Insulin like growth factor-1 (IGF-1) is a substance which in manufactured by recombinant DNA technology. IGF-1 is the primary mediator of the growth promoting effects of human growth hormone. As such, the substance also can stimulate the growth of bone, muscle, and internal organs. Its effects on skeletal muscle are also highly hyperplasic, meaning it causes an increase in cell number. Unlike human growth hormone, however, this substance has very strong insulin like effects. It can support growth by increasing the uptake of amino acids, glucose, and fatty acids, but lowers blood sugar levels so efficiently that it can induce severe hypoglycemia if to high of a dose is taken. The increased uptake of fatty acids may also mean that the drug can increase the amount of body fat that is stored by the users. The United States FDA approved the medical use of IGF-1 in 2005. It is sold under the brand name of Increlex manufactured by the pharmaceutical company Tercica Inc. Tercica licenses this technology from Genentech, which was the first company to sell synthetic human growth hormone in the United States.
The effect of muscle hyperplasia that IGF1 can help promote is the primary reason why it has become so popular among bodybuilders. It is believed that IGF1 may be able to produce localized growth in the muscles that the IGF1 is administered into post-workout. However this effect of the hormone remains more theoretical in nature because of the lack of research available on the subject using human subjects. Despite this many users still claim that they have seen results from IGF1 when using it for this explicit purpose and it remains within the realm of possibilities. However simply because science can not discount the result as implausible does not mean that it is a given either. Among the other anabolic effects that IGF1 can produce in the body are things such as increasing protein synthesis, increasing nitrogen retention, as well as inducing the growth of more muscle fibers. When an appropriate amount of amino acids (protein) is available, all of these actions within the body are able to be completed. It has been demonstrated that IGF1 can help to improve collagen production as well as the reproduction of cartilage in joints.
The hormone has also been shown to exhibit the ability to act as a neuro-protector and promoter mainly because IGF1 receptors are located in the tissue of the brain. It has been demonstrated that there is a potential for when supplemented with IGF1 a decrease in the progress of some brain diseases can be brought about as well as slowing the deterioration of brain function in some elderly subjects. However similar findings or any evidence of improved brain function or capacity has not been demonstrated in young, healthy individuals. Obviously by helping to promote these anabolic mechanisms for growth IGF1 also acts as an anti-catabolic. This would be beneficial to those users in a calorie deficit or in other circumstances that place them at risk of losing muscle mass. IGF1 also has the ability to positively affect lipolysis in users if other necessary conditions are met, namely proper diet and training protocols. When combined with the ability to preserve muscle mass, IGF1 appears to be an attractive choice for those that are attempting to decrease their body fat while maintaining as much of their muscle mass as possible.
IGF1 is composed of seventy amino acids, the same number as insulin. As stated earlier, it is primarily secreted by the liver. The stimulus that is responsible for this secretion is the presence of growth hormone. In fact IGF1 is primarily the causal connection between growth hormone and its anabolic and anti-catabolic capabilities. This is not to say that effects caused by growth hormone could be produced with only IGF1, but rather that the two compounds are very much related to one another and both are needed for optimal tissue growth.
In terms of dosing for IGF-1, users have reported seen good results when administering dosing ranging from 100 to 160 mcg per day. This total dose would be split into several injections, most of which would likely be administered post-workout.