Comparison
MGF vs PEG-MGF
Both are IGF & growth factors, so the meaningful differences are in kinetics, evidence and regulatory status.
| MGF | PEG-MGF | |
|---|---|---|
| Class | IGF & growth factors | IGF & growth factors |
| Evidence | Animal models only | Animal models only |
| Human trials | ~1 | None published |
| Half-life | ~5-7 minutes | ~48-72 hours |
| Reported range | 100-200 mcg | 200-400 mcg |
| Frequency | Post-training, localised | 2-3x weekly |
| Routes | Subcutaneous, Intramuscular | Subcutaneous, Intramuscular |
| FDA approved | No | No |
| Research use only | Yes | Yes |
| Banned in sport | Yes | Yes |
| Studied for | Satellite cell activation research, Muscle repair studies | Systemic muscle repair research, Recovery protocols |
| Reported side effects | Injection-site reactions, Transient fatigue | Injection-site reactions, Fatigue, Headache |
MGF
Mechano growth factor is the IGF-1Ec splice variant, produced locally in skeletal muscle after mechanical overload or injury. Its distinct C-terminal E-domain peptide acts independently of the IGF-1 receptor to activate satellite cells and promote myoblast proliferation, positioning it upstream of the differentiation signalling that mature IGF-1 drives. Its extremely short half-life in circulation is the central practical problem and the reason the pegylated form was developed.
PEG-MGF
Pegylation attaches polyethylene glycol to the MGF peptide, increasing its hydrodynamic radius and shielding it from renal filtration and proteolysis. This converts a compound cleared in minutes into one measurable for days, trading the localised, pulsatile action of native MGF for systemic exposure. Whether that trade preserves the satellite-cell effects that make MGF interesting has not been established in humans.
MGF vs PEG-MGF: common questions
What is the difference between MGF and PEG-MGF?
Both are IGF & growth factors. MGF: A splice variant of IGF-1 expressed by muscle in response to mechanical loading and damage. PEG-MGF: Mechano growth factor with a polyethylene glycol chain attached, extending its circulating half-life from minutes to days.
Which has stronger evidence, MGF or PEG-MGF?
They sit at the same evidence level: animal models only. MGF has about 1 human studies and PEG-MGF about 0.
Are MGF and PEG-MGF FDA approved?
Neither is FDA approved for any indication.
References
Regulatory and primary sources
- WADA Prohibited List ↗ · current year
- FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
Published literature
- Growth factors and muscle ageing.Exp Gerontol 2004.PubMed 15501012 · doi:10.1016/j.exger.2004.08.010
- Growth factors, muscle function and doping.Curr Opin Pharmacol 2008.PubMed 18353722 · doi:10.1016/j.coph.2008.02.002
- Ageing and local growth factors in muscle.Scand J Med Sci Sports 2003.PubMed 12535315 · doi:10.1034/j.1600-0838.2003.20235.x
- IGF-IEc expression, regulation and biological function in different tissues.Growth Horm IGF Res 2010.PubMed 20494600 · doi:10.1016/j.ghir.2010.03.005
- Impact of Physical Exercise on Endocrine Aging.Front Horm Res 2016.PubMed 27348867 · doi:10.1159/000445158
- Gene expression in skeletal muscle.Biochem Soc Trans 2002.PubMed 12023866
- Age-related loss of skeletal muscle function; impairment of gene expression.J Musculoskelet Neuronal Interact 2004.PubMed 15615114
- GLUT1 regulation of the pro-sclerotic mediators of diabetic nephropathy.Am J Nephrol 2013.PubMed 23817135 · doi:10.1159/000351989
- Gene expression in muscle in response to exercise.J Muscle Res Cell Motil 2003.PubMed 14609023 · doi:10.1023/a:1026041228041
Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.