IGF1 and sarcopenia: The reason why maintaining IGF-1 levels is effective in preventing and delaying sarcopenia lies in its dual regulatory role in skeletal muscle protein metabolism: IGF-1 binds to IGF-1 receptors (IGF-1R) on muscle cell surfaces, activating multiple intracellular signaling cascades (such as the PI3K/Akt/mTOR pathway, PI3K/Akt/GSK3β pathway, and MAPK/ERK pathway), thereby promoting muscle protein synthesis (17, 18).