posted July 14, 2000 06:48 PM            

Some ardently believe that it is the holy grail of anabolics, unsurpassed in its ability to promote muscle growth. To others it is barely an effective fat burner, and clearly a waste of money in light of its high price tag. Getting a consistent point of view regarding the use of this drug is likewise an impossibility, as everyone you speak with seems to have a different opinion on if or how to use it. I am taking of course about human growth hormone, one of the most costly, sought after and probably least well understood performance-enhancing drugs in the athlete's arsenal. Indeed GH is a drug with potential to benefit the athlete/bodybuilder; otherwise it would not be such an ingrained part of competitive athletics. It clearly affects muscle mass, however its mode of action is quite different from steroids. It likewise bears relevance to understand specifically what growth hormone does in the body, and especially why there are a number of other substances that should be used concurrently to enhance its anabolic potential.

In the human body growth hormone has two distinct mechanisms of action. The first includes the direct effects of this hormone, the most notable being the stimulation of lipolysis (fat loss) in adipose tissue. This is accomplished by enhancing catecholamine-induced lipolysis via an increase in beta-adrenergic receptor concentrations in adipose cells (1). Growth hormone also acts to oppose the activity of receptor bound insulin in many body tissues, including the liver where it stimulates the release of glucose. GH also acts indirectly via stimulating the release of insulin-like growth factor-1 (IGF-1) in many tissues including the liver, skeletal muscle and adipose tissue. IGF-1 is responsible for the tissue building (anabolic) activity we associate with GH therapy, accomplished primarily by an increase in cell number in nearly all body organs. IGF-1 may also stimulate a positive nitrogen balance, however this effect is not well maintained or consistent. It is here where we see both the first unique benefit and drawback to GH therapy as a means of increasing muscle mass. It increases cell number in muscle tissue, clearly a beneficial effect not notably seen with anabolic steroids, however it does not dramatically enhance the rate of protein synthesis (which would affect cell size). It is for this reason that anabolic steroids are typically added to a cycle of growth hormone, as the two drugs synergistically promote tissue growth through separate means.

But there are other drugs that typically should be used in conjunction with growth hormone if we are desirous of achieving an optimal effect. One reason for this is the need for simple replacement, as GH therapy is shown to negatively impact the level of certain hormones in the body. This is explained by the fact that high levels of IGF-1 serve as a negative feedback trigger for the hypothalamus and pituitary to stop releasing growth hormone. This feedback is principally achieved by the hypothalamic release of somatostatin, a hormone that signals the pituitary to stop releasing GH. The problem is that somatostatin receptors are found in many other tissues, and consequently this hormone acts to lower the release of other hormones such as TSH (thyroid stimulating hormone) and insulin during GH therapy. With the level of use typically associated with athletes, the lowering of these hormones can become notable.

It is often reported by athletes that the addition of insulin and a thyroid hormone such as Cytomel (T-3) or Synthroid (T-4) will counter this hormonal reduction and greatly enhance the effects of GH therapy. Insulin for instance not only helps to promote protein synthesis, but it also increases the transport of select amino acids and glucose into muscle cells (2), two extremely important activities in the quest for an anabolic state. Thyroid hormones also help to maintain an enhanced thermogenic (fat-burning) and anabolic state by maintaining a normal or enhanced level of cellular metabolic activity. We must remember that thyroid hormones are the primary regulators of body metabolism, and as such they effect not only the rate in which fats are utilized by the body, but also proteins and carbohydrates. Left unchecked, a lowering of insulin and thyroid hormone concentrations will at some level work against the anabolic and thermogenic activities of growth hormone.

Insulin therapy may also be of great benefit for less simple reasons. The first reason being that insulin directly lowers the level of certain IGF binding proteins in the blood (3,4). The background here is very similar to what we see with testosterone. Only a small fraction of the hormone is actually free to interact with receptors at any given time, as most is found in "bound" form, meaning the hormone is temporarily attached to a protein that restricts it from exerting any action. Only once it detaches from the binding protein is it active. With IGF-1 we wee a similar relationship between the free percentage at any given point and the level of activity displayed. As we increase the unbound fraction of hormone, we clearly salso increase the anabolic response as more hormone is free to bind with receptors. For some reason anabolic steroid use has also been linked to a lowering of a specific IGF binding protein (IGFBP-3), which appears to be another method that steroids can enhance the anabolic effect of GH therapy (5).

So what does an appropriately supported GH cycle look like? For starters most find that 4 IU's of growth hormone are needed daily at a minimum to elicit a strong effect. With a typical cycle running 8-10 weeks this can add up. The only advice I can give on this is to shop for the cheaper versions (Chinese GH can be quite reasonable for example), or to buy in bulk (U.S. Serostim kits are ideal as they contain as much as 126 IU per kit). The insulin dosage would be much more tailored to the individual (after safe personal experimentation), but typically around 1 IU per 15-20 lb. of bodyweight, administered immediately after training. A second application daily is sometimes shown to further help, perhaps in part because any IGF binding proteins affected by insulin will rise and fall in direct response to its concentration (a second application allows for more time with enhanced IGF-1 activity). The amount of thyroid hormones used will again also be tailored to the individual, but a typical dose would be 50-100 mcg for Cytomel, or 200-400mcg Synthroid. The dosage of either drug is to be slowly built up to in the beginning, and tapered off of at the conclusion of therapy. This is to avoid any sudden shock to the system, as both high or low thyroid levels can present a number of unwelcome side effects to the user (including irregular heartbeat, sweating, irritability, psychic/mood changes and nausea).

If we look back to try and find a reason why there are vastly conflicting reports about the effectiveness of GH therapy, it seems logical that a lack of ancillary drug use could have played a big role in a user's disappointment. The bottom line is that growth hormone taps a unique and clearly beneficial path toward an anabolic state. If we further exploit this by promoting growth through other means such as enhancing protein synthesis (steroids, insulin), increasing nutrient uptake in cells (insulin) or maintaining an elevated metabolic state (thyroid hormones) we have an extremely effective way of inducing new muscle growth. Alone however, growth hormone simply does not appear capable of imparting great mass gains to the user. It likewise seems understandable why most who do not invest in such a detailed stack and use GH alone usually find fat loss the primary benefit. Dosage is also an important consideration in whether or not good results will be achieved. Due to the fact that growth hormone is extremely expensive (many times more costly than steroids), many users are reluctant to invest in an appropriately sized cycle. They will ultimately tinker around with small dosages, and find a very poor return on their money in terms of solid results. This is clearly a mistake with growth hormone. If you are going to invest, you might as well do it right, full dosage of at least 4iu daily, ancillaries, steroids and all.

By William Llewellyn

References:

1-Growth Hormone treatment of hypophysectomized rats increases catecholamine-induced lipolysis and the number of beta-adrenergic receptors in adipocytes: no differences in the effects of growth hormone on different fat deposits. Yang S, Bjorntorp P, Xinglu L, Eden S. Obes Res 4 (1996): 471-8.

2-Physiologic Hyperinsulinemia Stimulates Protein Synthesis and Enhances Transport of Selected Amino Acids in Humna Skeletal Muscle. Biolo G, Fleming RY, Wolfe R. J Clin Invest. 95 (1995) 811-19.

3-Identification of an insulin-responsive Element in the Promoter of the human gene for Insulin-like Growth Factor Binding Protein-1. Suwanickul A, Morris S, Powell D. J of Biol Chem 23 (1993) 17063-68.

4-The IGF system in metabolism regulation. Binoux M. Diabete Metab 21 (1995): 330-7

5-Growth hormone induced increase in serum IGFBP-3 level is reversed by anabolic steroids in substance abusing power athletes. Clin Endocrinol (0xf) 49 (1998): 459-63