IGF 1 LR3 does not promote growth in late gestation growth restricted fetal sheep American Journal of Physiology Endocrinology and Metabolism American Physiological Society LONG R IGF I 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 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 + MASS Cycle = CRAZY Growth? #askDave