What is IGF-1 LR3 and how does it differ from regular IGF-1 for muscle growth?

IGF-1 LR3 (Long R3 IGF-1) is a modified version of insulin-like growth factor-1 with 13 additional amino acids and an arginine substitution that makes it more resistant to breakdown and extends its half-life from approximately 12 hours to 20-30 hours. Unlike regular IGF-1, the LR3 variant binds less tightly to IGF-binding proteins, allowing more of the peptide to reach target tissues and activate receptors. Research indicates IGF-1 LR3 provides approximately 2-3 times greater cell activation than unmodified IGF-1, supporting both muscle cell enlargement (hypertrophy) and the development of new muscle cells (hyperplasia).