Slow Burn by Stu Mittleman

I’m meeting up soon with an old friend who I haven’t seen since 2013. It was then he lent me his copy of Stu Mittleman’s book Slow Burn – Slow Down, Burn Fat and Unlock the Energy Within and I’ve realise it’s now time to return it! Having taken it off the shelf in readiness for our meet up, I was reminded of its content which credits Phil Maffetone for helping Mittleman’s training.

When I first read the book almost ten years ago, the ideas within it weren’t entirely new but they were still a puzzle as to how they fitted into the picture of my training to improve it. Just like John Douillard’s book Body, Mind and Sport and Maffetone’s Big Book of Endurance Training the ideas of unlimited energy and running slower to get faster seemed so promising. It was the following summer when I tried MAF training with gusto and saw that it simply didn’t work as I hoped.

Stu Mittleman is not a household name but fortunately he gives us his credentials early on. The first marathon he ran was Boston in 1977. In those days you needed a sub-3 time to qualify so he trained for a couple of weeks then ran a 2hr46 marathon (6:20/mile)!  Instantly he’s cluing us into his endurance capabilities. The book later tells us about how we was a champion ultrarunner who set a world record by running 1,000 miles in 11 days, 20 hours, 36min and 50 seconds. About how he ran almost 600 miles in six days but also how this was preceded by a struggle with injuries. It was Phil Maffetone who fixed him and taught him how to train using his age-related heart-rate formula. It’s fair to say some of what Mittleman wrote in this book, published in 2001, is based on Maffetone’s wisdom.

It’s a very readable book divided into three sections – how to THINK, TRAIN and EAT for the distance.  Each section has short chapters giving you time to digest what they have to say before you move on. There’s a lot of good information to think about.

How to THINK for the distance

Mittleman explains shifting from a goal-oriented approach to a process-oriented one. He gives the example of a group of twenty-six first time marathoners he had to train for the New York marathon in only nine weeks. Instead of focusing on finishing, he got them to experience (and therefore enjoy) the day by focusing on the twenty six aid stations positioned at each mile. He also explains how he approaches training day-by-day and how to enjoy runs.

To a coach or anyone who has worked in project management the idea of breaking a big goal into a series of intermediate steps of milestones is second nature. Of course twenty-plus years ago, when the book was written, fewer people were clued up to this approach; and performance, times, goals and Personal Bests still dominated their thoughts. Today the culture of marathons has changed and it is now common to have complete novices running marathons in 5-6 hours and not worrying about times.

How to TRAIN for the distance

How to TRAIN is the section that most interested me to read. I glossed over the initial chapters which focus on listening to your body by muscle testing / applied kinesiology, use of acupressure or reflex points and buying the right shoes for your feet. I rarely getting injuries and since the book was written much more information has become available about which shoes to buy as well as instore gait analysis etc.

Where How to Train gets interesting is in its explanations on learning to breathe deeper and giving you metaphors for good running form. I already knew how to breathe deep from Body, Mind and Sport and while the metaphors themselves are nothing I’ve ever applied apart; the idea of them is great. The best metaphor is the idea of “rollercoastering the hills” i.e. slow down as you run up them and speed up again on the down.

Discussion then moves into an explanation of fat-burning vs sugar-burning and its effects on the body. This is much the same ideas Phil Maffetone puts forward about how fat-burning is the way to stay healthy while sugar-burning leads to stress, illness and injuries. As I explained in the MAF Training Review series the general principle is right but it has been oversimplified into inaccuracy. Mittleman is a little more moderated stating on page 120 “You’ll lose the point if you reduce [it] to sugar is bad and fat is good”. As we’ll see in his heart-rate training system learning to burn fat dominates his training system but he does allow you to do faster work each week.

Mittleman HR Training system

Like Maffetone, Mittleman’s system begins by subtracting your age from 180. As I stated in my MAF series there is no scientific connection between age and how the body burns fat or sugar so this system is off to a negative start from the beginning.

Nonetheless it breaks training into three zones termed Mostly Aerobic Pace (MAP), Mostly Efficient Pace (MEP), Speedy Anaerobic Pace (SAP). The top of the MEP is 180-age, the bottom is 10 beats lower. The MAP zone is the 20 beats below the MEP zone. The SAP zone is the 20 beats above it.  Like the Maffetone formula, you are then allowed some adjustments depending on your experience and health. Finally Mittleman says to fine tune the zones based on how you feel in them. This final step seems to undo the point of using the formula.

Let’s work through for me as a 50-year-old runner:

180 – 50 = 130 MEP upper limit, so MEP lower limit is 10 lower at 120bpm.

I can raise it by 10 beats because I’m an experienced endurance athlete:

  • MEP range becomes 130-140bpm
  • MAP is there 110-130
  • SAP is 140-160

On paper these sound okay and Mittleman then details three levels of training for casual, recreational runners through to the more competitive. In his top level programme you run 3 MAPs, 2 MEPs, 1 SAP each week. This doesn’t seem like a bad mix.

The SAP training sessions are quite light volume (in my opinion) involving intervals lasting from one-to-five minutes. On the first week you total only seven minutes in the SAP zone and in week twelve it maxes out at four intervals of five minutes – twenty minutes worth. Then he strongly recommends taking a prolonged break of three months from SAP workouts; so only doing two blocks per year.

My training compared

The setup of my sessions for a week looks similar – I typically do three harder session each week and four recovery runs. One of my harder sessions is a long run which is not highly intense and would be the equivalent of an upper MEP / lower SAP session. The other two workout days would more likely involve entering the SAP and even going above it if I’m in a phase of shorter intervals. On recovery runs, when my legs are very depleted I struggle to get out of the MAP (sub-130) zone but more usually I’m hitting 130-140 thereby including some MAP work.

In “When You Need MAF” I analysed a typical training week for myself and looking at it again with these zones I find I’m nowhere close to what Mittleman is advocating. On the week in question I spent only 40mins in MAP, 2hr47 in MEP, 2hr55 in SAP and 22mins above SAP. When I look closer at his SAP programme I find I do more in one week than the whole twelve week’s programme (2hr27!)

The most significant line in the book is on page 195 “While running in my MEP target zone of 145-155, I reached the point where I could maintain a steady 5:45 per mile. I wasn’t straining or uncomfortable.”  This is the sort of heart-rate I use on my twice-weekly Steady runs and sometimes approach on my long runs. While I don’t have the endurance ability of Stu Mittleman, I can run 7:00 per mile at heart-rates in this range with the same effortless feel.

I’ve been following my regime for months and continue to use it while making progress and seeing my pace vs heart-rate improve. I’ve yet to pick up any of the injuries or illness that seem to be put forward as a reason to use age-related heartrate training. It’s hard to see what benefit I would derive from running slower more often and barely doing any training at threshold or faster.

How to EAT for the distance

I have to admit I didn’t make it far into this section. I read a book on nutrition many years ago which I tried to follow but any running books pushing me towards a diet that cuts out sugar doesn’t appeal to me. My diet is dominated by carbohydrates and the suggestion that I cut these out leaves me wondering what I’d eat as I don’t like cooking and I don’t eat a lot of fruit and vegetables. That said, I don’t eat sweets or crisps although there’s usually room for a slice of fruitcake or a flapjack!

I have always eaten to my hunger and while this is not a perfect strategy, I’m fit and healthy. What I have noticed is once I finally figured out how to do endurance training, I stopped getting hungry, I even stopped wanting cake. While my diet is still dominated by carbs – cereal, bagels, bananas, rice, pasta, bread and potatoes – I only eat when I feel hungry. Often I don’t feel hungry even after coming back from a long run.

What I now understand is how I used to train depleted my muscles of their glycogen and set me up to crave carbs to replenish the stores. As you improve at endurance training two things happen; firstly you improve the aerobic quality of the intermediate fast-twitch so that they still use glycogen but much more efficiently and secondly you tend to stop doing sessions that use the fast-twitch muscles which are fuelled by glycogen.

Let’s return to the biography I gave in the beginning. Mittleman was already endurance-trained and capable of running a 2hr46 marathon when his journey began. He could run 6:20/mile off little training and later states he can run 5:45 at 145-155HR in his MEP zone. Mostly Efficient relates to what I see as aerobic glycolysis. It still uses sugar but efficiently as the zone name suggests.

He states on page 189 that he’s happy running at 12min/mile pace for his MAP run three days per week and that he was once asked by Runners World why he ran twenty miles per day to which he answered it’s all he had time for! That’s the sort of thing you expect from ultrarunners who are interested in running for five hours or more but it’s no route to success over shorter distances. Ultra training for long distances requires many hours and miles of training and it can only be done at slow paces or the body will break down.

So we see he’s recommending eating strategies that are appropriate to his event. What we have to remember is the context of Mittleman’s running career. He is a champion ultrarunner. He is out for hours on his races and no doubt trains for hours each week. The average pace of his 100-mile world record is 7:44/mile and while that might sound fast to some runners, it’s not in the context of shorter races. I’d expect that to be a heart-rate of around 115bpm. There’s no doubt fat-burning adaptions are very important for races lasting over an hour particularly marathons and ultras. Any runner interested in middle distance or parkrun will benefit from improving their aerobic base but will need to encourage both fuel sources and this is true for the 10K and half-marathon as well.


This is a book filled with information that can help people build a greater understanding of how to approaching training. What I particularly love is the chapter where Stu Mittleman describes the different sensations you will feel as you move up the training intensity scale. When you’re on a slow, low heart-rate jog you can be in tune with the sights and sounds of the world barely breathing; when you’re doing anaerobic intervals your attention will narrow and everything thing will be focused on trying to catch your breath and get to the end of the effort. I believe running by feel is one of the most important skills all runners could learn.

I don’t agree with using heart-rate monitors to train and applying an age-related formula even less so. I agree though with mixing up the week to have slower paced runs dominating the schedule and this fits with the 80:20 rule. The idea of improving the aerobic system by improving mitochondria is important to all distance runners but this doesn’t necessarily mean fat-burning.

The areas of the book I skip are the sections on muscle testing and what to eat. The latter is more down to my own preferences and the area of applied kinesiology is considered a pseudo-science. Linking say knee pain to stressed out adrenal glands affecting the Sartorius muscle seems tenuous to me and doesn’t fit with anything I’ve experienced but then I rarely get injured or ill.

I hope I don’t sound overly negative about the book. When I read it, I found there was much I already knew but I’m a voracious reader when I get interested in a subject. I think for many people there’s much they could learn but they then need to put it into context of what it is for. This is a book about how to run marathons and ultras if you’re not too worried about your time or getting fast quickly. It doesn’t make any claims that it will help you over shorter distances because I don’t think it can.