In plain English
MGF is a version of IGF-1 that muscles make when they are stretched, worked or damaged. It acts as an early repair signal, waking up the muscle’s stem cells. The short synthetic peptide sold as MGF is based on the unique tail of this growth factor.
What it's used for
- Muscle repair after training or injury
- Local muscle growth
- Recovery
Benefits
In animal studies, MGF activated muscle stem cells, improved muscle repair after injury and increased muscle size, and it has also been studied for heart and nerve protection. Users report faster recovery in the muscles where it is injected.
How it works
In simple terms: MGF is the muscle’s own “I’ve been worked, start repairs” signal.
After muscle strain, the IGF-1 gene is spliced into the MGF form. Its unique tail activates satellite cells (muscle stem cells), which multiply and fuse into the damaged muscle. Regular IGF-1 then takes over to help those cells mature.
Development history
- 1990s: Discovered by Geoffrey Goldspink and colleagues at University College London, who named it for its link to mechanical loading.
- Later: Made as a short synthetic peptide and adopted by users; a longer-lasting pegylated version, PEG-MGF, followed.
Typical protocols
These ranges are what users commonly report.
| Use | Dose | Timing | Length |
|---|---|---|---|
| Local repair or growth | 100–200 mcg, split between muscles trained | Right after training | 4–6 weeks |
Cycling
Commonly run for 4–6 weeks, then a break.
Administration options
Injected into or near the muscle just trained, because it breaks down within minutes in the blood.
Reconstitution and dosing calculator
Usually comes in 2 mg vials, mixed with 2 mL of bacteriostatic water.
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This tool does arithmetic only. It does not choose a dose or confirm that any substance is right for you. Double-check every result against your syringe and your clinician’s instructions.
Side effects and safety
- Users report it is generally well tolerated; injection-site soreness is the most common complaint.
- Possible low blood sugar.
- Long-term effects in people are unknown.
- People with active cancer are usually advised to avoid growth factors and growth hormone-raising compounds.
- Avoid during pregnancy and breastfeeding.
- Prohibited in competitive sport (WADA).
Common stacks
- IGF-1 DES or IGF-1 LR3: MGF is often used right after training, with IGF-1 later.
- Growth hormone peptides.
Storage
Powder: refrigerate or freeze. After mixing: refrigerate at 2–8 °C and use within about 3 weeks.
Compare with
- PEG-MGF: the same peptide made long-lasting so it can be injected under the skin and act throughout the body.
- IGF-1 DES: a different local growth factor with a similar timing pattern.
Frequently asked questions
MGF or PEG-MGF?
MGF lasts minutes, so it is injected right into the trained muscle. PEG-MGF lasts much longer and is usually taken a few times a week.
References
- Goldspink G. Mechanical signals, IGF-I gene splicing, and muscle adaptation. Physiology (Bethesda). 2005;20:232-238.
- Yang SY, Goldspink G. Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation. FEBS Lett. 2002;522(1-3):156-160.