the two primary energy sources for locomotion: we either moved slowly and steadily or “fight or flight” fast, and we became stronger and healthier the more we used only those energy systems.

But here’s the real take-home message for us: We did not evolve to rely heavily on a carbodydrate-fueled energy system, and yet, carbohydrate metabolism seems to rule our lives today. Yes, carbohydrate (in the form of glucose) can play a major role in the production of energy in skeletal muscle, but it turns out that the heart and skeletal muscle prefer fatty acids (fat) as fuel over glucose.

Our hunter-gatherer ancestors didn’t regularly ramp their heart rates up for over an hour a day like so many of us do now. Even when the concept of organized hunting came along, it would appear that our hunter-gatherer ancestors relied more on superior tracking ability (using our highly evolved and exceptionally large brains) and walking (using our superior fat-burning systems), rather than on actually “chasing down” their prey. In fact, squandering valuable energy reserves (and increasing carbohydrate [glucose] metabolism by a factor of ten) by running hard for long periods of time was so counterproductive it would have likely hastened your demise (imagine chasing some game animal for a few hours and – oops – not succeeding in killing it. You’ve spent an incredible amount of energy, yet now you have no food to replace that energy. You have suddenly become some other animals prey because you are physically exhausted).

So, what does all that mean for us in the 21st century seeking to maximize our health and fitness?

Well, we know that this current popular high intensity aerobic pursuit is a dead-end. It requires huge amounts carbohydrate (sugar) to sustain, it promotes hyperinsulinemia (overproduction of insulin), increases oxidative damage (the production of free radicals) by a factor of 10 or 20 times normal, and generates high levels of the stress hormone cortisol in many people, leaving them susceptible to infection, injury, loss of bone density and depletion of lean muscle tissue – while encouraging their bodies to deposit fat. Far from that healthy pursuit we all assumed it was! What, then, is the answer?

Knowing what we know about our hunter-gatherer ancestors and the DNA blueprint, we would ideally devise an aerobics plan that would have us walking or hiking several hours a day to maximize our true fat-burning systems and then doing intermittent “life or death” sprints every few days to generate those growth spurts that create stronger, leaner muscle.

However, since allocating a few hours a day to this pursuit is impractical for most people, we can still create a plan that has a fair amount of low level aerobic movement, such as walking briskly, hiking, cycling at a moderate pace, etc a few times a week and keep it at under an hour. Then, we can add a few intense “interval” sessions, where we literally sprint (or cycle or do anything intensely) for 20, 30 or 40 seconds at a time all out, and do this once or twice a week.

If you are willing to try this new approach, but haven’t sprinted for a while, you may want to ease into it. Start with maybe three or four the first time, resting two minutes in between and, after a few weeks of doing this, work your way up to a workout that includes six or eight all-out sprints after a brief warm-up. An easy few minutes of stretching afterwards and you’ve done more in less time than you could ever accomplish in a typical “80-85% Max Heart Rate” cardio” workout. That’s exactly type of the plan I do myself and that I give all of my trainees now.

Let’s recap:

The benefits of low level aerobic work (walking, hiking, cycling, swimming):
– increases capillary network (blood vessels that supply the muscle cells with fuel and oxygen)
– increases muscle mitochondria
– increases production of fat-burning and fat-transporting enzymes
– more fun, because you can talk with a partner while doing it

The benefits of interval training (sprinting in short intense bursts)
– increases muscle fiber strength
– increases aerobic capacity (work ability)
– increases muscle mitochondria (the main energy production center in muscle)
– increases insulin sensitivity
– increases natural growth hormone production

The costs of chronic (repetitious) mid- and high-level aerobic work
– requires large amounts of dietary carbohydrates (SUGAR)
– decreases efficient fat metabolism
– increases stress hormone cortisol
– increases systemic inflammation
– increases oxidative damage (free radical production)
– boring!

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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. I really enjoyed this article and I found it very informative. It is pretty long and I think it might have been easier to read with better formatting.

    My best thoughts,

    Bradley Woods

    Bradley Woods wrote on July 29th, 2007
  2. Hi Mark, is there scientific evidence supporting what you’ve found in your experience? If there is could you send me a few links? I would be interested to look into this further.


    Sonya wrote on August 13th, 2007
  3. Men’s health magazine is suggesting that you are correct. Keep up the good work!

    G. Richards wrote on August 22nd, 2007
  4. So would running five miles in 45 minutes three times a week be considered too much?

    Ella wrote on September 14th, 2007
    • keep up the good work that is a grreat time most people i talk to don’t get that close i don’t no how old you are and what your goals are, but i’m 48 and thats what i’m doing on a hilly road surface actually around 40 min. My 4 miles in the flat surface is 25 min ian i fill a little unfit due to running in the snow i hate it can’t wait for the summer.

      cam wrote on February 5th, 2012
  5. By doing cardio 1-2 times per week and no more than 20-30 mins per section, plus total body mass training, you will minimize fat while you get bigger in muscles.

    aerobics-cardio wrote on October 4th, 2007
  6. Mark,

    I’m curious about what you mean by “low level” cardio. I understand that this means reducing our time in aerobic exercise, and thus going shorter distances.

    But I am still wondering about relative effort. Do you suggest that we all stay in heart zone 2? Is heart zone 3 ‘low level’? Is heart zone 4 the forbidden zone?

    Forgive me for understanding the world through the readout on my Polar monitor! Thanks for your great article,

    Mike H.

    Mike H. wrote on November 8th, 2007
    • Low level means not reducing the amount of time you workout but reducing the intensity level of your exercise

      CRO-MAGNON wrote on August 17th, 2011
  7. Mike,

    Depends on your level of fitness. The idea is to burn only (90%) fat when you train aerobically. For very fit people, this might be as high as zone 3, but for most it will be walking briskly, hiking, biking at medium pace, etc. Then you reserve the really hard stuff for short anaerobic bursts (intervals) once or twice a week.

    Remember, all this is advice for someone wishing to maximize health, energy, longevity etc…If you are deciding to compete, then you might choose some more radical compromises.

    Mark wrote on November 8th, 2007
  8. Hi Mark, Have you heard of a product called Isagenix? I have been using it and having great results. I wondered if it is as good for me as it seems to be? I’ve lost weight and have more energy, this product is a health and wellness that cleanses the toxins out of my body. All the ingredients seem to be what I need but I thought with you in the health business you would know if this kind of cleansing is good for the body? It seems to be the new thing to do, but is it the best I can do? Thanks, Roxie

    Roxie wrote on February 26th, 2008
  9. Roxie,

    Isagenix has a number of products. Because they are an MLM, I would not rate their products highly. OK ingredients at exhorbitant prices. Also, not a big fan of “cleansers.” That said, if you are getting the results you want, who am I to steer you away?

    Mark Sisson wrote on February 27th, 2008
  10. It sounds to me like you experienced a classic case of overtraining and overuse injuries, and are now claiming high intensity cardio as the problem.

    The problem was not the intensity at which you worked, but rather the frequency by not allowing your body proper rest and recovery. All exercise is beneficial (low intensity aerobic, high intensity aerobic, very high intensity intervals) to overall health. However, you must recognize the intensity and frequency at which you work and allow your body time to recover and grow stronger.

    And exercise promoting hyperinsulinemia? That’s news to me! I’d like to see your sources on that one…

    Jonathan wrote on March 18th, 2008
    • I fully support Mark on this one. I was being over-trained by a Kung Fu instructor and it was only 2 days per week; but for an hour each time. I was also suffering ALL of the symptoms Mark described. I am still in recovery mode now. The cortisone was dissolving my muscles and making me weaker and I was also suffering from hyperinsulinemia. I even started collapsing. And I am a type O, which is meant to be suited to extreme exercise routines. I’m all for Mark’s method of training now.

      Angelina wrote on February 4th, 2010
    • “The problem was not the intensity at which you worked, but rather the frequency by not allowing your body proper rest and recovery. ”

      You can count me as a fan of marks, but I agree with his comment 100%.

      Alex wrote on January 28th, 2011
  11. Jonathan,

    Not sure you got the message here. Of course I overtrained. That’s what many many marathoners and triathletes do. That’s the point. Any exercise IS good provided you do the right amount and allow the proper rest. Most who compete do not allow proper rest.

    The necessary high carb diet is what promotes hyperinsulinemia – not the actual training. No sources necessary for that.

    Mark Sisson wrote on March 18th, 2008
    • When I first read all your posts against cardio, it was a bit much to take, as I really enjoy going for jogs and bike rides. However, in this comment you say that any exercise is good given you do the proper amount and allow adequate rest? I find I always feel a lot better and sleep more soundly when I get out and jog three or four miles/bike 6-8 miles, and don’t really need to consume vast quantities of carbohydrates. My current diet looks like fish and eggs for breakfast, usually some kind of stir fry or meat and a large tub of broccoli/green beans for lunch, and some kind of meat with a heaping plate of leafy greens for dinner, with maybe a few pieces of fruit on the side for snacks (all animal food and most plant food is organic). Assuming I could maintain this fairly primal method of eating, and my runs are conducted at a fairly comfortable pace, do you think this type of exercise is particularly harmful for my health? I do a bit of strength training as well, as not to become imbalanced.

      James wrote on May 14th, 2011
  12. Completely agree.

    As a trainer myself I rely on diet and weight training to bring about results rather than pointless joint bashing such as running and fixed pivot shitty machines like the cross trainer.

    People used to think the earth was flat and now we know better. Its only a matter of time before people feel the same about endless hours on the CV equipment.

    Neil Mcteggart wrote on March 25th, 2008
  13. Do some kettlebell then think again this whole cardio issue.

    David wrote on June 10th, 2008
  14. David,

    I’m not sure I get where you are going with that. What are you saying?

    Mark Sisson wrote on June 10th, 2008
  15. Sorry,I wanted this comment in an another post of an another homepage. This post was in another browser:).

    David wrote on June 10th, 2008
  16. Mark,

    I have been reading your site/blog for several weeks and am very impressing by both its content, and your positive attitude.

    In terms of fat loss, (assuming that one is eating correctly in terms of macronutrient ratios, adequate protein consumption, caloric leves), what would be your cardio/interval suggestions?

    I am assuming low level cardio (i.e. 30 min of steady state interval walking, swimming, etc) and 2 HIIT type worksouts per week?

    Sudip Jha wrote on June 25th, 2008
  17. Sudip,

    2 HIITS per week for sure. The rest can be 30 minutes or even 2 hours each, as long as it’s very low level stuff (walking, hiking, etc) Once the Heart Rate gets abover 55-60% max, that’s when you can (and should) reduce the time. When you get to 75-85% max HR, you can get a lot done in as little as 20 minutes. What we DON’T want is 90 minutes or 2 hours of 75-90% Max every day.

    Mark Sisson wrote on June 25th, 2008
  18. Mark,
    I think this site is excellent and have been influenced by it to try your 30 day primal challenge. Til now I have been a marathoner and steady state jogger guy.
    However I have been more persuaded by your physical condition as evidenced on your videos than by all this conjecture about how primitive humans lived.
    The fact is if you look at the San people (Bushmen)of the Kalahari who still lead stone age lives, their method of hunting is to a) dart an animal such as a kudu with a small poison arrow then b) send out one runner to chase it down and literally run it to death. The kudu sprints out of sight but the hunter keeps pressure on it by jogging steadily on its trail. It can take an entire day of steady state jogging before he reaches the exhausted animal and then he will kill it with a spear. So, based on that evidence it would seem that the ability to jog steadily for hours on end has been of great evolutionary advantage to humans. . .
    Anyway, thanks for all the great information!

    Joe wrote on July 11th, 2008
  19. Joe, you must be referring to that Men’s Health article on the San Bushmen. I disagree with the premise. You’ll note that they don’t run hard and long…they “trot” which is actually the kind of low level aerobic activity I’m talking about and saying is OK. Also, they don’t do it every day (once you have a kudu, you don’t go out and get more without a nice freezer to keep the extra in). They don’t train to do this as if it’s a race against the animal. Instead they track it and methodically pace themselves while the wounded, drugged animal sprints and rests. Using their human mental superiority, they “cut the tangents” and slowly move in on the animal. All in all, if I were allowed to do that in the USA, I would consider it a totally Primal activity – one that my other intense training would allow me to do with relative ease once or twice a week. Just because we “can” do it once in a while doesn’t mean we should train for endurance events every day.

    Glad you dig the site. Keep watching.

    Mark Sisson wrote on July 11th, 2008
  20. Hi Mark,

    I enjoyed your post for the most part. And I agree with 99% of what you said. The main difference is I know that I was designed not evolved. But the mechanics you describe are what we were designed to do.

    I am a molecular biologist, personal trainer and former bodybuilder so I have a deep interest in this subject.

    I found your post because I have not trained one bit since getting married 5 years ago (new baby, started my own company…etc) and just started training in Brazilian Jujitsu and the cardio intensity when “sparring” (basically wrestling) is intense!

    I find myself every two or three days (if I don’t take a day off) getting heart palpitations (with a heart rate of 48-55)… it is really anoying and a little scary. I had a cardiologist friend check me out and my ekg was ok.

    Did you ever traing anyone who went from zero cardio for over 5 years to 100% heart rate max training for over an hour? How did they feel?

    I know, I know… Do as I say, not as I do.. Hey I’m human.

    Kevin wrote on August 7th, 2008
    • Maybe YOU were “designed”. If have been “designed”, I demand a full refund and a sack full of hammers. I think the kid linked in my name might want one, too. Being production line defects, and all. Your “designer” has a sick, twisted streak that results in things like ossifying tissue until the person afflicted suffocates. In my universe, it’s an unfortunate consequence of faulty reproduction processes. Which seems a lot less mentally ill, honestly.

      Ginger wrote on January 5th, 2010
      • Ginger, there’s nothing wrong with somebody’s having (and stating) a different belief.

        Dust wrote on March 16th, 2012
        • Indeed.

          brainfan wrote on July 17th, 2012
        • What does his “belief” really have to do with this subject? Why is it necessary to mention it?

          Sienna wrote on September 29th, 2012
    • Kevin,
      you can have an okay ekg and still have heart problems. I sometimes have the same symptoms and went to the doc about it. My ekg was fine. It took a heart sonogram to show where my heart was strained. More than likely from the years of overtraining I put myself through. I still train but like Mark I’ve cut way back, I listen to my body, rest whether I want to or not, and work on eating right.

      tiger blood wrote on April 6th, 2011
  21. Kevin, normally you should spend a few weeks or months easing in to an intense training program. Gradually building up from slower aerobic activities to brief intense bursts, etc. As long as your ekg is OK, I guess I can’t add much.

    Mark Sisson wrote on August 8th, 2008
  22. I know you’re right, I just don’t know how to do it with something like Jujitsu where your opponent is going full throttle. I mean if I don’t put at least equal effort, I am going to get tapped out… I’m going to see if I can get some suggestions from the instructor today.

    I appreciate your web site and specifically this page, as I have always believed the science behind what you’re saying (less evolution of course)…

    Kevin wrote on August 8th, 2008
    • twat

      DN wrote on May 12th, 2009
      • what does this mean?? twat????

        Scrotie McBoogerballs wrote on August 12th, 2010
        • Twat is another word for the genitals of a woman. It can also be used to describe someone in derogatory terms. In this context I think DN was referring to Kevin’s inability to handle a little bit of BJJ. The insult was probably uttered due to Kevin’s arrogant sounding post, in which he felt the need to unnecessarily disparage evolutionary theory (why people still do this despite the extensive evidence backing it up is beyond me. Guess there must be significant signs pointing to the mainstream ulterior theories of where we come from….) and inform us of his beliefs.

          Ty wrote on November 27th, 2013
    • Know how you feel Kevin. I went into Kung Fu after children and had the exact same problems. Before then I used to be incredibly fit, did body building and the whole works. Then straight into extreme Kung Fu workouts after having so many years off and I also thought I had heart problems but my doctor also assured me that I was okay. But I had a lot of other things wrong with me instead due to the overexercising. See post above.

      Angelina wrote on February 4th, 2010
  23. To clarify ATP is used all the time independent of what energy system is used to generate it.

    you seem to infer ATP is not used during activity that is not sprinting.

    I also contend you are unlikely to be able to “trot” a Kudu to the point of exhaustion at a low heart rate.

    the fact the runner is not achieving a sub 3 hour marathon pace does not preclude he is making a sustained effort or that the effort is not daily does not invalidate long sustained efforts as a natural activity. The women carrying firewood on her head is most likely making a sustained effort even walking.You don’t see a lot of talking going on while women carry heavy loads for hours a day… stick 20kg on your head and walk for 4 miles

    there is millions of women who do substantially more than that 365 days a year. . however how primal is that activity?

    I think you primal model is in need of checking not least in that you have odd ideas about hominid evolution. The main problem with a primal model is there probably is and never was a standard regime.

    However interval training is highly effective but this is nothing new or absent from endurance training.

    I am unhappy with the propagation of the evolution certainties on this site.. but in your defense your training regime appears to be quite beneficial if not enjoyable, there is a large supportive social aspect

    did primal man engage in 8 high intensity sprints a day with limited recovery intervals?

    Boris wrote on September 7th, 2008

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