Stability and Strength Training a la Maffetone

This post continues a little saga I have going on about the aerobic system and fat-burning in relation to other aspects of training, mostly due to my continuing work with Phil Maffetone and MAF Fitness.

People often ask how—or whether—strength training fits into the MAF method, particularly during times of aerobic base building.

My answer, of course, is YES. (Provided, of course, we usefully define what “strength training” means).

The MAF method prescribes exclusive aerobic exercise—defined as exercise that has a virtually nonexistent anaerobic component—in 3 different situations:

  • When ill, injured, or overtrained.
  • When recovering from any of the three.
  • When doing a period of sports-specific aerobic base-building.

In all other situations, we recommend that 80% of all athletic activity be aerobic, while the remaining 20% (which includes competition) can be anaerobic. But this post I want to talk about how strength training fits into situations 1-3.

The foremost problem with asking how (or whether) strength training fits into these situations is definitional. Strength training, broadly defined, is training which allows the body to exert more force into its environment. And based on this definition, some, but not all, strength training is accepted.

The big question is this: what kind of training is aerobic?

For that, we have to look at why the body recruits the anaerobic system for certain activities. The answer is twofold: (1) because it needs to produce a lot of low-end torque—a relatively high amount of power in a short amount of time—and (2) because that activity is going to last for a few seconds—before anaerobic channels exhaust themselves.

This rules out one particular kind of activity: heavy strength training where the body fatigues itself after a few repetitions. Here is your benchmark: if you can only do 5-8 repetitions before exhaustion, it is because you have recruited anaerobic channels.

This holds regardless of whether the heart rate is “low enough” to be aerobic—or hasn’t climbed enough to “be anaerobic.” So, my suggestion to people is to do strength exercises of more than 12 repetitions.

But there’s another caveat: exercises of more than 15 repetitions are not necessarily aerobic. (For example, a 100 yard sprint consists of 65 repetitions—65 steps—at best). So, for these high (15+) repetition exercises, it’s important that the heart rate reflect that the body is working overwhelmingly aerobically—at what Dr. Maffetone describes as the MAF Heart rate.

Good examples of strength exercises with the potential to be aerobic are: proprioceptive (very light load) deadlifts and squats, push-ups, pull-ups, etc.

I also often recommend stability training as an acceptable supplement for periods of “exclusive” aerobic base training. However, this comes with an important caveat: while stability training is very low-intensity work—which means that it very rarely interferes with aerobic base building—strictly speaking, it is an anaerobic exercise.

Stability is achieved and maintained by very quick, continuous movements of the small muscles of the body, in order to counteract tiny losses of balance before they become serious. Providing stability is therefore largely the responsibility of extremely fast-twitch Type IIX muscle fibers, which rely primarily on anaerobic uses of sugar in order to produce energy quickly enough.

Whenever we are training stability, we are training the anaerobic system.

Is this a problem for aerobic-only training? Not in most cases. If you think about it, “aerobic-only” running has a massive stability component: the entire body must be stabilized every step through constant use of Type IIX muscle fibers.

But these stabilizations are small enough in comparison to the primarily aerobic work of running, that anaerobic debt doesn’t rack up in a way that transforms aerobic running into “anaerobic exercise.”

The point at which stability training becomes anaerobic is when it starts raising the body’s stress levels—when it asks the body to exceed the aerobic threshold (a.k.a. the MAF heart rate).

Whenever you want to do stability or strength training without hindering your aerobic base-building, take your heart rate monitor with you. It’s (almost) as easy as that.

22 thoughts on “Stability and Strength Training a la Maffetone”

  1. Hi Ivan,
    I find this post a little confusing. I was under the understanding that say 20-30 push ups, or body weight squats would always be anaerobic regardless of heart rate. I have done low rep weight training and my HR has not exceeded MAF. From reading Dr Maffetone books he states that high weight/low reps weight training is less likely to interfere with the aerobic system.


    1. James:

      I’m surprised he would say that, unless he’s referring to something very specific. High weight produces a lot of lactate (even when the heart rate doesn’t get up there) just because there’s no choice but to use fast-twitch muscle fibers—which are anaerobic.

      But when you’re doing full-body work-outs that extend for more than 12-15 reps AND don’t go over the MAF heart rate, that’s when the body recruits the aerobic system.

      There’s very little difference in principle between running, push-ups, or bodyweight squats: from an exercise type perspective, running is a series of alternating plyometric bodyweight lunges. If anything, because of the increased stability requirement, running under the MAF heart rate would have a far greater anaerobic component than high-rep bodyweight squats under the MAF heart rate.

      (For example, there’s NO difference in the type of exercise—meaning, the system used—between running 1,000 steps and say, doing 1,000 continuous (low-height) box jumps if both activities remain under the MAF heart rate.)

      It’s important to frame high-rep exercises under the MAF heart rate not as “exercises which don’t interfering with aerobic development” but as “aerobic training,” which is for all intents and purposes what they are. In other words, what makes running under the MAF heart rate aerobic isn’t a property of running, but due to the fact that it satisfies the conditions I (but really Phil) outlines: high reps and remaining under the MAF heart rate.

      All this said, circuit training that goes above the MAF heart rate (high reps with an anaerobic component) would wreak a lot more havoc to your aerobic base-building than high-weight, low-rep exercises. Perhaps that’s what Phil was talking about.

      And by all means, I’d love if you could put Phil’s comment in a little context for me—do you remember what he was talking about?


  2. Hi Ivan
    I think I read about this in the ‘Big book of health and fitness’ published 2012 and also in this article and this one
    High reps would cause quite a lot of fatigue wouldn’t they even if HR doesn’t exceed MAF. For example doing 30 push ups or 50 squats, I wouldn’t call that an aerobic workout even if my HR didn’t go above MAF. I think Phil said that weight training and calisthenics are always anaerobic regardless of HR. There is only a very small percentage of people that would be able to do enough reps at a low enough HR to call it an aerobic workout.

    Do you not think for someone completing regular aerobic workouts that there is too much of a crossover doing high reps exercises?


    1. James:

      There wouldn’t be anaerobic crossover if they stay under the MAF heart rate.

      (Nothing in the articles you mention, and certainly nothing I’ve discussed with Phil, would lead me to think that he’d disagree with my post.)

      Let me tell you for sure that there is no way to have a high level of anaerobic function while maintaining a low heart rate (without it climbing quickly) and there is no way to have a low level of anaerobic function at a very high heart rate: the hormonal responses that create a high heart rate are the same ones that activate the anaerobic system (and ditto with a low heart rate and the aerobic system).

      Here’s an article I’ve written on this particular topic, in case you’re interested.

      Running MAF (for 30-45 minutes at a time) is an extremely high-rep exercise. There’s no difference in principle between running and most calisthenics: they are all high-rep bodyweight hybrid movements.

      For high-rep exercises, the heart rate that is “low enough” to be aerobic is the MAF heart rate. If (1) your body isn’t beginning to fatigue after 15 reps, you know that you’re using primarily oxidative pathways. And (2) if your heart rate doesn’t go above MAF, you know that it is almost certainly ONLY using oxidative pathways. Any exercise that fulfills those requirements can be called aerobic because you are getting all the signs that (1) you are using the aerobic system and (2) not the anaerobic.

      That said, what would happen to a lot of people during calisthenics is that they’d have to make a choice: once they started to do push-ups, intending to go high-rep, they’d see that their heart rate starts climbing extremely quickly (because they weren’t using aerobic channels in the first place).

      In other words, perhaps it’s possible that 99% of people wouldn’t be able to do high-rep push-ups or pull-ups as an aerobic workout because their aerobic fitness isn’t nearly high enough (so they have to use the anaerobic system). But if they COULD stay under the MAF heart rate throughout, it would be aerobic.

      Some people could do high-rep bodyweight deep squats, and others could do high-rep shallow squats with minimal weight (for example) and call both exercises aerobic if they fulfill such requirements.


      1. Do you think that low rep high weight (avoid significant fatigue) is the way to go for strength training? For an endurance athlete and the ‘average’ person?


      2. I think that it all depends on what system you want to train, and why.

        Low rep high-weight is only going to help you for running depending on how well you integrate it: if you do gait-based strength exercises (Staggered Romanian Deadlift, for example) and you use running-specific plyometrics you’ll see pretty good crossover from your strength gains.

        A good athlete (even a “pure” endurance athlete) needs to be well rounded. For example, I’m training for an ultramarathon in May and I’m developing my own lower-leg course (similar to what Bruce Lee wanted for his forearms) because the more strength and mobility I have in my lower leg, the less likely it’ll be that I’ll get leg cramps, knee pain, and the less likely that my heart rate will shoot through the roof in the later stages of the race.

        It’s a combination of slow strength, odd-impact plyometrics, all-around mobility, and eye-foot coordination.

        Will that training slow down the development of my aerobic base?

        Almost for certain. But while the overwhelming majority of my training is in fact MAF base training, (and the most important system in my body is my aerobic base), training these other systems (lower-leg plus knee) will make me a more resilient running machine.


  3. Yeah I know all about being aerobically in great shape but being not well rounded at all. About 9-10 years ago, I used to do a lot of road cycling, it was the only exercise I did at the time, barring a small amount of walking. I had zero upper body strength and not great leg strength either and poor posture/imbalances etc.

    I remember one day I went on a mountain hike with a fair amount of elevation gain with friends, I found it way easier than they did going up the mountain and I felt great at the top. However coming back down the mountain was a nightmare for me, my legs and feet not used to weight bearing exercise gave me all sorts of trouble and I was struggling as much as the others who were a lot less ‘fit’ than me. My shoulders and back were also hurting from carrying a rucksack that I wasn’t prepared for.

    Ever since then I’ve tried to make my fitness more rounded – not always successfully – but I’ve never fell back into that trap of my fitness but being only specific to one are at the expense of all others.


    1. That’s good. You’d be surprised how many people never realize that. And if you’re in any sport that is a little bit hybrid (like trailrunning) you’re going to be a far better performer if you’re well-rounded.


    1. I’m not sure. Could be, depending on context.

      Typically, he draws the line at exercises that have some anaerobic component (even if they’re a mixture of aerobic and anaerobic).

      So, in a way, he first divides exercises into substrate utilization categories (whether you’re above or below the maximum rate—not percentage–of fat-burning) as the first and most important indicator, then the presence or absence of lactate (the point really being the creation of H+ or not), and finally whether the alactic anaerobic system is active or not.

      (Usually, the first 2 converge).

      In other words, he’s asking “which systems are in play” before asking “which systems are dominating activity.”

      In a (very small) nutshell, the reason why Phil cuts up the pie that way is because it’s the simplest way to “first do no harm” (primum non nocere). Having a choice between health or performance (or having the choice of betting one way or another), Phil will bet the way of health every time.


  4. I remember you mentioning in another comment you were curious on the effect of psychological factors on the effect of stress.

    If we consider the contribution of a particular energy system an ‘effect’ of the level of perceived (and actual) stress by the brain as you suggest on this blog, then someone doing a run that should be technically ‘higher intensity’ but who does not believe that this run is harmful and who is enjoying the run, would experience less general and metabolic stress than a person who is running closer to MAF but who is fretting about the damage it may do him and who is not enjoying the activity.

    We know there are more stress hormones produced in the bodies of people who don’t enjoy exercise. So a high intensity session done (and genuinely enjoyed) may in some scenarios have the potential to cause less stress on the organism than a ‘hated’ low intensity activity.

    If our brains perceive a stress – even if imaginary – it will trigger a real physiological stress response (distress to use Selye’s term).

    MAF definitely plays into this because it introduces running to the body at a ‘safe intensity’ which is most likely to be perceived as ‘pleasurable’ and ‘non-threatening’ but of course this is not a strict rule. A few exceptions that would break it is:

    – Doing a MAF run with a compensation pattern due to injury which would still be interpreted as a threat – pace would likely be very slow because heart rate would be elevated because of the increased stress response which would be the way to recognise the metabolic manifestation of this
    – Doing a MAF run but hating the activity (i.e. you are the type of person who hates running – especially slow running). You may still get a stress response because your brain is antagonistic towards the activity (what Dr Romanov would call a failure of energy at the spiritual and mental gates – i.e. lack of genuine connection to the activity being performed)


    1. Rene:

      Sorry for the late response.

      I completely agree with all of your points, to the extent that there is very little left for me to say.

      Your point about high-intensity being enjoyable is, I think, an extremely important caveat, or rather consideration, to keep in mind when discussing the MAF Method and low-intensity training.

      I know that I need a lot of stimulation (tiring hill running), for example. When I started doing MAF training, I stopped training high-intensity cold turkey, and I began to get a little depressed. In fact, I find that during the deep winter, I do best training comparatively little but having a 1:1:1 ratio of high:medium:low intensity training. I think that this is because I need the stimulation, as per your point above.

      I think that a discussion of these subjective components of stress, as well as our attitudes towards certain types of training and how they stack up with (or against) physiological stress is a topic for at least a few blog posts.

      I think I also want to speculate on how this experience may be different for people, say, who have different distributions of muscle fibers. Will someone with a huge ratio of Type I to II(x) fibers have the same preference as someone with a higher percentage of II(x) fibers? Does this even factor?

      (I believe it does).

      Do you know of any research to this effect?

      This also reminds me of the “big monkey, small monkey” theory of movement—where some people are just wired to move more. I wonder if the “big monkeys” (big movers) are such because they happen to have greater distributions of Type I muscle fibers, and therefore the necessary neurological machinery to run them. (I make no argument as to which is the cause and which is the effect—the muscle fibers or the neurological machinery).

      And I said that I had very little to say… I hope this doesn’t overwhelm you, but it is a very interesting can of worms you opened with this discussion.


  5. Hi Ivan
    Wondered if you could answer this one. So yesterday I did some bodyweight exercises (squats, lunges, push ups etc) and I wore my heart monitor, It never exceeded 138 (my MAF HR is 154), the most reps I did of any exercise was 30. I did this for about 15 minutes (including rest periods). I have muscle soreness from this (DOMS). I never get muscle soreness (unless its a long workout) from say a 1 hour MAF run or bike ride or elliptical/rowing machine workout. However in an earlier reply you said if you can do high rep bodyweight exercises without your HR elevating above MAF then it is aerobic?


    1. It’s because you were using new muscles in new ways, and creating novel stability demands (which are met by using Type IIX anaerobic fibers). To use squats as an example, the hip, knee, and foot range of motion you are using in high-rep squats is probably twice as big as when you run. Doing those movements over and over probably got you using sections of muscle that you don’t use a lot, creating stability demands that you don’t often see, which require anaerobic function of particular muscles to be met.

      But the overall experience of the body—predominantly which fuel and which system you’re using—was undoubtedly aerobic. If it had been anaerobic (meaning that the body had to switch into anaerobic mode) you would have seen your heart rate rise above the MAF threshold.

      So, while the DOMS you are feeling correlates quite well with the places and extents that you were using anaerobic muscle fibers for stability, your heart rate throughout the workout is telling you that the main training response produced by the workout will be aerobic.

      (If you had been using anaerobic muscle fibers to power your body’s primary movement, your heart rate would have gone through the roof).


  6. Hi Ivan & James
    I loved this conversation. I find it very confusing though. I’m sure I read somewhere in the big book that all weight bearing exercise is anaerobic regardless of heartrate? I can’t get my head around all the info.

    Liked by 1 person

    1. Sarah:

      Yes, that may have been written in the book. But consider this: what is the difference, in principle, between someone running with 25 extra lbs body fat and someone with 25 lbs in a weighted vest?

      In other words, what “weight-bearing” can mean in the sense used in the book is very narrow.

      Let me give you another example: some the biggest reductions in running economy are caused by wearing heavier shoes. Does that make a MAF run in ultra trail runners “weight-bearing” as compared to a barefooter? What about a MAF run with one 1.5-lb weight on each hand (a.k.a. two 16 oz water bottles)? What if you are wearing a light running backpack?

      The kind of weight that would be allowed by the constraints I set out in this article would be probably a little more than what you would carry in a MAF run (but not an overnight aerobic run), but far less than your average strength training session at the gym.

      Under these parameters, you’d be doing majority bodyweight (bearing) exercises, and perhaps stuff such as very light-duty overhead lunges.


  7. Good information. We are embarked on Primal Endurance from Sisson/Kerns but still want to keep some strength training during the aerobic period. If we use HR to stay at or below MAF would that be the key to stay below during this period, as my HR spikes during strength even at 12-20 reps. Any further advice would be appreciated!


  8. Hi Dennis, I’m in the same boat. Wanting to be a strict MAF adherent with my endurance projects (swim,bike,run) and to stick with my 2x weekly in the gym. Sounds like the starting place is to first pay attention to HR during resistance training work outs and see where I fall MAF wise. I’m really surprised that this subject is as “slippery” as it seems to be. If you stumble across any more helpful info either from your own experiments or other sources please share.


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