What Is MGF (Mechano Growth Factor)? Dosage & How to Track It
Also known as: Mechano Growth Factor · IGF-1Ec · IGF-1 Ec Isoform
MGF — Mechano Growth Factor — is a splice variant of IGF-1 (called IGF-1Ec in humans) that your muscles produce naturally in response to mechanical stress, like resistance training or injury. Community protocols run it subcutaneously once daily, commonly 100–300 mcg, often timed right after training since that’s when your own MGF signal would naturally spike. Its native form clears in minutes, which is why PEG-MGF — a slower-release version — exists as an alternative. Educational only.
What MGF is and how it works
MGF is short for Mechano Growth Factor — not a separate hormone, but a splice variant of IGF-1 that your body makes when muscle tissue is mechanically stressed or damaged (heavy training, an eccentric-heavy workout, or an actual injury). In humans the specific variant is called IGF-1Ec; it’s produced locally, inside the stressed muscle itself, distinct from the liver-derived IGF-1 that circulates systemically.
Mechanistically, MGF’s job appears to be activating satellite cells — the muscle’s own resident stem cells — pulling them out of quiescence so they can proliferate and fuse into existing muscle fibers, a core part of how muscle repairs and grows after damage. It’s also been studied for a role in bone-fracture repair, through a related but distinct signaling pathway from the IGF-1 that drives whole-body growth.
The discovery and core mechanism is legitimate published science, but most of it is in animal and cell models — human trial data on injectable synthetic MGF specifically is minimal, and it’s not FDA-approved for any use.
Typical dosing & reconstitution
MGF ships lyophilized and is reconstituted with bacteriostatic water. Community protocols run 100–300 mcg once daily subcutaneously, titrated up over the first few weeks, and commonly timed post-workout — the logic being to mimic the natural post-training window when the body’s own MGF signal spikes.
Reconstitution sets your concentration and units:
| Vial | BAC water | Concentration | 1 unit (U-100) ≈ |
|---|---|---|---|
| 5 mg | 3 mL | 1.67 mg/mL | 16.7 mcg |
At 1.67 mg/mL, a 200 mcg dose is 12 units. Run your own vial and water through the reconstitution calculator to lock in the exact units for your dose.
Half-life & what it means for frequency
Unmodified MGF has an extremely short half-life — often described as just a few minutes in circulation — because it’s rapidly degraded once released. That’s consistent with its natural biology: it’s meant to act as a fast, local signal right where muscle damage occurred, not as a persistent circulating hormone.
That short window is exactly why the pegylated version, PEG-MGF, exists — attaching polyethylene glycol slows clearance and turns a minutes-long local signal into something dosed once daily and acting more systemically. Unmodified MGF, by contrast, is sometimes injected directly into the trained muscle post-workout to try to get a local effect before it clears.
What to track & common side effects
Generally reported as well tolerated at community doses, with injection-site irritation the most common complaint. Because it’s an IGF-1-pathway signal, the same broad cautions that apply to other IGF-1 compounds — an active cancer history, blood-sugar sensitivity — are worth a doctor conversation before starting.
What’s worth tracking: dose, timing relative to training (since that’s the whole premise), and the recovery or strength outcome you’re actually chasing — a log makes it possible to see whether the post-workout timing you picked is associated with better sessions or better recovery.
How to track MGF in Stackeddd
Log MGF alongside your training sessions so you can see whether the post-workout timing is actually landing — the whole premise is riding the same window your body’s own MGF signal uses. Track the recovery or strength trend you’re chasing next to it.
Model it yourself · free, no account
Reconstitution Calculator
Model it yourself: enter your vial size and BAC water and the Peptides tab returns concentration and exact units for any dose — the same math built into the Stackeddd app.
Related compounds
Related reading: What peptides can you mix in the same syringe? · Peptide reconstitution math: how much BAC water to add
Frequently asked questions
What is MGF used for?
MGF is studied for muscle repair and growth — it activates satellite cells (muscle stem cells) after mechanical stress or injury, and has also been studied for bone-fracture repair. Evidence is largely preclinical; it’s not FDA-approved for human use.
What is the half-life of MGF?
Very short — often described as just a few minutes for unmodified MGF, since it’s meant to act as a fast local signal at the site of muscle damage rather than circulate. This is why the pegylated version, PEG-MGF, was developed for longer, once-daily dosing.
How do you dose and reconstitute MGF?
Add bacteriostatic water to the lyophilized vial — a common setup is 3 mL into a 5 mg vial, giving about 1.67 mg/mL. Community protocols run 100–300 mcg once daily, often timed shortly after training.
What’s the difference between MGF and PEG-MGF?
They’re the same core peptide — PEG-MGF has polyethylene glycol chains attached, which slows clearance dramatically. Unmodified MGF lasts minutes and is sometimes injected near the trained muscle; PEG-MGF lasts much longer and is dosed once daily systemically.
This is educational information, not medical advice. Doses and protocols above reflect published references and community practice — protocol decisions belong with your prescribing physician. Generic names used throughout. How this reference is built & how the AI is tested →
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