MGF is IGF-1Ec, the splice variant skeletal muscle releases when training damages it, and its job is to tell satellite (stem) cells to multiply and rebuild the fiber. Researchers like it because that signal is native, local and extremely fast. Worth saying up front: a rigorous replication failed to reproduce the effect, so the benefit is still contested.
- MGF (IGF-1Ec) activates muscle satellite cells, driving proliferation and local repair after mechanical damage.PubMed: mechano growth factor
- Its half-life is only about 5 to 7 minutes, so its action is studied right at the damaged tissue.PubMed: mechano growth factor
- A rigorous two-lab replication (Fornaro 2014) found the MGF peptide did not affect muscle-cell proliferation or differentiation, so the benefit is unproven.Fornaro 2014 replication
- Reported effects are local and modest, limited to the exposed muscle rather than systemic.The Complete Peptide Guide p.72
- The pegylated form, PEG-MGF, is the version studied when longer, systemic action is wanted.The Complete Peptide Guide p.72