Where a substance is placed and where its effects occur are different questions. A local-delivery claim needs evidence about distribution and outcomes; it cannot be established simply by naming a nearby muscle.
A rat wound-chamber study investigated how IGFs and related compounds left a local fluid compartment. LR3 cleared more rapidly than native IGF-I in that model, with labeled material detected beyond the local site. This is evidence about experimental distribution, not a method for selectively enlarging a human muscle.
“Local” needs a definition
A study may measure concentration at a delivery site, movement into circulation or a response in nearby tissue. None of those alone establishes that all effects remain restricted to that location.
The wound model is also not a human resistance-training study. Its observations cannot rank injection locations, establish a technique or predict the amount of tissue growth in a selected body part.
A related misconception is that reduced binding to carrier proteins must mean longer persistence everywhere. The wound-fluid result shows why compartment-specific evidence matters: binding can influence retention as well as receptor access.
When evaluating a local-growth claim, look for direct measurement of distribution and the intended tissue outcome. A diagram, a receptor explanation or a testimonial about a pump does not supply that evidence.
This article intentionally gives no injection guidance. A research preparation should not be repurposed for human use on the assumption that local placement limits its risks.
The useful conclusion is that LR3 distribution has been investigated in an animal model and cannot be described by a simple “stays where it is put” rule. Whether a particular formulation has a local or systemic effect is an empirical question requiring appropriate study, not a feature that can be chosen through internet advice about a site.