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 Recombinant Human LR3 IGF 1(E51R) Protein IGF 1 LR3 does not promote growth in late gestation growth restricted fetal sheep American Journal of Physiology Endocrinology and Metabolism American Physiological Society Organ weights in response to Long R3 insulin like growth factor 1 (LR3 Download Scientific Diagram