MGF
Mechano growth factor — IGF-1Ec splice variant
The IGF-1 variant muscle produces after mechanical loading. Sound biology as an exercise-repair signal, with no human trial of injected use.
- Category
- Repair & Recovery
- Half-life
- Not established in humans
- Cycle length
- Not established — no human protocol exists
- Level
- advanced
Overview
MGF stands for mechano growth factor, the IGF-1 splice variant muscles produce in response to mechanical loading and injury. It is a signalling molecule generated on the spot, in the tissue that has just been loaded, which is why it has a plausible role in how exercise actually builds and repairs muscle. It is included in the repair section of this library because that is its honest position: a well-described piece of muscle physiology that became a grey-market product. What exists in humans is the biology; what does not exist is a single controlled trial of giving it as an injection.
How it works
MGF is an alternative splice variant of IGF-1 produced when muscle is mechanically loaded or damaged. Unlike systemic IGF-1, it acts largely locally, and it appears to activate muscle satellite cells — the stem cells responsible for repair and new muscle formation — before the later, IGF-1-driven phase of repair. Its short action relative to systemic IGF-1 is part of why it is described as a repair signal rather than a growth signal.
Reported benefits
- Expressed naturally in muscle after mechanical loading and injury
- Increased muscle mass in rodent studies with direct administration
- Repair-oriented mechanism rather than a general growth stimulus
- A clear mechanistic link to exercise adaptation
Reported benefits describe what the published literature and user reports suggest — not a promise of outcome for any individual.
Dosing reference
There is no established human dose. Rodent studies used direct intramuscular administration; no controlled human study of injected MGF exists.
MGF's proposed value is local repair at a specific site, which is why it is described as being injected into a trained muscle. That rationale is plausible physiologically and completely untested in humans.
Community-reported: 200–400 mcg immediately post-training, injected locally, for two to four weeks; PEG-MGF reported at 200–400 mcg per week. No human pharmacokinetic data supports any figure.
These figures are what people report using in public communities. They have not been studied, verified or checked against certificates of analysis, and they are not a recommendation, a prescription or a target to aim for.
Where the reported amounts come from
Amounts are reproduced for education only. Doses from trials cannot be assumed to suit anyone else, and community-reported amounts are frequently wrong. Self-administering unapproved compounds carries serious risk.
The research picture
Human muscle biopsy studies show that MGF expression rises after resistance exercise and after injury, and animal studies show that delivering it locally increases muscle mass and satellite-cell activity. It fits neatly into the accepted sequence of events in muscle repair. Exogenous use is a different matter. There is no published human trial of injected MGF, no pharmacokinetic data and no dose-finding work. Because it is a variant of IGF-1, the broader concerns about growth-factor signalling — including proliferative risk — apply in principle, and locally injected material from unregulated suppliers is exactly the category where identity and sterility problems are common.
Preclinical & non-clinical data
Animal studies show mechanically damaged muscle expressing a local IGF-1 splice variant that pushes satellite cells toward repair, and injecting the variant increases local muscle protein signalling in rodents. Everything published is animal or cell work; there is no human study of MGF at all.
Non-clinical data comes from cells and animals unless stated otherwise. It answers whether a compound is worth studying in people — not whether it is safe or effective in them.
What users report
Reporting lives almost entirely in resistance-training circles, where the pattern described is a local injection into a trained muscle after sessions, with claims of faster soreness resolution and site-specific fullness over a few weeks. The accounts are sparse, and MGF and PEG-MGF are routinely conflated in them, so they cannot be read as describing one compound. Enlarged or painful injection sites are the most frequent complaint.
Where these reports come from
These are unverified personal accounts collected from public sources. They are not evidence of effectiveness or safety, they have not been independently checked, and they are not a recommendation to use anything described.
Possible side effects
- Injection-site pain, swelling or infection
- Muscle soreness
- Unknown systemic effects
- No long-term safety data
Safety notes
No human safety data. As an IGF-1 family molecule, proliferative risk is a theoretical concern, and repeated intramuscular injection adds infection and fibrosis risk at the injection site. Not appropriate for anyone with an active malignancy, and not established in pregnancy.
Stacking
Sometimes combined with IGF-1 LR3 in the reasoning that MGF handles early repair and IGF-1 later growth. The combination increases growth-factor exposure with no evidence of benefit and no safety data.
Related compounds
BPC-157
Body Protection Compound 157 — pentadecapeptide
Repair & Recovery
The repair peptide the rest of the field is measured against.
TB-500
Thymosin Beta-4 fragment
Repair & Recovery
Systemic repair signalling, rather than site-specific.