Overview
MGF (Mechano Growth Factor), also designated IGF-1Ec, is a splice variant of insulin-like growth factor 1 (IGF-1) produced locally in muscle tissue in response to mechanical loading and injury. Unlike systemic IGF-1, MGF is transiently expressed at the site of damage and specifically activates quiescent muscle satellite cells — the resident stem cells responsible for muscle repair and hypertrophy. It is used in research and by athletes interested in accelerating muscle recovery.
Mechanism of action
MGF arises from alternative splicing of the IGF-1 gene: a 49-base-pair insert in exon 5 causes a reading frame shift, producing a unique carboxy-terminal E-domain peptide (the MGF E-peptide) that does not bind the IGF-1 receptor and signals through distinct, incompletely characterized pathways. When muscle fibers are subjected to mechanical strain or damage, the IGF-1 gene is preferentially spliced toward the MGF (IGF-1Ec/Eb) isoform. The resulting MGF E-peptide activates quiescent satellite cells — inducing proliferation without differentiation — expanding the progenitor pool available for repair. Mature IGF-1 (primarily IGF-1Ea splice variant) then drives satellite cell differentiation, fusion into existing fibers, and net fiber hypertrophy. This two-phase sequence (MGF: proliferate; IGF-1Ea: differentiate) explains why exogenous MGF, timed post-exercise or post-injury, may amplify the hypertrophic response. Pegylated MGF (PEG-MGF) extends the very short half-life of the native peptide from minutes to days.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| Muscle recovery / satellite cell activation | intramuscular | 200–400 mcg | 2-3x per week post-workout | Native MGF has a very short half-life (~minutes). Many researchers prefer PEG-MGF for extended action. Inject near the worked muscle group post-exercise. |
| PEG-MGF muscle recovery | subcutaneous | 200–400 mcg | 2-3x per week | PEG-MGF extends half-life significantly, allowing less frequent dosing. Subcutaneous or intramuscular administration. |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
In vitro, the MGF E-peptide significantly increases satellite cell proliferative lifespan and delays senescence at concentrations as low as 3 ng/ml, with maximal effect around 100 ng/ml. Animal studies demonstrate that MGF injection post-muscle injury accelerates fiber repair and increases cross-sectional area in rodent models. A 2017 Molecular Brain study showed MGF promotes neurogenesis in aging mice, suggesting neuroprotective properties beyond muscle. No human clinical trials have been completed. Most human-relevant data comes from in vitro cell culture experiments with primary human satellite cells, which confirm MGF-E peptide activation at multiple age groups.
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with MGF for synergistic effects.
Legal status
MGF and PEG-MGF are unscheduled research chemicals with no FDA-approved medical use. Not approved for human administration. Sold legally as research chemicals in many jurisdictions, though the same FDA enforcement actions affecting other peptides have affected MGF availability in the US. Prohibited by WADA in competitive sport.
Where to get it
Verified directory — coming soon
PeptaHub is building a verified supplier directory with third-party testing data, compliance status, and reader ratings.