September 7, 2021

What Is MAF Training, And Is It Effective?

Phil Maffetone’s MAF Training is a popular training method among endurance athletes, but is it effective?

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I first learnt about Phil Maffetone and his work in 2009. 

I stumbled upon his book, The Big Book Of Endurance Training And Racing, as I tried to learn more about fat burning and how you could increase an athlete’s ability to generate energy from fat.

I had moved to Singapore in 2008 to pursue my coaching career, and soon after that opened our first high-performance lab where we started doing a lot of metabolic testing.

Early on, it became clear that most of the athletes we measured were heavily reliant on carbohydrates and not good at burning fat. Many had excess body fat and had trouble in the later stages of races. These issues are a problem, so I searched for the factors that influence fat metabolism, hoping to transform people into metabolically flexible fat burners.

After reading Phil’s book, I knew we were on the right track. 

I grew up in New Zealand and was exposed to the benefits of aerobic training at a very young age. Arthur Lydiard had pioneered the approach to training endurance athletes with a lot of aerobic volume, and most coaches Downunder had adopted his approach since the 1960s. 

It served me well – with a sprinkling of high-intensity training, of course – throughout my pro career, and I was comfortable prescribing aerobic training and having athletes use a heart rate monitor as an objective measure of intensity.

What I was less familiar with at the time was the role nutrition played in fat burning, health and performance. 

What Is MAF Training?

Simply put, MAF training is a philosophy about how to train and a set of tools Phil developed to help athletes perform better.

MAF stands for maximum aerobic function, and the idea with MAF training is to train at, or below, your MAF heart rate ceiling to improve your aerobic function and increase your fat burning ability. 

As Phil says, “there are a lot of fit but unhealthy athletes”, and this is primarily the result of too much intensity in training, a poor diet rich in processed carbohydrates, and high overall stress levels. 

MAF training and the tools Phil designed are a response to those problems. 

The 180 Formula

The 180 formula is a formula for calculating your MAF heart rate. It’s a simple calculation where you deduct your age from 180. You then add or subtract from this number based on several lifestyle factors that Phil has set. The end result is a heart rate ceiling that you do all of your training at or below.

Phil states that this heart rate is suitable for everyone and is the same across sports. I like this formula, and we use it a lot in our programmes, but I disagree that it works for all and across sports. 

Lactate and metabolic testing are far more accurate ways of determining training zones. As we’ve seen many times in our lab, an athlete’s actual MAF heart rate often differs significantly compared with the formula heart rate.

The MAF Test

To track the progress of your aerobic development, Phil created the MAF test. The MAF test is a simple test performed at the MAF heart rate. At Coached, we mainly use it as a running test, but you can also do it on the bike and in other ways.

We aim for the test to last around 40-minutes. That means that you’ll be running somewhere between 4 – 8km for most athletes depending on your fitness level. Once you have determined the distance you wish to run, you run at your MAF heart rate to completion. As you run, your pace slows in response to fatigue. This decrease in pace is normal and expected; however, aerobically fit athletes will slow much less than someone unfit.

Over time, with the proper training and lifestyle habits, you’ll see that your pace at MAF heart rate improves. Below is an example of one of our athletes over five months.

MAF test progression for Coached athlete, Ming

It’s important to note that this athlete wasn’t exclusively following the MAF training protocol. He was on a Coached programme that includes some high-intensity throughout and other specifics. His MAF heart rate was also calculated via lab testing.

As you can see, his pace increased by 2-minutes per kilometre at MAF heart rate in the five months that he tested – a significant improvement.

The MAF test is helpful because it tells you if you’re headed in the wrong direction, either from too much anaerobic exercise, too little aerobic exercise or any imbalance that is having an adverse effect on the aerobic system. It objectively informs you of an obstacle long before you feel bad or get injured and allows you to course correct.

The Two-Week Test

One of the quickest ways to kick start your fat burning is to do the Two Week Carbohydrate Intolerance Test. 

The Two Week Test is a simple but not easy test where you lower the carbohydrates in your diet significantly for two weeks. The reduction in carbs lowers blood sugar, so you produce less insulin. An increase in fat burning is the result.

After the test, you slowly and progressively add carbs back into your diet to see how they impact you.

Here are the results of my fat burning tests that I did at the start and the end of the Two Week Test several years ago.

Orange represents fat being used for energy, while blue represents sugar.

Before Test


After Test


As you can see, you can dramatically change how your body uses its energy in a short time.

I usually do the Two Week Test two to three times per year. We also use it as a framework for our As A Matter Of Fat nutrition challenge that we host inside Coached.

So, Is MAF training effective?

Yes, it can be effective. However, you have to be patient.

If health is your exclusive focus, MAF is a nice option. If performance is your primary goal, there are better training approaches than exclusively training by heart rate at your MAF heart rate.

I’m an enthusiast of the MAF and Two Week Tests and use both personally and with our athletes.

I’m also a proponent of the need to develop your aerobic system and fat burning capabilities. Where the Coached approach differs from MAF training is in the prescription and detail of training.

We still include a lot of aerobic training, especially if you’re recovering from injury or illness. Nevertheless, we carefully use high-intensity training and use hills and other forms of strength training and specifics that help produce a quicker result without compromising health and risking injury.

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Ben Pulham

Ben Pulham is the founder of Coached, a personalised training programme that helps runners & triathletes optimise, track and enjoy their training.