MAF Plus 20

Peter Defty (of OFM fame) suggests that fat adapted athletes can increase their MAF number from 180 – age (with correction factors added/subtracted) to 200 – age (same correction factors) (Primal Endurance Podcast – #90: Peter Defty Talks Optimized Fat Metabolism).

His reasoning is that the heart rate is 10-15 beats per minute faster in fat adapted athletes (from the FASTER data). He reasoned that Maffetone came up with the number based on non-fat adapted athletes and that once fat adapted the number can be shifted up.

Tempting Idea, but…

I’ve had the same thoughts before and I’d really like to accept Defty’s ideas since I’m getting tired of mostly walking. I’d like to run more. But I’ve also had no injuries in the past few months. Recovery has been so easy that I’m finding myself doing two MAF efforts a day. I’d hate to jeopardize that.

I don’t think I’m getting much faster doing MAF, but I wonder if sticking with MAF and doing intervals would improve my speed. I do feel like I am improving my leg strength at MAF and they are not a limiting factor when I’m out for more than an hour.

The limiting part of MAF is that after 4 or 5 miles I can only run a few steps until I have to start walking again.


Of course, Maffetone’s approach is that MAF is MAF. And it’s 180 – age (with correction factors).  The program is fixed and doesn’t need to be changed. The athlete who is not yet fat adapted will burn more carbohydrates at MAF and the athlete who is fat adapted will burn more fat at MAF. This shift away from carbohydrate reliance to fat adaptation is the goal of MAF when done with the recommended lower carbohydrate diet.

20 Beat Shift – VO2 Data

To see what a 20 beat increase would do, take a look at my VO2max fat/carbohydrate oxidation curve. At my MAF (122 bpm) I am currently burning nearly all fat and very little carbohydrates.

Shifting up by 20 bpm from 122 to 142 just happens to be the 50-50 crossover point of calories from fat and carbohydrates. This will cause glycogen depletion which has good and bad aspects. My current view is that staying out of that range is the smartest idea since cycling glycogen doesn’t promote lower glycogen stores since the body responds by over saturating glycogen stores.

Shifting right by 20 bpm could have the advantage of causing a further shift of the curve to the right and increasing my fat oxidation at that same heart rate. If that is the effect then it would be positive since in the end I could have a higher VO2max and improved fitness.

Critique of MAF number

One difficultly of the Maffetone MAF number is that there’s no real explanation of the basis for the number. Maffetone himself says that the number can be adjusted based on actual metabolic tests but he never exactly explains how to adjust the number nor exactly what he based the number on other than observation of a lot of his clients/patients. The number fit the tests within a few beats but Maffetone never explains the derivation of the number in enough details to explain what lab test he used and what the correlation to the tests is. Maffetone has spent a lot of energy explaining what it isn’t (lactic threshold, VO2max, percent of max heart rate, etc) but not a lot explaining what it is. Without tying it to some external metric it’s hard to judge the value of the metric.

Is MAF at the cross-over point for a non-fat adapted athlete but the point of maximum fat burning in a fat adapted athlete? It is true from my data that 122 is the sweet spot. It is literally the peak of fat oxidation (the black theoretical curve fitted line) where no carbohydrates are being burned. Ten beats lower is still in the prime fat burning zone. For me, lower numbers are even ketone burning (evidenced by the RER of less than 0.7).

Rate of Perceived Exertion (RPE)

Mowing my lawn raises my heart rate beyond the MAF range and makes me sweat. MAF makes me sweat when it’s warm outside but it’s a pretty gentle pace. I could do exercises at 142 max and it would be fine. I know because I’ve mowed the lawn (and done CrossFit) at higher rates.

I don’t think I am going to change what I am doing at the moment but I will bear it in mind for the future. I did 5 sessions last week of 5Km or longer and I’d like to keep up the volume.


MAF Training And Metabolic Syndrome

There’s an interesting study which looked at two months of training at FATmax to see what the effects on Metabolic Syndrome (Dumortier M, Brandou F, Perez-Martin A, Fedou C, Mercier J, Brun JF. Low intensity endurance exercise targeted for lipid oxidation improves body composition and insulin sensitivity in patients with the metabolic syndrome. Diabetes Metab. 2003 Nov;29(5):509-18). The study showed good improvements from MAF level of training intensity.

The patients exhibited a significant reduction in body weight (- 2.6 +/- 0.7 kg; P=0.002), fat mass (- 1.55 +/- 0.5 kg; P=0.009), waist (- 3.53 +/- 1.3 cm; P<0.05) and hip (- 2.21 +/- 0.9 cm; P<0.05) circumferences, and improved the ability to oxidize lipids at exercise (crossover point: + 31.7 +/- 5.8 W; P<0.0001; LIPOX(max): + 23.5 +/- 5.6 W; P<0.0001; lipid oxidation: + 68.5 +/- 15.4 mg.min(-1); P=0.0001). No clear improvement in either lipid parameters or fibrinogen were observed.

There were significant improvements in the markers of Metabolic Syndrome.

The surrogates of insulin sensitivity evidenced a decrease in insulin resistance: HOMA%S (software): + 72.93 +/- 32.64; p<0.05; HOMA-IR (simplified formula): – 2.42 +/- 1.07; P<0.05; QUICKI: + 0.02 +/- 0.004; P<0.01; SI=40/I: + 3.28 +/- 1.5; P<0.05. Significant correlations were found between changes in body weight and HOMA-IR and between changes in LIPOX(max) and QUICKI.

Here’s a longer term study which shows positive results over a longer time period (Drapier E (2018) Long term (3 years) weight loss after low intensity endurance training targeted at the level of maximal muscular lipid oxidation. Integr Obesity Diabetes 4).

Average weight loss was -2.95 ± 0.37 kg after 3 months, -4.56 ± 0.68 kg after 1 year, -5.31 ± 1.26 kg at 2 years and -8.49 ± 2.39 kg at 3 years.

The beauty of this study was that it compared low intensity exercise to a low fat diet.

This study shows that this low intensity exercise training maintains its weight-reducing effect 3 years while diet is no longer efficient, and that this effect is initially related to muscular ability to oxidize lipids but that metabolic and behavioral adaptations have been further developed and contribute to a long lasting effect.

The results are powerful.

Here’s a third related study (J. O. Holloszy and E. F. Coyle. Adaptations of skeletal muscle to endurance exercise and their metabolic consequences. Journal of Applied Physiology 1984 56:4, 831-838).

The major metabolic consequences of the adaptations of muscle to endurance exercise are a slower utilization of muscle glycogen and blood glucose, a greater reliance on fat oxidation, and less lactate production during exercise of a given intensity.

These adaptations play an important role in the large increase in the ability to perform prolonged strenuous exercise that occurs in response to endurance exercise training.

From the results:

…Probably the most important of these is an increase in mitochondria with an increase in respiratory capacity. One consequence of the adaptations induced in muscle by endurance exercise is that the same work rate requires a smaller percentage of the muscles’ maximum respiratory capacity and therefore results in less disturbance in homeostasis.

A second consequence is increased utilization of fat, with a proportional decrease in carbohydrate utilization, during submaximal exercise.


FATmax Training Results

In principle, training at FATmax (Maximal Fat Oxidation Rates in an Athletic Population) should result in significant loss of body fat and the resulting improvement in body composition. However, it is something of a surprise just how few studies have been performed to determine the effectiveness of this type of training. A meta-analysis (A. J. Romain, Physical Activity Targeted at Maximal Lipid Oxidation: A Meta-Analysis. (J Nutr Metab. 2012; 2012: 285395.) took a look and only found 15 total studies of this subject which fit their criteria. These studies were relatively small but the results were encouraging.

This meta-analysis confirms the conclusions of the individual studies, that are very low intensity training targeted at the level of maximal fat oxidation significantly decreases body weight, fat mass, waist circumference and total cholesterol. On the average, the effects of this variety of training are thus well confirmed, and their average magnitude is more precisely described.

Study Limitations

Only 5 studies include a control (nonexercising) group. There were also no longer term studies.

Volume of Training

Interestingly, some studies demonstrated an important average weight loss (8 kg over two months) with a protocol based on 90 min/day exercise at the level of maximal lipid oxidation. This could suggest that large weekly volumes of exercise training may be much more efficient than those used usually (i.e, 3 × 45 min/week).

Loss of Visceral Fat

The study called out a reference paper (Ohkawara K, A dose-response relation between aerobic exercise and visceral fat reduction: systematic review of clinical trials. Int J Obes (Lond). 2007 Dec;31(12):1786-97. ) which indicated that there is a dose response between aerobic exercise and loss of visceral fat.

… at least 10 METs x h/w in aerobic exercise, such as brisk walking, light jogging or stationary ergometer usage, is required for visceral fat reduction, and that there is a dose-response relationship between aerobic exercise and visceral fat reduction in obese subjects without metabolic-related disorders.


Running Slow

I’ve taken my MAF training to a certain point where I am running a lot more than I was before but still not for very long. I’d like to be able to run the whole time – except perhaps on really steep hills like the Lincoln Brick hill.

I think the problem is that when I start running I am going too fast and my heart rate climbs too quickly. I need to work on running slower. I probably need to do this work on a track to avoid hills (I live in SW PA where it is very hilly nearly everywhere).

Here’s a video of the Niko Niko method which is very similar (Niko Niko uses a low intensity steady state training at a heart rate just below the bottom of the MAF range).

The key points in this video are:

  1. Be conscious about small steps and pitch. The woman in the video is taking steps where her shoes don’t go past the other shoe.
  2. Keep your back straight. Don’t lean forward into the run.
  3. Relax your shoulders. Your arms should move naturally.
  4. Breathe naturally.
  5. Slightly raise your chin and look far ahead of you.
  6. Be conscious about forefoot landing. Don’t land on your heels.
  7. Do not kick the ground.

There is a MAF video by Sherpa Herb along similar lines.

I am going to start working on this. I’ve been doing about three days a week with an hour or more each time so I feel like my consistency has held up.

MAF at One Month-ish

I did a second MAF baseline yesterday. There was more running than the last MAF baseline. Here’s the first MAF baseline (Heart Rate Training (HRT) – Part 7). I re-crunched my data from the first MAF test. Here’s the heart rate from Strava (I only had the Samsung Watch at the time). I can see I was lower on the heart rate range than now.

Here’s the heart rate data from yesterday – the Polar Strap data.

I only had two points where I went over my MAF rate and that was for a very short time.

Here is the same data from my watch (for apples-apples comparison):

I don’t trust the glitches on both of the watch charts. Not sure what the glitch was, but other than that the data is pretty comparable on both.

Performance Increase?

The idea of MAF is that you will see a performance increase. Here’s the two MAF benchmark split times.

The two mile, three mile, and for mile splits were all about 30 seconds faster so I am making good progress in improving my aerobic fitness.


Nerding Out on Data

I like Strava for tracking my MAF runs but it doesn’t work well for me with my Polar Chest Heart Rate Strap (HR-7). So, I’ve switched to Polar Beat/Flow for the HR-7 strap since it’s easier to read the heart rate while running. I still use Strava along with Samsung Health. The watch sends data to Samsung Health and Samsung Health sends data to Strava. I still don’t like the result since the heart rate data gets blocky. Here’s an example:

So how did I get the data?

This is the fore-warned nerdy part. I’ve written a Python script. If you don’t know Python skip the rest of this post since I can’t support the code. If you care, the Python code is here on GitHub. Again, I can’t support the code. It uses libraries that are here.

After running the pyStravaParse code. I then open the CSV file (spreadsheet format) in LibreOffice (a Microsloth EXCEL clone). I can’t support your spreadsheet choice either.

The data looks like:

Time (secs) Lat Lon Elev Heart_Rate (bpm) HRmax (bpm) HRmin (bpm)
0 39.908913 -79.71205 323.7 93 122 112
2 39.908913 -79.71205 323.7 93 122 112

HRmax and HRmin are hard coded as string constants at the start of the code. They are based on your MAF number. They could be replaced by 180-age and 190-age.Data_Time is offset in seconds.

I then select the Time, Heart_Rate, HRmax and HRmin columns like this:

Select Insert, Chart.

Choose Chart Type – XY (Scatter) then Next.

For Data Range you should already be OK if you selected data above. The select Next.

For Data Series you should already be OK. Then select Next.

For Chart Elements enter your title, etc as below. After entering in the titles, select Finish.

You should get a result like this.

To edit the chart double click in the chart. Then right click on one of the numbers on the heart rate axis. You should then see.

Select Format Axis. Then enter your own heart rate range numbers. I selected Minimum of 80 and left the maximum at 140.

You should get something like this.

I also like to move the legend to the bottom and move the graph up a bit.

Not a bad result but it’s easy to see the blockyness of the data. The Polar strap does better. I don’t have data for that same run since I bought the Polar strap later but here’s a recent image.

Not bad!


Measuring Heart Rate

I’ve said it before but it bears repeating.

A man with two clocks never knows what time it is.

Today I went out with my Polar Chest Strap and Samsung Gear Sport watch. I got two very different sets of data. Normally, I would trust the chest strap over the watch since the watch sometimes runs too high. This time I trust my watch over the chest strap. Why?

Two charts

Turns out that Strava can export a GPX file which can be read by EXCEL. (EXCEL complains about the data a few times but opens it OK). Here’s the two charts.

Judging by Past Performance

I’ve walked up the same hills before and have an idea of what happens with my heart rate. By one mile I’ve gone to the post office and started walking back up a hill. The Polar has my heart rate at 70 which seems way too low. The Samsung has my heart rate at 100 or so which makes more sense.

Judging by Rate of Perceived Exertion

The last half of the Samsung data has my heart rate in my MAF range (112-122). That makes sense given where I was in the walk and my rate of perceived exertion. Here’s the MAF range added to the Watch data.


The splits show I was behind my normal pace (messing with the monitors plus I was on hills) but not that far behind the pace.


Other than going to the Post Office (upper left circle) I did my typical route.

The pace and elevation data are:


I think I didn’t wet the Polar strap well enough. It was less than 70 degrees and relatively dry so the strap could have been too dry. I didn’t sweat on the walk either.

Next time I will wet the chest strap better.


Athlete Van Wilder – Part 2

In an earlier post, I took a look at Van Wilder (Another VO2max Test – Van Wilder). He was a low carb guy but has bumped up the carbs. quite a bit. The day before the VO2max he ate quite a few carbs.

Let’s look close to see if our VO2max curves are comparable to the Volek FASTER chart. Here’s the FASTER chart:

The HCD (High Carbohydrate Diet) looks like an inverted parabola and can be modeled as a 2^X function. Due to the distorted hump, the LCD (Low Carbohydrate Diet) looks like a higher order polynomial (more than a square = 2nd order). Assuming a 3rd order polynomial would model the curve better. Revisiting the VO2max data for Van Wilder (as a third order polynomial):

Here is my VO2max data (also as a third order polynomial):

My curve looks more shifted to the right similar to the FASTER graph. Both of the graphs have the same 50%-50% calories point at about 80% of VO2max.

Van Wilder’s MFBGS (Maximum Fat Burning Glucose Sparing) point is at around 43% of his VO2max. My own MFBGS is quite a bit higher at around 61% of my VO2max. Does that provide any real advantage? Certainly my 20+ years older doesn’t help me out.

Van Wilder’s MAF Number

Van Wilder is a well trained athlete but he’s constantly injured. He should have a reduced MAF number but let’s assume he’s at the 180 – 35 = 145 heart rate.

Van Wilder’s MFBGS point is at around 118 bpm. At his MAF number he’s well into carbohydrate burning (around 65% fat and 35% carbs).



There is another slow steady heart rate training called Niko Niko. Here’s a good page describing it (NIKO NIKO PACE – THE GENTLE PATH TO SUCCESS).

The formula for heart rate is different than the Maffetone MAF heart rate. Niki Niko uses:

138 minus half your age.

So for me at 58 that would be 138 – (58/2) = 109 bpm. That’s not too far below my MAF heart rate of 112-122. It it at an interesting point on myVO2max test results as well. A heart rate of 109 actually has a higher fat oxidation rate than the extrapolated curve (where the real world data veers from the idealized curve). It is certainly a good point for fat burning.

The MAF number has shifted my performance upwards in just the past three weeks. Here’s my splits from my MAF test three weeks ago compared with my MAF 5 mile this AM. I’ve had to go from walking to a little jogging and walking mixed together.

That’s a pretty good improvement – around a minute and a half.

Heart Rate Monitors

A man with two clocks never knows what time it [really] is…

I’ve got two heart rate monitors now. One is a Polar H7 chest strap. The other is a Samsung Gear Sport Watch. They are fairly close to each other.

Here is the data from the Polar H7 chest strap as recorded by Strava.

Here is the data from the Samsung Watch as sent from Samsung Health to Strava.

The average is within one and the general trends are close.