Does TR overly train a glycogen dependence?

If you stop to consider that we are only able to bring in about 60g-90g of carbs per hour, that implies that our carb dependent workload is limited to somewhere around 67w to 100w per hour. for long endurance events As such, it is critical to be able to metabolize a considerable amount of fat in order to push the pedals hard. If I am constantly cramming in carbs in order to manage the TR plans with a heavy focus on sweetspot and threshold work, aren’t I shooting myself in the foot if long endurance events are my focus? I.e. the sustained power build and century plans seem very ill suited for my types of events.

This was more or less validated by a very recent INSCYD Test with lactate. My TR FTP is ~293w, my XERT and WKO4 FTP are ~285w, my INSCYD AT is ~230w (213w to 246w). The INSCYD Test with Lactate shows that at a paltry 191w of work, I am burning 62% carbs. At 230w to 246w, INSCYD shows me burning pure glycogen…I.e. I was producing a ton of lactate at these lower levels, which I think is largely a function of relying so much on carbs to be able to even attempt the more strenuous prescriptions of sweetspot and threshold work in the mid-volume sustained power build and century specialty plans.

If I assume I have 400g of carbs available on board between the muscle stores and liver that can be employed to work for 10 hours, I would have ~44w/hr to work with (400g x 4kcal/g = 1,600 kcal / 3.6/w = 44w/hr. If I can input another 83w/hr (75g/hr) that means anything over 127w must come from fat oxidation. Therefore, I am effectively capped at ~191w to ~200w of work/hour for long events.

I think there is something too being able to work at a higher percentage of a lower FTP vs a lower percentage of a higher FTP…as such, I question the efficacy of the sustained power build and century specialty plans as the prescription for long endurance athletes…? To be clear, I am not advocating a keto diet, but rather a plan that could focus more on fat oxidation as a fuel source. Sweet spot and threshold work does not really allow for this…

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Preface: I am not an expert in this area, but have a few points to offer that I think are correct and relevant.

  • That ignores the on-board stores already in place for most instances, unless someone has ended up in a very depleted state.
  • It also ignores the ability of the body to process fat for use as well. This varies with work load, but is present in most of the power zone except for the top end that is restricted to short duration. This appears to alter and reduce in the presence of carbs, but comes to use when those carbs cease to enter the system.
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This is why Seiler’s 80/20 is so useful; the aim is not to do lots of longslow rides, but rather train your body so your long rides are not slow
You get to the stage where you are pushing 250 watts in an endurance zone with a low hear rate and you will be competitive in a huge spectrum of endurance events/fondos

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Unfortunately the only way to train your body to improve your ability to use beta-oxidation to burn fat is to do lots of long steady distance at low intensities. Most people just don’t have the time to put in the necessary miles. So yes almost by necessity TR workouts don’t really train for fat burning except maybe Traditional Base.

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He does actually cover both of those later. I’m not sure the analysis is right, but it does eventually cover fraction of power from fat and on-board stores.

I am, though, immediately suspicious of any analysis that results in the unit “watts per hour”.

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there is a plan, its called Traditional Base High Volume:

Traditional Base has been around long before anyone talked about polarized training and 80/20.

If you like to read, there is a book from 2006 called Base Building for Cyclists by Thomas Chapple and the forward is written by Joe Friel (Training Bible author). Yes, an ENTIRE BOOK ON IMPROVING FAT OXIDATION as fuel source.

Make the time and go do a real traditional base.

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yep, its a time crunched problem not a TR problem. Carmichael outlines it in his book too

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This is why I did the test with lactate readings. Lactate is relatively easily measured in blood, and is the byproduct of muscles using glycogen as a fuel source. Pyruvate—I think it’s called?—is the by product of fat oxidation , but much harder to measure. You can therefore, reasonably bucket sources of energy at given insities.

@Nate has sad that he’d rather have a higher FTP, but work at a lower % of it, vs a lower FTP and a higher % of it. I’m questioning that logic, particularly if the intensity at which you metabolize fat does not improve in a corresponding manner.

In my n=1 case, I believe that my body’s ability to oxidize fat actually declined as my FTP rose through the build phase. I used to be able to spin 250w for 30 min intervals back in April with a max HR at the end of the interval of 152. Today, that is probably more like 230ish watts. A recent attempt at 242 for 30 mins had my max HR around 162…

Frustrating, given Leadville is my A-race. :cry:

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Ignore your HR. I don’t think you can glean how much fat you are burning from that.

If you want to know how much you’re oxidizing fat you need to do a gas exchange test. It might be easier to find in your area than you think.

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That’s next on the list of testing to do…

In terms of bucketing the sources of energy, do you have any comments on my approach and/or math?

How did you get your lactate measurement and how did you get the percent carbs vs fat?

Ear lobe blood draws, and measure with a Lactate Scout 4 meter.

This was the protocol and lactate readings. How the INSCYD software interprets it is well beyond me… hopefully this pastes okay?

Interval Power Start (W) Duration Steps

warmup 100 3:00
rest 50 1:00
warmup 120 3:00
rest 50 1:00
warmup 140 3:00
rest 50 1:00
warmup 160 3:00
rest 50 1:00
warmup 250 3:00
rest 50 1:00
rest 125 3:00

					Lactates approx every minute until lactate decline		
		Pre-test Lactate	Duration of Test	End Heart Rate	Lactate sample	Lactate value	Time relative to end of test

Test Run 1 242 5:00 1.7 5:00 152 1 1:03 3.4
Recover 160 10:00 2 2:05 3
3
4
5
6
7
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9
10
Lactates approx every minute until lactate decline
Pre-test Lactate Duration of Test End Heart Rate Lactate sample Lactate value Time relative to end of test
Test Run 2 285 5:00 2.3 5:00 166 1 1:03 6.7
Interval 9 160 10:00 2 2:02 8.5
3 3:03 7.8
4
5
6
7
8
9
10
Lactates approx every minute until lactate decline
Pre-test Lactate Duration of Test End Heart Rate Lactate sample Lactate value Time relative to end of test
Test Run 3 356 3:00 2.3 3:00 176 1 1:01 11.6
Interval 11 160 10:00 2 2:10 12.1
3 3:01 10.1
4
5
6
7
8
9
10
Lactates approx every minute until lactate decline
Pre-test Lactate Duration of Test End Heart Rate Lactate sample Lactate value Time relative to end of test
Interval 12 408 3:00 1.8 3:00 180 1 1:00 13.7
2 2:05 15.9
3 3:03 17.5
4 4:04 19.8
5 5:08 15.9
6
7
8
9
10

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that doesn’t tell you anything about fat metabolism as you wouldn’t be limited by glycogen during a 30 min interval unless you were coming off a 24 hour fast

I feel like you are my data brother :smiley:. This is awesome.

Maybe take a screen shot of the table? Looks like it didn’t paste well.

Doing this from my iPhone on the train ride home, so hopefully this works better:

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You’re also saying that you’re probably capped at about 68-70% threshold for long events (10 hours). You might be able to ride a bit higher if you ingest more carbs (you have it at 75 grams an hour; you might be able to do 90…or maybe even 110 if some reports are to be believed).

That seems right in line with what we’d expect.

IE: 290 FTP * .7 = 203 watts

If you get your FTP to 350, I don’t see any world where you’d still only do 203 watts. I’d expect more like 350 FTP * .7 = 245 watts

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Perhaps, assuming fat utilization improves…my personal sense [in my situation] is that this hasn’t happened. VO2Max intervals haven’t been a problem, and 10-15 minute TR thresholds haven’t been a problem, but long 30 min tempo intervals have degraded materially. Not sure why this would be the case, but it is… :confused:

I think they have the data in the last two columns flipped.

So it sounds like you got up to 19.8 mmol/L!!

To give you a reference point Chad peaked at around 8-9 mmol/L when we did this. We both had the classic lactate exchange point at 4 mmol/L.

Jonathan had crazy high lactate like you do. He also tested at 1.5 pre test, and it looks like you’re 1.7 pre test. I’m trying to find the exact results but I can’t find the spreadsheet :frowning:.

It sounds like you might be genetically predisposed to producing a ton of lactate just like Jonathan does. That’s not a bad thing. Chad looked back through some research and found 10 elite triathletes who could hold 10 mmol/L of lactate for an hour!

Here’s Jonathan’s lactate and respiratory exchange data (at the lower levels) paired together.

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I find those really hard if I eat too close to working out. I need a solid 3-4 hours of absolutely no food. If the 1-2 meals before that are high carb I’m good.

One 30 minute tempo interval shouldn’t be hard whether your fat adapted or totally carb dependent. If you have low blood sugar it can be a real drag.

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Here’s my result. This is when we measured my FTP at 275 based on lactate and TR tests.

The cross over point is where they’d classically consider my endurance zone. So at a 275 FTP that’s about 210 watts or about 76% of threshold. That doesn’t mean I could hold that for 10 hours though.

I should do this again now that I have a higher threshold and a high carb diet. I’d be willing to bet a few dollars that I’d be burning more fat calories per minute now.

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