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Myofibrillar vs Sarcoplasmic Hypertrophy

Coach, my understanding is that you’ve described there’s no such thing as myofibrillar vs sarcoplasmic growth in the sense of one does not only lead to an increase in the contractile elements and the other only lead to an increase in non-contractile fluid; the actual difference is the neurological component is absent in what is considered “sarcoplasmic”.

That makes sense. It brings up two questions in my head:

  1. Why does what is typically considered “myofibrillar hypertrophy” lead to a denser/harder physique?

  2. Conversely, even though what is considered “sarcoplasmic hypertrophy” also leads to an increase in the contractile elements of a muscle fiber, why does that type of training lead to more, for lack of better terms, fluid retention? Or am I missing the point and it still leads to an increase of non-contractile elements, it just also increase contractile elements?

Thank you.

I’ll be honest, I’m oscilating back and forth between whether there is such a thing as myofibrillar and sarcoplasmic hypertrophy. Many scientists I respect say that there is no such thing (Stuart Philips for example) but indirect evidence might suggest that it does exists.

As far as the denser looking physique goes though, it’s simply a matter of a higher muscle tone even at rest. And muscle tone is nothing more than a partial state of activation and this is a neurological phenomenon. A more efficient nervous system should lead to a higher muscle tone. So training programs that focus on neurological efficiency should contribute to giving you a harder look.

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Water retention is closely related to cortisol levels because cortisol increases the levels of aldosterone and the vasopressin, and a higher level of these hormones lead to an increase in fluid retention.

Also, growth hormone and IGF-1 increase intramuscular water retention (that’s why a lot of people think that GH builds a lot of muscle, in reality it only blow up the muscles by pulling water in).

So a type of training that would lead to both a higher level of GH/IGF-1 (higher lactate production, as seen in pump work, tends to do this) AND cortisol (again, high volume will o this), could lead to intramuscular water retention.