I am sure many of you are looking around and/or have tried many different supplements, in an attempt to; bulk, improve strength, get lean, shredded, cut, dench..(the list goes on). I aim to give you an insight into the benefits or lack of, behind taking IGF-1 as a supplement, allowing you to make up your own mind about it.
So a little background on IGF-1 in case your unaware, as I was till a few months ago, Insulin-like Growth Factor to give it is full name is used to promoted hypertrophy and increases in lean muscle mass. IGF-1 is key in children as is a substrate released from Human Growth Hormone (HGH) causing individuals to grow in stature (through natural means), once an adult HGH becomes denatured, however the effect of IGF-1 is still prevalent.
What’s been found..
Scientists are constantly looking into the various methods and effects of muscle growth, IGF-1 being a large topic of interest. It has been proven that the dosage of IGF-1 is not important and small doses show the same gains as large ones, which are greater than if you were to take HGH (steroids just aren’t worth it). A test comparing IGF-1, showed that with NO training there was a ~10% increase in muscle mass compared to no IGF-1. These sorts of gains are further enhanced with resistive training. Although a reasonable amount of work has been done on humans, I’m sure you can understand that for ethical reasons behind excessive studies, studies on rodents are more common (not that I condone animal testing, is just what has been done) and consistently show that those who are over expressive with IGF-1 have significantly large gains with resistive training (~35%). With numerous studies showing similar finds the effect of IGF-1 in humans, providing sufficient evidence that IGF-1 does increase muscle mass and lead to hypertrophy. With these studies finding gains after just two weeks of increased IGF-1.
Is it all good?
Having said that IGF-1 increases hypertrophy, you may be on your way to purchase some for personal supplementation, I beg you bear with me for a little longer while you read through the last bit of information I have for you.
Yes, IGF-1 leads to hypertrophy, however the gains in muscle mass are only present on skeletal muscle and not respiratory muscles. Although you may see this as a benefit as you can’t see your respiratory muscles, however if your respiratory muscle are unable to cope with the sudden increase in skeletal muscle the consequences could be very severe. Furthermore IGF-1 is only able to bind with the muscle membrane to produce recovery and growth, and therefore needs to be present in the autocrine system (refers to actual muscle tissue), not endocrine. Simply speaking the endocrine system refers to your blood stream and therefore supplementation of IGF-1 will increase levels in blood stream which has no effect on muscle growth, as the IGF-1 is unable to bind with muscle.
Soo.. to conclude; the hormone IGF-1 does produce hypertrophy, however the supplementation of this hormone does not increase levels within the muscle cells to aid any benefits. If you had planned on trying out this as a supplement, I strongly recommend that you save your money.
Adams & McCue (1998) Localised infusion of IGF-1 results in skeletal muscle hypertrophy in rats. J Appl Phys 84: 1716-1722
Lee, S et al (2004) Viral expression of IGF1 enhances muscle hypertrophy in resistance trained rats. J Appl Phys 96: 1097-1104
Spangenburg EE et al (2008) A functional insulin-like growth factor receptor is not necessary for load-induced skeletal muscle hypertrophy. J Physiol 586: 283-291
Linke WA & Kruger M (2010) The Giant Protein Titin as an integrator of Myocyte Signalling Pathways Physiology 25: 186-198