Understand the source comparison
Local (autocrine/paracrine) versus systemic action
The conceptual heart of the comparison is spatial scale. MGF, as a splice product induced within loaded muscle fibers, is framed as an autocrine/paracrine signal — produced where it is needed, acting on neighboring cells, and disappearing quickly.[5] IGF-1 LR3
No winner is assigned.
This page preserves a source comparison for education. It does not add a rating, recommendation or clinical judgment.
- The conceptual heart of the comparison is spatial scale. MGF, as a splice product induced within loaded muscle fibers, is framed as an autocrine/paracrine signal — produced where it is needed, acting on neighboring cells, and disappearing quickly.[5] IGF-1 LR3, delivered exogenously and resistant to the binding proteins that would normally sequester it, is by design a systemic agent that circulates and can act on IGF-1 receptors throughout the body. This distinction has real biological consequences: a localized, self-limiting signal and a persistent, body-wide one are not merely different doses of the same thing, and the animal literature on localized IGF-1 expression illustrates why. A muscle-restricted, locally acting IGF-1 transgene sustained hypertrophy and preserved regenerative capacity in aging mouse muscle without producing the systemic pathology seen in whole-body IGF-1 overexpression models.[15] Locality, in short, appears to be a feature rather than a limitation.