PeptidePeptideGrowth factorIGF-1 splice variant

PEG-MGF

Also known as Pegylated MGF · PEG Mechano Growth Factor · PEG IGF-1Ec

Written by enwyReviewed 15 Jul 20261 sources0 comments

PEG-MGF is a pegylated synthetic version of Mechano Growth Factor, a splice variant of IGF-1 (IGF-1Ec) produced by muscle in response to mechanical overload. Pegylation is claimed to extend its otherwise very short half-life, and it is marketed for muscle repair and hypertrophy. Essentially no controlled human data exist; use is preclinical-derived and anecdotal.

01 Overview

Mechano Growth Factor is an alternatively spliced product of the IGF-1 gene that appears transiently in damaged muscle and is thought to activate satellite cells before the systemic IGF-1 response takes over. PEG-MGF attaches a polyethylene glycol chain to the synthetic peptide to slow renal clearance and enzymatic breakdown, which vendors present as making it viable for injection every few days rather than needing repeated local dosing.

The evidence base is almost entirely rodent and cell-culture work on the native MGF sequence, not the pegylated research-chemical product sold online. There are no published human trials of PEG-MGF, no pharmacokinetic characterisation in people, and no regulatory approval anywhere. Reported benefits come from bodybuilding forums rather than data.

02 Mechanism

The MGF C-terminal peptide is proposed to activate quiescent muscle satellite cells and promote their proliferation, supporting repair after mechanical damage; pegylation slows clearance to prolong exposure.

03 Dosing

Tier	Dose	Route	Notes
Anecdotal	200–400 mcg	SubQ	Forum protocols only; typically dosed post-workout or every few days. No validated dosing exists.

04 Effects

Effect	Magnitude	Evidence
Satellite cell activationMGF activates and proliferates muscle satellite cells in rodent and cell-culture models.	Not quantified in humans	Preclinical
Claimed enhanced muscle recoveryUsers report faster recovery, but no controlled human data support this.	Unquantified	Anecdotal

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
Injection-site reactionsRedness, swelling or irritation at the injection site.	Mild	Common with subcutaneous peptides	Anecdotal
Unknown long-term / theoretical growth-signalling riskAs an IGF-1-related growth signal, theoretical concerns about promoting proliferation of existing abnormal cells exist but are unstudied for this peptide.	Moderate	Uncharacterised	Unconfirmed

06 Legal status

United States

Not FDA-approved; sold as research chemical

Not approved for human use; WADA-prohibited in sport. · as of Jan 2026

07 References

Mechano growth factor, a splice variant of IGF-1, and muscle repairJournal of Physiology (review)

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.