MGF
24-amino acid C-terminal peptide fragment derived from IGF-1 splice variant
- Class
- IGF-1 splice variant
- Half-life
- ~5-7 minutes (native) · hours (PEG-MGF)
- Route
- Intramuscular
- Cadence
- Multiple per week
- Evidence
- Animal data primarily
Overview
MGF is a 24-amino-acid peptide that your muscles produce naturally after they get damaged or overloaded — the C-terminal fragment that gets cleaved off when the IGF-1 gene splices in response to mechanical stress. It's named 'mechano' because it shows up fast after you train hard, peaking within 1-4 hours, then drops off. The idea: it kicks satellite cells (muscle stem cells) into gear to start the repair process, while the regular IGF-1 that comes later handles the actual rebuilding.
Geoffrey Goldspink's lab at University College London characterised it in the late 1990s and early 2000s. The hypothesis is compelling — MGF as the 'first responder' that activates the repair crew, IGF-1 as the 'builder' — and it's become popular in bodybuilding and research peptide markets. The catch: almost all the evidence is in cell culture or rodents. No human clinical trials have been published on injected MGF or its PEGylated version (PEG-MGF, which lasts longer). And one major replication attempt by two pharma labs in 2013 couldn't reproduce the claimed satellite-cell effects at all.
Two forms circulate in the research market: native MGF (clears in 5-7 minutes, almost useless systemically) and PEG-MGF (pegylated to extend half-life to hours). Neither is approved anywhere. WADA bans MGF explicitly under peptide hormones / growth factors. The actual peptide you'd get varies wildly between sellers — structure isn't standardised, purity is unverified, and at least one black-market analysis found a C-terminal amidated analogue instead of native human MGF.
Safety considerations
A few of the safety signals worth knowing — the full list, with dosing context and what to monitor, is inside AIx Core.
- Not approved for human use by FDA, EMA, or any regulator. Sold as research chemical — purity, actual peptide identity, and sterility are unverified.
- WADA prohibits MGF at all times under S2 (peptide hormones / growth factors). Using it makes you ineligible for tested competition.
- Theoretical risk of uncontrolled satellite-cell proliferation — MGF activates stem-like cells. Long-term safety in humans is completely unknown.
+ 3 more safety notes inside AIx Core →
Commonly monitored
Markers and signals people track when researching MGF.
- IGF-1 serum levels (to check for systemic spillover)
- Fasting glucose and insulin (IGF-1 family effects)
- Subjective recovery rate and muscle soreness
- Injection site reactions (IM injections carry more local irritation risk)
- Any unusual lumps or masses at injection sites (theoretical satellite-cell overstimulation risk)
Frequently asked questions
What is MGF?
24-amino acid C-terminal peptide fragment derived from IGF-1 splice variant. MGF is a 24-amino-acid peptide that your muscles produce naturally after they get damaged or overloaded — the C-terminal fragment that gets cleaved off when the IGF-1 gene splices in response to mechanical stress. It's named 'mechano' because it shows up fast after you train hard, peaking within 1-4 hours, then drops off. The idea: it kicks satellite cells (muscle stem cells) into gear to start the repair process, while the regular IGF-1 that comes later handles the actual rebuilding.
How is MGF administered?
Intramuscular, typically multiple per week.
What is the half-life of MGF?
~5-7 minutes (native) · hours (PEG-MGF) — Native MGF clears in minutes; PEGylated form extends activity to several hours.
Is MGF approved for human use?
MGF is investigational — not approved by the FDA, EMA, or MHRA for human use at the time of writing.
What does the evidence show for MGF?
Evidence tier: Animal data primarily. Kandalla et al. 2011 (Mech Ageing Dev): MGF-24aa E-peptide significantly increased proliferative lifespan of human satellite cells from neonatal and young adult donors in vitro, but not from old adult donors — suggesting age-dependent responsiveness.
What is commonly monitored when researching MGF?
Commonly tracked markers + signals: IGF-1 serum levels (to check for systemic spillover), Fasting glucose and insulin (IGF-1 family effects), Subjective recovery rate and muscle soreness, Injection site reactions (IM injections carry more local irritation risk), Any unusual lumps or masses at injection sites (theoretical satellite-cell overstimulation risk).
Related compounds
Open this in AIx Core for the full picture
Mechanism breakdown, receptor pathway diagram, full safety list, monitored items, source citations, and one-tap add-to-protocol. Free with any account.