What is the dosing range for MGF?

MGF is typically dosed at 100mcg (low), 200mcg (moderate), or 300mcg (high) mcg, administered Post-workout (within 30–60 minutes of training), 3–4x weekly. These ranges are aggregated from preclinical research and community protocols — not medical dosing guidance.

What are the reported side effects of MGF?

Reported side effects of MGF include: Localized muscle swelling at injection site (normal response), Hypoglycemia (less pronounced than IGF-1 DES but present), Very short half-life means side effects are brief, Potential overuse injury if post-workout injection is used consistently without adequate recovery.

Performance

MGF

Also known as: Mechano Growth Factor, IGF-1Ec, Insulin-like Growth Factor splice variant

MGF is a research compound not approved for human use. For informational purposes only.

📚 Content aggregated from:3 peer-reviewed sources·r/Peptides community·PubMed / NCBI

Overview

MGF (Mechano Growth Factor) is a splice variant of IGF-1 produced locally in muscle tissue in response to mechanical loading (exercise, especially eccentric loading). Unlike circulating IGF-1 which is produced primarily by the liver, MGF is generated within the muscle itself and acts locally to activate satellite cells (muscle stem cells) — the cells responsible for muscle repair, growth, and adaptation. It is considered the primary local anabolic signal generated by resistance training.

Research Summary

MGF is encoded by the IGF-1 gene but produced via alternative splicing that generates a unique 49-amino acid C-terminal E-peptide (Ec peptide). The Ec peptide has distinct biological activity from the IGF-1 domain — it directly activates satellite cell proliferation through a receptor pathway separate from the standard IGF-1R. Studies in rodents show that local MGF injection produces significant muscle hypertrophy in the injected limb without systemic IGF-1 elevation. MGF expression spikes within 30 minutes of resistance exercise and declines over 24–48 hours — aligning precisely with the post-exercise anabolic window.

Dosing Range

low

100mcg

moderate

200mcg

high

300mcg

Units: mcg · Frequency: Post-workout (within 30–60 minutes of training), 3–4x weekly

Dosing ranges are aggregated from preclinical research and community protocols. Not medical dosing guidance.

Administration Routes

Intramuscular injection (into worked muscle — critical for local effect)Subcutaneous injection (produces more systemic distribution)

Reconstitution Notes

Reconstitute with bacteriostatic water to 1mg/mL. MGF is highly unstable in biological fluids — half-life of native MGF is only ~5 minutes in serum due to rapid peptidase cleavage. Use immediately post-reconstitution. Consider PEG-MGF (the PEGylated variant) for a longer-lasting alternative.

Step-by-step reconstitution guide →

Supplies you'll need

Insulin Syringes (U-100)Reconstitution Needles Lambda BAC Water Alcohol Prep Pads

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Reported Side Effects

Localized muscle swelling at injection site (normal response)
Hypoglycemia (less pronounced than IGF-1 DES but present)
Very short half-life means side effects are brief
Potential overuse injury if post-workout injection is used consistently without adequate recovery

Research Papers

3 peer-reviewed sources

Mechano growth factor (MGF) — a tissue-specific IGF-1 splice variant

Journal of Physiology2000

MGF activates satellite cells and promotes muscle hypertrophy after exercise

FASEB Journal2003

The E-peptide of IGF-1Ec (MGF) specifically activates satellite cells

Biochemical and Biophysical Research Communications2011

Community Experiences

Aggregated from public forums. Anecdotal — not clinical evidence.

r/Peptides

Community protocols using MGF post-workout for localized muscle hypertrophy — comparison with PEG-MGF.

View original thread

r/bodybuilding

Bodybuilding community experience combining MGF with IGF-1 LR3 and GH peptide protocols.

View original thread

Overview

Every time you perform a set of heavy squats or bench press, your muscle fibers experience mechanical stress that triggers a localized biological response. A key part of this response is the production of MGF — a splice variant of IGF-1 produced right there in the muscle, by the muscle, for the muscle. MGF is the molecular signal that tells satellite cells "the muscle was worked — grow and repair."

MGF vs Circulating IGF-1

Most discussion of the GH/IGF-1 axis focuses on systemic IGF-1 from the liver. MGF is different:

| | Systemic IGF-1 | MGF | |-|---------------|-----| | Produced by | Liver (GH-stimulated) | Muscle fibers (mechanically stimulated) | | Distribution | Systemic (bloodstream) | Local (acts in producing tissue) | | Receptor | IGF-1R | IGF-1R + separate Ec peptide receptor | | Half-life | Hours to days | Minutes (5–10 min native) | | Primary role | Systemic growth, metabolism | Satellite cell activation, local repair |

The Satellite Cell Story

Satellite cells are muscle stem cells that sit dormant between muscle fibers. They are the source of new muscle nuclei (myonuclei) needed for hypertrophy. The sequence:

Mechanical load → muscle fiber damage
MGF is spliced from the IGF-1 gene in the damaged fiber
MGF activates satellite cells → they proliferate
Activated satellite cells differentiate and fuse into existing fibers, adding new myonuclei
More myonuclei → greater protein synthesis capacity → hypertrophy

Without satellite cell activation, muscle fibers can increase in protein content but not gain new nuclei — which ultimately limits the degree of hypertrophy achievable.

The Injection Timing Window

MGF expression peaks within 30 minutes of exercise and returns to baseline by 24–48 hours. This aligns with the post-workout "anabolic window." Injecting MGF within 30–60 minutes of training — intramuscularly into the worked muscle — attempts to amplify the endogenous MGF signal that training already produces.

Native MGF vs PEG-MGF

The biggest limitation of native MGF is its extreme instability (~5 minute half-life). PEG-MGF (PEGylated MGF) solves this with a polyethylene glycol attachment that extends half-life to ~24–72 hours, allowing systemic distribution and less frequent dosing. See the PEG-MGF profile for details.