IGF-1 or insulin-like growth factor 1 (brand name: Increlex) is a growth factor which is very closely related to insulin.  It carries the same amount of amino acids as insulin and responsible for the anabolic reactions to GH.  IGF-1 is an important factor in childhood growth and is highly anabolic in adults. It is also known by the brand name Increlex and the generic name mecasermin.

Background

In the 1970’s, IGF-1 was known as as “Sulfation Factor” and “Nonsuppressible Insulin-like Activity” (NSILA).  In the 1980’s, it was known as “Somatomedin C.”  The most popular type of IGF-1 available on the Black Market is a longer lasting version (more amino acids in length) known as Long R3 Insulin-like Growth Factor-I or Long R3IGF-I.  Lr3igf-1 is more potent than the lesser versions which are no longer available on the black market. Of that type of IGF, there are two types commonly available (Media and Receptor grades, respectively). These last two types of IGF mostly just refer to the purity of what is actually in the bottle.

Action

IGF-1 is released in the liver and binds to the IGF receptors within the cells, which ultimately causes a stimulation of cell growth (both causing new tissue formation and existing tissue growth) and an inhibition of cell death.  It is a highly anabolic and anti-catabolic compound. For the athlete or bodybuilder, this had many positive effects: increased nitrogen retention and protein synthesis because it is highly anabolic.  IGF-1 (in the presence of sufficient protein) actually promotes growth of new muscle cells, which increases the overall number of cells in the muscle.

IGF protects the neurons of the brain as well as promotes growth of new motor neurons, making it more possible to rapidly learn new skills during its use.  IGF-1 is also responsible in connective tissue production, improves collagen formation and aids in cartilage repair.  Similarly, it affects the bones by aiding in bone production and repair.