IGF 1 LR3: Dosage Results and Safety Guide Vita Bella Health What is IGF 1 LR3?, Insulin Like Growth Factor 1 Long R3 (IGF 1 LR3) is a modified version of IGF 1 with a longer half life, making it significantly more potent and effective for muscle growth, IGF 1 LR3 tells your muscle cells to grow, repair, and absorb nutrients better. It works directly at the muscle level to help you build lean muscle and recover faster.What it is IGF 1 Insulin like growth factor 1 promotes cell cycle progression via upregulation of cyclin D1 expression through the phosphatidylinositol 3 kinase nuclear factor B signaling pathway in FRTL thyroid cells Acta Pharmacologica Sinica