Alan Couzens Profile picture
Apr 24, 2022 5 tweets 3 min read Read on X
Spending this morning doing something I've wanted to do for a while:

Diving into the database to explore the relationship between lactate and fat oxidation

Conclusions:
For high levels of #FatBurning- you want:
* Low lactate at AeT
* High AnT relative to max
* Low max lactate Image
By throwing max power into the mix, I'm starting to get a nice little model together.

With most of the fat oxidation predictions on the test set within half a kcal/min of actual! e.g. ImageImage
And, if you're interested in "normal" lactate numbers, here are the averages from the dataset (mean VO2max of 52ml/kg/min, 75kg bodyweight)

AeT - 170W @ 1.4 mmol/L
AnT - 238W @ 3.2 mmol/L
Max - 287W @ 7.8 mmol/L Image
And mean fat oxidation for the group at AeT:

4.17 kcal/min

And the model prediction based solely on the average lactate data & max power.... Image
Though, I probably shouldn't use the term "normal" to describe this (52 ml/kg) group. Maybe "desirable" is a better term.

Everything becomes relative when you're working with #Ironman athletes, especially in Boulder 😊 Image

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More from @Alan_Couzens

Jan 22, 2023
A few brief thoughts on the implementation of #AltitudeTraining 👇
* Up to a limit, providing the right altitude is used and the athlete is healthy, IME, *everyone* is a responder.

* That said, there's large variability in response to a given altitude & elevation must, therefore, be individualized according to resting SpO2 (<95%)
* The required elevation to elicit this drop in SpO2 can change with repeated exposures & even with adaptation during long exposures, therefore it's useful to have various elevation options.
Read 9 tweets
Oct 29, 2022
The #Nutrition Thread:

While most athletes have a training plan, few have a well thought out nutritional plan.

This is a big mistake as nutrition is absolutely integral to improved performance and health!

Keeping track of your nutrition is not that hard.

Ideas to get started
1/ Categorize your current training volume. For me:

- Recovery Day ~1hrs
- Normal Loading Day: ~2hrs
- Long Day: ~4hrs
2/ Come up with appropriate energy and macro targets for each day. You may want to get your BMR tested & work with a nutritionist on this, but my *personal* targets:

- 50-100g CHO + ~100g/hr of training
- 1g/lb BW protein per day
- 0.5-1g/lb fat per day (lower end for wt loss)
Read 13 tweets
Oct 27, 2022
Why is this a problem?

Let's talk muscle fibers...

A brief thread 👇 Image
We all have 3 basic muscle fiber types.
- Slow oxidative (aerobic, fat burning)
- Fast oxidative glycolytic (aerobic, sugar burning)
- Fast glycolytic (anaerobic, sugar burning)
There are 3 primary measures that separate the 3:
- Size
- Oxidative potential (capillaries, mitochondria, enzymes)
- Fuel type (glycogen content)
Read 12 tweets
Oct 5, 2022
The geometry that all endurance athletes need to understand (with apologies to Osler)..

A brief thread 👇
The all too common pattern...

- Athlete begins aerobic base work & is frustrated by slow rate of improvement.

- Athlete ratchets up HIT & is impressed by how quickly they improve.

- The proverbial bubble bursts and the athlete is back where they started.
We could add an additional step here...

- Athlete doesn't learn their lesson & only remembers how quickly they initially improved with HIT and so returns to it with the hope of the same improvement!

Of course, they're further down their base triangle right now, so the peak is⬇️
Read 4 tweets
Oct 4, 2022
Random thoughts, old man grumbles and personal revelations...

My top 10 tweets from Q3 2022!! 👇
10. Don't waste your time setting training zones based on a percentage (of max HR, FTP etc).

Every athlete is an individual & needs to be tested.

9. If you're not coming in with a focused nutritional plan, you're either overeating or undereating. Guaranteed!

Read 11 tweets
Sep 27, 2022
A question arising from my zone tweet yesterday:

"Aren't AeT & VT1 basically the same thing?"

No.

Here's why...

A brief thread 👇 Image
While it depends on definitions to each of the above, generally VT1 is defined via the ventilatory equivalents method:

"A rise in VE/VO2 *without* a rise in VE/VCO2"

In practice, this means the grade of VE goes up, the grade of VCO2 goes up but the grade of VO2 remains the same
You can see this it the VT1 point in the chart above.
- VO2 (top line) doesn't change
- VCO2 (next line) changes course & approaches VO2 line
- VE also changes gradient (slightly)

In the test above, this (VT1) occurs at 250W
Read 7 tweets

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