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IGF-1 LR3 (Insulin-like Growth Factor-1 Long R3)

Category: Muscle Growth. Status: Research compound.

A modified IGF-1 with R3 substitution and N-terminal extension reducing IGFBP binding, increasing half-life and potency 2-3x over native IGF-1.

How it works

Activates IGF-1R while evading IGFBP sequestration. Triggers PI3K/Akt/mTOR for protein synthesis, satellite cell proliferation, and amino acid uptake into muscle.

Key facts

  • Molecular weight: 9,111 Da
  • Half-life: 20-30 hours (vs 15 min native)
  • Bioavailability: High (SubQ/IM)
  • Storage: Lyophilized: -20°C. Reconstituted: 2-8°C for 21 days.

Dosing overview

  • Typical dose: 20-50 mcg
  • Frequency: Daily (post-workout)
  • Duration: 4-6 weeks
  • Route: Subcutaneous or intramuscular injection

Protocol notes

  • Run 20-50 mcg daily, typically right after training.
  • Often injected bilaterally/locally into the muscles just trained for a localized growth signal.
  • Kept to short 4-6 week blocks due to limited safety data.

Reported benefits

  • Potent anabolic effects
  • Hyperplasia (new muscle cells)
  • Extended half-life
  • Enhanced recovery
  • Improved nutrient partitioning
  • Satellite cell activation

Possible side effects

  • Hypoglycemia risk
  • Gut growth (prolonged)
  • Joint pain
  • Tumor promotion (theoretical)
  • Water retention

Research

  • IGF-1 LR3 pharmacokinetics and muscle anabolism (2020): LR3 modification increased bioactivity 300% with proportional protein synthesis increases.
  • Local IGF-1 for muscle hypertrophy (2019): Site-specific injection produced 15% greater hypertrophy via satellite cell activation.

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Research and educational reference only. Not medical advice.