Getting Van Wilder to Boston

The Big Question Remains

How to best fuel Van Wilder’s (Another VO2max Test – Van Wilder) next marathon? It is six weeks away and he’s not far from qualifying for the Boston Marathon. Is it best to shift to a high carb low fat diet for the marathon?

Pace vs Heart Rate Test

We did a test of pace vs heart rate.  The test was done on a track in 800 meter distance increments with speed matched to 10 bpm heart rate steps every 2 laps (of the 400 meter track). We downloaded the average data from the logging application.

We then overlaid the pace vs heart rate data with fat-carb oxidation rates from Van Wilder’s VO2max test. Here’s the resulting curves:

The top curve is running pace. Van Wilder’s fastest pace was almost a 4 minute mile. At that rate, he was have been oxidizing around 22 calories of carbs and 9 calories of fat per minute. The rate is also not sustainable due to the high exertion required.

Van Wilder has to run the marathon in about 3 hours. That’s 26.2 miles/3 hrs = 8.7 mph. That’s 60 min/hr divided by 8.7 miles/hr = 6.9 minutes per mile. That’s a heart rate of 155. That is also around 15 calories per minute from carbs and 12 calories per minute from fat. 15 kCal/min * 60 mins = 900 kCal/hr. If he can feed 360 kCal/hr from carbs that’s a net of 540 lost per hour. In three hours his muscle glycogen will be completely gone (assuming it can all be used).

Probably can’t get there from here – at least at the current performance.

Update 2018-09-14

Van Wilder suffered a hip injury and had to drop out of his qualifying marathon last week. That was the last chance for the season.


Volek Talks about the FASTER Study

A video from 2015 where Dr. Volek talks about the FASTER Study (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

  1. Fat adapted athletes become “bonk proof” (see my post about that).
  2. Group of ultra-runners.
  3. More athletes volunteered than could be tested.
  4. Matched groups.
  5. LCD group was 70-20-10 F-P-C.
  6. HCD group was 25-15-60 P-F-C.
  7. Day 2 was three hours at 65% of VO2max (see my post about that). He later stated it ended up being at 64% of VO2max.
  8. They thought peak fat oxidation would be lower due to other studies documenting lower rates. They could have told from any low carb VO2max test that the peak rates were higher in Low Carb dieters.
  9. It looks as if they picked the 65% number based on this study (Achten J1, Gleeson M, Jeukendrup AE. Determination of the exercise intensity that elicits maximal fat oxidation. Med Sci Sports Exerc. 2002 Jan;34(1):92-7.).
  10. Volek showed the same graph from the VESPA article with the shift up and to the right of the fat oxidation curve (see my post about that).
  11. The statistically identical glycogen levels before, after and at the end of recovery were a surprise to Volek (as they are to me). Does fat allow the glycogen stores to refill? He thinks there is a chronic adaptation in LC athletes. It isn’t likely to be peripheral insulin resistance since the athlete’s muscles were biopsied to measure the glycogen levels, right? Alaskan sled dogs may provide a clue?
  12. Athletes were on LC for an average of 19 months.
  13. Gene expression differences between the two groups still being analyzed. Glycogen metabolism gene differences.
  14. LDL Cholesterol levels were much higher in LC athletes. HDL was also much higher in LC athletes.
  15. LDL Particle distributions were better in LC athletes (fewer smaller and more large LDL).
  16. Insulin Resistance scores were much better in LC athletes (top 1% of population).
  17. Half the high carb athletes have switched to low carb diet after the study.



FASTER Again – Checking a number on Ben Greenfield’s data

Ben Greenfield was a participant in the FASTER study (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

Ben’s VO2max number was 61.1. The FASTER study was supposed to be performed at 64% of VO2max. For Ben that should have been 61.1 * 0.64 = 39.1. At that rate Ben would have been using 67% fat and 37% fat as his fuel for the three hour treadmill test.

But that’s not what Ben’s actual data shows.

Ben’s VO2 numbers were 35.8-37.0. Now that’s not that much different, but in this case it’s a significant difference. At 36.5 Ben is at a much different fuel mixture (80% fat and 20% carbs).

I am not suggesting there was any cheating here but the numbers really didn’t match the words of the study.

And repeated here:

And here:

There may be a clue here:

Was Ben adjusted downward? Even if he was the adjustment should have been done based on the VO2max testing. The number should have been 39.1 not 36. Here’s Ben’s VO2max testing result.

I am concerned about this difference. I’d like to know what’s up. There’s a huge difference between 2/3 Fat to 1/3 Carb and 4/5 Fat to 1/5 Carb. Especially over three hours. Especially when you end the race with low glycogen stores.

The details matter.


MAF and Resistance Training

I’ve spent a little bit of time thinking about the compatibility of MAF Heart Rate Training and weightlifting – generically termed resistance training (RT). Since the activity is relatively short duration and the heart rate isn’t past the MAF Heart Rate it seems on the surface like it would be compatible to do both.

One thing to consider is that VO2max testing is done on a treadmill which increases the speed and angle every couple of minutes. Resistance training lasts for seconds. The Rate of Perceived Exertion (RPE) of the VO2max testing isn’t all that hard until it gets towards the end of the test. The RPE of weightlifting is substantial under significant loads so using RPE as a test this would indicate that there is an issue.

My measurement for whether an activity is aerobic or anaerobic is the Respiratory Exchange Ratio (RER). RER is correlated to heart rate in the VO2max test but rarely considered in RT. There is a study which looked at RER in RT (Scott. Quantifying the Immediate Recovery Energy Expenditure of Resistance Training. The Journal of Strength and Conditioning Research · April 2011) in terms of Excess Postexercise Oxygen Consumption (EPOC). To review:

The respiratory exchange ratio (RER) is calculated as steady-state CO2 produced divided by steady-state O2 consumed and is typically defined from values of 0.70 representing total fat oxidation to 1.00 representing total glucose oxidation.

Here’s the RER data from the study for RT. Note the RER values are all well over 1.0 which indicates anaerobic exercise range.

Another interesting comment helps explain the RER values above 1.0:

During and after exercise, RER values above 1.00 are generally thought to be the result of nonrespiratory CO2 production: The bicarbonate buffering system, for example, involves the removal of hydrogen ions with concomitant CO2 production and hyperventilation blows off ‘‘extra’’ CO2. Yet a true measure of the RER is best found only when the system is in a steady state of gas exchange.

To the subject at hand:

Rapid glycolysis (as part of anaerobic metabolism) ceases when muscle contraction stops so that recovery is considered to be aerobic in nature. If this is true, both fatty acid and lactate oxidation may play a significant role in fueling the immediate energy expenditure needs of recovery. Unfortunately, substrate oxidation immediately postexercise and particularly after anaerobic-type exercise has not been studied well enough to draw specific conclusions. Because of this, it must be assumed here that when muscle contraction immediately stops, glycolysis is limited to the point where fat and lactate are the predominantly oxidized fuels.


FASTER10 – Ben Greenfield – Three Hour VO2 testing

The main test that Ben test was a three hour treadmill test in the FASTER study (Jeff S. Volek, Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, Stephen D. Phinney. Metabolic characteristics of keto-adapted ultra-endurance runners. Metabolism, Volume 65, Issue 3, March 2016, Pages 100-110.).

In Ben Greenfield’s case the activity was done at an average of 60% of VO2max. At that level of effort Ben got 85% of his energy from fat and 15% from carbohydrates. Here’s the data from the three hour treadmill test.

%VO2max FATcal CHOcal %cal-fat
58% 10.013 3.1007 76%
61% 12.394 1.2341 91%
59% 11.722 1.4985 89%
60% 11.645 1.8409 86%
61% 11.154 2.5325 81%
Average = 60% 11.386 2.046 85%

An interesting question is the trend of the oxidation over the three hours. Here the graph of the data is interesting. The blue line is energy from fat and the brown line is energy from carbs. The x-axis is time. Note that as time proceeds Ben is drawing less and less energy from fat and more and more from carbohydrates. The R^2 values show a strong significance.

Ben’s individual Fat Oxidation data is not too far off of the data from the study. The average makes it look as if a person could continue on seemingly forever but Ben’s data shows that is not the case.

Similarly, his carb oxidation rate is very similar to the average since it shows a steady climb up.

It should also be recalled that although fat provides 9 calories per gram and carbohydrates provide 4 calories per gram fat is burned less efficiently for energy – about 10% less efficient than carbohydrates.


Ultra-Endurance Walking and Running Events

A study looked at the studies on fueling ultra-endurance events. Ultra-endurance is defined as activities (walking and running) which take at least 6 hours. The study was (Eric Williams. Nutritional implications for ultra-endurance walking and running events. Extreme Physiol Med. 2016; 5: 13).

Given that the majority of an ultra-endurance athlete’s training is spent engaged in lengthy durations of aerobic activity, many of these athletes are well adapted to utilizing lipids via oxidative phosphorylation

Fat burners! But during the event itself how hard are they hitting it?

When the athlete is exercising at the standard marathon pace that requires 80–90% of maximal oxygen consumption (VO2 max) or above, carbohydrate will be his or her primary fuel source and could provide up to 96% of the energy being expended.

This is an issue with Low Carbohydrate diets since glycogen stores are reduced greatly. This is also why Phinney’s endurance tests are done at 62% of VO2max.

The paper had a nice graphic which shows the elements involved in performance in marathons.

Each of these would be interesting to look at in detail.


Fat Adapted Athletes

Here’s a great study on fat adapted athletes (Lambert EV, Speechly DP, Dennis SC, Noakes TD. Enhanced endurance in trained cyclists during moderate intensity exercise following 2 weeks adaptation to a high fat diet. Eur J Appl Physiol Occup Physiol. 1994;69(4):287-93.).

The study looked at five cyclists and compared them on a High Carb vs a High Fat diet.

Despite a lower muscle glycogen content at the onset of MIE [32 (SEM 7) vs 73 (SEM 6) mmol · kg −1 wet mass, HIGH-FAT vs HIGH-CHO, P < 0.01], exercise time to exhaustion during subsequent MIE was significantly longer after the HIGH-FAT diet [79.7 (SEM 7.6) vs 42.5 (SEM 6.8) min, HIGH-FAT vs HIGH-CHO, P<0.01]

Looks like they have an almost 2x advantage when it comes to endurance.

How long did it take to convert these athletes from Carb Adapted to Fat Adapted?

These results would suggest that 2 weeks of adaptation to a high-fat diet would result in an enhanced resistance to fatigue and a significant sparing of endogenous carbohydrate during low to moderate intensity exercise in a relatively glycogen-depleted state and unimpaired performance during high intensity exercise.

Only two weeks!


We All Are Hybrid Engines

A hybrid engine can run on more than one fuel. Hybrid cars run on electricity (from a battery) or gasoline (which charges the battery).

Turns out the human body is a hybrid engine. We can run on carbohydrates or fat. We can also run on Protein but it’s not efficient as a fuel (Glycogen Replenishment After Exhaustive Exercise).

The ability to switch between fuel sources is key to the ketogenic diet. Someone who is not fat fueled takes days to fully make the switch between fuel sources. But it turns out we are always running on a hybrid system regardless of whether or not we are ketogenic. For instance, overnight we are fasting until we eat and the carbohydrates in our system are depleted.

Similarly in exercise we switch from the various fuel systems in our body.  Athletes on High Carb (HC) and Low Carb (LC) diets were put onto a treadmill and run for hours. These curves show the metabolic flexibility of the LC diet.

The top graph is the rate that fat is oxidized (burned). The LC diet provides fat as a fuel very quickly and at a much higher level than the HC diet.

The bottom graph is the rate of carbohydrate oxidation. The LC diet doesn’t have the carb repositories (glycogen stores) that the HC diet has so they don’t get much energy from glycogen stores. However, unlike the HC diet the LC diet provides consistent amount of carb energy throughout the workout.The HC diet has a high level at the beginning but drops over time which results in the characteristic bonk of the long distance runner.

Note that even the HC diet eventually requires body fat for fuel. It just doesn’t have instant access to the fat like the LC diet.

What I Observe In the Gym

I do CrossFit for exercise. CrossFit is commonly viewed as a glycogen intensive sport (J Physiol. 2013 Sep 15; 591(Pt 18): 4405–4413. Muscle glycogen stores and fatigue. Niels Ørtenblad, Håkan Westerblad, and Joachim Nielsen).

A Typical CrossFit Workout

Today’s Workout of the Day (WOD) was:

That’s 21 minutes of Box Jumping, Push-ups, Burpees, Back Squats, Hang Cleans, and Up-Downs (Burpees without pushups). That’s fairly short (not like running a marathon. It also includes 3 sets of 30 Wall balls. Quite a good workout.

Why Do CrossFit?

Note, I said I do CrossFit for exercise – not for sport. I don’t care what my exercise times are at CrossFit. I care if I get an effective workout. And I measure effectiveness by the accepted standard of heart rate .

Heart Rate as Metric of Effectiveness of a Workout

From the Mayo Clinic Website:

Gauging intensity using your heart rate

Another way to gauge your exercise intensity is to see how hard your heart is beating during physical activity. To use this method, you first have to figure out your maximum heart rate — the upper limit of what your cardiovascular system can handle during physical activity.

The basic way to calculate your maximum heart rate is to subtract your age from 220. For example, if you’re 45 years old, subtract 45 from 220 to get a maximum heart rate of 175. This is the maximum number of times your heart should beat per minute during exercise.

Once you know your maximum heart rate, you can calculate your desired target heart rate zone — the level at which your heart is being exercised and conditioned but not overworked.

The American Heart Association and the Centers for Disease Control and Prevention recommend a general target heart rate of:

  • Moderate exercise intensity: 50 to about 70 percent of your maximum heart rate

  • Vigorous exercise intensity: 70 to about 85 percent of your maximum heart rate

My Own Results

Here’s my heart rate as recorded by my Samsung Gear Sport watch:

The first part (0-30 minutes) was a chipper (the coach tells you what to do) which included a whole lot of stuff (pushups, jumping jacks, forward lunges, PVC work, sit-ups, squats). That got my heat rate as high as 160 near the end. The rest period then let my heart drop to “normal” range. Then the WOD…

I am 57-years old. To calculate max heart rate the standard way is to subtract your age from 220. So my max heart rate is 163. I hit that rate during the workout and I felt it. I had to stop and breath/rest at spots.

At the end I had spent most of my time at 85% (138 in my case) or more of my max heart rate. But I had energy left to clean up and started cleaning up immediately. It wasn’t that I didn’t work out hard. It’s that I am not glycogen dependent.  (Heart Rate Calculator).

The different oxidation rates of carbs and fat may provide the reason why I  can work out at a high heart rate but not be depleted at the end of the workout.

Both oxidation charts are in grams but remember that a gram of fat contains 9 calories of energy and a gram of carbohydrates contains 4 calories of energy. And the repositories of glycogen are in the hundreds of grams total. That’s a calorie repository of around 1600 calories, give or take. And it starts to drop quickly over time.

The repositories of fat are in the many thousands of grams. If you have just 22 lbs of fat, that’s 10 kg of fat or 90,000 calories available. Fat energy stays pretty constant. That may explain why I can keep moving after the WOD ends.

I work out for the express purpose of depleting my glycogen stores.


Does Exercise Increase Energy Expenditure While Dieting?

Here is a study that looked at resting energy expenditure (REE) under a calorie restricted diet (L C Henson D C Poole C P Donahoe D Heber. Effects of exercise training on resting energy expenditure during caloric restriction. The American Journal of Clinical Nutrition, Volume 46, Issue 6, 1 December 1987, Pages 893–899).

The seven subjects were moderately obese women put on a calorie restricted diet. The test was lasted nine weeks. They were exercised for three weeks at the end of their diet at 70% of their VO2max.

Resting energy expenditure (REE), maximum oxygen uptake (VO2max), and body composition were measured in seven moderately obese women during 9 wk of dietary restriction (800 kcal/d). During weeks 4-6, subjects underwent exercise training (30 min cycling/d, 5 d/wk, at 70% VO2max).

The conclusions were:

The first 3 wk of caloric restriction decreased REE by 13% (from 1437 +/- 76 to 1254 +/- 66 kcal/24 h, means +/- SEM, p less than 0.05).

That shouldn’t be a surprise since weight loss results in a reduction of Energy Expenditure.  The numbers need to be compared closely to the actual weight loss to see how much of the reduction in TDEE was from the weight difference and how much was from metabolic adaptation.

How was their performance affected?

Exercise training increased VO2max (from 1717 +/- 108 to 1960 +/- 120 mL/min, means +/- SEM, p less than 0.05)

Their VO2max showed a substantial improvement for only three weeks of training. It would have been interesting to have a control group which was not put on the exercise program to tease out whether some of this was due to weight reduction or it was due to the exercise.

but did not elevate the dietary-depressed REE (from 1254 +/- 66 to 1262 +/- 62 kcal/24 h).

It looks like the REE did show an increase but it was not statistically significant.

The greatest decrease in body fat (3.7 +/- 0.4 kg) occurred during exercise training, resulting in a small apparent increase in REE when expressed per kilogram total body weight. However, expressed per unit lean body mass, REE remained suppressed throughout the period of caloric restriction.

At 70% of VO2max they were at a good rate for loss of both carbohydrates and fat stores. It would be interesting to see their actual rates of substrate metabolism.

Their conclusions?

We conclude that exercise training of sufficient intensity to substantially increase VO2max does not reverse the dietary-induced depression of REE.

This is interesting since there’s a common assumption that exercising will cause people to burn more calories at rest but that wasn’t the case in this particular situation.

However, the increase in VO2max itself was worthwhile as it indicates a gain in fitness.