Insulin-like Growth Factor 1 (IGF-1) is a hormone that plays a crucial role in childhood growth and continues to have anabolic effects in adults. The anabolic mechanism of IGF-1, especially in the context of muscle growth and repair, involves several key processes:

1. **Muscle Protein Synthesis**: IGF-1 stimulates muscle protein synthesis. It activates signaling pathways (like the PI3K/Akt pathway) that lead to increased muscle protein production. This is crucial for muscle growth and repair.

2. **Cell Proliferation and Differentiation**: IGF-1 promotes the proliferation and differentiation of satellite cells, which are precursors to mature muscle cells. This helps in the regeneration and repair of muscle tissue.

3. **Inhibition of Protein Degradation**: IGF-1 can inhibit the breakdown of proteins in muscle cells, a process known as proteolysis. This further contributes to muscle growth by ensuring that the rate of protein synthesis exceeds the rate of protein breakdown.

4. **Interactions with Growth Hormone (GH)**: IGF-1 is produced in response to GH and mediates many of the growth-promoting effects of GH. GH stimulates the liver and other tissues to secrete IGF-1, which then acts in an endocrine manner as well as locally within muscles.

5. **Enhanced Nutrient Uptake**: IGF-1 increases the uptake of glucose and amino acids into muscle cells, providing the necessary building blocks for protein synthesis and energy for muscle growth and repair.

6. **Activation of Stem Cells**: In muscle tissue, IGF-1 is thought to activate stem cells, contributing to muscle regeneration and hypertrophy (increase in muscle size).

7. **Angiogenesis**: IGF-1 can promote angiogenesis, the formation of new blood vessels, which improves blood flow and nutrient delivery to growing or repairing muscle tissues.

In bodybuilding and sports, IGF-1 is sometimes used for its anabolic effects. However, its use outside of prescribed medical treatment is generally considered illegal and can have significant health risks, including increasing the risk of certain cancers, due to its potent cell growth-promoting properties.