IGF-1 LR3 101

IGF-1 LR3, or Insulin-like Growth Factor-1 Long R3, is a peptide hormone that is a derivative of Insulin-like Growth Factor-1 (IGF-1). It is a popular compound among bodybuilders and athletes because of its ability to promote muscle growth and improve recovery after exercise.

In this article, we will explore IGF-1 LR3 in detail so you can understand how it works, what to expect from it and how to use it to maximize your gains and reach a whole new level of size.


IGF-1 LR3 is a synthetic analogue of IGF-1 that has been modified to have a longer half-life in the body. The peptide consists of 83 amino acids, with an additional 13 amino acids at the N-terminus that serve to increase its stability and half-life.

The long R3 extension at the C-terminus further enhances the peptide’s stability and bioavailability by preventing it from binding to IGF-binding proteins (IGFBPs) that would normally inhibit its activity.

The result is a half-life of around 25 hours, which allows for once-daily administration. Other forms of IGF-1 have sub 30-minute half-lives.


IGF-1 LR3 works by binding to the IGF-1 receptor, which is found on the surface of many different cell types, including muscle cells. Once bound, the peptide activates a cascade of signaling pathways that ultimately lead to an increase in protein synthesis and muscle growth. IGF-1 LR3 also has anti-catabolic effects, meaning that it can help to prevent muscle breakdown and improve recovery after exercise.

Other benefits include:

  • Improved recovery: IGF-1 LR3 will speed up recovery after intense workouts and also improve one’s ability to heal injuries.
  • Incredible pumps: IGF-1 LR3 causes amazing muscle pumps and muscle fullness that can reportedly last for many hours after exercise, especially if combined with vasodilators like Tadalafil or Citrulline.
  • Enhanced fat loss: IGF-1 LR3 will increase metabolism and promote fat loss (not to a dramatic extent, but it’s a welcome benefit nonetheless).
  • Increased bone density: IGF-1 LR3 will increase bone density, which is important for overall health and longevity.
  • Improved immune function: IGF-1 LR3 will improve immune function, which can prevent a whole host of illnesses and infections.


IGF-1 LR3 is great, but it is not side-effect-free. The main risk that comes with IGF-1 use is that it can grow existing tumors at unprecedented rates.

This means that if you have a tiny tumor (whether benign or malign) that has not been detected or given you any problems yet and you expose it to IGF-1, it may grow to the point where it becomes a real threat really quickly.

For that reason, I would not advise men over 40 to use IGF-1 without first getting checked and scanned for tumors.

Other long-term side-effects of IGF-1 include the excessive growth of certain body parts like feet, hands, nose and organs.

Some users also report joint pain, hypoglycemia, swelling and acne.


The recommended dosage for IGF-1 LR3 is 25 to 50mcg a day, injected subcutaneously in the morning. I would not recommend running it for more than 4 weeks a time in order to avoid the build up of dangerous side-effects.


IGF-1 LR3 is a potent muscle-building peptide that can work synergistically with Anabolic Steroids to provide incredible gains in muscle mass, strength and recovery. Unfortunately, it is not without its risks, so only advanced enhanced bodybuilders should consider using it.

William Davis

William has been studying and experimenting with bodybuilding pharmacology for over 6 years. After being an independent researcher for all these years, he has decided to share his knowledge with the bodybuilding community through his science-based articles. His approach to enhanced bodybuilding can be summed up in the saying “less is more”, as he believes that prioritizing harm mitigation and looking for ways to maximize the positives is the key to longevity in bodybuilding.

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