# IGF-1 LR3

> IGF-1 LR3 is a modified analog of insulin-like growth factor 1 in which an extra 13 amino acids are added to the B-chain and a single substitution reduces binding to IGF-binding proteins. This modification extends its circulating half-life far beyond native IGF-1, allowing more sustained receptor activation. Within the research and performance community, it is discussed primarily as a systemic anabolic agent believed to support muscle tissue growth and recovery. It is not an approved pharmaceutical product, and human clinical data specific to muscle-building outcomes are limited.

- URL: https://www.lifeconverted.com/peptides/igf-1-lr3
- Also known as: Long R3 IGF-1, LR3 IGF-1
- Primary category: Muscle & Performance
- Effectiveness rank: #17 in Healing & Recovery; #2 in Muscle & Performance; #999 in Growth Hormone
- Evidence level: Emerging research
- Route: SubQ or IM (Often injected subcutaneously for a systemic effect, or intramuscularly into a trained muscle for a more localized effect.)
- Dose range: 20-60 mcg
- Dose tiers: low 20 mcg; moderate 40 mcg; high 60 mcg
- Half-life: Approximately 20-30 hours
- Timing: After a workout
- Cycle: 4-6 weeks on, 4-6 weeks off (Extended systemic use is often cycled off to allow IGF-1 receptor sensitivity and endogenous signaling to normalize; protocols vary widely and are not standardized in clinical literature.)
- Storage: Store lyophilized powder refrigerated (2-8°C) or frozen for long-term storage; once reconstituted with bacteriostatic water, keep refrigerated and use within 2-4 weeks.

## Mechanism of action

IGF-1 LR3 binds the IGF-1 receptor, activating the PI3K/Akt/mTOR pathway that drives protein synthesis and cell growth, while reduced binding-protein affinity keeps more of the compound free and active in circulation. This prolonged receptor signaling is proposed to support satellite cell proliferation and nutrient uptake in skeletal muscle. Because IGF-1 receptors are expressed throughout the body, effects are not confined to muscle tissue alone.

## Reported benefits

- Reported support for lean tissue accrual when combined with resistance training
- Proposed enhancement of nutrient partitioning toward muscle over fat
- Suggested support for connective tissue and muscle recovery
- Extended systemic activity compared with native IGF-1 due to reduced clearance

## Reported side effects

- Hypoglycemia, particularly when combined with insulin or during fasted states
- Potential for organ growth (organomegaly) with prolonged high-dose use
- Injection site irritation
- Theoretical concern for promoting growth of existing abnormal or cancerous cells due to broad growth-factor activity

## Common protocols

- Once-daily subcutaneous injection on training days
- Post-workout intramuscular injection into the trained muscle group

## Stacking notes

Frequently discussed alongside growth hormone secretagogues (e.g., GHRP/GHRH compounds) given the GH-IGF-1 axis relationship; combining with insulin or insulin-sensitizing agents raises hypoglycemia risk and warrants particular caution.

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Educational information only, not medical advice. Full disclaimer: https://www.lifeconverted.com/disclaimer