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Muscle GrowthHormone Optimization

IGF-1 LR3

Long-acting IGF-1 analogue for sustained anabolic activity

Overview

IGF-1 LR3 (Long Arg3 Insulin-Like Growth Factor-1) is a synthetic analogue of human IGF-1 modified to include a 13-amino acid N-terminal extension and an Arginine substitution at position 3. These changes drastically reduce its binding to IGF-Binding Proteins (IGFBPs), extending its half-life from ~20 minutes (native IGF-1) to 20-30 hours. This allows for sustained activation of muscle growth and repair pathways.

Chemical Information

IUPAC Name
Long R3 Insulin-like Growth Factor-I
Sequence
MFPAMPLSSL FVNGPRTLCG AELVDALQFV CGDRGFYFNK PTGYGSSSRR APQTGIVDEC CFRSCDLRRL EMYCAPLKPA KSA.
Molecular Mass
9111 Da
Formula
C400H625N111O115S9
IGF-1 LR3 Chemical Structure

Mechanism of Action

Functions as a super-agonist of the IGF-1 Receptor (IGF-1R). Normally, 99% of circulating IGF-1 is trapped by binding proteins (IGFBPs) and rendered inactive. The 'Long Arg3' modification prevents this binding, keeping the peptide free and biologically active for up to 30 hours. Upon binding to the receptor, it triggers the PI3K/Akt/mTOR signaling cascade, the master switch for protein synthesis and muscle hypertrophy. Simultaneously, it inhibits the FoxO pathway (which causes muscle breakdown) and counteracts myostatin signaling. Uniquely, it also promotes hyperplasia (splitting of muscle cells to create new fibers), not just hypertrophy (swelling of existing fibers).

Potential Research Fields

HypertrophySarcopeniaTissue RepairDiabetes (Insulin Sensitivity)Catabolic States

Recent Research

Research in 2024 focuses on IGF-1 LR3's role in 'regenerative rehabilitation'—using the peptide to prime tissues for physical therapy. Studies indicate that while native IGF-1 fluctuates rapidly, the sustained action of LR3 makes it a superior candidate for reversing severe muscle atrophy in immobilized patients. Interestingly, new metabolic research highlights its 'nutrient partitioning' effect: it shuttles glucose and amino acids into muscle cells rather than fat cells, improving body composition (lean mass vs. fat mass) even in the absence of heavy resistance training. Preclinical trials are also investigating its synergy with Follistatin, finding that the combination (IGF-1 LR3 + Follistatin) produces greater hypertrophy than either agent alone.

Bibliography / Scientific References

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Peptide Information Guide
Administration Type
Injectable (Intramuscular/Subcutaneous)

Injectable administration protocol for research.

Vial Strength
1mg
Reconstitution
Reconstitute with 2ml bacteriostatic water
Dosage Options
0.15 mg (15 units)
Mon-Fri
Protocol based on user specification (Check syringe calibration)
Schedule
5 days/week
Timing: One specific day.
Duration
4-6 Weeks
Potential Side Effects
Hypoglycemia (low blood sugar)
highdose-dependent
Gut distension (high dose)
moderaterare
Research Use Only

This information is for research purposes only. Always consult with a healthcare professional before starting any peptide protocol. Individual responses may vary, and proper medical supervision is recommended for all peptide therapies.