Muscle hyperplasia

[karky]

Quick question. Can it happen through training?

I've heard of hypertrophy (bigger muscle cells) happening, but I've also heard of hyperplasia (making more cells) happening. However, I've also heard it can't happen
So I want to hear it from the experts

Also, if it can happen, any specific training that seems to trigger it?

[Matthew]

You've been asking a lot of sciencey questions lately. Have you been reading text books, or articles online?

[Lisa~]

This article might add to your understanding:

Muscle Fiber Hypertrophy vs. Hyperplasia by Jose Antonio

[Frank.S]

Added growth hormone/igf-1 has been shown to cause hyperplasia, some research with extreme stretching in birds has shown the same.

training can increase IGF-1 levels, but I have found anything showing that this is enough for significant increase in muscle fibers.

edit- lisas link sums it up good.

[karky]

Originally Posted by Matthew

You've been asking a lot of sciencey questions lately. Have you been reading text books, or articles online?

I'm just a smart guy :p

Well, I've had some biology, and it intrests be alot. Wasn't anything about this in my biology book, but I like to know the science behind stuff.

That's one interresting article Lisa.
Question: Myogenic stem cells (sattelite cells) can cause hypertrophy and hyperplasia. Do we have an unlimited number of these? Does the body make more if you were to use alot of these in making hypertrophy and hyperplasia? Or do we just have such a huge ammount of these from birth that it doesn't limit us.

I ask because I know stem cells (the ones at the very beginning that can become anything) are very debated and does not exist in adults (a bit unsure about that one). But I know that we have "other" stem cells like the sattelite cells. Just steem cells that are not completley differentiated yet. That's why I want to know if we have an unlimited number of those or not..

Sorry I'm lacking a bit of the terminology here, it's been a long time since I learned about this stuff in addition, I learned about it in Norwegian :p. Hopefuly those of you who know about it will know what I mean.

Again, thanks for the article Lisa, I just love this stuff. But I'm afraid you've now unleashed something no one can control.. my curiosity

[Lisa~]

I'm glad you liked the article karky, but I don't know the answers to your questions. You're getting into stuff that's a bit over my head here.

[youngliver]

Here's a link that might answer some questions about stem cells...

http://stemcells.nih.gov/info/basics/basics4.asp

[karky]

Originally Posted by Lisa~

I'm glad you liked the article karky, but I don't know the answers to your questions. You're getting into stuff that's a bit over my head here.

I'm going to my home town tomorrow, and I got my biology text book there. I'll try to look up some stuff.. maybe even hunt down my old biology teacher

[karky]

I recently read a big discussion about whether hyperplasia is possible or not (in humans), where it was said again and again that all the "top Phds" said it wasn't possible. Does anyone here have an opinion? do you think it's possible, or not? and if so, why?

I decided to just bump this old thread of mine instead of making a new one.

[PowerManDL]

I doubt it's possible due to the way human muscles are innervated neurologically.

The mammals that have shown functional hyperplasia, ie satellite cells actually becoming functional muscle fibers, are multiply-innervated and their fibers connect intrafascicularly (which is a long way of saying "they connect to each other"). Humans on the other hand have fibers that (in most cases) run from origin to insertion, and are singly-innervated (one axon per fiber).

What this likely means is that even if the actual fiber were to develop from a satellite cell, it wouldn't be "wired in" to the nervous system. The cell fusion we've adapted seems to be more efficient for human needs anyway; multiple nuclei and nuclear domains means larger cross-sectional areas and force-production ability.

[Frank.S]

Interesting PMDL..

I do think that IGF-1/GH have been shown to create hyperplasia in humans, but who knows if its functional muscle (damn, I said 'functional').

[PowerManDL]

The IGF-1 pathways are part of the chemical trigger for sat cell proliferation and activation, and also play a part in later cell fusion; it'd be a likely place to start if there were such a mechanism in place in humans, but IIRC there's been nothing showing it to happen conclusively beyond that.

[karky]

Originally Posted by PowerManDL

I doubt it's possible due to the way human muscles are innervated neurologically.

The mammals that have shown functional hyperplasia, ie satellite cells actually becoming functional muscle fibers, are multiply-innervated and their fibers connect intrafascicularly (which is a long way of saying "they connect to each other"). Humans on the other hand have fibers that (in most cases) run from origin to insertion, and are singly-innervated (one axon per fiber).

What this likely means is that even if the actual fiber were to develop from a satellite cell, it wouldn't be "wired in" to the nervous system. The cell fusion we've adapted seems to be more efficient for human needs anyway; multiple nuclei and nuclear domains means larger cross-sectional areas and force-production ability.

That's interresting. Isen't it possible that the new muscle fibers (if we assume hyperplasia can happen) would somehow connect to the nervous system. I'm a bit out of my leauge here though, just asking questions.

[PowerManDL]

Unless there's something going on at the peripheral level w/ the motoneurons or the NMJ, which has never been observed, then no it's not very likely.

I should note that the hyperplasia I noted above in non-human mammals is actually fiber splitting, not maturation of the satellite cells into new fibers, which is what would have to happen in humans.

[karky]

You're saying human muscle fibers can't split into two muscle fibers? If so, why?

[PowerManDL]

Because of what I said previously; human fibers are singly-innervated, meaning only one motoneuron attaches to a given fiber.

Mammals that show fiber-splitting have multiply-innervated fibers, meaning more than one endplate (neuron connection) per fiber, and otherwise arranged in a different fashion. Which means that there's more than one "wire" available in the case of splitting, if that makes sense.

[EricLikesLifting]

I have heard from almost everyone that the number of muscle fibers is fixed, or that hyperplasia isn't possible. Scientifically, right now, myostatin and myostatin blockers are a more hot research area. Myostatin is a growth factor that limits our muscle growth. There is still a lot of research going on right now, and I honestly don't know a whole lot about it. If you search on the web, there are certainlly myostatin 'blockers' that are for sale but they are all garbage so don't bother trying to gain anything but information and knowledge (although some testing is being done).

For your viewing pleasure, here is a cow with a genetic mutation such that myostatin is not produced or inhibited.


Hope that somewhat satisfies your curiosty.

[PowerManDL]

Myostatin (and other negative feedback loops, that's just the big one) is an interesting thing, regarding sensitivity to training and what not. However it only impacts hypertrophy in fibers, not the hyperplasia response.

There's gonna be some fun stuff in this area coming in the next few decades, no doubt, from the myostatin blocking (which may or may not play out unless it's done in an embryo, but it *might* have effects in training), to the MGF coding to other fun stuff like SARMs (ie, steroids that only effect muscle tissue). Being able to hack the body at the chemical level will open up all kinds of doors.