The MAF Experiment

After completing the San Francisco 1st Half Marathon (SF1HM), I asked myself, “What’s next?”  Besides Ragnar Napa in mid-September, which I intend to run just for fun, I don’t have any goal races on the calendar…which is just as well considering my gimpy state.  Even though I managed to run most of SF1HM, surprising even myself, I knew that the run-walk strategy was just a band-aid to complete the race and not the way I wanted to continue training.  I wondered what would be the best way to ease back into running and rebuild my running base?

Enter: Maximum Aerobic Fitness (MAF) training, a.k.a. low heart rate training (LHRT).  The concept of MAF training was first introduced by Dr. Phil Maffetone, who, while working with elite endurance athletes — the most famous of which was 6-time Ironman World Champion Mark Allen — came up with a method that uses low HR to optimize aerobic fitness.  The basic idea is to only train in the “aerobic” zone for an extended period of time (~12 weeks) in order to build a base, upon which one can then train anaerobically (e.g., speed/track work).  The general argument is that most runners veer into anaerobic territory during easy runs, preventing them from effectively building an aerobic base.  (For more information, this document by Dr. Maffetone describes the basis of MAF training and how to execute it.)

I’ve written before about using heart rate monitors (HRMs), but the chest strap always bothered me (at best) and chafed me (at worst).  Plus I always got weird HR spikes at the start of my run.  I’d describe my previous experience with the Garmin HRM as very frustrating and occasionally painful.  When I recently found out about the Mio Link, a HRM you can wear like a wrist watch, my interest was immediately piqued.  After consulting a few online reviews and getting good feedback from Kimra, I ordered one from REI.  I’ve used it 3 times and so far, so good!  It’s not perfect, but it’s been much less frustrating compared to the chest strap.  And best of all?  No chafing!  I’ll write a more in-depth review after using it for a few more weeks.

Looking super cool with not one, but two huge devices on my wrist.

Looking super cool with not one, but two huge devices on my wrist.

Anyway, so one of the reasons I was originally turned off by HR training was the HRM itself.  Now that I had the Mio Link, the (HR training) world was my oyster!  Why was I drawn to MAF training?  Well, I first heard about it from blogger Miss Zippy, who chronicled her generally positive experience with MAF training last year.  Also, this post from a LHRT forum on RunningAhead gets to the heart of why I wanted to give MAF training a try (some editing by me):

1. What might indicate that I could really use some low heart rate training?
You have poor aerobic fitness, which doesn’t necessarily mean that you aren’t a good or a fast runner. You can be running 2:45 marathons and have poor aerobic fitness (which means perhaps you’re capable of 2:15 or faster marathons and hence you can probably run a 5k in about 14 minutes). Maybe you run a 20 minute 5k, but a 4 hour marathon. Here are some possible indicators:
a. There is no pace “relationship” between your shorter distance races and your longer distance ones. What does this mean? There’s a good explanation in Hadd’s article below, but there are some rules of thumb to the effect that, if you assume you are properly trained for the distances you are racing, your pace will decrease by the same amount, each time you double the distance of your race, usually somewhere between 12 and 16 seconds, depending probably on genetics. Therefore, on the lower end, one who runs 5 miles at an 8 min/mi pace would run 10 miles at 8:16/mile, and 20 miles at 8:32/mile. The relationship may degrade some, particularly as the distances get longer in between (say 5k to marathon, or even half to marathon), but you should still see a relationship. If the math is getting too messy for you, you can use a common pace calculator, such as that at McMillan Running and see whether your short distance times project out to long distances. If your marathon is more than 20 minutes slower than what your half predicts, then there’s a good chance you have an aerobic problem, assuming (1) you completed a full training program for the marathon and (2) the marathon was not in abnormally high heat and/or humidity or had other significant environmental factors…
c. You always burn out somewhere between mile 16 and 22 in a marathon, no matter how much carbohydrate you take in.
d. You have difficulty completing your long training runs and your pace slows down in the last several miles, just in order to finish them…
f. You are sore most of the time and possibly plagued by minor injuries frequently, or you get sick quite often…
h. You are very reliant on carbohydrates to get you through training runs.

Re: point a — McMillan predicts that I should be able to run a sub 4:10 marathon, but my PR is 4:32.  All of my shorter race times line up, from 5K up to half marathon, and the marathon is the one outlier.  Yeah, I ran two very hilly marathons this year, but I still think I underperformed at MCM last fall.  Was it due to a poor aerobic base?  Maybe, maybe not.   Another pace-based argument is that my “easy” pace has not gotten faster over the past 2 years of dedicated running, despite my 5K to half marathon PRs falling substantially.  I should point out that MAF training is geared mostly towards longer events, like the marathon.  The thought is that you can get by shorter events with an inefficient aerobic base.  However, since I’d like to eventually return to marathons (or longer), building a solid aerobic base is fundamental.

What are the purported benefits of MAF training? Again, from RunningAhead:

3. What benefits might I reap from low HR training?
a. You’ll train your body to use fat for fuel at a reasonably fast running pace (reasonably fast means different things to different people). With enough of this training, this means that you can preserve your precious carbohydrate stores throughout very long races. You can avoid “the wall” and “bonking” in marathons and longer races.
b. Running at a much lower level of effort, aerobically, will be much less taxing on your body, even if you end up as fast as or faster than your original training pace.
c. You will strengthen your legs and hips tremendously.
d. You will be adding an additional fuel tank that you didn’t realize that you had.
e. You will develop significant aerobic speed, which means you may reach speeds that you were doing before low HR training at very high level of effort, with ease.
f. You will eliminate as strong of a reliance on carbs during most races, and certainly training runs.

I’ve also read that, because you tap into fat-burning more efficiently with MAF training (and consuming less fuel on long runs), most people lose a considerable amount of weight with this method.   There’s also quite a bit of anecdotal evidence on the interwebs of MAF success stories (examples here, here, and here).  Maybe it’s my science background, but I enjoy being a one-woman experiment when it comes to running.  And y’all know that I love my numbers/data.  Thus, since I don’t have any goal races coming up and because I’m coming back from injury anyway, I figured, what do I have to lose by giving this a try?

Before I go tell you how week 1 went, let’s discuss the downsides of MAF training.  The biggest one is that it requires very slow running, usually on the order of 1-3 minutes slower than your current easy pace.  Why so slow?  The point is to guarantee that you’re only working your aerobic system and not crossing into anaerobic territory.  The slow running can get boring, but it also means missing out on social runs with running buddies and less racing.  (Technically, you’re not supposed to race at all, but I’m willing to break a few rules.)  Second, I find the “180 formula” (see below) sort of arbitrary, but I’ll give it a shot and see what happens.  Third, always having to wear a HRM (and Garmin) means that you become dependent on these gadgets and can never go on a “naked” (tech-free) run.  And finally, it forces you to focus on your HR and not on how you feel, which can also be annoying.

After 3 LHR runs this week, I’ve been pleasantly surprised at how these cons haven’t bothered me at all.  The slow running has actually been nice, because unlike a typical “slog”, where I usually shuffle along, I’ve been focused on running slowly with good form, which in turn has been better for my “injuries”.  In fact, I’ve felt really great after all 3 LHR runs this week —  no aches or pains to speak of, which is something I haven’t been able to say in months.  I’ve also found concentrating on HR instead of pace to be less stressful and more purposeful.  I think that’s due to me associating pace with performance/fitness, whereas HR is more abstract in my mind.

Anyway! So what are LHR runs like?  My goal max HR is 138 (180 – 37 {my age} – 5 {recent injuries/fitness loss}).  For any run, the goal is to warm-up for 12-15 minutes at max minus 10, so my warm-up target HR is 128.  Then, I run as close to max HR as possible without going over, and finish by cooling down for 12-15 minutes, which means ramping back down to 128.  I haven’t been great about cooling down because I never think that far ahead, but otherwise my runs have gone as planned.  As predicted, my pace at max HR is slow — usually between 11-12 minutes/mile.  The funny and surprising thing is that I feel like I’m working quite hard despite the slower pace.

Today, I did my first MAF test, which is suggested every 4 weeks to monitor aerobic fitness and progress.  It’s recommended that the test be done on a flat course with as few variables as possible, so I went to the Hayward Shoreline, which has almost 0 elevation change.  The test is comprised of a long warm-up at HR of 128 (I did 2 miles), 1-5 miles at max HR (I did 4), and cool-down (1 mile).  The numbers:

Warm-up miles: 12:32 (HR: 123) and 12:23 (129). Cool-down mile: 13:03 (134).

Test miles and HRs:
1 – 11:23 (135)
2 – 11:37 (137)
3 – 11:43 (137)
4 – 12:01 (137)
Avg: 11:41 (137)

The first test serves as a baseline rather than as an indicator or assay.  I won’t know until the next test whether MAF training is working, but I’m really curious to see how it goes (or doesn’t)!

And because this has been a super runnerd geeky post, here’s a photo of our new cat, Puff Daddy:



Howdy! My name is Jen and I live in the San Francisco Bay Area. I like to eat, run, and blog, but not usually at the same time.

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17 comments on “The MAF Experiment
  1. Sherry says:

    Firstly, your new cat is gorgeous!
    Secondly, I find the 180 kind of random too, but I suppose it brings the goal max HR down to a true base level, mine would be 127. I have been HR training using a % of Working HR (max HR – resting HR) which for me means running between 143-164 bpm – substantially higher than 127 but at least I am running! I usually average 159bpm, if I try to go slower I find my form really suffers (slow cadence, long foot-on-ground time) and I often wonder if that contributed to my injury. I’ve often thought about MAF but I’m not sure I have the patience. Hopefully you have great results from it – and convince me otherwise!

    • Jen says:

      It seems like the 180 formula is just a jumping-off point, since HR is so variable between individuals. Die-hard LHRT people say to never deviate from the 180 formula (except if you’re under 20 and over 60), but I feel like % HR is probably just as effective. I think they say 70% HR is equivalent to the 180 formula for most people. In the end, everyone needs to figure out what works best for them and what their running goals are. Like, for you, it makes no sense to run too slowly if you feel like your form suffers.

  2. Mike says:

    Admittedly I know less than I should re: training by heart rate (though I keep telling myself I’ll look into it), so look forward to following your progress and learning more about MAF training.

    Do you listen to the Natural Running Network podcast? Its host, Richard Diaz, is an old-school coach here in SoCal who swears by heart-rate training, and talks about it in the podcast whenever he can (often at great length, while his guest sits in silence). The episodes can be hit-and-miss, but one episode back in May featured a heart-rate training Q and A. The show is also sponsored by Mio, so if you’re interested in learning more about heart-rate training, it may be worth a listen. Apparently Larisa Dannis, a recent guest on the podcast and the women’s runner-up at Western States this year, trains entirely based on heart rate.

    And speaking of interesting data, have you tried strapping the Mio Link on Sasha’s wrist and comparing his “before Puff Daddy” and “after Puff Daddy” heart rate profiles? PD’s an awfully shiny new presence to have to compete with…

    • Jen says:

      Thanks for the links/podcast recommendation, I’ll have to look into it! I know a lot of ultra runners swear by HR training, but I wonder how many stay strictly below their aerobic max.

      That would be a great experiment to do with Sasha. I’ll have to work with Mio to develop a cat prototype!

  3. Grace says:

    Puff Daddy? Fluff Daddy, more like. Cat looks like a rascally furball!

    The MAF training regimen makes sense to me. Like you, I was following Miss Zippy’s experiment. The only caveat i’d have is that 180 is not a hard-and-fast rule because every individual is different and I believe there are gender differences too (erm citation required…I have to go hunt for it)! Even when I am very fit I have a (relatively) bunny-rabbit heart rate.

    Also the ‘Is LHR training for you?’ list was amusing…my marathon time is way, way slower than my pace at other distances, but I can definitively say it ain’t from hitting the wall! 🙂

    • Jen says:

      Yes, I think you’re right about gender differences. Women and smaller people generally have higher HRs, I think. The 180 formula is actually one of the main reasons I stayed away from MAF training for a while — it seemed too “one size fits all”. I feel like the key is to not be so rigid and to be able to adjust your max HR to what you think works best for you. From what I’ve read, it seems like people actually benefit more from targeting HRs lower than their 180 formula HR — I guess that just ensures that they stay in the aerobic range.

      Puff Daddy *is* a rascally furball! He’s been eating our other cat’s food while he’s not looking!

  4. Jan says:

    That is really interesting! I need to look into that maybe given how injury prone I’ve been lately. However, like you said, I might need to give up social runs w/ some of my buddies. 😦

    • Jen says:

      Sorry to hear that you’re still dealing with injuries! It totally sucks to give up social runs. Would any of your running buddies be willing to go on hikes or run/walks? I had assumed that no one would want to slog along with me, but I’ve had several friends offer to hike or jog at my glacial pace with me.

  5. Cathryn says:

    I can’t wait to see how you this goes, it sounds pretty amazing. And oh that cat!!!

  6. Huh, this is really interesting! I’ve been curious about MAF training since I read about it on runthisamazingday, so thanks for this thorough overview. How is it, mentally? Is it very boring?

    • Jen says:

      Mentally, it’s very challenging. As previously mentioned, I have to put my ego on the shelf and not think about my paces or how slow they are. Long runs have been the toughest because of cardiac drift — i.e., the longer you run, the higher your HR is, the more you have to slow down to stay under the max aerobic HR target. By the end of 2 hour long runs, I’m moving at like 13-14 min/mile — glacial!! I guess the other part that’s challenging is not seeing immediate benefits. I was hoping that my pace would come down 5-10 seconds per week, but so far it doesn’t look like it’s budging. But then again, I’ve only been doing this for 2 weeks, so I have to constantly remind myself to be patient… which is really hard. Physiologically, it takes 12 weeks of consistent running to build a good base, so I have to keep my eyes on the prize.

      One thing that has been helpful for me is to focus on running time and not mileage. Currently, my goal is to run 4-5 hours a week. And on a positive note, I ran/jogged 22 miles last week, which is the most I’ve run (and not run-walked) in months, and almost completely pain-free… which is actually a big deal, but I took it for granted until I really thought about it.

  7. […] can already tell that my MAF training experiment is going to be full of highs and lows.  A little over a week ago, I was in a funk after my 2nd […]

  8. […] back to my adventures in MAF training!  You may or may not remember that I did my first MAF test 4 weeks ago, during which I got an idea of my baseline fitness.  It’s recommended that MAF testing be […]

  9. […] we are, 8 weeks into my MAF experiment, which means that I just did another MAF test this past Saturday.  I knew that going into the […]

  10. […] I did my 4th MAF Test as part of my MAF Experiment.  A brief recap: I started doing MAF (or Maximum Aerobic Fitness) training in August as a way to […]

  11. […] I move on, here’s a quick summary of my thoughts on my MAF Experiment and also what I’ve […]

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4/28/19: London Marathon

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