When most people talk of IGF-1 they are in fact usually talking about the popular IGF-1 LR3 variation.
Having a very short half-life (< 10 minutes) and being acutely unstable, IGF-1 in its base form is not commonly used by bodybuilders or athletes. The two popular variations, IGF-1 LR3 and IGF-1 DES, are both modifications of the base protein and possess superior qualities for use; less sensitive, more potent and a longer half-life.
IGF-1 LR3 – while IGF-1 in its base form has a half-life of fewer than ten minutes, IGF-1 LR3 has a half-life of a day. With such an extended half-life the hormone has a far greater timeframe to circulate around the body, bind to receptors and exert its effects.
With IGF-1 LR3 it is neither necessary nor effective to perform site-specific injections as the hormone will have ample opportunity to propagate from the injection site given its half-life.
IGF-1 DES – being the shorter, more potent variation available, IGF-1 DES has a half-life of around thirty minutes and is far more unstable than that of LR3.
Site-specific injections using IGF-1 DES can be particularly effective and worthwhile, with bodybuilders typically injecting the muscle group they are about to train pre-workout. The theory behind this is sound; high lactic acid build up causes the IGF-1 receptors to be more accepting, therefore injecting into a muscle group that is about to be trained should provide the best results.
Pre-workout site injections are taking advantage of the inbuilt biological response which naturally occurs during a workout – lactic acid builds up in the muscle being work, signalling for the release of HGH and IGF-1 to help repair the micro-traumatised muscle tissue. The body is smart and the IGF-1 ends up where it’s needed; binding to the receptors which have been deformed by the lactic acid.
Naturally produced by the liver, IGF-1 is a hormone similar in structure to that of insulin, hence its name. During childhood it is one of the primary hormones responsible for growth and remains a powerful precursor to cell growth in adults – something bodybuilders and athletes have naturally taken an interest in!