Most people hear “growth hormone” and assume it must be one of the most powerful muscle-building tools.

It’s not.

And the reason why comes down to what is actually happening inside your muscle cells.

This is where most explanations fall apart—so we’re going to simplify it without skipping the important parts.

Whether you’re on TRT, using other androgens, experimenting with peptides, or none of the above—understanding how these systems work is valuable. This is not medical advice. I’m not recommending anyone take anything—only explaining the science and, where relevant, my own experience.

When you lift weights, you create tension in the muscle.

That triggers a signal inside the muscle cell that says:

“We need to grow.”

This activates something called mTOR.

👉 mTOR = the “build muscle” switch

Once mTOR is on:

Growth hormone (GH) works mostly by increasing IGF-1.

When IGF-1 reaches the muscle:

→ it binds to the IGF-1 receptor
→ activates a pathway (PI3K → Akt → mTOR)

In simple terms:

IGF-1 helps push the “build muscle” switch harder

That sounds powerful—but here’s the catch:

Training already turns mTOR on strongly

So IGF-1 is doing this:

It does NOT:

IGF-1 works through the same pathway that training already uses

So it can:

But it cannot:

fundamentally change how much muscle you’re capable of building

Now this is where everything changes.

When testosterone (or steroids) enters the muscle:

→ it binds to the androgen receptor
→ that complex goes into the nucleus (control center of the cell)
→ and changes what the muscle is programmed to do

Androgens don’t just push the signal…

They change the muscle itself

👉 The muscle can now produce more protein

Satellite cells are like:

extra “worker units” that can be added to a muscle fiber

Androgens:

👉 This increases how much muscle that fiber can build

👉 pushes the gas pedal a little harder

👉 upgrade the engine

75 Days to Shredded is the exact zero-BS system I used at 47 to lose 25 lb of fat and gain 6 lb of muscle.