IGF-1 LR3 (also known as Long R3 IGF-1) is a long-acting analog of insulin-like growth factor 1 studied for growth signaling. This page covers what the published research does — and does not — establish about it in relation to muscle growth and recovery.
IGF-1 LR3 is researched for Growth signaling — which is why it appears in discussions of muscle growth and recovery.
Research status: Primarily a research reagent; limited human safety data.
How IGF-1 LR3 is thought to work
IGF-1 LR3 is a modified, longer-acting version of insulin-like growth factor 1. Changes to its structure extend its half-life and reduce binding to carrier proteins, making it a research tool for studying IGF-1 signaling, growth, and cell proliferation.
What it does not establish
Affects blood sugar and cell growth pathways; potential risks around proliferation. Not an approved therapy.
Nothing on this page is a recommendation to use IGF-1 LR3, and Selpho publishes no dosing, reconstitution or sourcing information. Read how we decide what goes in the library.
Other peptides researched for Muscle Growth
A synthetic peptide widely studied for tissue repair and gut health.
A fragment related to Thymosin Beta-4 studied for recovery and flexibility.
A growth-hormone-releasing hormone analog studied for GH support.
A selective growth-hormone secretagogue studied for its clean GH-release profile.
An orally active growth-hormone secretagogue (a non-peptide) studied for GH/IGF-1.
Frequently asked questions
Primarily a research reagent; limited human safety data. Research relevant to this area covers growth signaling. That is a description of where the research points, not evidence that it will work for you — and Selpho does not provide dosing or medical advice.
Primarily a research reagent; limited human safety data.
Affects blood sugar and cell growth pathways; potential risks around proliferation. Not an approved therapy. Always speak to a licensed healthcare professional before considering any peptide.
IGF-1 signaling, cell proliferation, and body composition — largely as a research reagent.
The "Long R3" modifications extend its duration of action and reduce binding-protein affinity compared with native IGF-1.
Is IGF-1 LR3 right for your situation?
Describe your goals and the free Peptide Advisor will match them against the research — no signup, no sales pitch.
Ask the Advisor — freeThis page is for educational purposes only and is not medical advice, a diagnosis, or a recommendation to use any compound. It contains no dosing or purchase information. Always consult a licensed healthcare professional before considering any peptide.