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.

MAF is MAF

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.

 

Polar App Zones

The heart rate zones in the Polar Flow app are misleading. Here’s a recent run.

The problem with the Polar app is that the zones are based on assumptions which may not apply for you. More specifically your fuel is a mixture between fat and carbohydrates and the hard edges these applications show don’t reflect a mixture.

I had my own VO2max tested in a lab. I know what my fuel mixture is at a particular heart rate. My Polar app shows me in fat burning below 111 bpm and “fit” above that point. My MAF range is 112-122. My VO2Max test showed my fat/carb burning at 90% / 10% at a heart rate of 124.

But I am fat adapted keto for two years so I am primarily a fat burner. This is why MAF works well for me. My 100% fat burning heart rate is 117 which center of MAF. As long as I am in the MAF zone I’m burning nearly all fat – even though the Polar Flow program says otherwise.

FASTER Study – Three Hour Magic Number

In previous posts I’ve taken a critical look at the FASTER study (FASTER Again – Checking a number on Ben Greenfield’s data). In particular, I took at look at Ben Greenfield’s three hour data (FASTER10 – Ben Greenfield – Three Hour VO2 testing). Ben looked like he still had gas left in his tank after three hours of sub-maximal running.

The Vegan

But what about Damian Stoy (FASTER Subject 43)? He’s a vegan who is not at all fat fueled. He never got more fuel from fat than 50% and that was at 45% of his VO2max.

At 64% of VO2max, Damian was getting nearly zero of his energy from fat. His carbohydrate oxidation rate was ~10 kcal/min. So, in three hours of running, Damian burned ~1800 kcals which has to be close to his entire glycogen stores.

My conclusion? Beyond this time and intensity being carb fueled isn’t a great choice. The reason that marathons are 26 miles is historical and practical. People just can’t run hard for longer times.

 

Fat Burning – Running vs Cycling

In a previous post I took at look at the exercise intensity which produced the maximum fat oxidation rates (Maximal Fat Oxidation Rates in an Athletic Population). A study took a look at the fat oxidation rates which happen when exercise is performed at the FATmax rate with cycling and running.

There was a significant difference in the rate of fat oxidation between the two (Juul Achten, Michelle C Venables, Asker E Jeukendrup. Fat oxidation rates are higher during running compared with cycling over a wide range of intensities. Metabolism, Volume 52, Issue 6, June 2003, Pages 747-752.).

Maximal fat oxidation was 28% higher when walking [ed: did they mean running?] compared with cycling, but the intensity, which elicits maximal fat oxidation, is not different between these 2 exercise modes.

These are interesting results. Although both exercises were done at the same intensity level (as measured by heart rate) they resulted in different amounts of total fat oxidation.

This leads me to conclude that although cycling and running can be both done at the MAF heart rate they are not equal for fat oxidation rates.

What About Rowing?

It would be interesting to see what the fat oxidation rate at FATmax is for rowing (ROW) and other modes. Turns out there’s a study for that too. (Egan B, Ashley DT, Kennedy E, O’Connor PL, O’Gorman DJ. Higher rate of fat oxidation during rowing compared with cycling ergometer exercise across a range of exercise intensities. Scand J Med Sci Sports. 2016 Jun;26(6):630-7. The study found that:

…FATox is higher during ROW compared with CYC exercise across a range of exercise intensities matched for energy expenditure…

The details show:

Despite similar oxygen consumption, rates of fat oxidation (FATox ) were ∼45% higher during ROW compared with CYC (P < 0.05) across a range of power output increments.

The crossover point for substrate utilization occurred at a higher relative exercise intensity for ROW than CYC (57.8 ± 2.1 vs 42.1 ± 3.6%VO2peak , P < 0.05).

Putting the Pieces Together

  • Rowing is ~45% better than cycling.
  • Running is ~28% better than cycling.
  • Rowing should be ~17% better than running.

Mechanism to Explain Differences

The degree to which an exercise engages muscles determines the maximum fat oxidation. Rowing has more muscle involvement than running which has more muscle involvement than cycling.

 

 

 

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, et.al. 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, et.al. 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!

 

Ketogenic Ironmen

Nice short study on Keto and Ironman ultra-endurance events (Maunder E, Kilding AE, Plews DJ. Substrate Metabolism During Ironman Triathlon: Different Horses on the Same Courses. Sports Med. 2018 May 18. doi: 10.1007/s40279-018-0938-9.).

Given the finite human capacity for endogenous carbohydrate storage, minimising the endogenous carbohydrate cost associated with performing exercise at competitive intensities should be a goal of Ironman preparation. A range of strategies exist that may help to achieve this goal, including, but not limited to, adoption of a low-carbohydrate diet, exogenous carbohydrate supplementation and periodised training with low carbohydrate availability.

Given the diverse metabolic stimuli evoked by Ironman triathlons at different performance levels, it is proposed that the performance level of the Ironman triathlete is considered when adopting metabolic strategies to minimise the endogenous carbohydrate cost associated with exercise at competitive intensities. Specifically, periodised training with low carbohydrate availability combined with exogenous carbohydrate supplementation during competition might be most appropriate for elite and top-amateur Ironman triathletes who elicit very high rates of energy expenditure.

Conversely, the adoption of a low-carbohydrate or ketogenic diet might be appropriate for some lower performance amateurs (> 12 h), in whom associated high rates of fat oxidation may be almost completely sufficient to match the energy demands required.

Nicely put.