# myofibrillar & sarcoplasmic hypertrophy



## Tom_B (Sep 14, 2006)

I was wondering if someone could help explain the difference between these two to me?
From what I can gather or find, myofibrillar is the increase of the size of contracticle fibers .. 
So in basic terms what does this mean? Is this what makes that 'dense' look? Is this the type of hypertrophy that helps to increase 'tone' within muscles through more contractions? Kind of like a Bruce Lee look .. small, dense and hard.
(I also realize Myofibrillar is also more related to strength than sarcoplasmic hypertrophy..)
Now Reasearch has told me that sarcoplasmic hypertrophy is an increase in non-contractile components of the muscle such as glycogen, water, minerals, mitochondria, etc
Now I have no sweet clue what this means?? ... Does this mean that the actual SIZE of the muscle tissue will increase allowing more/better/better flow of glycogen/water/minerals and all that stuff?

If anyone could help me wrap my mind around this, it'd be much appricated.

*also a random extra question. Would working in the 15-20 rep range effect sarcoplasmic hypertrophy? Or would this work/accomplish something completely different?


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## ihateschoolmt (Sep 14, 2006)

From what I remember one this, myofibrillar was increasing the cross sections in a muscle making you strong and not bigger. Sacroplasmic is making your muscules retain more fluid and making them look bigger. something like that, do a search I think I made a thread about it a long time ago.


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## ihateschoolmt (Sep 14, 2006)

Oh yea, and 15-20 reps would be more endurence do like 7-10 reps for sacroplasmic, and for scaroplasmic train differently. You don't do explosive movements and do slower reps.


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## Tom_B (Sep 15, 2006)

Thanks!, I managed to find that thread and the link to a atricle that was in it.
Okay pretty sure I get it now, although the stuff I have read myofibrillar aslo increases size not just strength. If your looking for just strength it's more of a neural thing rather than hypertrophy (1-3 rep range)
myofibrillar -> strength and size through increasing the density of filaments (working in the 4-6 reps range, and a bit of 6-8 rep range with quick sets lasting about 20-30 secondsa).
Sarcoplasmic -> Only an increase of size through increasing sarcoplasm and non contractile proteins, giving you the benefit of more mitochordia in the cell  helping with breaking glucose into ATP which will help with protein synthesis and muscular endurance. But if your filaments outgrow your mitochondria then  it's harder for your body to produce ATP, which lowers protein synthesis ..

So if working in the 15-20 reps range (or even higher) is more of an 'endurance' then doesn't this techinacally stimulate sarcoplasmic hypertrophy as there is also a long TUT that the muscle goes under?

I think I get it  hahaha


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## Witchblade (Sep 15, 2006)

Note that you should train in all the rep ranges for bodybuilding purposes to get all sorts of hyperthrophy. Primarily in the 6-12 range of course, but you should do some 1-5 and 15+ stuff too to make all the parts of the muscle grow.


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## GFR (Sep 15, 2006)

All are BS except this one.


http://www.unm.edu/~lkravitz/Article folder/hypertrophy.html


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## CowPimp (Sep 15, 2006)

Myofibrillar hypertrophy is the growth of the myofibrils.  I have read that they also split into a greater number of myofibrils as well.  The myofibrils contain the sarcomere, which is the functional unit of muscle tissue.  This is the one that affects strength, you are correct.  It is best achieved through higher intensity weight training with sufficient volume to spark structural adaptations.

Sarcoplasmic hypertrophy is an increase in intracellular fluid volume; the intracellular fluid is called the sarcoplasm, hence the name.  So, yes, energy stores go up with this form of hypertrophy as glycogen is contained primarily within the sarcoplasm.  This is best achieved when moving closer toward the endurance end of the spectrum.

Both of these lead to an increase in muscle mass.


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## PWGriffin (Sep 15, 2006)

CowPimp said:


> I have read that they also split into a greater number of myofibrils as well.



This is the theory of hyperplausia correct??  And has that been proven in humans or is it all still theoretical?


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## Tom_B (Sep 16, 2006)

Thanks Cow. I was reading a training article by Lyle Mcdonald where he was mainly talking about this and gave a brief explanation, but I wanted to make sure I completely understood the science behind it.


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## CowPimp (Sep 16, 2006)

PWGriffin said:


> This is the theory of hyperplausia correct??  And has that been proven in humans or is it all still theoretical?



Not quite, no.  It's not an actualy increase in the number of muscle fibers, but an increase in the number of myofibrils, which are part of the muscle fibers.


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## Gordo (Sep 16, 2006)

> It's not an actualy increase in the number of muscle fibers



That's dictate at birth isn't it? There's no natural way to increase the number of fibers, I think.


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## CowPimp (Sep 16, 2006)

Gordo said:


> That's dictate at birth isn't it? There's no natural way to increase the number of fibers, I think.



Maybe.  There is just no proof of it right now.  It has been shown to be possible in animals.  However, due to ethical complications, it can't be effectively tested for with current methods.


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