Frontiers Sheep recombinant IGF 1 promotes organ specific growth in fetal sheep IGF 1 LR3 Dosage Guide: Benefits, Timing, and Results i313 IGF 1 LR3 tells your muscle cells to grow, repair, and absorb nutrients better. It works directly at the muscle level to help you build lean muscle and recover faster.What it is IGF 1 Mechanisms of IGF 1 Mediated Regulation of Skeletal Muscle Hypertrophy and Atrophy