Mechano Growth Factor (MGF) is a splice variant of insulin-like growth factor-1 (IGF-1) that is naturally produced in muscle and other tissues in response to mechanical stress or damage. It plays a critical role in initiating local tissue repair, particularly by activating muscle satellite (stem) cells, which are essential for muscle regeneration and growth. MGF is often described as the “first responder” in muscle recovery, setting the stage for subsequent growth processes driven by systemic IGF-1.