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.
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
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.
In a study done on young adult mice, a compound responsible for
increased secretion of IGF-1 in muscle fibers was administered.
There was an average increase of 15% in muscle mass and a 14%
increase in strength. When the study was then conducted on adult
mice, there was a 27% increase in strength in the injected muscles
as compared with non-injected muscles. It was also found to prevent
aging of the muscles. Muscle mass and muscle fiber growth were
similar to the levels found in young adults. These effects are most
likely due to the ability of IGF-1 to activate satellite cells,
therefore stimulating muscle rejuvenation (1).
In studies conducted where GH and IGF1 were used together, a
greater increase of Lean Body Mass and fat reduction was found than
by use with each compound alone (2). Researches also believe that
use oftestosterone would also increase IGF levels in muscle (3). In
a 12 week study on subjects using IGF-1, IGF-1+GH, or GH alone
subjects in this study, gained around 3kgs of lean mass, and lost
around 2kgs of fat(4) .
The complete human IGF-1 Long R3 IGF-1 is 2-3 times more potent
than IGF-1 due to less ability to be made inactive by IGF binding
proteins (5) (6).
Most users opt for a dose of about 100mcg/day injected bilaterally
in the muscle group just trained, immediately post workout.
I suspect that in the coming years, more and more professional
athletes will be using IGF, as it is very difficult to test for,
and many have switched over from GH to this compound already.
Anecdotally, IGF seems to stack best with Trenbolone and
Testosterone, and there’s certainly some synergy between these
compounds. Lately, MGF is being added to most IGF protocols.