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IGF 1 - Insulin Like Growth Factor 1 - Somatomedin C

IGF1 is a polypeptide hormone about the same size as insulin, or 70 amino acids; its a member of the "super family." No, this is not the same family Clark Kent belongs to, but rather its a family of substances identified as growth factors. Its a highly anabolic hormone released primarily in the liver (but also in peripheral tissues) with the stimulus of Growth Hormone (GH). It is responsible for much of the anabolic activity of GH, including nitrogen retention and protein synthesis (12) as well as muscle cell hyperplasia (increase in number of muscle cells), as well as mitogenesis (the growth of new muscle fibers). It can also induce skeletal muscle hypertrophy by activating the phosphatidylinositol 3-kinase (PI3K)-Akt pathway(9). In fact, IGF-1 acts on several different tissues to enhance growth via several mechanisms. Its also important to note that GH and IGF-1 are interrelated, they produce a host of divergent effects (5).As you may already know, GH and IGF levels are both elevated dramatically following exercise, and this may be a primary factor in the anabolic effects of weight training. In fact, IGF-1 may be possibly used as an anabolic substitute for GH (2) in many instances. IGF-1 is, therefore, necessary as well as sufficient in muscle growth (anabolic)(1) and has been shown to also be highly anti-catabolic agent as well (2)(3). As with all anabolic substances, IGF-1s anabolic effects are still limited only by the protein (amino acid) supply within muscle cells (6) (7). Thus, as you may expect, IGF works much better when you are eating enough protein.

IGF1 may be of particular interests to athletes, as it may improve their ability to learn new skills and techniques relevant to their sport. You see, IGF is a known neuroprotector and neuropromotor(13)(14)(15), which means new skills could be learned more quickly with IGF use, and for the elderly, some of the cognitive effects of aging could be staved off or possibly halted entirely with administration of IGF1. This also has exciting implications for the medical community studying Alzheimers and other such diseases. This is because there are IGF receptors within the brain (16) and in motor neurons (17).

Growth Hormone,Steroids,PGH

Also of note, and of special interest to both athletes and bodybuilders who are rehabbing an injury is that IGF is vital to the proper production of connective tissue, and exogenous IGF administration may improve collagen formation and aid in the repair of cartilage. (19)(18). IGF is also vital to proper bone density and bone density regulation (20).

IGF administration may be highly useful for rehabilitation of any kind of joint injury experienced by athletes and bodybuilders, and would greatly decrease recovery time as well as increase the strength of the recovered area.

So now we have a basic idea of what IGF does and how it works, so I think we can start looking at how well it works, and what kind of results we can expect from it. While I was (exhaustively) researching this compound, I found a study which provided just the type of answers we are looking for. This study examined the injection of a compound which was responsible for directing over expression of insulin-like growth factor I (IGF-I) in differentiated muscle fibers. The researchers concluded that IGF-I expression promotes an average increase of 15% in muscle mass and a 14% increase in strength in young adult mice. Its nice to be able to put some numbers on this compound, huh? But those effects are not all that the researchers have found. IGF also seems to prevent aging-related muscle changes in old adult mice! These old mice experienced a 27% increase in strength as compared with uninjected old muscles. Muscle mass and fiber type distributions were maintained at levels similar to those in young adults. The researchers have speculated that these effects are primarily due to stimulation of muscle regeneration via the activation of satellite cells by IGF-I (8). Regardless of the mechanism of action, the results from this study are pretty exciting. A 15% increase in muscle mass, and a 14% increase in strength are no small increases. Consider this, if you are a typical 100kg (220lb) bodybuilder, you would be a 115kg (250lb) bodybuilder after those kinds of results from IGF-1! If you were a powerlifter whos best bench press effort was previously 200kgs (440lbs), then you could expect to be able to bench press 500lbs after using IGF1! Ok, so you cant exactly use that study on mice to justify those numbers, but you get the idea. IGF-1 works and it works very well. Even if we could realistically expect 7% gains in muscle mass and strength (half of the gains experienced in the study), then this drug would be able to blast many bodybuilders and athletes through the plateaus that experienced trainers often endure.

So how can we use this stuff? Well first lets talk about creating an ideal environment for IGF1 to function. See, as youve already read, there is a very great interdependence and synergy between IGF, Insulin, and GH. It has been clearly observed in studies that when GH and IGF1 are used together, youll get greater results in the accumulation of Lean Body Mass than you would by using either of them alone (10).In addition, there is a very strong probability that testosterone would be synergistic to GH (4), and would also increase IGF levels in muscle (11).

Lets take a look at a chart showing what happens when you use IGF-1, IGF-1+GH, or GH alone:

Changes in body weight, lean body mass, and fat mass 6 and 12 weeks after therapy. Values are the mean changes and 95% Cls. * = significant differences compared with baseline (P < 0.01). The following are the numbers of patients in each treatment group at weeks 6 and 12: recombinant human growth hormone plus insulin-like growth factor 1 (rhGH + rhIGF-1), 13 and 9, respectively; rhGH, 12 and 11, respectively; IGF-1, 1D and 4, respectively; placebo, 14 and 11, respectively(10).

As that chart clearly shows, you will lose more fat and gain more muscle when you combine GH and IGF-1 than you would using either alone. The subjects in this study, over 12 weeks gained around 3kgs of lean mass, and lost around 2kgs of fat. Clearly, when we use IGF, we are going to want to use it with GH. And we know that GH functions best when used in conjunction with testosterone. And since we know that GH increases insulin sensitivity, we can throw in some insulin with that GH, and if we are using insulin and dont want to get fat; Id be most comfortable if I could add in a fat burner like T3 with it.

So there we have a laundry list of items essential to get the most out of our IGF use but lets be honest, if you have the money to use IGF (and IGF is expensive stuff), then you should really be including these other items to maximize its effects.


So how much IGF do we use? What kind do we buy? How much will it cost? Well, the most popular type available on the Black Market right now is Lr3igf-1 (Long R3 Insulin-like Growth Factor-I or Long R3IGF-I) which is an 83 amino acid analog of human IGF-I comprising the complete human IGF-I sequence with the substitution of an Arg for the Glu at position 3 (hence R3, clever name, right?), as well as a 13 amino acid extension peptide at the N-terminus. Huh? Well, that all adds up to make Long R3IGF-I significantly more potent (2-3x) than IGF-I in studies, because it has a lower affinity to be rendered inactive by IGF binding proteins (22) (23). Yeah, everything youve read about IGF-1 still holds true for this version, but its just a bit more active in the body, and hence more potent. Also, its basically the only type you can get your hands on at this time, nobody carries the "lesser" versions of it anymore. SO, youll pay around $150.00 for 1mg (1000mcgs/mg).

And how much do you use? From the people Ive spoken to, Ive noticed that the magic happens between 60mcgs and 120mcgs per day, in divided doses. In general, people who have used less, and even up to 50mcg/day have had mediocre results. People who have used more have suffered headaches and nausea, and generally not much more in the way of results.


  1. Hormonal Responses and Adaptations to Resistance Exercise and Training. Sports Med. 2005;35(4):339-361.
  2. Clinical uses of insulin like growth factor I (IGF-I).Ann Intern Med. 1994 Apr 1;120(7):593-601.
  3. PROTEIN BREAKDOWN IN MUSCLE FROM BURNED RATS IS BLOCKED BY IGF-I AND GSK-3 {beta} INHIBITORS. Endocrinology. 2005 Mar 31; [Epub ahead of print]
  4. Growth Hormone and Testosterone Interact Positively to Enhance Protein and Energy Metabolism in Hypopituitary Men. Am J Physiol Endocrinol Metab. 2005 Feb 22; [Epub ahead of print]
  5. Are the metabolic effects of GH and IGF-I separable? Growth Horm IGF Res. 2005 Feb;15(1):19-27.
  6. Murphy MG, Plunkett LM, Gertz BJ, He W, Wittreich J, Polvino WM, Clemmons DR. MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism. J Clin Endocrinol Metab. 83(2):320-5, 1998
  7. Fryburg DA, Jahn LA, Hill SA, Oliveras DM, Barrett EJ. Insulin and insulin-like growth factor-I enhance human skeletal muscle protein anabolism during hyperaminoacidemia by different mechanisms. J Clin Invest. 96(4):1722-9, 1995
  8. Viral mediated expression of insulin-like growth factor I blocks the aging-related loss of skeletal muscle function.Proc Natl Acad Sci U S A. 1998 Dec 22;95(26):15603-7.
  9. Molecular mechanisms modulating muscle mass. Trends Mol Med. 2003 Aug;9(8):344-50. Review.
  10. Recombinant human growth hormone, insulin-like growth factor 1, and combination therapy in AIDS-associated wasting. A randomized, double-blind, placebo-controlled trial. Ann Intern Med. 1996 Dec 1;125(11):865-72.
  11. 3 Am J Physiol Endocrinol Metab. 2002 Mar;282(3):E601-
  12. Growth hormone and IGF-I therapy in the hypercatabolic patient. Baillieres Clin Endocrinol Metab. 1996 Jul;10(3):447-63. Review.
  13. IGF-I neuroprotection in the immature brain after hypoxia-ischemia, involvement of Akt and GSK3beta?Eur J Neurosci. 2005 Mar;21(6):1489-502.
  14. Interdependence of oestrogen and insulin-like growth factor-I in the brain: potential for analysing neuroprotective mechanisms. J Endocrinol. 2005 Apr;185(1):11-7.
  15. Neuroprotective gene expression profiles in ischemic cortical cultures preconditioned with IGF-1 or bFGF. Brain Res Mol Brain Res. 2004 Nov 24;131(1-2):33-50.
  16. The role of the somatotropic system in cognition and other cerebral functions. Semin Vasc Med. 2004 May;4(2):167-72. Review.
  17. Insulin-like growth factor type 1 prevents hyperglycemia-induced uncoupling protein 3 down-regulation and oxidative stress. J Neurosci Res. 2004 Jul 15;77(2):285-91.
  18. Role of insulin like growth factor-I in repair response in immature cartilage. Knee. 2005 Apr;12(2):113-9
  19. Oxidative stress induces IGF-I receptor signaling disturbances in cultured human dermal fibroblasts. A possible mechanism for collagen biosynthesis inhibition.
  20. Age-related femoral bone loss in men: evidence for hyperparathyroidism and insulin-like growth factor-1 deficiency.J Gerontol A Biol Sci Med Sci. 2004 Dec;59(12):1285-9.
  21. Metabolic effects of growth hormone in humans. Metabolism. 1995 Oct;44(10 Suppl 4):33-6.
  22. IGF-I variants which bind poorly to IGF-binding proteins show more potent and prolonged hypoglycaemic action than native IGF-I in pigs and marmoset monkeys.J Endocrinol. 1997 Nov;155(2):377-86.
  23. In vivo actions of IGF analogues with poor affinities for IGFBPs: metabolic and growth effects in pigs of different ages and GH responsiveness. Prog Growth Factor Res. 1995;6(2-4):385-95. Review.

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