Growth Hormone & IGF Axis
PEG-MGF (Pegylated Mechano Growth Factor)
Commonly used for
Muscle RegenerationRecoveryMuscle & Strength
What is it?
PEG-MGF (Pegylated Mechano Growth Factor) is marketed as a modified, longer-acting version of mechano growth factor (MGF), a splice variant of IGF-1 that is naturally upregulated in muscle tissue after mechanical stress or injury and activates muscle progenitor/satellite cells.
Mechanism of action: IGF-1 splice-variant signaling; Activates muscle satellite (stem) cells (preclinical); Naturally upregulated in muscle after mechanical loading/injury
What do people use it for?
Proposed indications: Muscle regeneration (preclinical); Recovery; Muscle hypertrophy (preclinical)
How is it used? / Dosing
Commonly reported by peptide clinics†: 200-400 mcg once or twice weekly
Bodybuilding/research-chemical community sources commonly report 200-400 mcg once or twice weekly, reflecting its pegylation-extended half-life relative to unmodified MGF. No human clinical trials exist -- this reflects community convention, not evidence.
†Reported by peptide clinics and compounding pharmacies -- not derived from human clinical trials. Not an individualized recommendation. Actual use should be supervised by a qualified provider.
Typical clinical dosing schedule: No established clinical dosing. Not an approved therapeutic agent; used in laboratory/research settings only.
Administration: Subcutaneous or intramuscular injection (research settings) — No established clinical dosing
How does it compare?
Compare with:
How well does it work? / Evidence
? Emerging / limited evidence
An "emerging / limited evidence" rating means rigorous research hasn't caught up yet -- not that this peptide doesn't work. Many peptides in this category are newer or simply understudied rather than proven ineffective.
Evidence rating: ⭐⭐☆☆☆ — Peer-reviewed research supports mechano growth factor (MGF, an IGF-1 splice variant/IGF-1Ec-associated peptide) as naturally upregulated after mechanical loading or injury and capable of activating muscle progenitor cells in experimental studies. "PEG-MGF" specifically — a pegylated, longer-acting research/commercial version — is poorly represented in mainstream peer-reviewed pharmacology; the established biology below describes native MGF, not a verified PEG-MGF clinical product.
Safety & side effects
Common side effects: Injection-site reactions, Hypoglycemia (insulin-like effect)
Serious risks: Theoretical concern for stimulating malignant cell growth given IGF-1 pathway activity; Unknown long-term safety
Monitoring: Blood glucose, Clinical adverse effects
Legal & regulatory status
Legal status: Not FDA-approved for human use. This is a research compound, not a medication — any use should only occur under the direction of a licensed healthcare provider, and its legal availability varies and changes frequently. Verify current status independently before considering use.
Regulatory status: Research peptide • Not FDA approved
Who should avoid it?
Contraindications: Not established. Avoid in:; Pregnancy; Active malignancy (IGF-1 pathway activation is a theoretical concern in cancer biology); Uncontrolled endocrine disease
Pregnancy & breastfeeding: Avoid.
Research & references
Matheny RW Jr, Nindl BC, Adamo ML. (2010). Mechano-growth factor: a putative product of IGF-I gene expression involved in tissue repair and regeneration. Endocrinology, 151(3), 865–875. Kandalla PK, Goldspink G, Butler-Browne G, Mouly V. (2011). Mechano Growth Factor E peptide (MGF-E), derived from an isoform of IGF-1, activates human muscle progenitor cells. Mechanisms of Ageing and Development.