How HGH Works: Boosting IGF 1 for Muscle Growth Yizhe Wang posted on the topic LinkedIn IGF 1 LR3 does not promote growth in late gestation growth restricted fetal sheep American Journal of Physiology Endocrinology and Metabolism American Physiological Society 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 IGF 1LR3 QK041 Recombinant human bovine porcine IGF 1 LR3 protein