Expression of IGF 1 Isoforms after Exercise induced Muscle Damage in Humans: Characterization of the MGF E Peptide Actions In Vitro In Vivo Ran my first IGF 1 LR3 cycle IronMag Bodybuilding Forums IGF 1 LR3 The Muscle Building Peptide Everyone's Talking About IGF 1 LR3 is one of the most powerful performance peptides used for muscle growth, recovery, and fat loss. It's a modified version Same Origin, Completely Different Research Profiles MGF and PEG MGF both come from the same IGF 1 gene. But one lasts 7 minutes and the other lasts 3 days. Here is what that difference