Max aerobic function (MAF) test

Max aerobic function (MAF) test

The “max aerobic function” (MAF) test is part of our ChampionsEverywhere program for prevention of underperformance in our athletes. This test does not focus on under-recovery and overtraining as much as it tries to detect whether your recent training has damaged your level of aerobic fitness and through this provide an early indication of problems with your training. The creator of the test – Phil Maffetone – says it should really be called the ‘Minimal anaerobic function’ test as we are looking at the intensity where you burn the greatest proportion of fat versus sugar. You can also get this test in a laboratory by asking them to find your ‘Fatmax’ heart rate.

We ask all athletes to complete this test twice during the General phase and at the end of the Related and Specific phases of training as well as during Competition time. This way we can finish every specific phase with an evaluation of how well the aerobic foundation on which all your performances in-season will be built remains intact.


The “Max Aerobic Function” test was invented by Dr Phil Maffetone who helped scientifically confirm Lydiard’s theories that you first need to develop your aerobic foundation to its maximum, and then you should resume harder training. As such, the test perfectly supplements anyone undertaking a Lydiard build-up.


  • Determine your target heart rate (if you are a coached athlete, our coaches will provide this as part of your programme, otherwise use the 180-formula) or run at an intensity of 3 (see our RPE chart)
  • Warm-up well (at least 15 minutes)
  • Wear a heart rate monitor and ensure it is working properly before starting the test
  • Find an even 5 mile (8 km) course, you can use a track, that you will have permanent access to for all future tests
  • Setup your watch to take splits, preferably every mile, but kilometre splits can be used as well as long as you are consistent each time
  • Once your heart rate is close to your target, begin the test
  • Run as close to your target heart rate for the entire duration of the 5 mile/8 km run. Ensure you record your splits or that your watch is doing this automatically
  • If done correctly, ever mile or kilometre should be slightly slower than the first
  • Reset your watch on completion of the test and do a short jog to finish off

When to do it

We recommend the following cycle in our training programmes for the tests:

  • During the preparation to begin training or during the FUNDAMENTAL phase
  • Week 4 and 8 of your GENERAL phase
  • Every two weeks during the RELATED phase
  • Every two weeks during the SPECIFIC  phase
  • Always at the same time and on the same day of training. We recommend replacing the “out and back” in week 4 and 8 of the GENERAL training phase and the “progress calibration runs” and “time trials” of the RELATED phase. In the last week of the SPECIFIC phase do the test as part of the longer mid-week run.
  • As the “MAF test” is generally easier than “Out and backs” and “PCRs”, you can use the weeks when you do this test as your “step-back” periodisation weeks – e.g. reduce all workouts that week to the shortest durations with a view to fully absorb the previous weeks.
  • Every month during racing season when continuing racing after your first peak event

You should not do the test more often than every month as you risk becoming too obsessed with analysing the results in those cases. Your weekly progression of recovery and training is better tracked using our “weekly athlete evaluation” questionnaire.

If you are running 60 minutes or less for your long runs currently, you should perform the MAF test over a 3 mile (5 km) distance instead of the prescribed 5 mile (8 km) above. Ultra-runners should consider testing over 10 miles for more accurate results for their distances.

Example of results

Maffetone test results example
Example of 5 mile splits for a runner doing a MAF test

How to interpret the results

  • If your splits are generally slower than in a previous test generally means one of two things: 1) your recent training has been too hard and not balanced with enough easier running and your aerobic capacity has suffered as a result or 2) you were unusually fatigued before going into the test, this could be the first indicator of general underrecovery/underperformance
  • If your splits get progressively faster during each individual test (for example if your first is 7:30, then 7:25 then 7:20), first check that you are running at the correct heart rate. If you were, the results may indicate errors with your heart rate monitor or insufficient warm-up taken before beginning the test.
  • Check that your course is as uniform as possible. Running on a very undulating course will not provide a correct reading of results

Important points

  • Always warm-up well to get your heart rate settled before beginning.
  • Check your heart rate monitor is working properly: slightly wet the sensor pads, ensure it is tucked securely under your pectoralis muscles (chest) and does not slide around. Ensure you do not have too many loose layers of clothing creating friction and static electricity.
  • Pick the flattest possible course and ensure you access the same course for each test and preferably at the same point of each week following exactly the same preparations. If you have had breakfast before previous runs, then have breakfast before later tests. The less variety in your testing routine, the more reliable results you will get.
  • Do the test on a track if you have easy access to one, flat pavements or even trails in parks are great choices. Avoid too soft terrain such as heavy grass.
  • Wear the same shoes or type of shoes whenever possible.
  • Check your heart rate regularly to ensure you do not deviate too much from the intensity but try, over time, to learn how the pace “feels like” so you do not have to look at your monitor every few seconds.
  • Setup your watch to show your heart rate very visibly so checking the reading does not disturb your rhythm too much.
  • It is important to do this test more regularly once anaerobic training commences as one or two excessively hard sessions can be enough to start a downward slide in your condition and you need to catch these early to allow enough time to correct course ahead of your peak race.
Read more about the test at Dr Phil Maffetone’s website.

Rate of perceived effort:

3 (~60-65% of Heart Rate Reserve)

Experienced competitors/elites: 

This test works exactly the same for experienced competitors and elites. Such athletes should expect to have very low heart rate readings at speeds up to 6 minutes/miles or beyond. However, sometimes even these runners have severe problems with their aerobic capacity and this test will help them rectify it.

A great example of this is how Mark Allen, the six time Ironman champion, used the test to establish the best training intensity for his aerobic workouts. Working with Dr Phil Maffetone, Allen discovered that at his target heart rate of 155bpm he could run no faster than 8:15 min/mile. Shocked by this findings, Allen proceeded to train for a full year at only aerobic intensities and a year later his pace at 155bpm improved to a blistering 5:20 min/mile. Even better, he reduced his risk of injury and overtraining and propelled himself to unprecedented success in the Ironman event.

During my 15 years of racing in the sport of triathlons I searched for those few golden tools that would allow me to maximize my training time and come up with the race results I envisioned. At the top of that list was heart rate training. It was and still is the single most potent tool an endurance athlete can use to set the intensity levels of workouts in a way that will allow for long-term athletic performance. Yes, there are other options like lactate testing, power output and pace, but all of these have certain shortcomings that make them less universally applicable than heart rate. – Mark Allen, Working your heart – the secret of training smart


  • Relaxation
  • Aerobic
  • Fat burning


  • Even pacing
  • Mastering long run pace

Biggest mistakes:

  • Watching the clock every few seconds, don’t disrupt your running rhythm
  • Tensing up and being nervous because it’s “a test”. Relax, this is easy running.
  • Doing the test more often than every 4 weeks. The test is meant to measure effects of training and these effects take time to become apparent in this test.
  • Panicking after a very poor test. Take stock and see if anything unusual happened in the week: illness, lots of stress or something else and perhaps redo the test the following week if you have a feeling the results don’t reflect your current form.
  • Running too hard in the test or purposefully overestimating your heart rate because “certainly it cannot be that low”. Test heart rates are commonly in the area 140-150 and no higher (sometimes lower).
  • Inserting rapid bursts of speed to “make splits match predictions” or “quickly raise heart rate”. If heart rate is a bit too low, just gentle up the pace until you are back where you should be.

How to use the results

  • If the pace in your MAF test is much slower than the pace prescribed for an athlete of your level in our training programmes it means that your aerobic foundation is weaker than your race results indicate and you should run slower during your longer aerobic runs in particular.
  • We cross-check your pace against the pace calculated for your training schedules by using previous race performances to ensure you have the necessary aerobic fitness to regularly aspire to hit those paces in training without straining.
  • By using the pace from the MAF test for your longer aerobic workouts, you ensure that you can manage the main requirement of completing a Lydiard-based aerobic build-up: exercising in a similar way for many months, day after day, without the need for enforced breaks.

How do I know if my paces are sufficiently aerobic?

It can be very hard to pick the right training pace initially as you can easily stray into a pace that is just a little bit too anaerobic which will break you down over weeks instead of build you up. In general, the more running experience you have, the steadier and harder aerobic paces you can tolerate in high volume.

Should you still harbour doubts about whether this test will add value to your training consider Phil Maffetone’s comment on why it is so important to know what energy system is dominating during your longer aerobic runs:

The real question is which system is predominating—which are you relying on? Is your body burning mostly sugar and less fat? If this is so, your anaerobic system is the one turned on more than your aerobic body. While you may not notice this, especially if it’s an ongoing problem, but your energy and endurance is not what it should be, you are vulnerable to aches and pains, body fat content is too high, and you’re under too much stress as the anaerobic system is connected with our fight or flight stress mechanism. In short, your health is compromised. Instead, you want long‐term energy to be free of fatigue, maximum support for your joints and bones, injury‐free muscles, good circulation, and increased fat burning to slim down. You want both optimal health and great fitness. – Dr Phil Maffetone, Think you know what being aerobic is?

Signs that you need to do the test

The following symptoms indicate that your aerobic efficiency is disintegrating and you should conduct the test to confirm:

  • Constant soreness and tiredness after workouts
  • Cravings for sugars and carbs
  • Impaired training performance
  • Restlessness and irritability
  • Increased resting heart rate
  • Longer than 24 hour recovery needed from workouts
These are symptoms of a type of overtraining called the “sympathetic type” brought on by excessive use of the anaerobic energy system which affects, in severe cases, proper functioning of your thyroid gland.


The standard “out and back” and “progress calibration run” workouts can be used as a replacement for the MAF test if you find it too difficult or technical to execute. In that case, simply ensure that you always pick the same “steady” intensity week after week and that you pick a 5 mile to 10 mile “out and back” course which you can repeat. This course does not have to be even as you would compare your overall time. Again, it is important to do the workout with this in mind only every 4 weeks. During aerobic training it is normal to have a few “ups and downs” as your body adapts to the heavier training loads. Thus you could easily have a bad “out and back” or “PCR” somewhere along the line without the need to panic that your aerobic efficiency is crumbling away.

An even lower intensity variation is the ‘Niko Niko’ run to be detailed in upcoming articles.

More information

Phil Maffetone’s books “The Big Book of Endurance Training” and his recent publication “The Big Book of Health and Fitness” explains the science behind the MAF test and the method in even more detail, straight from the mouth of its inventor. Also see this interview with Dr Maffetone or this video interview (MAF test is explained about 18 minutes in)

Also published on Medium.

The following two tabs change content below.


Director and coach at Borg Coaching Services
Rene Borg is the head coach of Glendalough AC and a passionate runner competing over all distances and terrains.

Latest posts by René (see all)

9 Responses to Max aerobic function (MAF) test

Leave a reply