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 1 LR3 active protein P05019.1 MyBioSource Localized Igf 1 transgene expression sustains hypertrophy and regeneration in senescent skeletal muscle Nature Genetics Igf 1 LR 3 Enhanced Pharmaceuticals IGF 1 Therapy Improves Muscle Size and Function in Experimental Peripheral Arterial Disease ScienceDirect IGF1 stimulates greater muscle hypertrophy in the absence of myostatin in male mice in: Journal of Endocrinology Volume 234 Issue 2 (2017)