The Evidence Continues to Mount Against Chronic Cardio

Chronic CardioIt’s been awhile since I did a post on chronic cardio. I had a good string of them going several years ago, and I thought I’d done a good job explaining why I was so opposed to excessive endurance training. Despite my attempts to clarify, though, I still receive a lot of questions and comments about cardio. People just have a tough time divorcing themselves from the notion that cardio – as much as you can cram into your schedule – is the key to health and fitness. I don’t blame them, really. It’s conventional wisdom, after all, and it’s what I thought for years and years. Clearly, another post is needed.

Evidence against chronic cardio continues to mount, so there’s a lot to cover. But before we get to all the research, I have a few thoughts about the heart.

Here’s the thing about the heart: being an involuntary muscle, it has no say in the matter. It pretty much feels nothing, too. It’s along for the ride. Just like the liver, kidneys, pancreas, thyroid, adrenals, etc., the heart responds to biochemical signals. It’s a demand organ. Minor changes in blood chemistry (epinephrine, cortisol, insulin, lactic acid, hemoglobin-depleted RBC’s, to name a few) cause it to respond by beating faster or slower, forcefully or not, to keep pace with the muscles’ (and other organs’) demand for oxygen and fuel. During exercise, it’s the brain that starts this whole process with a (usually) conscious decision: “I think I’ll run to that tree.” That thought prompts the muscles of the legs to start moving faster and the arms to pump. The new, increased demand for oxygen and added fuel (over and above normal resting metabolism) signals the heart to start to fulfill the demand, to pump harder and faster. It’s obliged to do so. Period. No choice. That’s also why it’s always a bit behind schedule: it takes more than a few seconds to ramp itself up once the action begins and a few seconds or minutes (or hours, in the case of an over-trainer) to ramp down, once it’s over.

The problem with chronic cardio is that we can force our brains to override some of the tiredness (no pain, no gain, pal) and discomfort in the legs – and to a certain extent even the lungs – and keep doing these hard endurance workouts incessantly day in and day out. The ostensible limiting factor is the ability to burn fat or, at the very least, the amount of glycogen still left in our muscles. That’s what eventually brings us to a halt, frequently because we have willed ourselves to keep going through the wall at all costs. But the heart is often over-worked in this scenario, just trying to keep up with that “inhuman” (and inhumane) desire to run, cycle, or swim further and faster in pursuit of…what? A medal? A ribbon? Bragging rights? It can’t say no. It attempts to do as we bid it. And because the heart feels little-to-no pain – unless, perhaps, it feels the REAL pain of a heart attack – it very often suffers silently as a result without us ever knowing. The walls of the heart start to hypertrophy over time the same way a biceps muscle does when you do curls. But do a few too many curls and your biceps will get sore quickly. Force yourself to do a few more and you could even tear something and be out of contention for a few weeks. We know when to stop before that bicep tears.

Cardiac muscle doesn’t tear that way when over-worked, but it does enlarge and thicken with chronic overuse. In some – most – people the thickening is probably not life-threatening, but in some cases, as with dozens of world class athletes I have personally known, this thickening can cause all manner of issues later in life. Atrial fibrillation has become a mild epidemic in my generation of life-long aerobicizers; several of my friends have had pacemakers or defibrillators implanted before the age of 40 to head-off those sporadic life-threatening cardiac enervation problems. A few more friends have lost significant cardiac function and a few have died.

But don’t take my word for it. The silent epidemic of heart issues among endurance athletes is getting serious attention in the research community. Let’s take a look at some of the latest research.

Cardiac Arrhythmias

Cardiac arrhythmias are abnormal electric activities of the heart. An arrhythmia can describe a heart that beats too fast, too slowly, too irregularly, or too “fluttery.” An arrhythmia doesn’t always indicate or foretell heart trouble, but it’s a common risk factor. One of the more common varieties is atrial fibrillation (AF), which describes a fast, irregular heartbeat. AF is strongly linked to stroke and cognitive decline.

Endurance athletes are at a greater risk for atrial fibrillations than the general, non-running public. One recent study of cross country skiers even found that the best athletes, the top performers, were more likely to have cardiac arrhythmias than the rest. Moderate exercisers, meanwhile, are at a lower risk for AF than the general, non-running public. A recent comprehensive study offers several potential explanations for the increased risk:

  • Increased fibrosis (scar tissue formation) in the heart.
  • Myocardial injury to the heart, as evidenced by post-training elevated cardiac biomarkers typically used to diagnose injury. Probably not a big deal so long as you recover fully from your training, but most cardio junkies can’t wait that long to log more miles.
  • Excessive amounts of inflammatory markers brought on by training. These markers have been linked to AF.

Endurance-related AF usually starts off infrequent. The older you get and the more miles you log, the more entrenched and regular your atrial fibrillation may get. Some studies found that around 40% of athletes with AF eventually progress to persistent AF, where it’s happening on a regular basis. That’s the troubling kind of AF that may presage serious cardiovascular problems, like stroke.


It’s totally counterintuitive to think that endurance athletes are at risk for arterial plaque. “You mean to tell me that the wispy greybeard whizzing past my house in short shorts every evening could have clogged arteries? No way.” Maybe, just maybe.

A 2011 study found evidence of carotid and peripheral atherosclerosis in a group of marathoners. Although there was no control group of non-runners in that study, another study compared the arteries of marathon runners to a control group of sedentary non-marathoners. Marathoners had more calcified plaque in their coronary arteries, which has been linked to stroke and dementia. The tricky thing about these cases is that endurance athletes with atherosclerosis don’t evince the regular signs. Whereas your typical sedentary guy with extensive atherosclerosis will probably have all the hallmarks (metabolic syndrome, abdominal obesity, hypertension, etc.), marathon runners with atherosclerosis don’t fit the traditional cardiovascular risk profile.

It might be time to add “trains for endurance athletics” to the list of risk factors.

Oxidative Stress/Overtraining

It’s no secret that endurance training induces oxidative stress on the athlete. That’s how we get better – by encountering a stressor, being broken down a bit, and then recovering stronger than before so that the next time we encounter the stressor, we’ll be better than the last time. Whether we’re talking strength training, marathon running, cycling, gymnastics, martial arts, or even studying for a trigonometry class, we have to challenge our physiology to get better, and challenges to the physiology mean oxidative stress. Problems arise when we don’t let up, when we keep the intensity elevated and the days off few and far between. We’re constantly in that post-workout state, and it starts to look like chronic oxidative stress for all intents and purposes. Even if our times are improving, we’re not truly recovering. It’s a two steps forward, one step back kind of thing.

So. Those are just a few of the reasons I am no fan of chronic cardio (and don’t get me started on the bad backs, osteoarthritis, hip and knee replacements and chronic tendonitis among my former elite endurance peers). A strong will can be a great thing for survival, for business and for relationships, but it can also get you in trouble if you don’t pay attention to your training load.

Having said all that, I am still a big fan of weights, of brief, intermittent interval training and I am all for doing a fair amount of mixed low-level cardio, the kind that doesn’t overstress the heart or involve so much repetitive joint motion that it causes chronic injury. That makes sense in an ancestral context. You’re expending energy at a high rate, but you’re not going long enough that it becomes a liability. Or, if you’re going long, you’re taking it easy enough that you have the energy to make it back home, possibly carrying food.

I’m not even against a long training run or ride once in a while, provided you are trained, rested and allow enough recovery afterwards. I’m even OK with running marathons occasionally or jumping into a short triathlon now and then. As a species, we obviously have the capacity to go long and relatively hard every now and again. It’s the chronic, day-in, day-out long, hard stuff that is counter-productive. If you did that twenty thousand years ago, when your next meal – and that of your entire family/tribe – was on the line, when calories were somewhat precious, when you didn’t have an air-conditioned caravan of trainers, massage therapists, and coolers filled with electrolyte drinks following along after you, you’d be foolish. You simply wouldn’t do it.

That we can run marathons (and do other stupid things) and know that we’ll get out alive is a luxury of modern living. There are so many other less damaging ways to achieve what I would call high-level adaptive fitness by using a variety of training methods, all of which can be cardio-protective and joint strengthening when done the right way in at the appropriate times. Heck, when it comes to hypertension, blood lipids, and type 2 diabetes, walking is just as effective as running – without the potential downsides. Everyone can walk. Everyone thinks they can run, but running is a skill that must be learned. To run with poor form is to welcome injury, doubly so if you’re running an excessive amount. And all this will be addressed in detail in my forthcoming book, Primal Endurance. For now, use your brain and listen to your body.

My point, of course, is that the human organism is made for short, intense bursts of activity laid atop a foundation of frequent slow moving. We aren’t “supposed” to run as hard as we can for two or three hours. We’re not supposed to run with the express purpose of “burning calories.” We can certainly choose to do those activities, and we’ll become adapted (or perhaps inured) to them, and they may even make us “fit,” but they’re not the healthiest, most efficient path to fitness. Chronic cardio is the meandering, roundabout trail that will get you there with a ton of bruises, scratches, a tick or two, and a sprained ankle. Oh, and you might get eaten by a bear along the way.

Your choice.

Thanks for reading, folks. I’d love to hear your thoughts on cardio, both chronic and otherwise. Let me know in the comment section!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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241 thoughts on “The Evidence Continues to Mount Against Chronic Cardio”

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    1. +1000

      I tried to explain this to a chronic cardio friend (she’s already had joint surgery at 35!) but it gets lost.

      1. Yeah, I have a sister-in-law who at 40 is physically worn out, has had joint surgery multiple times, thyroid cancer, hair is thinning, can’t sleep, etc but says she will keep on running even if she has only stubs to go on. Should I mention she won’t give up her low fat high carb diet either?

        1. Genetics probably has a lot to do with your sister-in-law’s poor condition at age 40 as well.

  1. This sounds like yet another case of too much of something being just as dangerous as too little. Thank god we all know where the sweet spot is now!

    1. Yes, this is an interesting post considering we’re in the middle of Tour de France fever – ultimate in chronic cardio?
      I enjoy my once-a-week long 14km run, I run along the river, listen to podcasts and take it easy Yes, I find it relaxing. But any more running than that or if I train hard, I get grumpy, sore and over it very quickly.

  2. I ran for years; from cross country in high school to marathon running into my 30s. I thought getting sick, tired and exhausted was all part of the journey to strengthen my physically and mentally. I finally broke down and quit once I came across MDA. How could I not listen to a former elite runner, right?

    1. From one who has done marathons and martial arts I always thought that training was as very well described – ” we have to challenge our physiology to get better, and challenges to the physiology mean oxidative stress.”

      I agree entirely with – ” Problems arise when we don’t let up, when we keep the intensity elevated and the days off few and far between”

      I have seen a lot of people break down because they do not give the body sufficient rest


  3. I wonder if Crossfit’s programming falls into “brief, interval training,” because sometimes I feel like the metcons are too much.

    1. When i quit doing Crossfit everyday my bodyfat percentage dropped and my sex drive skyrocketed. N=1, but I’m never going back. Chronic HIIT is worse than Chonic cardio in my opinion.

      1. I fell in love with you a little bit when I read your last sentence. That is all.

    2. There was a great post on a while back that pointed out that Crossfit, done wrong, is just trading chronic cardio on a treadmill for chronic cardio with weights! I have been in a Crossfit gym for almost three years, and have really plateaued from the complete randomization and too-intense metcons three times a week. My current plan is to metcon only one day a week, and work on my olympic lifts the other days. I also run ultras, which I would argue are not chronic cardio because they are done at such a low pace, I stay in the fat-burning zone with a relatively low heart rate. “Move frequently at a slow pace”

      1. David, from my experience it does not really matter what running events you do (I went from 21/42K to ultras myself) but what you do in the training phase 😉

        1. I agree, and now realize my post was not very clear. I actually don’t “train” very much for the events I do, short of long runs (damned near hikes) on the weekend, very few miles of faster-paced stuff during the week, and Crossfit / weight training. Not a lot of high heart-rate tempo runs, which is what I think Mark has in mind with his criticism of chronic cardio.

      2. Wow. I just joined a cross fit gym and was wondering the same thing with cronic cardio in mind. You mentioned metcons and ultras?have me a lot to research. Thank You very much!!

    3. It definitely doesn’t, IMHO. Those WODs are simply too long for “metabolic-conditioning”. The sub-10-minute workouts seem okay, but I see plenty of them last 20 minutes and longer.

      Basically, you’re pushing your glycolytic pathway to the max (AKA, sugar-burning metabolism) when you get into these prolonged bouts of Crossfit. If I am correct, this is the same thing as running on the treadmill for an hour. In my writings, you can tell that I’m definitely not a fan of Crossfit –

      In response to David Pryor, Robb Wolf is totally on point. In addition to being totally shunned by big-shots who run CrossfitHQ, Robb Wolf unaffiliated from Crossfit because his gym focuses on strength, power, and super-short metcons.

  4. Hi Mark,

    Love the website and read it daily. However, I don’t get your obsession with telling people to avoid chronic cardio! I’m sure that the vast majority of people out there are not training for marathons at an elite level. What seems more likely is that you’ll turn someone off from training for their first 5k or 10k or half-marathon out of fear of doing more harm than good! I know you often preach to “move often at a slow pace”, but I think it would be nice to supplement these articles with more encouragement to do healthy amounts of cardio.

    1. I’d have to agree with you here. I just got out of high school where I ran cross country and track and while I was never the fastest, I was miles ahead of my buddies that ran extra miles after practice or 20+ miles over the weekend. It was a rule that I ran slowly in practice and did no weekend running and almost always beat the guys that did. The only time I didn’t win was against a genetic freak who could run three times as much as the rest of us and keep going.

      1. Mark,
        embedded in one of the above posts is a very important piece of the puzzle. With chronic cardio we have to distinguish between fast and high intensity. The real issue is dose (time x intensity). Many coaches advocate their elite athletes working at low intensity for the bulk of their training and this low level intensity may be very fast by non-elite standards. For example, a friend of mine while training for the Olympic marathon trials would do the bulk of his miles at a pace that would allow him to comfortably carry on a conversation with me while I was completely unable to reply. I’m at 90% and he is at 70% even though the pace was 7min/mile. An individual who is new to exercise may be up around 80% max HR with a brisk walk. The issue is intensity level more than actual speed. A heart rate monitor is very effective for helping people get a feel for training intensity and especially seeing how intensity creeps up during the course of a run over time. You my start at a pace that is 70% and may finish at 85% 60 minutes later.

      2. Mark, thanks for linking those posts again. I actually enjoy running, but then a chronic cardio post comes up and I think, poop, I’m killing myself. The posts that you linked above remind me that when I go for an easy jog because I want to, and it’s nice and slow, it’s not actually chronic cardio.

        I still love the 4,000-calories-a-week post. It takes a LOT of exercise to burn that much!

    2. “I think it would be nice to supplement these articles with more encouragement to do healthy amounts of cardio.”

      I think that’s exactly what he did when he said “walking is just as effective as running” and “everyone can walk.” His point is that running has become the most recommended form of “fitness” in America, even though most people don’t know how to do it properly and most people overdo it and that a couple of decades of doing it wrong can lead to serious issues, even among non-elite athletes. Running is something humans do when they want to catch something or get away from something. If you want to have fun and get some exercise, spouse-wrestling is a much better use of time. 😉

        1. I think you must be doing it wrong, spouse wrestling is definitely HIIT.

    3. “I’m sure that the vast majority of people out there are not training for marathons at an elite level. What seems more likely is that you’ll turn someone off from training for their first 5k or 10k or half-marathon out of fear of doing more harm than good! ”

      Someone might skip a totally pointless running contest in favor of daily walking or learning to weight lift properly? Quelle horreur! 🙂

      Unfortunately, I disagree. I know many people who completely equate fitness=running, one who is determined to destroy her health over it. These type of posts are very much needed occasionally.

    4. I would personally like to see a lot more information about middle of the road cardio. There is a lot of wiggle room between walking and 100 miles a week. It can’t be all bad.

    5. If you want the cardiac and fat burning benefits of cardio, powerlifting is a much better way to get them, and you don’t risk overtraining. Likewise, hiit does this as well, except it doesn’t make you as much stronger as powerlifting does. Training for half marathons or 5ks is stupid; if you are strong (like a decent powerlifter) and have a low body fat percentage (you can get this from diet) you can do one of these easily at a moment’s notice. I have before. There’s no reason to screw up your health so you can do it.

  5. By all means keep jogging, if you want to be skinny fat. Lift heavy stuff and walk a lot in nature for a few months and see how much better you feel (and look).

    1. These two things are not mutually exclusive, you know.

      I don’t think running is going to make anyone fat.

      1. “I don’t think running is going to make anyone fat.”

        Actually…it can. The provisio is that you need to be doing serious mileage each week.

        Here’s how it happens, in an over simplified way. Running consumes a tremendous amount of energy in a short time. By the end, muscles have exhausted their stores of glucose and possibly even metbolised themselves for energy because the liver can’t supply glucose in time. The muscles, in need of recharge and rebuilding, stimulate the appetite.

        The hunger that comes is huge – it’s overwhelming because your body thinks you’ve just been chased by a tiger or something. So not only do you feel the urge to eat, you almost always feel the urge to overeat. And because of the nature of the work, you need to eat quite a few carbs to feel half decent again and for the next run.

        If you keep this cycle up, it’s easy to get to slightly overeating all the time just to stay in place, and carbs at that. That will prevent weight loss or even encourage weight gain.

        My friend, whom I promised I won’t mention again, often wanders around with quite the belly and doesn’t really look athletic because she thinks running gives her free reign to eat as much food as she feels hungry for, especially “good” carbs.

        1. This may be dependent on the distance and intensity. My typical runs are under 30 minutes, and not very hard. I do not find myself to be particularly hungry afterwards, and in fact I do this in the middle of intermittent fasting periods as I’m working on weight loss at the moment, and don’t find myself any more ravenous before lunch.

          So I stand by my earlier statement, slightly amended: Running won’t make you fat, in and of itself. However, over-training *in any kind of exercise* can cause problems. Fair?

        2. ^ This is exactly what happened to me in college. Exactly.

          At the end of my 4 years I finally decided I was quitting running (because I hated it) and would only do fun things to stay fit (playing sports, rock climbing, biking, handstands, cartwheels, what-have-you). I shed 30 of the 40 lbs I gained in college without even trying. Largely because my appetite was greatly reduced and I was working jobs that could be described as moving at a slow pace throughout the day.

        3. I am never as hungry after even a long running session as I am after a hard lifting session. I remember the first time I lifted weights about half a year ago, I was ravenously hungry–literally for days my appetite was crazy high. That’s calmed down, but I still get the feeling sometimes from lifting.

          Anyway, it is most likely the crap your friend is eating that’s making her fat rather than running. I run 30-40 miles a week (not too extreme I don’t think), lift 2x per week, and have been gaining strength and not much weight. I eat all I want/can of meat, vegetables, fruit, fat.

          I also question how much plaque buildup referenced in this article was from running and how much was from eating the tons of grains and carbs traditional marathoners consume.

      2. Hmmm…not to be obnoxiously contrarian, (although that’s in my nature) but I think there are a number of mechanisms that could essentially equate to “running making you fat”. The mechanisms could include:

        – When running causes muscles to atrophy from lack of resistance and the short range of motion involved in most running, (another big problem) you will effectively become like a lot of the people I see on treadmills who are basically skeletons surrounded by blubber, largely due to lack of muscle size and tone. So, did they get fatter? Proportionally yes because even if they “lost fat”, they lost more muscle due to all the running…
        – Mark may have posted it, but there was a study several years ago that suggested that strength training fundamentally changes how the body stores fat such that independent of calories burned, intake etc. , people who predominantly lift will be leaner (which is exactly what I’ve seen and experienced)…so, if running detracts from lifting, then running could be said to make you fat. One could argue that it is selection bias, but the leanest people I see in gyms are almost always spending the majority of their energy lifting not running.
        – As Mark has done a great job of describing, if running causes someone to become very carb-intensive in their diet, this can also lead to a degree of fat retention, especially if one has to cut back on their running for some reason.

        And an (admittedly anecdotal but highly representative, I think) observation… I have been noticing a woman at the gym where I work out who had very nice conditioning when she arrived, and she initially did leg presses and other leg-oriented lifting, although her legs are a little bigger than what some women might consider “ideal” ( I thought she looked great.) She switched over to chronic running however, and every time I see her she looks fatter and fatter, and her legs have lost tone and gained a layer of fat. I have no idea what she eats or anything else about her, but she seems like someone who has a natural tendency to retain fat and going from lifting and running a little, to exclusively running a lot seems like exactly the wrong thing to do if staying lean was her goal…
        So while running may not literally “make you fat”, making it the centerpiece of your training could (and for many people does) have that counter-intuitive result…

        1. “One could argue that it is selection bias, but the leanest people I see in gyms are almost always spending the majority of their energy lifting not running.”

          Are they truly lifters, or actually body builders? If body builders, they’re probably more diet-conscious than the average runner or lifter. As you surely know, muscles (and leanness) are made in the kitchen.

    2. If only I could run a little AND lift weights. Boy, that would be nice.

      Alas, it’s impossible to do both and live.

  6. I’m pretty new to the concept of Primal fitness and would appreciate people’s comments on my general week:

    – Several long walks.
    – 1 game (1.5 hours) of ultimate frisbee or one flow yoga class.
    – 3 crossfit classes (actual exercise less than the hour long class).

    I’m often sore and recovering, but I feel well and getting stronger/fitter. Is this too much exercise? Would it be considered chronic? Too much high intensity? I’m not one of those people that feel like a failure if they don’t puke during crossfit… but I’m still working pretty damn hard.

      1. Mantonat: For me it comes down to motivation. In years past, I’ve tried various self-directed exercise regimes that all quickly fail due to me making excuses. With sceduled classes, I just need to convince myself to show up and the trainers figure everything else out.

        1. And I probably sounded a little judgmental there. I get it that it’s difficult to find ways to stay fit when modern life isn’t really geared toward it. I did the gym thing for a few years and lost some weight, but I found that it wasn’t sustainable. I hated the regimen of doing the same stuff all the time, the drive to the gym, the smell of stale sweat, jostling for space with other sweaty people, etc.

          It seems like Mark takes every opportunity possible to talk about finding things that you enjoy doing that also involve getting the right kind of exercise (much easier for me in the summer than in the winter). After I quit jogging (it was killing my back) and going to the gym (it was killing my soul), I went off the rails and put on about 20 lbs. But just switching to a mostly primal diet and getting in regular walks combined with some heavy-duty yard work and other household projects, I dropped 15 of that pretty quickly and have been able to maintain it without much effort. My energy level is constant throughout the day and I never get tired unless I miss sleep, for the first time in my life. My goal is to get back to my low weight when I was a gym member, but that will require a little less beer and more of a commitment to some home exercises (planks, squats, push-ups, pull-ups) that I’m a little too sporadic about. I like to go play on the local playground equipment, but I get funny looks from the moms.

        2. Get yourself a pair of Gymnastics rings – you can get a set that can be attached to a variety of things at a cheap price. Then learn the “Muscle up” on rings, and you you can say good bye to needing a gym (just make sure you do weighted squats also, get a barbell for this purpose, or go full primal and use an old rock for weight). A complete workout can be done on the rings or bar, almost anywhere.

        3. “or go full primal and use an old rock for weight)” –Mantonat

          Thanks to Antiques Roadshow old rocks are now very expensive, can I use a new rock instead?

    1. I’d say this looks pretty good too. “maybe” drop to just 2 CF classes and do a lighter (maintenance) workout on the 3rd? Just a thought. or sub in a serious mobility class. Sounds like you need it anyway after the UF? I walk 3-4 times a week…about 50 minutes, and do 2-3 CF per week. An occasional soccer game in there too. For me it’s the games that cause the most soreness. 🙂 I’m 45 too.

    2. Honestly, you can’t really compare YOU to anyone else. I think it’s all about balance: balance in your diet, your exercise, your rest and recovery, and your stress levels. Do you beat yourself up when you miss a CrossFit class? Are you tired all the time? Do you get enough sleep? You have to be constantly asking yourself these questions and be completely honest with your answers.

      I’ve looked into CrossFit on several occasions; I’m a very competitive person and I love lifting, so several people have told me I would love CF. BUT I also played collegiate sports and feel I’ve gotten enough of those workouts that just beat the crap out of me for an hour with someone telling me to keep going, so I’ve decided to not do CrossFit. Instead, I play softball and volleyball, do lots of pushups, lift heavy about once a weak, and bike and go for short runs. I also walk to and from work and walk to our local market every day for lunch. Hourly wise, I’d guess we’re putting in the same amount of work, and I feel good and happy about what I’m doing. I’m not stressed about it, and I don’t feel “bad” if I don’t go for my pseudo-weekly run.

      Anyway, listen to your body. If you enjoy what you’re doing, you’re not stressed out over it, and you’re getting enough rest, then I’d say your doing just fine 🙂

  7. It is funny, that for my entire young adult life I prided myself on how “healthy” I was – biking to the gym each morning to take an hour long spin class. If I didn’t feel like I would drop dead I wasn’t working hard enough. It was a constant battle against fatique – but I was doing the right thing right? Strengthening my heart right? Wow….

    I definatly burnt out of that lifestyle and luckily around the same time that I fell across this website. I’m glad/relieved to know the key is really to easy low intensity cardio often – that suits my life now just fine and I never have an internal struggle to get moving – just happens and feels so natural. Crazy how good it feels just to be doing the right thing for my body. So glad I found this place and subsequently peace for myself.

  8. I agree that chronic cardio is dangerous, but at the same time I really enjoy distance running, so I stick with it because it’s better than no exercise. And I’m not going out and doing marathons every day, the max would be maybe 12 K once a week. I don’t view this as chronic cardio but maybe I’m wrong. I do need to work on the moving slowly frequently part of Primal living! A desk job really does nothing to help that haha.

    1. This is basically where I fall. I enjoy running. I don’t intend to ever run a marathon (maybe a half, at most), but I feel like 5k twice a week and a longer run once a week isn’t really overdoing it.

      Also I do high intensity weight training twice a week so my exercise isn’t all cardio.

      1. That sounds reasonable, especially if you aren’t trying to run too fast. I think Mark has recommended nothing faster than 10-11 minutes per mile.

        1. Sheesh, that’s barely running. I don’t think I could run slower than that if I tried.

        2. Mantonat, pace depends on relative fitness and how often you do it. I am not against a couple of hard runs or rides once in a while. It’s just that doing it every day or 4-5 days a week starts to become antithetical to health.

        3. I think that if you are doing something and you are enjoying it then you should keep doing it.
          I have just started training 3X a week for a 5k and I am really enjoying it, and have lost (excess) belly fat. I read articles like these and then I think “am I doing the right thing, but now I just remind myself that I am enjoying what I am doing and it works for me, so I shouldn’t worry”….

          That being said, extreme running/cycling (like every day) or big distances like marathon running, or doing so much cardio that you are addicted or do not have enough energy to put into other parts of your life seems unhealthy and unnecessary.

        4. I commute to work by bike once or twice a week (24 miles) and do a longer ride on the weekends of 40 – 50 miles. I used to ride like a bat out of hell thinking it was good for me. Since reading comments on the boards, I’ve begun to understand the wisdom of slowing down a bit. I believe trying to crank up the speed in my riding was increasing my cortisol level with the end result of no real weight loss. I enjoy my rides more now and I’ve actually lost a couple of pounds…win, win

  9. Before I came across MDA, I lost the bulk of my excessive weight via running. It turned into a second full time job, running at least every other day and as the mileage increased it became even more time consuming. I still run 4 or 5 local 10K events supporting a local charity or group, but I don’t run near the mileage that I used too. More importantly, I don’t feel like I need to run that kind of mileage anymore.

    1. It’s interesting because for me too I found that my weight comes off faster with running than it does with anything else… Bjj and crossfit and weight training included!

      1. Just thinking out loud, but I’m wondering if you lost any muscle through all the running? I run about once a week and also bike quite a bit, but what I’ve enjoyed about the PB is how strong I am feeling again. I haven’t seen a ton of movement on the scale, but I can see a definite change in body comp and strength gains, which leads me to believe that I am losing fat and gaining muscle, so at least my measly five pounds of weight loss is mostly (if not all) fat.

        Again, I think this all comes to balance. It seems Bryan got consumed with running, and it became a stressor in his life. If something, even exercise, becomes stressful and something that becomes consuming, I don’t think we should be doing it. 🙂 Having said that, I’ve always enjoyed lifting more than cardio, so I might be a bit biased!

        1. I became obsessed with ‘getting’ healthy and incorrectly assumed that running was the only way to do it. I don’t think I was losing muscle as I was running hills and steep terrain and getting faster. However, on my ‘off’ days I would I would allow myself to step away from my otherwise okay diet. Beer, cheese (Wisconsinite here), etc… After reading MDA, it’s the classic ‘what not to do’, I was at a point of treading water. Disappointed with not being able to lose that little bit around my core via running, I did a round of P90X Lean (without changing my diet). My body changed some and I felt strong. It was still a little disappointing that I wasn’t able to lose that extra bit of fat yet. It was stressful Stacie, I was busting my ass and not seeing the results that I wanted/expected.

          Enter Mark Sisson and MDA!

          I still run about once every two weeks, but I stop when I feel like I’m done and don’t push for all that extra mileage. Now between 3 and 6 miles is about as far as I go.

          Cheers all!!!

  10. What about the competitive athlete who is less “chronic?” This entry seems pointed to the non-stop athlete who doesn’t train smart and allow for proper – if any – recovery time. I’m a competitive cyclist who trains 6 to 8 hours a week and varies the weekly training pace with some hard days, endurance/moderate pace days, and easy recovery pace days. I even have a couple off days a week because that’s just life and having other responsibilities. I’ve been on a paleo/primal diet approach for about 3 months and am seeing my best form ever on the bike.

    Is there any research out there comparing the “mindlessly going non-stop” guy to the those who go in with a much more thoughtful and balanced training plan (and have not been eating the standard American diet)?

    1. I don’t have any research at alll, but I do have a free opinion (the best kind). 😉

      Do you actually enjoy that much training? Will you become pro? What does biking in general mean to you? Could you stop and pick up another form of exercise if you became injured? Could you get on your bike and simply enjoy the ride and the sunshine?

      If you’re not having fun (the *only* point is the competition), then it’s not something that encourages health. Cardio can be a very addictive activity (runner’s high anyone?). I know people who have sworn up and down how thoughtful they are – different from that “clearly crazy guy training over there”, but at the end of the day, an addiction is still an addiction.

      Ultimately only you know what biking means to you and how healthy you actually are.

      1. +1

        Along these same lines, has anyone read through Paleo for Athletes? I saw it at a sports clothing store and thought about buying it since I’m still fairly active and just love competition and sports, but then put it back because I didn’t think it would tell me anything that the PB hasn’t already.

      2. Well said. Combining a competitive personality with an addictive activity is a recipe for overworking.

      3. Of couse I enjoy riding my bike and competing, otherwise, why would I train? You don’t have to be a pro (and I never will be) to pursue a sport with a desire to achieve and improve.

        I prefer to call it a passion since it is my conscious choice (addiction is not a choice) and am well aware that competitive endurance is not the optimal path to health. Quite frankly though, I don’t care because it’s something I love to do. What I do care about is doing the best I can to mitigate the inflammation/damage and optimize my recovery and performance, which by default aids in long-term health. Hence my reasons for going full bore into a primal/paleo diet recently.

        Which brings me back to my original question about this study. Were the long term diets of the marathoners scrutinized at all? I’m not out there hammering on the bike everyday. As Mark stated “It’s the chronic, day-in, day-out long, hard stuff that is counter-productive.” Is there a happy medium anywhere in between?

        1. I had similar questions about the marathoners. They’re traditionally a high-grain, high-carb consuming bunch, both in the long-term and binging before races, which sounds like a more reasonable explanation of atherosclerosis to me than running.

          Of course, when you define a group as runners instead of high-carb dieters, it is most likely the running and not the high-carb dieting that will get the blame for any health ills.

  11. I’m on board, but this is not an easy philisophy for a 44 year old to accept. But it’s working, and I like it!

  12. I’m 62 and have run marathons and half marathons for quite a while. Now wisdom, injury, laziness and a little MDA have brought common sense into my life and I have wound that activity down. I still do one race a year, the Air Force Half, just since I’ve done about 20 in a row and want to do another 20. But I found Senior Olympics as well and now do 100, 200, 400, 800 and 1500 meter track and field. Times pretty much suck, but I am in the game. Doing intervals and twice a week weights is really fun. Doing my weekly 90 minute to 2 hour grinder run is also fun again since I don’t have a lot of miles competing for my precious muscle cells.

    Bottom line: Intervals and weights AND a little mid-distance cardio are all part of a good fitness program. Being fat adapted, using coconut oil as a supplement daily, and now, trying out superstarch, all seem to be the optimum path to sane fitness and most of all, keeping it fun!

    I can also still walk/play 18 holes and carry my bag and not be overly tired at the end. A non-trivial feat in Virginia summers. -JD

  13. I wish “sprinting” would get as hip and trendy as distance running does. Theirs no better feeling than when you get into that peak acceleration in my opinion…

    The problem is, you can’t exactly “spend an afternoon” doing it.

    Anyone want to start a sprint club in ATX?

    1. “hip and trendy” – you hit the nail on the head with that statement. Need proof? Just take a drive around town and start counting all the “26.2” and “13.1” stickers.

      My personal favorite is the 0.0 sticker 😉

      1. I never knew what those stickers meant. I’m definitely not a marathoner! I don’t even like to ride 26.2 miles in the car.

      2. “My personal favorite is the 0.0 sticker”
        Hah! If I ever see one of those I will totally buy it.

        Maybe you should start selling .1111 stickers.

        1. ok, guess I’m dumb – I don’t get the “.1111” comment….

  14. I have a related question– lately I’ve been doing a lot of heavy work in the garden (digging, forking, mattocking clay soil, laying pavers, uprooting small saplings) for multiple hours a day. I stop to catch my breath between exertions, but I’m definitely pushing my endurance levels (I’m a middle-aged woman) & I began to wonder if I might be overdoing it. Mind you, I feel great (1000 times better than days when I don’t get outside), but I adore gardening so much, & I used to be a running addict, so I can’t entirely trust my instincts! Does the variety of movements, stopping to recover, & so on, make up for the long-term pushing?
    I really want to believe that I’m doing my body good– I KNOW it’s good for my head!– but I’ve fooled myself before– any thoughts?

    1. paleo curious-
      I am only 10 months primal, but was also a former runner turned gardener. I’m sure gardening is excellent exercise but I would definitely listen to your body to know when to stop. I have an autoimmune condition so if I overdo it outside it gets ugly– surely transplanting that large shrub could wait till tomorrow? I’m getting stronger every month because I’m careful not to push it and at 43 years old I’ve NEVER felt this good.

      1. Thanks Stephanie! Nice to know a fellow convert. 🙂

        When you say “listen to your body,” how quickly do you get feedback? I surely know to look out for back pain or extreme exhaustion, but how can you tell if you’re just pushing a bit too hard, too often?

        1. What do you feel like the next day? If you feel good, you did it right. If someone ran you over with a truck in the middle of the night, you might have pushed too hard yesterday. 😉

          Just rest when it happens and you’ll be good to go. The goal is to feel good 80% of the time.

        2. Or least, my goal is to feel good 80%-90% of the time. I’m not sure that’s universal. 😉

        3. If that’s the criterion, I’m doing fine– I honestly feel better (& sleep *much* better) after hard garden days than when I’m stuck at the drawing table all day. But I would have said that about a hard run too until I ran my knees to bits… :-/ I was mainly carb-fueled then though, if that makes a difference.

          I’m a jitterbug by nature who somehow ended up in a line of work that is super-sedentary– I have to stay extremely still to paint the way I do– so when I have the chance, heavy gardening for hours feels absolutely wonderful! I just hope it’s as good for me as it feels.

  15. I started early January this year with MDA and shortly after found a local conditioning gym. My best weeks are a mix of gym, walking or cycling all for about 1 hour each for an average of 3 hours, for the week!

    I have lost 58lb to date.

    I am comfortable with this volume of workouts as it still allows for the rest of my life to continue as normal

  16. Thank you! This is perfect to show my family members. I have lost 70 lbs eating primal but I still have 50 to go. When I told my cousin I was going to be focusing on weight lifting this fall, maybe some o-lifting (she asked), she repeatedly and assertively told me that that it was too “static” and I needed to do some running. Static? Ha! Ever do a power clean? No, of course you haven’t. But her reaction is typical. Add the armchair exercise advisors to the red-meat-will-kill-you crowd. And don’t pay any attention to my chronic foot and ankle pain resulting from my days as a college athlete in the 90s trying to lose weight by pounding the pavement every day.

  17. Two – 25 minute body weight workouts and one 20 minute sprint session along with a few leisurely walks a week and I’m in better shape than when I was 25. That’s coming from a jock in their 50’s now! Call me a believer.

      1. Man, I really thought that was not going to be enough workouts to get in tip-top shape. That’s why I said I’m a true believer. Thanks for all you do Mark. The PB Fitness Pyrymid works!

  18. Hey Mark, I am curious about what the line is for “chronic cardio”. I understand why you might not want to do it, but I am not sure where the line is for too much and just right. I am fairly out of shape as it is and have been trying to walk an hour or two very slooow hours a day on a treadmill. Reason for the treadmill is that it has a padded deck and I have questionable knees. I figured this approach would help harden the legs up a bit and help prevent injury instead of going too hard and hurting myself. This this too long though? I need to loose some weight and don’t want to make it harder on myself by setting myself up for failure.

  19. I just got out of high school where I ran cross country and track and while I was never the fastest, I was miles ahead of my buddies that ran extra miles after practice or 20+ miles over the weekend. It was a rule that I ran slowly in practice and did no weekend running and almost always beat the guys that did. The only time I didn’t win was against a genetic freak who could run three times as much as the rest of us and keep going like he hasn’t done a thing. I don’t think there’s anything wrong with doing consistent longer runs as long as you keep up with everything else that makes us who we are. I know people that strength train to excess and are worse off for it and I know people who run to excess and are worse off for it, but I do know people who do both consistently that are much healthier, leaner and like me in high school better off than the everyday hypermilers I’ve come across.

  20. Agree, this topic deserves more attention. Recently had my RQ, cals, anaerobic threshold and VO2 measured at gym. Showed that at HR of 144-154, I burn 80% fat on my primal diet. Learned that my jogs were too fast. Keeping HR at or below 150 leaves me feeling better after a run than before. Mark, is a long (3-5 mi) slow “run” 3-4 times a week chronic cardio?

      1. Mark, thanks for your reply. New to MDA, PB. 3 mo ago, went primal. Have lost 15 lbs. feel great.
        As a gastroenterologist, I noticed some of my Crohns patients go into remission after eliminating grains.
        I’m sold on it.
        Sure you thought about being a doctor. You’re helping more people doing what you’ve done the last 20 yrs.
        Tom McGinn MD
        Omaha NE

  21. Thanks so much for writing this. It really couldn’t have come at a better time for me. I used to do Ironman Triathlons, marathons, etc – if it was long and slow, I did it. I thought I was in the best shape of my life when I did these. I since have had 2 kids and have fallen off the exercise bandwagon but keep saying that I need to get back. However, I found out in December that I have a genetic heart condition where my aortic tissue is weak, leading to it being enlarged. While it is not yet an aneurysm, it could potentially get there. My cardiologist has recommended I do a moderate amount of slow, easy cardio – swimming, biking, running, rowing with VERY light weights along with going on a beta-blocker. All of this is making my entire world as I see it turn around and I am having a rough time dealing with all of this. However, reading articles like yours make me feel better as I know my new goal should never be what I used to do, heart defect or not. What my doctor is prescribing (except for the beta-blockers part, still really need to come to terms with that) sounds like it is in line with what you are recommending as well. So thank you for this – at least I feel like my “alternative/Paleo” life is agreeing with the established medical community for once!

    1. You may want to get a second opinion on the beta-blocker, even if you love your Doc. Have someone really explain the drugs, their side effects, and any possible alternatives. If you end up needing to go there with drugs, (we just had a bought with modern medicine involving our infant daughter), you’ll feel a whole lot better about it and much more involved.

      1. Thanks Amy. I don’t actually love my doctor, and definitely plan on getting a 2nd opinion. I got a several month reprieve because I am still breastfeeding my son (he’s 11.5 months) but she wants me to go on the beta-blockers as soon as I am done. But when she explained that she also was trying to convince me that I should stop breastfeeding as there really was no point to do so after the baby is 12 months old and that really turned me off. She obviously has only one path in mind (drugs) and that path has no alternatives. Time for a fresh opinion in my mind.

        1. Ugh. I’m sorry – that is a turn off. My 18 month old daughter would disagree that there’s no point to nursing beyond 12 months. 🙁 (We’ve consistently weaned at 2, not 1).

          Anyway, it’s hard to find good Docs, but it’s sooo worth the time and effort to find one. We went through a few Docs before we ultimately agreed with the original opinion and went ahead with surgery for our daughter. IMO, we ended up with a better overall experience and more importantly, a better surgeon for our child.

        2. If you need a rebuttal for the breastfeeding: childrens adaptive immune system isn’t completely up and running until they are three. Until that time, they benefit from the antibodies they get through breastfeeding. And because mommies tend to get in contact with whatever the baby encounters, pathogen-wise, they tend to produce exactly the antibodies the little one needs. Kinda brilliant, really.

          In your case the question is if the benefit of ‘prolonged’ breastfeeding for your kid outweighs the benefit you could have from the meds. There may be a lot wrong with the medical establishment, meds can still save lives and/or greatly improve the quality of it. I can’t tell you what to do in this case, but I’d definately get a second opinion if this will help to get a better view of your options and the pro’s and cons, to make an informed decision.

  22. Re: endurance athletes and atherosclerosis

    I love Dr. Stephanie Seneff’s theory that atherosclerosis indicates a cholesterol deficiency. She argues that if the body’s default state is to heal, why would it put plaque so close to the heart? Maybe as a local storage site for cholesterol.

    Anyway, this theory jives with some research on the “cholesterol lowering” effect of intense exercise. Food for thought.

  23. Hey Mark,
    I just finished the book “Born to Run”. I’m sure you’ve read it, or heard of Barefoot Ted, or seen these tribes in the world that thrive on running ultra distances?? Help me out here… is it the technique? the story is so convincing that running HUGE distances is how we evolved, basically saying Grok himself was an ancient ultra runner!

    1. Christy,

      Not sure if you heard, but in an unfortunate turn of events, Caballo Blanco (Micah True) died of heart issues on a run some time in 2012. Of course one data point does not a theory confirm, but there is a lot of science backing up what Mark is saying whereas there isn’t a lot of science claiming the HUGE distances are healthy.

    2. Christy, we did evolve to be able to run upright, I agree. But we didn’t evolve to frequently run long distances at a high heart rate. Other than the Tarahumara, who are unique in the world really, no other “tribes” run very much. H-Gs have the ability to do persistence hunting once every few days (mostly as a result of always being Primally fit across a spectrum of ftness metrics), and if you’ve seen the videos, those guys aren’t running very fast at all. They are mostly jogging, resting, sprinting, cutting the tangent and using tracking skills. Then they usually rest for days after the kill.

      Ted is a great friend and teaches “persistence running” at our PrimalCon events each year. He is also quite against chronic cardio.

    3. Someday I think I should write “Born to Walk A Whole Lot and Sprint Occasionally” and see if I can make it best seller. Me thinks it would probably flop. 😉

    4. @ Christy: Check out a book called ‘The Old Way: The Story of the First People’. The author (and her parents) spent years with the Bushmen of the Kalahari (African Savannah – where modern humans evolved into modern human). The “runners” were few and far between. They stalked prey. They didn’t run after it at a steady pace for hours on end. Prey doesn’t run from predators like that either. And – even if we were “born to run” due to hunting down animals that can’t apply to the female of the species because we weren’t part of the hunting group. They would walk 12 miles or more in a day carrying more than double their body weight (includes an offspring or two) as they “gathered”. The men were the hunters the women were the gatherers and the gathering is what provided the majority of the food for the band. No we were not “born to run”. The human body is designed for movement. We were born to move.

  24. I did a few long distance hikes (3 months of daily marathon-length hiking in the wilderness with a pack on.) The result was not good. I lost muscle, I screwed up my metabolism royally, I intuitively felt that this was not healthy even though I loved knowing I could walk 30 miles in a day like some kind of super-woman and even though being out in nature like that is wonderful.

    Now I follow the Primal Blueprint Fitness recommendations: 1x/week sprint, 2-3x/week lifting, daily slow walking, one hike a week as my “play”. My body is stronger, healthier and better looking than it has ever been. I’m 48 years old and have never felt as young and healthy in my entire life.

    I wish you would write about your fitness program more, Mark. It has been a revelation and miracle for me. The diet is only half the story. The fitness program sealed it all in for me.

  25. I’m not sure exactly where I stand on chronic cardio due to the fact that when I lost most of my baby weight I was a chronic cardio-er (minimum hour a day runner). I lost the final lb’s switching over to a Primal way of eating however and have since maintained my lowest weight ever (with a 5 lb window), and kept my body fat percentage at 16/17 percent (41 year old mom of three). I lift weights a few times a week, throw in some yoga and do sprints maybe once a week. So… there are my two cents.

  26. Well Mark, I’ve resisted your efforts to get me to exercise for the past year and a half. Your new book probably will finally get me off my duff!

  27. Several years ago I ran a few marathons & did some longer triathlons, culminating in an Ironman. Looking back, I can’t say the training was enjoyable, but there was a great sense of satisfaction that I could set a goal, figure out what I needed to do, and then meet that goal. The human body is amazing in its adaptability. Recently I gave birth to my first child (more amazement at the human body) and am pregnant with my second. I’ve found that going for a few walks/hikes, strength training a few times/week, doing some yoga, and sprinting 1x/week (when not pregnant) has left me feeling great, although less aerobically conditioned than before. With all of the science out there, I agree that Primal Blueprint fitness is the optimal prescription for overall health, and it feels very natural & sustainable.

    However, my question would be: what types of activities are best for goal-setting? The occasional 5k or sprint triathlon? Climbing a challenging mountain? The occasional endurance event? While I don’t want to return to training almost exclusively for endurance events, I do see myself looking to set & achieve physical goals from time to time, especially once the kids get older. I would love any suggestions for this.

  28. I’m trying to think of this in terms I can relate to. Is someone who does an aerobics class three days a week potentially damaging their heart, or is this limited to “ultra” and “endurance” athletes?

    1. Alice, don’t overthink this. If you can do it 3x week and recover easily, then it’s not in the realm of chronic.

  29. I do not do cardio anymore. Not regularly at least.

    Long walks and upstairs sprints, together with weightlifting circuits seem to keep my heart well trained without the boring and repetitive running sessions. So well trained that, every 5-6 months, I decide out of the blue to do a nice long run on the treadmill at a sustained pace. Guess what? It seems I am just as fit as I was when I was running 4 times per week.

    No pain no gain? I would say: painless gain! How can you not love this?

  30. As my wife goes out to train for yet another triathlon, i tell her I am going to sprint down to the mailbox (200 yards) and back for my work out today.. Just after i finish cooking my bacon.

  31. I prefer walking – I walk 3 times a week, about 4 miles each. I live in the foothills of Northern CA and the route I take has considerable up and down-hill slopes,so it turns into a really good workout.. I don’t know if I could even run anymore. I have a touch of COPD so the walking is strenuous enough for me. I lost 40 lbs doing this as well as eating Paleo. Now I’ve added a weighted backpack to the routine to add intensity. Works for me.

  32. Hello 🙂 as a former jazz aerobics instructor from the 80’s I completely understand all the detriments of chronic cardio…. I am wondering if I could get some thoughts about my current situation. I live in the deserts of Southern California and while during the cooler seasons I can always get in those long “low and slow” walks and hikes, I’m not sure what to do in the summer……90 degrees by 9 am is a standard. I do own an elliptical and this is the most convenient thing to do. What might you suggest? Elliptical for an hour super slow a few times per week, no intervals for example?…..all suggestions welcome, thank you 🙂

  33. Food for thought to the marathoners: I had Jeff Galloway’s Book on Running. From what I recall Jeff talks about doing a seminar for marathon training. Jeff writes about a guy who asked if Jeff thought it were possible to only run once per week and not hit the 20 mile wall. Jeff said he didn’t think it was possible. But that’s how this guy was training; he was only running on the weekend. This guy only had time to put in one long distance run each week. Back then I had friends who thought they needed to run every day. I liked lifting weights too, and my argument to them was if you don’t lift every day I didn’t think you should run every day either. This once per week runner got me thinking about just how minimum volume a person could do and still get in the best shape of their life. When I was 47 years old I cut back to lifting only once a week per body part (3 workouts per week) and got my bench press up to 365lbs. Here I was through my earlier years (esp. 20s and 30s) trying to get my bench over 300. At 47 I was warming up with 300lbs and wondering why I had beat myself up so much (getting periodically over trained) from lifting too often.

  34. Completely agree. When I run I know I’m not doing it properly. My knees ache as do my hips and feet. I’ve always hated it and knew something was wrong. Now I know why, haha! I walk a lot at work (big warehouse) but have just started adding an extra one in the evening. Felt great. BTW have lost 3 kg in 3 weeks going primal. Wasn’t a fatty to start with but was starting to soften at the belly. Now much leaner at 81kg. Am at 12% body fat. Wanna dip below 10. Cheers! This is a great website! Bought the book!

  35. Has anyone read anything on endurance training and hypothyroidism? I’m a 40 year old male, in shape and healthy. Spent much of my 30s doing distance running and hardcore marathoning/racing to almost one marathon a year combined with many other races. Gradually my TSH levels increased to the point where the doc put me on meds.

    I HATE having to take a pill everyday (I don’t feel this way about supplements) and I can’t think that all the hardcore training had something to do with this.


  36. I’m a believer too. As a sugar burner marathoner I was 174 lbs at 18% body fat. Began primal blueprint this year and now 167 lbs at 12% body fat. Before I felt beat up all the time now I have energy to spare. I’ll never go back.

  37. Patrick,I also did marathons in my 30s and my TSH levels say I have hypothyroidism. I’m 42 now I feel great the large majority of the time, exercise primally now and refuse to take medication. Don’t let the number on a test dictate how you feel. I came to realize the days after a meal with gluten is when I feel sluggish so I cut out gluten all together. Simple but not easy.

  38. As a “Chronic Cardio” Success Story featured in the softcover PB, I have a few well-chosen thoughts on this topic of “chronic cardio”. Chronic cardio is a somewhat vague and mostly misunderstood concept, in my opinion. There is a broad spectrum of variables that go into appropriately defining chronic cardio in respect to each individual individually. Variables such as level of intensity, duration of exercise, conditioning of the individual, and their ability to recover from the effort. Is it “easy” on their mind, body and spirit? Do they feel energized or exhausted after their bout of endurance training? Did it raise their cortisol level and did it cause massive systemic inflammation in their body?

    Take for instance, elite Kenyan distance runners spend 90% of their time jogging at a pace which is at a level of intensity equated to a brisk walk for most untrained folks, hence would not qualify as chronic cardio because ultimately chronic cardio is when you overdo high intensity and high duration and do so too often with inadequate recovery.

    As for the various studies, such as about atherosclerosis and so forth, I doubt that the studies took into account the chronic cardio exercisers nutritional intake and status. Endurance athletes are notorious in over-imbibing carbohydrates and high glycemic foods that raise insulin and hence increase plaque in the arteries and so forth, which may be the major contributing factor to their heart disease risk, not so much the endurance training itself.

    What do you guys think about my take on this? Mark, do you want to throw in your two cents here, as I you know are well-acquainted with my story?

    1. I’m looking forward to any answer about this! I did not know about the Kenyan jogging style, for one. And it’s way true about the excessive carb intake. I’ve been a very good runner for over 33 years, and most of those were high carb. I stopped running my 5.5 miles/per day a year and a half ago and miraculously stopped having chronic colds and bronchitis. Now I catch NOTHING the rest of the office catches. But I still enjoy an occasional longer run with a friend, and still place high in races using sprints and lots of walking instead.

  39. I used to run cross country and track in college and was definitely the leanest when I was training 60 miles a week (even on a grain based diet). Its hard to quit chronic cardio because I’ve never had such a rush as breaking 18 for the 5k, or running a 10k at 6 minute miles. I may be ‘healthier’ now but I just feel fat and slow. Anyone else feel like this.

    1. I know people who complain about feeling fat and slow when they’ve stopped endurance exercise.

      To me, the focus of this post and their talks about is “the rush”. That’s endorphin addiction, buried in random time tracking (minute/miles) and body image.

      An addiction that requires running miles a week is probably better than many others I can think of, but it’s an addiction none the less.

      Truly appreciating what your other appendages are capable of might help ease the body image problem. Visit a nursing home and then feel the “rush” of taking a walk. Garden. Make a sculpture. Squat. Try a pull up or two. There’s an amazing amount your body can do when it’s not trying to cover for the damage caused by too much exercise. Good luck. 🙂

  40. Mark’s one of my heroes today in his late 50’s. I’m 54 and here’s one of my heroes from back in the day: Gary Player. He was a proponent of weight training and exercise before Tiger was even born. See what we’re capable of in our 70’s, the new 40!

    1. Thanks for the link Jeff. I love Gary Player. That man looks fantastic at 77.

  41. I was just discussing with a critical care MD at work the other day the mounting body of evidence supporting increased mortality from endurance exercise. Right now it’s looking like anyone who logs around over 30 miles a week is doing more harm than good.

    And a. fib. is no good either. With the lack of turbulence in the heart from ineffective heart contractions it makes your blood easier to clot and is one of the biggest risk factors for having a stroke. Once in a. fib. it’s likely you’ll have to be on blood thinners like aspirin, plavix, or coumadin. And that presents its on health issues as well…

  42. I am a former Cross Fitter and so glad I quit. I follow Rusty of and it’s made all the difference. I feel like I am finally losing fat after getting bigger and being constantly swollen at CrossFit. As a woman, that was hardly the way I wanted to look. Weights and HIIT training done separately several times a week plus playing around with diet, has bee a revelation.

  43. If only I didn’t have this bucket list goal of a sub 3 hour marathon I could give up these 70 mile weeks with speedwork. Yes – resistance training and MDA eating (but you gotta eat carbs with 70 miles/week too). I’m 52 and close to my time goal – and I swear once I achieve that i’ll back off..well…I’m planning on it anyway. One confession too – had mild AF last year.

    1. This paragraph is cardio (endorphin) addiction in a nutshell. Is continuing to damage your heart *really* worth a sub 3 hour marathon? Isn’t your life worth something more than a time on a clock and short lived rush?

      1. Mr. Kelley, give it a rest. You are a beautiful human and OK the way you are…

  44. I haven’t been to the gym since summer began! My two exercise buddies are ages 10 and 8. So far, we’ve done crossfit kids (so fun, but not overwhelming), played tennis, completed our own kid’s tri (50 swim, 1 mile bike, .5 mile run), taken “long” bike rides ( 5 miles), scooter rides (4 miles), water-gun freeze tag, playground tag, had a balance day (stilts, pogo stick, skateboard and slackline), sprints on the track, and hiked to the river where we went tubing for 1/4 mile and repeated. Oh, and sometimes we play at the pool (I swim laps during the break). Every day is fun, not a workout. I make sure I get in some strength training if one of our activities doesn’t cover it, but short and heavy. Stop worrying about getting a “workout” and go have some fun.

  45. While no one will ever accuse me of overtraining, I’m a 43 y.o. Female, 80% primal for 3 or so years, who spends about 6 minutes doing hill sprints, 3x a week. Add in a little gardening, the occasional walk or hike, and I look and feel great. Since I’m vacationing at the beach this week, the beach sprints are absolutely super-fun. I try the occasional push-up, and sadly, can rarely manage more than one – I admit that a little more body weight exercise would take care of that. But honestly, there’s never been an easier way to stay relatively bikini-ready.

  46. I’m still allowed to run the Boilermaker 15K this weekend, right?

    It’ll be my… 17th? (And maybe my first one at a non-obese BMI.) I trained as a careful slow fat person. My pace is ~11 minute miles. But I still have all my original joints!

    A primal-curious friend asked me how I justify my running in light of your concerns over chronic cardio. I theorized that I probably run too slow for it to count. Would that be a fair assessment?

  47. I was a very competitive soccer player all my life (22yrs playing). I played in college, olympic development program, and professional. I loved every bit of it and would never regret one second of it. I didnt do it for the medal i did it because i loved it. I think a big problem athletes have is that many of us are never taught anything about health and nutrition. We play to the max but dont have the proper nutrition to rebuild. MY coaches only ever taught me how to play but not how to eat or take supplements. We are pushed and pushed then taught to push even harder. In college for two weeks we practiced twice a day. Then we’d go to the cafeteria for pizza and cookies and grape juice. There was no rebuild strategy! And we were actually taught not to listen to our bodies. Well that being said i believe with the proper education we can safely play the sports we love. There is a spiritual aspect to the love of a game that i think not everyone can understand. I wish i had the knowledge about healing i do now but im glad that i can atleast use it to help young athletes. Reading this seems like its trying to scare people. My heart is fine and i have many tests toshow how healthy i am. I guess the love i have for soccer made happy cells.

  48. Hi, Mark, or anyone else, please can you tell me what kind of Resting Heart Rate we should be aiming for then?
    And what kind of significance it holds regarding health.

    It’s just we are conventionally told that higher resting heart rate / pulse [above 70 say] is bad and lower resting heart rate / pulse is good [say below 70].

    It seems the way to really lower your Resting Heart Rate is through Chronic Cardio. If you look at different kinds of athletes those in more power/speed related sports/events tend to have higher Resting Heart Rates than those in the more cardio related sports – marathons, Tour cycling etc.

    One more thing. What does Chronic Cardio being bad mean for athletes that require it for their training? Is it just part of the “sacrifice” for success [A necessary evil say] or is there somehow another way to train for long distance events etc?

    1. Disagree. I’m 57 and I have a resting heart rate of an avg. of 50 bpm. I sprint once a week for 20 minutes. Do two 25 minute bodyweight exercises. I do a few meandering walks at an average pace around the neighborhood. That’s only 70 minutes a week of pushing it.

  49. Surely there is a difference between endurance athletes who eat traditional health junk fare and those that eat whole foods and eat plenty of fats. We need a study depicting the latter group.

    1. Why?

      A human body is not a machine. We have limits, we wear down and need to rest and rebuild. A perfect diet will not overcome constantly pushing a body to it’s outer limits and especially the heart, as Mark noted.

      If you’re going pro for a short time, I understand the training. If you love a sport, I get it, but I tend to think you’d want to cut back so you don’t have a crappy 5th, 6th, 7th and 8th decade. It turns out the fun factor is also the health factor, too. 🙁

  50. I play soccer (actually futsal) two times a week for 1 hour and a half in an intense way (without even thinking because it’s so good), with a lot of intense bursts. It’s really tiring and the other day I do no exercise (a bit of walking going home). I try to do strenght training twice a week too, and nothing more. Maybe I’m overdoing it? But it’s so good, I don’t wanna stop 🙁

    1. I played yesterday and it seems that I’m not overdoing it, because it’s more like walk a little / sprint like crazy / kick the ball / stop / run to the initial position. And I actually feel great after the game and the day after.

  51. While healing from concussion, one of the limitations I had when it came to returning to exercise was a heart-rate cap. I could go for a certain period of time at a predetermined heart rate. For a period of time, this was 145BPM for 40 minutes. I would do this 6 times a week, and it actually hurt my head quite a bit – even though I would say that I was okay. Last summer, I decided I was done with the pain and the stagnant weight loss, and I just started walking outside every day. I walked for about an hour. Suddenly, my weight dropped, I felt healthy and my head was finally clear, and I came back into balance. When my clients ask me now, I always advise against chronic cardio, though they can’t seem to get past the CW about it. Someday.

  52. Yes despite much evidence to the contrary, it’s hard to skew my mind towards the fact that chronic cardio doesnt achieve as much weight loss as interval training but I am getting there!

  53. I’d rather stab myself in the eye than spend my time in the gym. My trail runs are the most therapeutic and healthy (mentally at least) thing I do for myself. I guess I will die any second from all my “chronic cardio” (this is not what Mark is suggesting but how many commenters seem to interpret this post which is silly).

  54. Chris from the Extreme Weight Loss TV show just told the contestant, “This is a marathon, not a sprint,” while he was chastising her for dropping down to only 400 calories per day and was snacking on edemame. Sad 🙁

  55. I started distance running in 1976. I was a smoker and heavy beer drinker in college. I threw it all away and got in shape or so I thought. Now at 58 I’m looking at a hip replacement in 1-3 years. I constantly have knee, back, and hip pain. Oh if I had only known then what I know now. I’m now on the Paleo diet. I sprint on a stationary bike and lift twice a week. I’m in better shape at 58 than I was at 28. My blood pressure is lower and when I’m not feeling too much joint paint I’m on top of the world. Keep up the much needed advice Mark.
    Jeff Taylor

  56. I suppose I’m a bit confused. Forgive me if this will sound naive, but I thought that the point of training and exercise was to get oneself to higher level of ability and skill. If you are, for example, training for a, you are increasing your bodies ability to do more than it could before. And if your body can comfortably do more than before, isn’t that what good health is all about?

    Of course, I’m no marathoner, I don’t have time for that sort of thing. But I always assumed that if you COULD run a marathon, you would be in better health than someone who could not. In my mind, greater ability equals better health, equals more comfort and happiness and satisfaction, etc. What am I missing here?

    1. Oops. Meant to write ‘training for a triathlon. Lost in spell check…

    2. That’s the rub: health and fitness are two separate things. You can be very fit yet unhealthy, or very healthy yet unfit. One is from diet, the other from exercise. The old (1960s-to-present) wisdom, dating from the ‘Aerobics’ book and revolution, was that marathoners would live forever and could never get heart disease. Completely wrong.

  57. Hi Mark,

    I thought arrhythmia was caused by doing too much HIIT rather than chronic cardio?

    Speaking from an endurance athlete’s point of view, doing long course races or running long distance is actually addicting. It’s not so much about the pain as HIIT is 1000x more painful! But it’s the trance-like state after running how-many-miles that got us hooked. Of course, we often find ourselves tired, cranky and hungry as if we had constant PMS.

    I’m honestly torn between love and hate for chronic cardio but on the other hand, I’d love to find the proper nutrition that supports endurance training and optimum recovery. Is there a chance you can delve into details about the subject in the future posts?


  58. I run frequently, minimum of 5 times a week, for about 2 hours at a time with something longer on the weekend, and have done for a while now. Occassionally, like today infact, I woke up later than usual, tired and have decided instead to rest. It’s bound to happen once in a while. Point being, I wouldnt be able to keep my routine if I pushed myself hard every day. I run when I feel good, hike up hills I can’t comfortably run up, and generally love being outside running, especially early in the morning when the sun rises. I feel the most human I ever feel when I run trails. From what i’ve read on this site, I have concluded the secret of ‘primal’ running is all or (almost) nothing. Sprint, or go easy. Nothing in-between. The secret to ANY running regime? More base, less speed!

  59. Hi,

    Would about half of an hour of interval training style jump roping daily be considered excessive. I can’t run very far or well, because my knee kills me, but somehow the jump rope doesn’t hurt at all. And, by interval training style jump roping I mean switching between jumping as hard and fast as I can to a super easy jog style jumping to catch my breath, all the while while switching between leading feet, or jumping with both, and other variations. Thanks for the input!

    1. My apologies, that first sentences was meant to have been a question, with a question mark. :D:D:D

  60. Well, now I’m thoroughly confused. I just finished Christopher McDougall’s book last night “Born to Run” and found it inspiring and made me want to pick a marathon to train for. Although I don’t recall the book addressing heart issues it did address other common injuries and suggested the solution was getting rid of the overly cushioned running shoes. It also suggested we evolved as humans because we were adept at endurance runs in order to practice “persistence hunting”. How could we have evolved based on our capacity for endurance but have flawed hearts making endurance too risky? Maybe the heart issues aren’t because of chronic cardio alone but a combination of chronic cardio if it’s coupled with the modern SAD diet or some other factor?

  61. I wish the title of this was “chronic ANAEROBIC cardio”I have been a big fan of Dr Phil Maffetone’s approach and I embrace my HR monitor I use for every run. It irks me when I hear folks talk about how fast or long they ran a race without any care of their heart rate. It is essential information. The aerobic system in our bodies is very efficient and can grow to be highly efficient but not when anarobic activity is the norm! I am sure there is a study out there which has looked at the health effects of aerobic cardio over the long term but I haven’t seen it. Too many times those who report this lump anaerobic and aerobic together. They are very very different. And the impact on the heart in the long term is also. Grok didn’t have one but we all need to have one handy if we want to know which system we are using and I sure think we all could and should have much more deeply developed aerobic systems before we take on a lot of anaerobic excercise:)

  62. The article implies running/cardio causes Atherosclerosis – not true!! But running masks the symptoms (as you point out) of a diet that causes Atherosclerosis. There is a widespread assumption among runners that they can eat anything, and many can because they don’t put on weight. But the internal damage from a bad diet isn’t caused by running any more than by weights/gym workouts. I have to say, I don’t understand why gym rats are so down on people who like to run. It is a mystery to me why they even care.

  63. Great article…I have a question, though.

    Monday – Friday, I walk 2.5 miles in the morning, between .5 and 1 mile while at work (walking to and from my car which I park .25 miles away from my office), and then walk for about 5 miles in the evening. I mix in some more intense, but not that intense elliptical for 30-60 minutes at the gym. I also do some strength training in the morning for 30 minutes.

    If I am tired, I’ll just rest in the evenings. I usually rest on Sundays. Mondays I get out for 10 miles with no strength training.

    Is this considered over doing it according to the studies referenced?

  64. I’m all for n=1 and followed the primal diet since end of February. I’ve lost 14lbs from a healthy weight of 159lbs to 144lbs standing at 5’11”. I ran a marathon in June. My next n=1 is the maffetone heart rate method whereby I will not go above a heart rate of 148 until I have an aerobic base built up. I don’t consider this “chronic cardio” -I honestly think Grok and his relatives spent their lives roaming the plains of Africa looking for food and hunting animals and had massive endurance bases. I agree with the primal diet and once your aerobic base is built I believe in sprinting and lifting heavy things butI think we should be cautious about how we advise people how to or how not to exercise. Overtraining is a result of people thinking they are doing chronic cardio but are actually edging over into anaerobic training at all times during their training sessions. Read Maffetones stuff it makes as much sense as the Primal diet and he advocates the low carb diet too.

    1. I bet most of the folks who ran that marathon with you had no idea what their HR was and didn’t care to know. It is essential. Good for you!! Maffetone, Sock Doc and Dr Mark C all are big proponents of getting the aerobic base fully formed and that takes much longer than most folks want to invest. That’s why I worry for folks who are doing to much HIIT stuff right now NOT knowing about the risks and without solid aerobic preparation. Jen what is the sustained pace you are running at that HR of 148 and where was it before when you began? Thanks

  65. Mark,
    I have a treadmill desk and I walk on it as I surf the net and stuff. I walk at about 2 to 2.5 mph. I do this because sitting is supposed to be terrible for you.

    Would this qualify as “chronic cardio” and be destructive?

    My understanding is that the human being was supposed to walk. A lot.

  66. Okay, I have a question. I just happened upon this website via Facebook and read all the comments thus far. Really interesting.

    I’ve had a weight problem all my life and have done all the diets and fell off all the wagons. Been in the gym and out of the gym though mostly out. I got laid off from my gov’t job back in February and since I have nothing to do besides look for work I figured it’d be a good time to work on my fitness. Well for the past 13 weeks I’ve been swimming a half mile 5x a week. I was doing mostly backstroke so it would take me an hour. After my hour of swimming I do work with the water weights and with a resistance band. Last week I started doing breaststroke and freestyle and found that the half mile only took me a half hour so I went ahead and started doing a full mile which takes an hour with those strokes as well as 30-40 minutes of water weights and resistance band work after my laps. Is this chronic cardio?

    I REALLY enjoy swimming and have never swam for fitness before. I never knew that swimming burns SO many calories! So far I have lost 12 lbs but tons of inches! I didn’t measure in the beginning but I’ve lost 2 sizes in my shirts and 1 size in my pants! Again I’m enjoying it immensely but am wondering since reading this if I am doing chronic cardio?

  67. I am new to the PB fitness. After 1 body weight workout of 2 cycles at the easiest form I am in PAIN the next day. I am in very poor shape. I am 35. I weigh 258 down from a high of 306 3 months ago. The body weight workout seems like a cardio because I am gasping for breath. Should I be doing this twice a week or at first should I do it only once a week?

  68. Dave I used to run myself into the ground at 8.00-8.30 pace for 10ks and half marathons. I hurt constantly and had continuous knee effusions, get thrown by ligament injuries and never was able to really improve because of long lay offs from running.
    At 148 I was sooooo slow to start with. 11.30-12.30! I’ve whittled this down to 9.00min/miles over two months and am injury free. My orthotics are gone and I walk around barefoot as much as I can. I feel like I could run all day. My marathon pace was just over 10min/mile pace and that was a month ago.

    1. Awesome Jen! I have been at it for a little over a year and went from a 13 min pace:( I am a slow gainer I suppose but now running in the 10’s and more importantly I feel great and ,like you, feel like I run for a very long time. Keep it up and let me know your progress.

  69. Im 48 now, have bad irregular heartbeat since over 3 years ago. Overtrained and underate for a good 20 years of my life. My years of flying witg the wind was a lot of fun….good for the ego. Now, not so much fun… heart is weak, 3k walk puffs me out….
    Still look good but dont feel good…
    I take the feeling good any day.
    Wish i know then what i know now, but would i have listened?

    1. + 1 to JDS….

      I was so very proud of my past running “prowess”..could run longer and longer distances fueled by so little food-wise…I think I was literally running on “youth”..but as a result….later on…at 53…I am seeing the toll this has taken on my energy levels. It takes great volition on my part to simply get out the door for long walks …when running long distances used to be such a breeze. Numerous fractures (tibia/ankles) did not “halt” me for years…now they have.

      Visually..I look the same as back then…but like JDS…I would “take the feeling good any day”….Great last point…”Wish I knew then what I know now, but would I have listened?”…I most definitely would NOT have listened

  70. Is 3 x 40min (wed, sat and sun) spin classes a week chronic cardio?

  71. The link below is a presentation by a research cardiologist that presents evidence that too much cardio is not good for your heart and arteries. It presents the results from some new studies and recommendations on what is the “right” amount of cardio exercise.

    If you run it is about 2-3 miles, 2-3 times a week at a 6-7 MPH pace (~10 min mile). It likely varies with the individual but a good rule of thumb.

  72. Hi Mark! (And anyone who reads this…)

    I am 24 years old and used to be quite slim for most of my life. I rode horses ever since I was 2 and in high school it was y full time job to ride/train/teach. I loved it. However, I stopped in college and felt I needed to keep fit by going to the gym. I got pretty skinny without really realizing it. Fast forward to senior year and I gained about 50 pounds while eating the same and working out. I was diagnosed with PCOS and insulin resistance. I lost a little weight with the CW tips I got from a nutritionist but then started a mix of low carb and primal (basically the only difference was that I ate dairy). For the past few weeks I have given up dairy to see if it makes any difference but I sort of just feel stuck. I do the insanity/insanity asylum vol 1/ asylum vol2 5 or 6 days a week. Do you think this is the reason I seem to have stalled? Does anyone else have experience with insanity? I get very little carbs bc my insulin resistance makes me fear I will gain weight easily. I am for 20-30g per day.

    I’m active throughout the day. I work as a vet technician so I am constantly on my feet. I would love to find time to ride again bc it really made me happy. Would decreasing my insanity and increasing my riding help my body relax and lose weight? Any comments greatly appreciated!

  73. Mark, could quantify the line between unhealthy “chronic cardio” and healthy “move slowly” exercise in terms of heart rate zone? I enjoy hiking and stand-up paddleboarding, both of which can range in intensity depending on pace and conditions from something I can do for hours with only mild elevation in heart rate and breathing to something that leaves me gasping for breath after a few minutes. I’d like to build up my endurance for these activities in a healthy way and could use some some objective metric (e.g. keep heart rate below 65% max) to be sure that I’m keeping my workouts out of the “chronic cardio” danger zone as my fitness level varies throughout the year.



  74. solid article and certainly good food for thought. that said, it appears as if those whom are labeling all endurance training as a march to death (which Mark is clearly NOT doing) have missed the point. the intensity one should stay at is personalized and dependent upon one’s current level of health and fitness, taking factors such as max HR, injuries (or lack of), history, and personal preferences into accout. one man’s ceiling is another man’s floor… this guy’s jogging pace may actually be a lot less intense than another’s brisk walk. the key is to find the sweet point, avoid overtraining, listen to one’s body, instill balance and moderation into the training… and have fun, all while properly nourishing body and mind.

    but the all or nothing perspective some preach is certainly not a wise one. “only a sith deals in absolutes.”

  75. I like to ride on the weekends, an hour gets me abut 20 miles which I do on Sat. and Sun. I’ll usually bump that up to 30 miles by the time August gets here but I may not do that this year.

  76. Hi.
    I’m 50.
    I do competitive road cycling. I’ve been doing it on and off since I was 17. For most of the 90s I did 10k running races along with 1/2 marathons.
    I was a Vegetarian for 17 years until I changed to being Vegan 2 /12 years ago.

    I have no joint problems.

    I ride & cycle race with men and women whose ages range from 17 to mid 80s. They’re still doing what they’ve been doing for years, decades even.

    Compare this to what we read, hear and see in the news with regards nations populace of diseased, overweight and immobile people.

    For the very few who suffer joints or heart problems the many who major on cardio exercise benefit greatly from it.

    Paul 😉

  77. I’m going to play devil’s advocate (I live primally, and it works great).
    What about the Tarahumara Indians? They eat a high carb diet, and do lots of cardio. And they live to ripe old age without heart, weight or joint problems. Why?

  78. Never liked long cardio sessions, just hated how my lungs and wind pipe would feel after 5 minutes of constant running, it just didnt feel right, on the other hand HIIT was always much more fun, particularly the resting bit! haha

  79. I love Mark’s posts about chronic cardio because the discussions in the comments section are amazing, passionate, and thought-provoking. Chronic cardio means so many different things to different people, so here’s ***My Two Cents***

    When I was in college and tried vegan and chronic cardio, I gained weight. When I say chronic cardio, I mean hopping on the treadmill every day come hell or high water and trying to keep going for an hour. It sucked. I got injured. I also gained five pounds super-fast.

    I added meat back into my diet (I think vegan lasted all of two months, max), started doing typical body-building split weight training, and every other day would pedal on a stationary bike at whatever pace I felt like for an hour while I read whatever guilty-pleasure magazine I felt like. It was “me time.” I lost all the weight I gained during my vegan/chronic phase.

    Note: I was still doing an hour of stationary biking a day, but I was not aiming for a heart rate and I was not aiming for a pace; I was aiming to be active while I read a favorite magazine. Total pleasure.

    A couple years later, I discovered Paleo, followed soon by Primal. I kept up my alternating weights/slow cardio, changed my diet, and honestly lost too much weight.

    Then I read that chronic cardio is bad for you, heavy lifting is good for you, lift big, eat big, do sprints. I gained weight. I also gained sluggishness. Sprinting only helps my time trials to a point, and then I actually have to DO the time trials. I don’t have to do a million long, slow runs to jump into an endurance event, but if I make my long, slow runs truly SLOW, I feel good, I maintain my weight better, and whatever event I want to partake in goes well. It’s still not chronic because I’m not pushing myself through any pain barrier, and I’m definitely falling into that 10-11 minute mile pace for the slow stuff.

    So, for me, I need a combination of weight training, sprinting, and some long, slow cardio (that is more difficult than walking — walking isn’t enough) to maintain my weight and my preferred level of fitness.

    A note on endurance events: they do not have to be “chronic.” I ran a half-marathon with a friend last fall, and my job was to get him to cross the finish line. He was eventually going so slow that I would run ahead a few yards, stop, cheer him on to keep going, and then when he caught up, I would run ahead, wait, cheer, run, wait, cheer… Nothing chronic about that.

    That’s my take on that. Fitness is definitely as individual as diet. One size doesn’t fit all.

  80. I am a little confused. I understand the sprinting part. But I don’t understand the rest. Is riding a bicycle for a long ride bad? Does it count as chronic cardio? If I walk on the treadmill for an hour, is this “chronic cardio?” How do you draw the line to what is “chronic cardio” that is not good for your body, and what is just doing long sessions of exercise that are good for you and not considered “chronic cardio?”

  81. I wonder if symptoms related to this were what got Bruce Lee. He trained endlessly…

  82. First of all, in the book “born to run”, McDougall says we are evolved to run. Running is uber-paleo because endurance running is why we are bipedal and have sweat glands all over our body and not hairy like monkeys. It was to do a form of hunting called persistence hunting. We had a tremendous evolutionary advantage over other animals because other animals cannot do endurance cardio and quickly overheat when they try.

    After that, if you recommend weight training, then why don’t we look at the health problems of professional bodybuilders or powerlifters? If we are going to look at professional endurance athletes’ health problems, then it’s only fair to compare them to bodybuilders.

    Yes, weight training can make you leaner (in terms of body fat percentage) but is carrying around 25lbs of muscle better than not carrying around that 25lbs of muscle? If we have extra muscles, our heart has to work harder to supply them with blood and so, over the long term might cause problems. Our body naturally destroys the muscles we don’t use and grow the ones we do and so, why would we want to grow muscles for the sole sake of growing them. By doing weight training, we are essentially hacking the body’s system of allocating resources to growing muscle to adapt to the environment.

    Couldn’t it be that the heart diseases are more linked with diet than with use. Maybe endurance athletes guzzle gatorade and their diet is pizza and beer that causes the heart problems. After all, endurance athletes are marketed a different way than regular people.

    Anyway, this isn’t something that can just be thought of on paper and figured out. Yes, endurance training can cause various forms of stress on the heart muscles but how significant is that that stress to the long term health? Maybe its just a few athletes who are training incorrectly that are having problems.

    1. That’s so true! People die weightlifing, but maybe that is because of all the artificial milks and foods they eat, supplements, sleep habits, etc. There is a middle ground for all types of fitness training, and applying great nutrition serves to enhance its health benefits.

  83. I think I once had a heart attack or something similar… it felt like my heart stopped beating for maybe 5 seconds or a bit more; then for about a week after I had an ache in my chest. This was caused by a reckless dose of recreational drugs. I still drank an energy drink or two every day after – oh, I can take it! (well, guess I could, since I recovered fine, but I bet I could have cut that time to half if I didn’t keep drinking Rockstars and Monsters (hey, I wanted to work fast cleaning garbage up so I could get a headstart on my homework or just chill out in the cafeteria and chug 25 cent small styrofoam cup coffees with as much sugar as the machine would pump out from pressing the button like an uzi and a muffine too! and teas in the factory cafeteria so I could read the newspapers from the floor or laze around or hide smoking weed in the change room or janitor closet or smoking area outside).

  84. What is chonic cardio? I have always hated running but was challenged to do a 5K. I started a couch to 5 k program. I discovered real quick that I hate the road running. I decided to go off road.I did do the 5k and ran the whole thing.

    Found that I really like trail running on hiking paths I have come across deer, moose, rabbit and all kinds of brush dwelling birds scaring the daylights out of me when they take flight. It has become a zen-like experience. I go at an easy pace. Is 1 to 3 miles a day, 2 or 3 times a week considered chonic? Should I scale back to once a week and walk the rest?

    1. Less than 6mile per day isn’t considered chronic from a previous article. Plus, if you’re going at easy pace, it probably doesn’t even register.

  85. Dear Mark,

    I’m a amateur bike racer who trains 8-12 hrs a week. And a little different than many chronic cardionistas –I only race 2-3 times per month, mostly short races, and I only race about 3 months a year.

    My only other exercise is walking, and I walk around 2 miles a day on errands and such. Oh, and I do a little plyometric activity to keep my hips limber and strong –compensating for the nearly one-dimensional movement in cycling.

    Since my longest races are about 3hrs, my training is set accordingly, broadly speaking, I do about two 3 hour rides per week at low-to-moderate intensity. I rest well for a day or two following these longer rides, sometimes with an hour of light spinning on a rest day, sometimes no riding. I throw in one more intense, but shorter ride per week. Some sprint work gets added here and there, but it’s minimal.

    I feel good and my blood tests look great. My diet still contains spikes of sugary stuff and some unplanned grains (pastry and beer), but most of my intake is high-quality primal.

    I feel good physically and mentally, sleep well at ~8hrs a night, spend lots of time in a relaxed, contemplative state of mind.

    Altogether I feel like I felt when I was a kid –the duration and intensity of play is very similar to my childhood days. Of course there was more impact with wrestling my brothers, climbing and jumping from trees, etc. decades ago. And I’d like to bring more of the latter, resistance/strength play, into my life now –so I’ll probably add some weightlifting in the near future.

    But with my current training load, which stays more or less constant throughout the year (with week long breaks 3-4 times/year for extra rest), my stress/rest balance feels right. And it wasn’t until I began this kind of training that my heart arrhythmia disappeared.

    I don’t think the bike is the best sport/exercise for the human body, but –for me– it brings an amount of sheer fun and joy that nothing else can match.

    Thanks for all your informative and enjoyable writing.

  86. When I was a child my dad told me that “You can’t believe 99% of what you see on television and 97% of what you hear.” Boy-o-boy, was he ever right! We are constantly bombarded with all kinds of commercials on television and adds in magazines that promote all kinds of diet and nutrition advice, exercise advice, medical advise, etc. And I have come to learn that the vast majority of all this advice is the exact opposite of what the truth is! The vast majority of it, if followed is destroying peoples lives and even killing people prematurely. I have come to learn that what ever is promoted… AVOID IT or DO THE OPPOSITE! According to the “oh-so-wise” talking heads, we are supposed to eat lots of grains (and then we wonder why people are obese and have all kinds of intestinal problems), avoid eating whole eggs, meats and dairy products (because they are bad for your heart) but eat their man-made replacement crap which will plug up your arteries and heart tighter than a pipe packed full of cement, drink their man-made/processed sugars (which cause FAT gain and brain problems, etc), pop this pill and that pill (which causes other problems requiring treatment with another pill) that we see advertised every 15 minutes on tv, run our a**es off since we mostly hear about or see people doing this, etc. Finally, the truth is starting to come out about all these lies because of sites like this one. I’ve already read several articles over the past few months prior to this one, that through research studies show that looong-boring cardio will make you fat due to muscle-loss and destroy your heart. My advice to people if they want to live a long healthy life, is to eat whole, unprocessed foods like our grand-parents and great-grand-parents did and avoid the processed garbage. Additionally, if you want to look weak and emaciated then run you a** off like a marathon runner. Personally, I want to look like a muscular, yet lean and well-defined or “ripped” sprinter. Short, yet intense exercise such as Metabolic Resistance Training (MRT), Metabolic Conditioning Training (MCT), and High Intensity Training (HIT, not HIIT, that’s High Intensity Interval Training) done NO MORE than 3x weekly, will perform wonders. One can use one of or even better a combination of these programs. The problem is people tend to OVER train. As you become stronger the rest periods and workout frequencies need to be extended to avoid adverse affects. People would do themselves a tremendous favor if they’d learn to ignore the vast majority of what bombards their minds daily. They’d also have more money in their wallets… after-all, that’s what these companies promoting this “garbage” are after anyways! Make the food and exercise industry rich by eating their garage and buying into every gimmick that comes down the pipe, then make the drug industry rich by taking their pills to treat the ailments caused by the crappy food and wrong exercise advice.

  87. Mark,

    I’m curious, how do you define intermittent interval training, i.e., how long, how often, etc.



  88. Mark,

    What do you consider, brief, intermittent interval training…how long, how often, etc?



  89. I do a 50 min outdoor MovNat class 2X a week and then walk/hike/play with my kids on a regular basis. MovNat has been incredible! I am faster, stronger & more skilled than I was a few months ago. My trainer throws in sprints once a week and we jog between our outdoor stations, probably a total of a mile each day.Recently my husband and I went white water rafting (the real kind where you actually paddle and steer the raft yourself) and I was surprised that we did better than my chronic cardio training sister (runner) and brother in law (cyclist). There is something to functional movement = true fitness. Not only is running/cycling damaging- it is is linear. You never learn to move efficiently outside your center. Fitness that makes life easier is so much more beneficial in the long term. If you have a MovNat trainer near you and are the kind of person (like me!) that needs to have it scheduled and be held accountable I highly recommend it.

  90. I’m guessing/hoping that the following is NOT chronic cardio, what do you think?

    At age 59, my max HR is 160 BPM, and once or twice a week I go on a five-hour bike ride, with an average HR of 120 BPM (75% of max).

    It sure is fun, it gets me off the couch, and I wouldn’t want to give it up.

  91. @Glenn Good advice, what kind of workout are you doing these days?

  92. First I have to admit that my own confirmation bias is rather strong on this subject (I love running a lot, so I run a lot), but still, I don’t think the general message of the article is fair, or accurate, so I wanted to share the following thoughts in response:
    1. The general idea articulated here regarding over working the heart through chronic cardio ignores the rather obvious point that cardio causes a significant reduction in resting heart rate. For normal people, even if you run an hour a day, and it only reduces your resting heart rate by 6-7 bpm, you are still going to see an aggregate reduction in daily heart beats. Thus, paradoxically, your heart is working less as a result of all that cardio. There is likely a point of diminishing returns, but I think it’s extremely rare for normal people to reach it.
    2. The study on AF is an interesting one, and the most difficult study cited here to explain away, as a chronic cardio guy. However, the study notes that, contrary to other references in the article, the effects of increased risk of AF from exercise are not persistent. The study concludes by stating that the increased risk of AF from exercise decreases over time, “probably due to the beneficial effects of exercise on other AF risk factors.” Other reviews of this study have concluded that the AF issues docmented here are “benign,” but please see my final point on this matter.
    3. You cite the 40% data point on athletes who develop persistent AF. However, the cited study combined both occupational and recreational activity in it’s “athlete” group and did not distinguish between types of exercise. Additionally, this study excluded individuals from its control group with other heart issues. Thus, the control group was probably healthier than the general population.
    4. The study cited on atherosclerosis has two problems: (1) The sample size is very small, and (2) the author of the study does not come to the same conclusion as you. He states the study “does not mean exercise is bad for your heart” but rather concludes that marathon running does not exclude you from potential heart trouble. He does not make the classic mistake of thinking correlation is causation.
    5. The study cited indicating walking is equally beneficial to running showed that running significantly reduced the risk of all of those diseases, and it appears that in showing the difference between running and walking they controlled for differences in BMI, which hardly seems fair. It’s kind of like saying- if we control for the benefits of running, then there doesn’t appear to be any benefits from running.
    6. Bone, joint and tendon issues are complicated matters. It seems that everyone has an anecdote that creates this causal relationship in their minds between running and long-term injuries. The research tends to show that bone issues arise when the muscles are weak, and admittedly, too many runners don’t do the necessary strengthing exercises. However, the research also consistently shows that running improves bone denisty over time. There are competing studies on what exercise is best for bone health, but running is generally good for bones.
    7. I found it rather conspicuous that you neglected to include any kind of data on mortality rates. Surely if running is so dangerous, it would decrease life expectancy, right? Comprehensive data collections overwhelmingly show that chronic cardio makes you live longer. As to the quanity of cardio on mortality rates, some have argued that there is a “U curve,” stating that there is a point of diminishing returns and once you reach around 60+ miles per week, your mortality is almost the same (but not worse) than sedentary groups. But again, that is only because of the controls placed on the benefits of running, such as BMI. Once those controls are removed, there is a nice correlation between large amounts of cardio and living longer.
    8. As a final point, I find it so interesting that so many of your readers believe that running makes you fat and unhealthy, and that their runner acquaintances are all fat and unhealthy. There seems to be strong confirmation bias in play because my anecdotal experience is diametrically opposed to theirs. But the next time I see a fat guy win the Boston Marathon, or the next time I don’t reduce waiste line and lose weight while training for a marathon (which is yet to happen), I will reconsider my opinion.

  93. I read scientific study somewhere that said that running more than 20 miles a week actually gives more stress to the body than can be beneficial, but not exercising will also put you back.
    I strive for a mile a day either running or swimming. and one day off. So that puts me at a perfect 6 miles a week: not too damaging, but not too slothful either

  94. I am new to PB. I started the Paleo lifestyle eating program August 1st. I am a 44 year old female who works nights and have for 22 years. When I began the program I was 305lbs. I am now 270lbs ( I was 264lbs on Xmas eve), I missed 3 days of exercise and had Ritz crackers with cream cheese for a Christmas treat. I am stunned that I gained 4 lbs back in a one “treat” day. It’s not sugar or milk chocolate or even ice cream! It’s very hard to comprehend the adverse effects those two items have had on my body. I have been exercising 7 days a week for one month-from the day after Thanksgiving to Xmas eve. I average about 2 lbs of weight loss per week and I’m not sure if I’m exercising properly. I have more weight to lose than the average person yet I tend to lose it at an extremely slow rate. I have been following the 7 day a week program and now wonder if I should double my efforts-maybe before and after work?? Should I do that, do the workouts need to mirror each other or should I stick with the PIC before work and just walk for an extra hour after work? I can’t sprint yet but my “sprint day” workout I walk at 3.7 mph for 30 mins and then I do a full body circuit weight lifting-I do this Monday, Wednesday, Friday and Sunday and then on Tuesday, Thursday and Saturday I walk for 1 hrs at 3mph. I usually eat 3 times a day and drink an emulsified veggie drink twice a day ( spinach, celery, cucumber, avocado, green apple, blueberries). I eat a protein and veggies for breakfast and lunch and a protein, veggie and a grapefruit for dinner. Any help and critique of my routine would be appreciated. Should I be concerned about the small amount of weight loss per week?

  95. What about Jiu Jitsu and Martial Arts…these considered Chronic Cardio

  96. So running kills? maybe i should quit track, put on 20 pounds and do nothing again like when I was 12, because THATS the key to longevity!

  97. Thank you for this article. I’m a perfect example. I am the gal that would run 5+ days a week either on the treadmill, trails, or at the local high school track running 4-5 miles at a time. To make a long story short, I recently had some blood work done and I showed a low WBC and an elevated fasting blood glucose level. I am certain it is the constant cardio to blame. I eat healthy–only carbs are rice and fruit in moderation, am thin, normal bp, normal cholesterol, etc. Through your other article, I am positive its the cortisol resulting from the excessive exercise that caused the elevated fbg and low wbc.

  98. All this chronic cardio philosophy preaching is full of belloni. The individuals who decide to go out and hammer all the time obviously have no insight of how to train correctly. Exercise should come to a point where it is therapeutic and not even considered exercise at all. Everyone has their own limits of pain, speed, workload, etc, but it is the way you go about interpreting the whole exercise environment which ultimately well define you as an athlete or recreational person looking for a burn. There is no one way to train or think a way. Interpreting exercise is not just “going as long as you can or training as hard as you can. It has to have more meaning. Like “what does embracing the pain” really mean? How do you define a rough patch when you are going through it? Do you appreciate this sort of exercise that you are bringing into your life or are you ego driven? Is it worth getting personal training services to help you achieve your goals? Questions like this that seem to have no simple answer as in “yes or no”, are the questions that you should be asking yourself.

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  100. Lets not forget about exercise associated hyponatremia which i suffered from over exercising and not adding sodium to my fluid intake regimen..I was drinking too much water and not enough sodium and the water flushed nearly all of the electrolytes almost completely low….i worked out and ran for 31 yrs now its time for a light retirement..Your body can only take so much and symptoms will creep up on you without notice..Our bodies was’nt design for all this abuse anyway so be healthy and enjoy life while you are still here..Walking and basic workouts like push ups , squats w/o weights, and etc are the best way to go ….

  101. I used to run 3 x three miles per week, I guess for about 20 years. I finally came to sense that I was abusing my body. Now, I walk two miles every day and do sprints about every ten days. This combination seems to be positive and the sprints are stimulating.and energizing.

    If you go back far enough in time, you finally reach the last of our unclothed, naked ancestors. Were they running down animals in the nude?

    Whenever possible I do the sprints bare-footed and even bare-everything–usually at special ocean beaches. When you try to do longer runs in the nude (as opposed to sprinting), the floppiness of the male genitalia can be quite aggravating and might even be unhealthy. I haven’t discussed this with other naturists, but I don’t see them running very much. Maybe this is another argument against chronic cardio, at least for males.

    When I was running, I discovered that a distance routine greater than three miles would finally lead to crippling Achilles tendon inflammation, but I was wearing shoes.

    I find it difficult to believe that ancestral humans could even survive in nature, let alone run down animals in blasting heat or sweltering humidity. Remember, those are the very climate challenges that modern humans are warned to avoid by staying inside and resting!

  102. Hi mark, So what do you think of the professional Thai boxers in Thailand who train cardio pretty much all day, from 6am in the morning a 6 mile jog, then pads, heavy bag, etc till the evening time 6 times a per week? Would you say this is bad?

    They seem to be very lean, and the cardio system is amazing.

    I have been trying to follow a easy version of there training and I must admit, I feel drain most days of the week trying to follow it plus go to work at the same time etc.

    I could see how this constant training could be catabolic and age the body especially if you past 25. But the problem is I love the training and the constant cardio, but I do feel depleted from it also.