When endurance training works

I’ve written at length about MAF training, or more specifically, the ineffectiveness of low heart-rate training especially when linked to age. It seems to me that most people don’t understand what is meant when it’s said building endurance will help them get faster. I hope this post will be useful by giving an example of when it works and how it affects your runs.

In September 2017 I ran the Solent half marathon in 1hr36. I set off way too quickly – running the first quarter mile at about 6:20/mile pace and the first mile coming in at 6:41. After that it was a slide as my endurance failed me and I got slower by the mile. Around mile 9 the course turned up hill which made the slowdown even more pronounced until I managed a final effort to the finish line. Here’s a graph clearly showing the decline!

After a week of recovery running, I embarked on building my endurance using my own method which doesn’t involve having my watch beep at me to stay under a certain heart-rate. Following a simple schedule of one hour Steady endurance runs on Tuesday and Fridays with a long run on a Sunday, I slotted in recovery runs lasting up to an hour on the other days. This gave me a total of around eight weeks where I was hitting around 60 miles – with a peak of 69 in mid-November.

Over these eight weeks, I took only one rest day and yet my legs were always ready to run the key Steady and Long runs. Each run I marvelled at how well it went and doubted that I would be able to repeat it a few days later. Yet each run came up and I never felt too tired or got injured. I could barely believe how my legs kept churning out the miles.

I ran the half marathon on September 24th where the pace began at 6:41 and just got slower. Two months later, on November 29th, I ran along the seafront for nine miles and here’s what the splits looked like:

After a first mile at 7:14 where my body was still warming up, each subsequent mile came in at 7:01 or faster. Mile 4 was the fastest at 6:51 but I barely slowed down. The time for these nine miles was 1:02:48 (avg. pace 6:59/mile).

Compare that to the first nine miles of my half marathon which were 1:03:57 (avg. pace 7:06/mile). You might think there isn’t much of a difference but remember this was a training run, not a race. I was doing this sort of run every three days, not taking a recovery week after it.

Remember that by the ninth mile of the race I was down to 7:39; here I was still at 7:01. The gap would only have got wider – it’s very clear to see here.

I ran a hard parkrun three days later on December 2nd. My last one had been in mid-August when I clocked 20:29; this time it was 19:37 – almost a minute faster. On my Steady runs I was only hitting a fastest mile at around 6:50/mile, on parkrunday I was able to push harder and run at 6:15/mile even though I’d done no training at that level in months.

Mile 1Mile 2Mile 3Last 0.11
19 August06:1606:4306:4906:1020:29
02 December06:1306:1106:2305:3619:37
(Apologies for using mile splits on a 5k but it’s easier for reference against the other data)

At both parkruns I set off with a fast first mile of around 6:15 but, before the endurance training I slowed significantly in the second and third miles just like when I ran the half marathon. On the latter parkrun, the endurance training came to the fore and while I still set off quickly the decline by the 3rd mile was much less. I remember running that day and it feeling like I had a booster on top of the endurance runs I’d been doing – an extra 30-40secs/mile dug out for when I raced.


It’s clear I was able to get faster through endurance training.

While I never trained to heart-rate I will highlight that on Solent 1/2M I averaged 163bpm; while on my Steady run of Nov 29th I averaged 149bpm with a max of 158bpm. I certainly wasn’t pushing as hard in training as I did during the race.

On the Steady run, which was typical during this training block, I spent over fifty mins at heart-rates over 150bpm which demolishes the age-related MAF formula’s calculation that as a 46-year-old man I should have been training to a heart-rate below 134. I certainly felt no strain and there were no health consequences incurred from doing so.

The other thing to note is the benefit of the endurance work was only possible because I already had the speed. At parkrun in August my fastest mile was 6:16 and, at the half marathon it was 6:41. All the endurance training did was train the body to hold onto that existing speed for longer. This is the nature of the endurance training – faster times occur because you are more consistent in your mile splits; not because it digs out more speed. Throughout this period, I never went to the track or did any interval work; I just worked on endurance.

MAF Training Review – Part 5 Why MAF why?

This post is the 5th in a series of five. Other posts can be accessed from the Readables menu tab.

My previous posts on MAF training are among the most popular I’ve written. Recently I’ve been wondering WHY people keep raving about this method before going quiet on it. It seems like every three or four months there’s someone on Strava or Youtube giving it a go. That I get so many people reading my posts about it is an indication they’re researching it.

Although my experience of Maffetone training was relatively recent, my first experience of low heart-rate training dates back to 1995 using the method in John Douillard’s “Body, Mind and Sport” book. I trained to a heart-rate max of 130bpm for a few months and got nowhere. I came back to it on at least three more occasions in the next decade and a half, still no success. I’ve been trying to remember back to when I first picked up Douillard’s book and what enticed me to give his method a try. While he’s not MAF, the premise is the same – build an aerobic base to get faster using low heart-rate training.

1) Grand promises

When I first read the Douillard book I was seduced by the grand promises it made. The story of Warren Wechsler, a 38-year-old guy who easily ran a 2hr53 marathon within eighteen months of starting the programme and could run six minute miles at heart-rates below 130bpm. Or the high school girl sprinting the last half mile of a cross-country race with her heart-rate maxing at only 140bpm. There was other stuff in the book about getting “into the zone” which tempted me and it all sounded great.

While MAF is never quite as brazen as this, his method also uses testimonials to make grand promises. Here’s a story straight out of his Big Book of Endurance Training and Racing (p.93-94):

Marianne Dickerson was a 23-year-old marathon runner who’d won the silver medal at the 1983 World Championships in a time of 2hr31.  She struggled in the following year with a lower back injury until meeting Maffetone. Using the aerobic heart-rate he calculated for her, she found she couldn’t run a mile in under eleven minutes. Over the next eight weeks she changed her diet and kept her training to MAF-HR. She picks up the story “Each week, I noticed my pace became quicker as I was able to run faster within my aerobic limits. After eight weeks of base building, he had me enter a 10K race. I was shocked at how easy the race felt. And my finish time was a personal record of 33:02. Miraculous, I thought, given that a mere eight weeks ago, I could barely run a mile under eleven minutes aerobically and now I was running 6.2 miles at an average pace of 5:18/mile.”

Wow! Who doesn’t want to be running 10K races in thirty-three minutes off a couple of months’ training?

2) Endurance not speed

MAF training is a method that will get you running faster. But what does the word “faster” really mean?  When you hear faster, you imagine your parkrun going from thirty minutes to twenty minutes or even quicker. (Fill in whatever a major improvement is for your level). After all, this is the hope which the Marianne Dickerson story is giving you. Except, this isn’t really what MAF training can do for you.

The actual benefit of MAF training is that it will build endurance – which is being able to hold onto a pace for longer. Let’s say your thirty minute parkrun has kilometre splits beginning at 5:30 and slows down by fifteen seconds each subsequent kilometre thus 5:45, 6:00, 6:15, 6:30. All MAF training will enable you to do is run every kilometre at 5:30 pace and therefore reduce your time to 27:30.

It’s not a lie or incorrect to refer to this as helping you get faster because your parkrun has improved and many would be happy with knocking two and a half minutes off. The problem is continuing with MAF training from there isn’t going to help you get any faster because it won’t add any speed i.e. your fastest kilometre will continue to be around 5:30/km.

To add speed you need to do some interval work or hills and these require you to exceed your MAF-HR which, by definition, is no longer MAF training. If you don’t do the speedwork, you’ll be running around to a limited heart-rate for months and seeing no further improvements.

The reason it worked for Marianne Dickerson is she already had her top speed in place and simply needed to refresh the endurance to get back to running 10K races quickly in a matter of months.

3) Simplicity

The simplicity of the age-related formula is a big temptation. It all sounds so easy – “All you have to do is take your age away from 180 to get your MAF heart-rate then avoid going over that number when you run”. It couldn’t be easier. People like things which are easy.

When I first bought a heart-rate monitor it came with an instruction guide to setting zones. 60-79% for aerobic, 80-90% hard workout, 90-100% hard anaerobic or some such. But you needed to know your maximum heart-rate and do some mathematics to set those zones. Then you needed to structure your weekly training to train within the appropriate zones and it was all beginning to get complex and need some thought which is one reason I never did it.

The encouraging simplicity of MAF is you just go out and do every run using the same MAF-HR.

4) Science and technology

The technology of using a heart-rate monitor suggests this is science and therefore it must work.

The reality, as I stated in my The Good, the Bad and The Ugly post is there is no science behind MAF’s formula and the heart-rate monitor can’t identify when you’re going aerobic or anaerobic to help you train effectively.

There is no science behind MAF’s age-related formula, only coincidence.

5) MAF training gives people who train too hard a break.

It’s a revelation to many people how easy an easy run should really be. I reckon many people who take up MAF training find it gives them a chance to have a break from their usual training regime. Amateur runners are notorious for pushing sessions too hard, week-in week-out, so when they discover the formula with all its promises, and find out how easy the runs feel it’s a revelation.

6) It avoids coaches and planning

Many runners have a routine or follow the training of the people they run with. When they’re not getting faster, they’re looking for a quick fix (as MAF promises) and don’t want to plan training sessions or ask for help. The simplicity of MAF training avoids both these things.

7) “It’s going to take a while to see results”

Many MAF trialists start off patiently because they’ve been told it takes a while to see results. This is both true and false. If your endurance training is working, you should see some kind of change within weeks. When I’ve gone back to base training, I start to see or feel some kind of improvement within two to four weeks. Training begins to feel easier, my legs get their spring back, heart-rates on similar runs can go up (“yes up!”) or down, you might begin to see better pace at the end of longer runs. These things begin happening within a matter of weeks if you’re getting it right.

On the other hand, if you’re an established runner building your endurance base from scratch, it will take a while for it to impact your races. There’s probably a big gap between your aerobic pace and your race pace. Arthur Lydiard stated it takes three years to see a marked improvement, but you will see an improvement in the first year and a greater one in the second but it’s later that you begin to see the major benefits.

8) Get rich quick

Like a pyramid investment scheme or multilevel marketing sales, you only hear from the people saying how great it is in the beginning. This encourages others into the fad. When they’re starting out on their get-rich-quick scheme they’re enthusiastic and motivated until they realise it’s not working and slink off quietly into the sunset.

There are rarely dissenting voices who say “I tried this and it didn’t work”. Even then, outside of my own posts, I’ve never seen anyone lay out what they did in their training, detail the ineffectiveness of MAF training and give solid explanations for why it didn’t work.

There’s many people talking about MAF training and what it promises but rarely do you hear from those same people when they’ve given up on it.

NB This isn’t to say well-executed endurance training is a get-rich-quick scheme, it’s not. I honestly believe Phil Maffetone was able to help athletes improve their endurance and times using his methods. I just don’t believe those methods are as simple as the age-related formula has people believing.

Why do they give up?

They get bored of jogging around at low heart-rate numbers doing the same thing every day and waiting for results. Ironically the simplicity of the system becomes its Achilles Heel as lack of variety leads to boredom. For most runners, a month of training is a long time and if they haven’t seen improvement by then, they start to lose interest (and rightly so in my opinion). If they have a race coming up, it takes priority and they go back into speedwork or workout mode.

For some people, the low heart-rate number has them jogging at excruciatingly slow places. There are issues of ego and embarrassment about being someone who usually clips along at seven minute mile paces having to slow down to barely quicker than walking pace. They start to fudge the numbers either stating the formula must be wrong because they have a high maximum or allowing themselves to regularly go over the limit as long as the average is lower than their MAF-HR. If they don’t see quick results, they bail on the method.

Ultimately the main reason runners give up is because it doesn’t deliver the grand promises. I’ve never heard of anyone successfully using MAF training outside of the books. Maybe there is someone for whom it works but I’ve not met them.

If you’ve given MAF training a go – please comment and let me know of your experiences – success or failure. Why did you give it a try? How long did you try it? What caused you to give up on it?

MAF Training review – Part 3 The Good, The Bad and The Ugly

This post is the 3rd in a series of five. Other posts can be accessed from the Readables menu tab. So far, in part 1 I discussed how the real Maffetone Method is a holistic system for living but most people are only interested in the low heart-rate training formula. In part 2, I plodded through my experience of nearly six months’ worth of MAF low heart-rate training. Now I look at what’s right and wrong with this as a training system. Let’s get critiquing …

My own experience with MAF training was not very positive and within this post, I’ll explain why. But my aim is not solely to run MAF training down, I don’t see Maffetone as some kind of salesman selling snake oil or a “get quick rich” scheme – he knows about health. As a chiropractor of many years’ experience there are some good things to be learned from his book and there are certainly some athletes who have had success working with him. So let’s begin by seeing what we can gain by understanding his work.

What MAF can teach you

Benefit 1 – Understanding Aerobic and Anaerobic training is very useful

Maffetone explains training can be fuelled in two ways – aerobically and anaerobically. Aerobic uses oxygen and is very efficient, anaerobic works independently of oxygen which causes fuel to burn quicker and creates waste products that limit or fatigue you.

While anaerobic energy enables you to hit your top speeds – after all sprinting uses it extensively, Maffetone explains the detriments of training anaerobically. It increases the acidity of the body, requires more energy and can have major downsides in terms of poor sleep, appetite, weight among other things.

Understanding that too much anaerobic training at the expense of aerobic training is an important concept to grasp and is quantified these days in Stephen Seiler’s 80:20 rule. Perhaps because Seiler’s research only appeared recently, the older MAF low heart-rate training is proposing something closer to a 100:0 ratio.

Benefit 2 – Understand the Aerobic/Anaerobic threshold

Scientists will tell you there is no definable “Threshold” where you cut over from aerobic to anaerobic mechanism. Your exercise is always fuelled by a mixture of both. While this is technically true, the reality to you as a runner, is there are times when it’s clear you’re relying on one type more than the other. Stephen Seiler found research indicating most sub-elite runners are training anaerobically 70% of the time and need to bring this down to 20%.

Benefit 3 – The premise behind lower heart-rate training is right

I remember while running Bournemouth Bay Half Marathon in April 1996, commenting to a chap running alongside me that my heart-rate was averaging 177bpm and he replied “That sounds rather high”. We were only running at about eight and a half minute miles and I went on to finish in 1hr51. This is exactly the sort of heart-rate that people Maffetone met were always training at, and what MAF training is designed to address and bring down. Had I been successful in getting lower heart-rates, I would have seen my half marathon times begin to improve. That’s what MAF low heart-rate training is all about and why the premise is right.

At the other end of the scale, I’ve run at nine minute mile pace with my friend Simon, who is a 2hr34 marathoner and his heart-rate was only 110bpm. That’s the heart-rate of a man who has built his aerobic system and is burning fat.

Somewhere between these two extremes lies the aforementioned threshold between aerobic and anaerobic where you want to do much of your training. MAF suggests this occurs at a heart-rate that is calculated using your age but as I’ll explain later, I don’t. The premise is correct, very low heart-rates e.g. 110bpm are burning fat; heart-rates up in the 180s are burning sugar, or more correctly the glycogen and glucose that is sugar-based. Training somewhere between these two endpoints will lead to effective training.

Benefit 4 – Warm-ups are great

Maffetone devotes a section of the book to getting athletes to spend at least twelve minutes warming up. Genuine warm-ups are one of the most under-rated things in distance running training.

Most people start their runs quickly and then slow down to a pace which feels comfortable. The problem is that by starting fast they activate lots of anaerobic, sugar-burning muscle fibres which are then able to kick in every time they’re needed. This is one of the reason why people say they can’t run slowly. Those anaerobic muscle fibres are the thing that cause high heart-rates.

If you start a run slowly, you only use as many muscle fibres as you need to get the job done and can stay aerobic much more easily. This is reflected in lower heart-rates and focuses the training on building the aerobic system.

Benefit 5 – Low HR training can teach you the feel of Easy runs

Most coaches agree “running your easy runs too fast” is the number one mistake runners make and it’s not even limited to amateur athletes. Even elite athletes can do it and send themselves into a spiral of overtraining and underperformance.

If you pay attention to how easy your low heart-rate training runs feel then you can begin to understand just how easy they need to be. Remember easy is a feeling not a pace.

Benefit 6 – MAF Method would probably help with the “obesity crisis”

While MAF makes no claim on this I found when I built my aerobic base up (using my own method) I stopped being hungry. I still ate carbohydrates but I could return from an 18-mile early Sunday morning run at 8min/mile pace, eat a bagel and banana and then not get hungry until the afternoon. I actually found myself having to schedule meals to avoid missing them! My lifelong desire for cake, crisps and sweets which had been a large part of my diet naturally ebbed away. It returns whenever I start to train more anaerobically.

When you consider there’s a sizeable proportion of the population who don’t do regular exercise, and they get out of breath quickly when they do, it suggests their aerobic systems are underdeveloped. If their aerobic systems are underdeveloped then they’re going anaerobic in even the simplest activities and they’re burning up sugars from the muscles which need to be replaced. This leaves them hungry and prone to eating quick-fix sugary food to sate their appetite.

If people were to develop their aerobic system then they could go about their day-to-day activities without ever needing to dip into anaerobic energy at all. This would give all the benefits Maffetone details around not revving up the central nervous system and getting stressed. It would lead to better fat-burning for fuelling activities and avoid hunger.

My doubts about MAF training

I’m looking here almost exclusively at training to a heart-rate determined by the age-related formula. That’s the part that’s grabbing most people’s attention and they’re promoting as MAF training. (It occurs to me as I write this that I’ve been referring to it as “low heart-rate training” which of course it probably isn’t for anyone in their twenties but allow me that indulgence).

A) The science behind the formula is debateable at best

At its simplest the MAF formula is suggesting that as you get older, you get better at burning fat. But, to my knowledge, there is no known mechanism to suggest all 20-year-olds will burn fat at 160HR, 30-year-olds at 150HR, 40-year-olds at 140HR, 50-year-olds at 130HR and 60-year-olds at 120HR. Even with the small 5-10 beat adjustments these numbers have no scientific basis.

I’m inclined to believe he’s substituted age for experience.

Typically a 50-year-old runner with thirty-plus years of experience will have a bigger aerobic base than a 20-year-old runner and this is why training at lower heart-rates may be better for them. The latter’s youthfulness does give them the ability to engage high levels of muscle which push the heart-rate higher than an older runner who, with the natural decline from ageing, has lost some top-end speed.

While the human body declines with ageing, it is not so abrupt that a forty year-old needs to train at twenty beats lower than a twenty year old. At close to age fifty, I’m running aerobically at 150HR where the formula predicts I shouldn’t run quicker than 130HR.

B) Maffetone defines aerobic exercise as fat-burning and anaerobic as sugar-burning

While this is a good simplification, it’s nothing like the science. It’s accurate to say the anaerobic system is sugar-burning but the aerobic system is a mix of fats and sugars. It’s possible to build an Aerobic system that is burning high levels of sugars – this is a process called Aerobic Glycolysis (also known as Slow Glycolysis) and generally equates to your marathon pace.

In fairness to Maffetone he does hint that some of the aerobic system’s energy will come from sugar – for example on p.23 he shows Mike Pigg running at 127HR as getting 30% of his energy from sugar. It’s when Pigg gets to 153HR that he’s beginning to go 50-50 between fats and sugars.

It’s difficult to get the body to pure fat-burning other than by being careful about what you eat. This is why a significant part of the bigger Maffetone Method (not just low heart-rate training) has you looking at your nutrition and trying a two week no refined carbs regime. But if you change your diet to remove most of the sugars then you don’t need to train to a heart-rate as you only have fats available to burn.

C) Fat-burning is only required for long distance events

Building the aerobic system is important for all distance runners but fat-burning (remember the aerobic system can also be sugar-burning) is only useful for racing events lasting longer than 1 – 1½ hours. That means twenty mile races, marathons and ultras.

Fat-burning can be useful for half marathons but when your times are closer to the top end of the field then you’re unlikely to run out of glycogen stores. If you’re running middle-distance, parkruns or 10Ks fat-burning isn’t going to help your race times.

It can be useful to develop your fat-burning for training runs as this leaves your glycogen stores in tact for harder efforts. This is especially true for cyclists and triathletes who do many more hours of training and therefore find it easier to deplete their glycogen stores (i.e. bonk or “hit the wall”) and these athletes seem to have made up a significant portion of Maffetone’s clientele.

Basically, fat-burning is unnecessary for racing the shorter distances but building a strong aerobic system, mainly based on aerobic glycolysis, is important.

If you’re a young runner training to a high MAF-HR then you aren’t solely working on fat-burning, you’re working on improving aerobic glycolysis. The MAF training will work but not because you’re fat-burning as he suggests.

D) Older runners can struggle with low heart-rate training

When I was forty-two, I trained to a MAF-HR of 138bpm which usually meant running no faster than 9min/mile. As I’ll show in a future post, my current training has progressed by running at heart-rates in the high 140s and 150s which are far in excess of my MAF-HR.

To progress you have to train at the point just before you start to increase the use of anaerobic energy (reread Benefit #2). This has variously been called the Anaerobic Threshold, Aerobic Threshold and Lactate Threshold among other names. It doesn’t matter what it’s called but it does matter that you’re training at it if you want to get faster.

As she approached age thirty, Paula Radcliffe was setting the world record for the women’s marathon, an event which is run almost exclusively using aerobic energy. She was running at heart-rates in excess of 180 where a MAF-HR would have limited her to 160-165 bpm.  Imagine therefore how limiting it can be for the oldest runners expected to train at 120-130 heart-rates but won’t see any improvement if their threshold heart-rate is higher.

E) It’s tough on Fast-Twitch runners

You may have heard of fast-twitch and slow-twitch muscle which are respectively good for speed and endurance. While slow-twitch is perfect for aerobic exercise, fast-twitch naturally works anaerobically and requires extensive development to improve aerobically. Even then it is less efficient than slow-twitch muscle and can easily switch back to anaerobic mechanism. This is the reason why after a weekend of sprints and drills, my own MAF training went backwards.

Of course, this is why heavily fast-twitch runners are better suited to sprints and shorter distance events. But even a mile world record holder like Peter Snell could run a marathon in under 2hr40 despite sitting down at the side of the road and taking a rest break after the first twenty miles! It’s not impossible to build a good aerobic base with fast-twitch muscle just harder and it’ll usually incur higher heart-rates which makes the MAF age-based formula less appropriate.

Naturally fast-twitch runners will retain FT muscle longer into old age so when you combine this with the previous point (D) you can see why I struggled with MAF training and why others may too.

Note this is why MAF training will likely work very well for slow-twitch runners who naturally run with low heart-rates and actually struggle to get their heart-rates up. They can push harder on all their runs without exceeding MAF-HR (unless they’re Paula Radcliffe) without going particularly anaerobic. But then they don’t particularly need a heart-rate monitor to hold them back.

F) Female runners may struggle with it

The female runners whose training I’ve observed tend to run with higher heart-rates and certainly this was the case for Paula Radcliffe (see last paragraph of point D).

In his book “Better Training for Distance Runners”, Peter Coe states that women tend to have higher heart-rates because their hearts are physiologically smaller and therefore pump less blood with each stroke which is compensated for by beating quicker.

Maffetone makes no distinction in his system for male or female runners or those who have higher maximum heart-rates. He’s very clear that maximum heart-rate don’t matter.

G) MAF training is not a system for training a beginner

It’s likely that if you try to run below a MAF-HR as a beginner runner you will quickly be exceeding it at all but the slowest pace. This could especially be the case if any of the previous three points apply.

At age 47, I got injured and after a three month layoff I resumed training. In my first week I was barely able to run ten minutes per mile without finishing runs at heart-rates in the 160s. I generally took my runs as easy as I could and my parkrun time was under twenty-four minutes after a month but I was rarely running below my MAF-HR. If I had stuck to a MAF-HR, there’s no way I’d have been at that level after a month and running sub-1hr40 half marathons six months later.

H) MAF training says nothing about volumes of training

While the book focuses on the intensity of your runs, it doesn’t give any concrete information about how much training to do; only in broad terms about “less is more”.

I dived in and did too much relative to my ability with 8-10 hours each week but I’d read elsewhere that low heart-training allows you to do as much you want. It turns out I simply didn’t need to be doing that much training.

How much you should do depend on what your body can take. When you’re beginning, you only need relatively short runs to create a training effect. A couple of hours spread out through the week will have a big effect. I currently train from 5-7 hours each week and get decent benefits from it. My friend Simon, the 2hr34 marathoner trains closer to 10 hours each week.

I) MAF training is not a speed system, it is about creating speed endurance

Although MAF training promises to get you faster, more often than not it’s helping you to race longer distances faster. It’s a subtle distinction. What I mean is that while you might be able to run one mile all-out in eight minutes, MAF training will simply enable you to build the endurance to do a parkrun or 10K at this pace but you won’t necessarily be able to run a single mile faster. That will only happen when you do some speed training. If you only ever do low heart-rate training, you’re eventually going to come up against a brick wall of no improvement.

This is why my first three months of Maffetone training saw no improvement in their average pace but why after I did a parkrun, it picked up – the parkrun acted as a speed session because I went all-out at it and my natural fast-twitch muscle kicked in.

If you never work on your speed side you’re never going to reach your potential. Maffetone does allow for some anaerobic interval workouts but you’ll only know this if you read the book. There’s not much details on these intervals and speed workouts or how they relate to different race distances.

Real world problems with MAF training

I’ve observed many runners who get enthusiastic about MAF low heart-rate training but I struggle to think of anyone who has benefited from its long term possibilities. This isn’t necessarily because MAF training is flawed but because the runners following it, don’t really follow it. Here are the common issues I see.

i) Runners don’t follow MAF training long enough to see the benefits

The aim of the MAF training is to build the aerobic system and this happens by the body improving the aerobic capabilities of slow and fast-twitch muscle. Biologically, muscle fibres start to grow more mitochondria which improve the use of oxygen; meanwhile the capillary network that supplies oxygen from the arteries to the muscle fibres becomes more extensive. It is these changes that allow cells to extract and use more oxygen from each beat of the heart hence why it then needs to beat less frequently to deliver the same oxygen levels.

The process for growing new mitochondria and capillaries takes six weeks so this is the minimum timeframe you should be focused on MAF training if you’re to get its benefits. But it’s not necessarily a one-off hit as you’ll usually be growing these on a rolling basis. So while the training you do in week 3 is reinforcing the growth that started a few weeks ago, it is also initiating further growth that will be realised in week 9. This is why the elites can stay in a base period for months.

However if you start racing or doing heavy speed workouts during your MAF training period, which is what I tend to have seen, the full benefits may not be realised. Often there’ll be a small improvement but not as good as they might have been had they committed. I’ve even seen suggestion that capillary beds can be destroyed if too much speedwork is done but I’m not sure how true this is.

The people I see raving about MAF training on Youtube, the web or Strava never seem to follow the system for a period of months like I did. It’s a fad for them. Invariably they follow it for some of their runs each week but then throw in a race or workout regularly. This is contrary to the idea of MAF training which, I believe, is supposed to be a continuous process.

They might as well go follow a marathon training plan and get the same benefits from high mileage and minimal speedwork

ii) Runners don’t actually stay below the calculated heart-rate

When I MAF trained I was dedicated to staying below the MAF-HR. I don’t see the same zealousness from other runners. Most of those I’ve seen trying it are capable of running decent times e.g. half-marathon in 1hr25 but to stay below their MAF-HR might require them to go back to nine minute miling aka “running too slow”. So they tend to slow their runs down to about eight minute miles and be content if their heart-rate averages the MAF-HR. Occasionally they will stop, walk or go up hills slowly but mostly they jog along doing an approximation of MAF training that doesn’t bear close scrutiny.

iii) Runners don’t use a decent heart-rate monitor

Until a decade ago all heart-rate monitors were chest straps which were usually accurate. You could get inaccuracy at the start of runs which was usually solved by giving it a lick before putting it on but otherwise they tended to be accurate.

The new generation of wrist-based heart-rate monitors are highly unreliable in their accuracy despite the manufacturers’ claims and any inaccuracy is usually put on the runner for not wearing the watch correctly. I’ve seen countless examples where runners have heart-rates in the 180s while jogging and then when they start doing fast intervals the heart-rate drops to the 140s. That’s a physical impossibility. The wrist-based monitors often lock onto a runner’s cadence but there may be other reasons behind their inaccuracy.

Whatever the reason I would only trust a chest strap heart-rate monitor from the current technology available. It may improve and there may be some which are already reliable so if you choose to go wrist-based, test it before you rely on it. And do that test under a variety of conditions, not just sitting on your sofa or walking to the local shop.

iv) Runners don’t do the warm-up

Runners who try MAF training almost always start their runs fast, only slowing down after a minute as the anaerobic boost runs out and they start to puff. The problem is they’ve then engaged more muscle than they can run aerobically with, this makes it much harder to stay under MAF-HR.

To compensate for increased anaerobic energy usage, the body invokes lactic clearance therefore that’s what they’re training rather than signalling to the body a need to adapt aerobically. Once lactate clearance kicks in, it’s possible to be running anaerobically and still see lower heart-rates.

A secondary issue of starting runs without a warm-up is heart-rate monitors can read inaccurately at the beginning of runs and this causes big headaches if the heart-rate monitor is constantly beeping say you’re running too fast. It often takes 8-10 minutes to settle down and has disrupted your rhythm if you’re trying to stay below a certain heart-rate. I used to worry on my MAF runs if my heart-rate was up in the 140s early on not knowing whether it was me running too fast or the monitor reading wrong.

As I explained earlier, Maffetone recommends doing a fifteen minute warm-up which helps to avoid these issues. Many of the MAF training advocates don’t have the patience or knowledge to do this.

The BIG flaw to MAF training

Heart-rate monitors don’t show the levels of lactate in the blood.

As I wrote back in Point D (and will reproduce here to save you scrolling back up): To progress you have to train at the point just before you start to increase the use of anaerobic energy. This has variously been called the Anaerobic Threshold, Aerobic Threshold and Lactate Threshold among other names. It doesn’t matter what it’s called but it does matter that you’re training at it if you want to get faster.

Most people understand the principle of Threshold training so I won’t go into depth about it. What I will point out is while there are various ways of identifying what the heart-rate at threshold is, only Maffetone suggests it is related to age. And quite simply – it isn’t.

It can vary drastically depending on your training. I have seen myself running at Threshold heart-rates of 127bpm after doing excessive amounts of speedwork yet two months later it’s up at 150bpm. There was no relationship between my age and Threshold heart-rate in those numbers and there won’t be in anyone else – other than by coincidence.

In well-trained runners the Threshold heart-rate is more consistent. Mine is usually somewhere around 152-153bpm when I’m running well. Coach Peter Coe said lab testing shows it’s usually around 150bpm in male runners but higher in women. Mike Pigg, who I mentioned earlier appears to be around 153bpm. I would be very careful about using a generic value like this to specifically define the Threshold but with experience you may be able to define where your own starts.


There are very few, if any, elite runners these days who train to heart-rate. If they do it’s usually to ensure their recovery runs are slow enough. If they are doing workouts by heart-rate, it’s likely they’ve derived their numbers either by taking lactate samples or by using heart-rates experienced in races. An age-based formula won’t identify it.

In my opinion, if you really want to train to heart-rate, you’re better off going with a catch-all number of 150 (or 160-170 for a woman) and see how your body reacts to it. I would aim to run recovery runs at least fifteen beats lower than this but not get too tied into staying exactly below or on the numbers. I’d look to do a warm-up that takes at least ten minutes to get close to my target heart-rate but I’d let my body guide me on how it wants to run. If I began to go over the target heart-rate then I wouldn’t be too concerned by a few beats but I would look to ease off and get back under target. I would aim to run the 150HR rate efforts no more than three times per week with the low heart-rate recovery runs on the other days.

That’s if I was going to train to heart-rate which I don’t.

Summing up MAF training

The idea of training to build an aerobic base is a good one for anyone involved in endurance sports. Whether this needs to be fat-burning or sugar-burning depends on the distance(s) you intend to race.

But the fundamental concept of using an age-related formula to decide on what heart-rate to train at is high flawed. There is no proven mechanism that reliably explains why a 40-year-old runner should train twenty beats lower than a 20-year-old runner.

Remember Phil Maffetone was a health practitioner who treated all sorts of endurance athletes so being a running coach was never his speciality. What the MAF method does well is to (re)build a healthy aerobic system. This allows runners to peak their training with anaerobic training for better race times, but MAF training itself is not a system for building top end speed. You will only go as fast in races as your top end speed allows. If you spend months creating a super-efficient aerobic system, it opens up the space to access speed at the top. If you never do speedwork you won’t be any faster over short distances but you will improve over longer ones.

While many of his clients found great success from following his methods, the success stories he details are of already-elite athletes in their respective long distance events. They were already fast and well-developed, MAF training just took them the final steps of their journey. For example, Mark Allen was placing in the top 5 of the Hawaii Ironman before he met Maffetone. He became a six-time champion when he improved his aerobic system because fat-burning is crucial in an event lasting over eight hours.

What Maffetone showed these athletes is how to build the aerobic system which is the foundation of endurance. That is half of running. The other half is the anaerobic system which helps create speed. Following the Maffetone approach as a complete running system is like listening to researchers who tell you that you can get faster by building VO2max through High Intensity Interval Training (HIIT). It’s only half the job. Good running coaches already understand how to combine these two halves of aerobic and anaerobic training to create endurance and speed to maximise the potential of a runner. It’s often self-coached runners who have fixated on one half or the other who profit when they introduce the other type of training.

If you go through Maffetone’s Big Book you will find all the athletes he gives specific details for are elite (i.e. they already have top end speed) and they are under thirty which gives them a higher MAF-HR to work with. It’s for this reason I repeat my belief that the Maffetone formula is a blunt instrument which could as effectively be replaced by a catch-all heart-rate limit of 150 beats per minute for male runners and perhaps 10-20 beats higher for women. The specific value you use would likely need to be individualised and decided upon once you’ve got used to your own typical values.

There are better ways to train than MAF training to be the best runner you can. These involve mixing periods of short intervals, long intervals, continuous runs, long runs and easy runs at a variety of paces to develop both speed and endurance.


Update – since publishing this, I wrote a further post proving my point about there being better ways to train. In it, I detail how I trained regularly breaking my proposed MAF-HR, often training to one the equivalent of someone twenty years younger than me yet still made progress. Read Part 4 here.

MAF Training review – Part 1 An Overview

This post is the first in a series of five which originally began as a trilogy – other posts can be accessed from the Readables menu tab.

Occasionally I come across runners on Strava or Youtube waxing lyrically about MAF training. If you’ve never heard of it, it’s a heartrate-based formula created by Phil Maffetone that focuses on building the aerobic system. As well as being a shortening of his name, he says MAF stands for Maximum Aerobic Function.

Phil Maffetone is a retired chiropractor who treated athletes from the 1970s onwards including triathletes like Mark Allen, runners like Marianne Dickerson and ultra-runner Stu Mittelman. Chiropractic is described on Wikipedia as being “concerned with the diagnosis and treatment of mechanical disorders of the musculoskeletal system” and this is the basis of the Maffetone Method.

While there are many articles around the web and Maffetone has an extensive website promoting his methods, the information in this series of articles is mainly drawn from his “The Big Book of Endurance Training and Racing”. It’s an attractive 500-page tome going into detail about training, its effects on human physiology and giving many examples of athletes he helped. It manages too avoid being to technical even though there is a good dose of biology thrown in. If you want insight into the human body and keeping it healthy then it’s worth a read.

Low heart-training with MAF

The core of the MAF Method, as others promote it, is low heart-rate training. At its simplest the MAF heart-rate is calculated by subtracting your age from 180 to give a maximum value that shouldn’t be exceeded. It’s not an average heart-rate to run at, it’s the heart-rate you aim to never go above. If you’re thirty years old, your MAF-HR is 180 – 30 = 150 and you try to never go over 150HR on your runs.

Depending on your recent health and training you tweak your MAF-HR by adding on, or subtracting, a few beats. For example, if you’ve been training for two years without injury or illness you can add on five beats to raise the MAF-HR you’ll be working to.

There’s a couple of exceptions anyone under sixteen should use MAF-HR of 165bpm, anyone over sixty-five may add ten beats if they’re in good health. This means almost everybody training to a MAF-HR is doing so between 125-165bpm.

The MAF test

For those who really get into MAF training there is the MAF test. Once every month, you run five miles at your MAF-HR and record the mile splits. The splits will gradually get slower but over the months you should see the overall numbers improving and your runs getting faster as the following example shows:

AprilMayJuneJuly
Mile 18:218:117:577:44
Mile 28:278:188:057:52
Mile 38:388:268:107:59
Mile 48:448:338:178:09
Mile 58:498:398:248:15
Example results from a series of MAF tests (p. 82)

Ideally you go into each test rested, warm-up prior to the test miles and run the same course under similar conditions every time to keep the comparison valid. Of course with seasonal variations, results can be affected by cold, heat, humidity and high winds but as long as you allow for this, you should see a year-on-year improvement.

The real MAF Method

Training to MAF-HR is the appealing “Train to a low heart-rate and your running will get faster” headline of MAF training. To the Youtuber and Strava disciples promoting MAF training, this is all it entails to get clicks and views.

In reality this is a cherry-picked aspect of Maffetone’s training philosophy which has the following four key points:

  1. Build a great aerobic base
  2. Eat well
  3. Reduce stress
  4. Improve brain function

As a chiropractor, his focus is on healing people and helping them to stay healthy, so he comes at this from a holistic perspective as the key points show. The focus of his training method is to get the body fuelling its exercise by burning more fat instead of carbohydrates. By staying away from sugar-based anaerobic exercise, stress remain low and the two halves of the autonomic nervous system stay in balance. Too much anaerobic leads to high levels of stress, the body kicking into “fight-or-flight” mode and all the negative effects which are seen in overtraining syndrome.

Certainly the low heart-rate training is a major aspect of the Maffetone Method but once the aerobic system is building up, it doesn’t preclude you from doing some anaerobic exercise. Beyond the evaluating what you eat and how you train; he also gives advice on foot strengthening, shoes, exercising to music, as well as how to reduce stress by setting better boundaries, staying in the present and learning relaxation techniques. To an extent, I’ve only scratched the surface in my summarising it’s a big book, that’s why it’s called “The Big Book of Endurance Training and Racing”.

Ultimately the true Maffetone Method is an extensive set of guidance aiming to help you find what will keep you healthy while training extensively. Like any good health system, it’s about learning how your own body reacts to training, to nutrition and identifying any weaknesses that need building up or eliminating. Low heart-rate training is simply the headline being attached to it.

Part 2 can be read by clicking here.