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Lexicon

Muscle & performance

MGF (Mechano Growth Factor)

A splice variant of IGF-1 that forms in muscle after load and is meant to activate satellite cells, with a purely preclinical record.

2 min read 1 sources Calculator Updated May 2026
Class
IGF-1 splice variant (IGF-1Ec)
Use
Subcutaneous / local (in mcg)
Half-life
very short
Status
Preclinical, no human data

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Equipment

Equipment you need

For reconstitution and injection you need a bit of basic gear. Here are solid, cheap options:

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What is MGF?

MGF, the Mechano Growth Factor, is a special splice variant of IGF-1 (IGF-1Ec) that forms in muscle after mechanical load or damage. The idea: MGF is the first signal that triggers repair and growth after a training stimulus.

Up front: the exciting effects come from cell and animal models, in humans the data on injected MGF is thin.

How it works

After a training stimulus the muscle briefly splices the IGF-1 gene to MGF. This activates satellite cells, the muscle's dormant repair cells, and triggers their proliferation. Only afterwards does the longer-lived IGF-1Ea form take over the actual building.

Injected MGF is very short-lived, which is why it is used locally and close to training, if at all.

What you need

  • The MGF vial (lyophilized powder).
  • Bacteriostatic water, U-100 insulin syringes, alcohol swabs.

Reconstitution

Use the calculator above. A 5mg vial with 2ml water gives 2500mcg per ml, 200mcg is then 8 units on the U-100 syringe. Just add the water to the vial and let it dissolve.

Dosing

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Injection

Subcutaneous, often locally into the trained muscle group. Disinfect the site, inject slowly, rotate sites.

What the research shows

The foundational work (Hill & Goldspink, 2003) showed that after damage the muscle first forms MGF and through it activates satellite cells, before the IGF-1Ea form takes over. That is a clean mechanism but described in cells and animals.

For injected MGF in humans there are no solid studies. It is clearly experimental.

Side effects

  • Solid human data are missing, so little is known about side effects.
  • Local reactions at the injection site.
  • As with IGF-related compounds, a growth-promoting signal is theoretically critical with pre-existing growths.

Practice

  • Keep expectations low, everything rests on cell and animal models.
  • If at all, close to training and local.
  • Banned in official competition.

Storage

Before mixing the powder is robust, normal room temperature (around 20 to 25 degrees) is fine, ideally kept in the dark. After mixing, keep in the fridge (2 to 8 degrees), do not freeze. It stays good there for at least 8 to 10 weeks with barely any loss of potency, in practice considerably longer. Swirl or shake to mix, both are fine.

Evidence

Sources

  1. 1 MGF as an IGF-1 splice variant activates muscle satellite cells after tissue damage (preclinical). Hill & Goldspink, The Journal of Physiology, 2003

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