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Other/Mixed Mitochondria slow vs fast fibers

Other strength modalities (e.g., Clubs), mixed strength modalities (e.g., combined kettlebell and barbell), other goals (flexibility)

Harald Motz

Level 8 Valued Member
Seems to be a high calliber study:

Very interesting with regards to Pavel's StrongEndurance...Q&D objective of "making fast fibers more aerobic" ...or "build mitochondria in fast fibers"

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Harald Motz

Level 8 Valued Member
Interesting.

My guess is you would get similar results studying rowers.
Pretty safe bet, I think too.

One takeaway seems:
- slow fibers (can) have a high number of mito to oxidize fat
- fast 2a fibers (can) have a high number of mito to be able to convert lactate to pyruvate to be oxidized in the mito (besides carbs/glycogen - lactate/pyruvate for fuel
- the superfast 2x fibers seem to be just that: superfast, superstrong, super tired fast (ATP/CrP for fuel)
 

Harald Motz

Level 8 Valued Member
Interesting.

My guess is you would get similar results studying rowers.
Pretty safe bet, I think too.

One takeaway seems:
- slow fibers (can) have a high number of mito to oxidize fat
- fast 2a fibers (can) have a high number of mito to be able to convert lactate to pyruvate to be oxidized in the mito (besides carbs/glycogen - lactate/pyruvate for fuel
- the superfast 2x fibers seem to be just that: superfast, superstrong, super tired fast (ATP/CrP for fuel)
 

watchnerd

Level 8 Valued Member
Pretty safe bet, I think too.

One takeaway seems:
- slow fibers (can) have a high number of mito to oxidize fat
- fast 2a fibers (can) have a high number of mito to be able to convert lactate to pyruvate to be oxidized in the mito (besides carbs/glycogen - lactate/pyruvate for fuel
- the superfast 2x fibers seem to be just that: superfast, superstrong, super tired fast (ATP/CrP for fuel)

The other takeaway is the variance between arms and legs, at least among skiers.

Although they concede that it might be worth it to study other populations like kayakers (arms only) vs cyclists (legs only):

A cross-sectional comparison of, e.g., kayakers or cyclists who train their upper or lower bodies specifically, would have allowed characterization of more highly trained muscles, for instance, with more extensive local blood flow during exercise. However, higher mitochondrial volume fractions have not been reported in larger groups and a cross-sectional design would limit direct comparisons between limbs. At the same time, it is important to note that our present observations and conclusions are relevant only for equally well-trained arm and leg muscles.
 

North Coast Miller

Level 8 Valued Member
Trying to wrap my head around just how the mitochondria is intersecting with muscle metabolism. My understanding of fiber type atpase specificity is seriously lacking.
 

guardian7

Level 6 Valued Member
Geoff Neupert (KB Strong, friend of SF) just had a good email series on autoregulated training Type 2x/a fibers for fat loss. In a nutshell, heavyish and explosive hybrid training in low rep repeat sets, autoregulated resting not letting rep speed and quality drop is a contrarian key to fat loss. With the article from the OP, it would seem that we should pay more attention to muscle fibre types, particularly lower body. SF has some other articles that are relevant for different types of muscle fibre emphasis. How to Build Your Slow Fibers, Part I | StrongFirst David Epstein's book, "The Sports Genes" also has some interesting information.
 

Ege

Level 5 Valued Member
Very interesting with regards to Pavel's StrongEndurance...Q&D objective of "making fast fibers more aerobic" ...or "build mitochondria in fast fibers"
@Harald Motz ; could you please shed more light for us mortals? What does this mean for Q&D? Does it mean, at least the objective of Q&D is attainable ?
Best;

Ege
 

Ege

Level 5 Valued Member
Thanks Ryan. At some point I will read, indeed as of now its best for me to focus on Swings and TGUs :) thanks again.
 

North Coast Miller

Level 8 Valued Member
@Harald Motz ; could you please shed more light for us mortals? What does this mean for Q&D? Does it mean, at least the objective of Q&D is attainable ?
Best;

Ege

Am not Harold, but the expected outcome from Q&D is already established via research on HIIT (is explained briefly in the book).

To my understanding though, this research goes a step further by demonstrating a direct oxidatitive capacity of some Type II fibers (if I’m reading it correctly), rather than simply improving the environment for type II via aerobic capacity support.
 

watchnerd

Level 8 Valued Member
Am not Harold, but the expected outcome from Q&D is already established via research on HIIT (is explained briefly in the book).

To my understanding though, this research goes a step further by demonstrating a direct oxidatitive capacity of some Type II fibers (if I’m reading it correctly), rather than simply improving the environment for type II via aerobic capacity support.

I think your interpretation is correct.

I'm also trying to discern if there is some implied mechanism of waved loading of the power curve inherent in cross country skiing where the legs generate a semi-explosive "push" using faster twitch muscles, and the arms add additional energy on top of that in a less explosive fashion as part of the propulsion dynamics.

I don't know enough about cross country skiing kinematics, but I do know that happens in rowing.
 

North Coast Miller

Level 8 Valued Member
I think your interpretation is correct.

I'm also trying to discern if there is some implied mechanism of waved loading of the power curve inherent in cross country skiing where the legs generate a semi-explosive "push" using faster twitch muscles, and the arms add additional energy on top of that in a less explosive fashion as part of the propulsion dynamics.

I don't know enough about cross country skiing kinematics, but I do know that happens in rowing.

I’m wondering what they might find if they sampled other athletes such as boxers, defensive backs etc. Everything will present on a sliding scale…

If these findings are correct, how do you even define fiber types if they cannot be separated definitively by ATPase? Also, are these survivor bias results, and what are the knock-on carryover attributes, if any?

Or am I reading this wrong and the study simply supports preferential density clustering of mitochondria near (on top of!) highly trained type II fibers, already observed as a result of HIIT. The fibers themselves still dependent on CrP or the 2 ATP from glycolysis? I lost track of the sample prep methods within the first sentence.
 

North Coast Miller

Level 8 Valued Member
Thanks for your kind answer. I guess I should not even ask this/a question without reading the book.

You should get the book, but in a nutshell the underpinings of Q&D are not theoretical. Strictly speaking the application is perhaps extrapolated, but 100% plausible/possible/maybe go so far as to say “to be expected”.
 

watchnerd

Level 8 Valued Member
I’m wondering what they might find if they sampled other athletes such as boxers, defensive backs etc. Everything will present on a sliding scale…

If these findings are correct, how do you even define fiber types if they cannot be separated definitively by ATPase? Also, are these survivor bias results, and what are the knock-on carryover attributes, if any?

Or am I reading this wrong and the study simply supports preferential density clustering of mitochondria near (on top of!) highly trained type II fibers, already observed as a result of HIIT. The fibers themselves still dependent on CrP or the 2 ATP from glycolysis? I lost track of the sample prep methods within the first sentence.

I'm sure there is survivorship bias, as there is in any elite sport.

I read it as your latter interpretation -- additional density clustering on top of highly trained type II. But I could be wrong, too.

As for fiber type distinction, I've listened to some podcasts that there is a movement now to consider the definition of distinct fiber types as being a bit obsolete -- that all muscle fibers exist on a spectrum between fast and slow twitch, and there is now more evidence that fibers can migrate along that spectrum, at least to some extent, due to epigenetics.
 

Don Fairbanks

SFG II
Certified Instructor
I'm sure there is survivorship bias, as there is in any elite sport.

I read it as your latter interpretation -- additional density clustering on top of highly trained type II. But I could be wrong, too.

As for fiber type distinction, I've listened to some podcasts that there is a movement now to consider the definition of distinct fiber types as being a bit obsolete -- that all muscle fibers exist on a spectrum between fast and slow twitch, and there is now more evidence that fibers can migrate along that spectrum, at least to some extent, due to epigenetics.
A brief bit here on the migration along the spectrum. He has another 2.5 hrs. worth in his 3 part series on the subject. And yes, highly training specific.

 
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