Call Us Today! 1.800.344.3404

Bulletin #71- Growth Hormone Physiology

Growth hormone is one of the hottest topics in bodybuilding (and the lay press). This month I want toexplain exactly what growth hormone is, how it works and how to increase your growth hormone levelthrough diet, exercise and supplementa-tion . Growth hormone (GH) is a protein hormone made by thepituitary gland, a small secretory gland at the base of the brain. Hormones, chemical messengers secreted byendocrine glands into the bloodstream, are delivered to target tis-sues, where they exert their effects. Un-like other pituitary hormones, GH has no specific target gland. It exerts its effects on nearly all body tissues(1). GH re-lease is controlled by two other hormones produced by the hypothalamus, a higher brainstructure. Growth hormone releas-ing hormone (GHRH) stimulates GH re-lease, while growth hormoneinhibitory hormone (GHIH) inhibits GH secretion. GHIH is also called somatostatin. The balance betweenthese stimulatory and inhibiting influences determines GH re-lease. What, then, determines the balancebetween GHRH and GHIH? Age and body composition are the most important factors. Aging and adipositynegatively influence GH release (2); however, GH release can be enhanced through diet, exercise andsupplementation. Although growth hormone is important to bodybuilders, its primary function is to promotegrowth during childhood. People born with a growth hormone deficiency will become dwarfs unless it isreplaced. Actively growing children have the high-est levels of growth hormone. Gradu-ally, GH releasedecreases with age. The decline in GH levels may in fact be the cause of some of the processes of aging.Growth hormone promotes growth of nearly all the tissues of the body (1), including bones and internalorgans. It stimulates cell division, causing tissues to grow.

Parrillo Performance

Bodybuilders who inject syn-thetic GH should understand that its effect is not limited to muscles; it effectsother organs as well. Acromegaly is a disease caused by overproduction of growth hor-mone by a functionalpituitary tumor. Individuals with acromegaly have charac-teristic deformities of the face, hands, feet andother body structures. While we want to optimize GH levels, more is not better. In addition to promotinggrowth, GH has a variety of metabolic effects (1,3), including increased protein synthesis and nitrogenretention, increased utilization of fat as energy and decreased carbohydrate usage. In elderly individualsdeficient in GH, restoration of more youthful GH lev-els promotes increased muscle mass and decreasedbodyfat. The natural decline in GH levels accompanying aging may be partially responsible for the changes inbody composition that occur as we grow older . GH seems to enhance protein synthesis in several ways (1,3).

First, it promotes transport of amino acids across cell mem-branes into the cells in which protein synthesisoccurs (1). The increased con-centration of amino acids inside cells means that more are available to be in-corporated into proteins . Second, it seems to stimulate the ribosomes to make more protein by amechanism independent of amino acid concentration. Ribosomes are the machines inside cells that linkamino acids together to form proteins. Third, GH promotes gene expression, increas-ing the amount of RNAinside cells. RNA is a nucleic acid molecule that contains the information specifying the sequence of aminoacids strung together to form a protein. In other words, the RNA contains the protein blueprint and tells theribosome what to do. This chain of events will result in increased protein synthesis if the cell containsadequate amino acids, energy, vitamins and other nutrients necessary for growth. This is an important pointto consider: In order for GH to be effective the cell must contain adequate nutrients and energy, otherwisegrowth cannot occur. Nutrition is abso-lutely critical . Finally, GH also seems to promote positive proteinbalance by de-creasing protein breakdown (catabolism).

One way it might do this is by increasing the use of fat as an energy source, thereby sparing body protein.Growth hormone increases the release of fatty acids from adipose tissue and increases serum-free fatty acidconcentra-tion (1). Furthermore, it seems to increase the oxidation of fatty acids as fuel inside cells. Itcauses cells to preferentially use fat as fuel over carbohydrate and protein (1). Not only does this reduceprotein catabolism, but it also spares glycogen. Some people have suggested that the increased availabilityof fat as fuel and the accompanying decrease in amino acid oxidation is the primary mechanism by which GHenhances nitrogen balance. This is controversial and poses quite an interesting hypothesis. We know, forexample, that the medium chain triglyc-erides in CapTri® are preferentially used as an energy source andspare amino acid oxidation. Perhaps this is why CapTri® seems to enhance lean body mass. It may work by asimilar mechanism.

Growth hormone also affects carbohy-drate metabolism. It decreases the use of glucose as energy, therebysparing glycogen. The exact details of this are not un-derstood, but again it may be related to the increasedutilization of fat. This has the effect of increasing glycogen deposition. When GH is administered to ananimal, it initially causes an increase in glucose uptake by the cells. After about an hour glucose uptake bycells decreases, prob-ably because the cells are so full of glu-cose by this time. This results in increasedserum glucose, which in turn stimulates insulin release . Furthermore, GH directly stimulates the pancreas,commanding it to release more insulin. In cases of GH ex-cess, these factors combined can promotediabetes. It also causes insulin resistance, so that larger than usual amounts of insu-lin are required to beactive. You may be aware that some bodybuilders who use anabolic steroids and growth hormone also useinsulin. This is the reason why. It was discovered that when GH is sup-plied to cells grown in a cultureoutside the body, it often fails to produce many of its effects. This led to the suggestion that perhaps someother compound might mediate some of the actions of GH. Sub-sequently it has been determined that theliver, and to a lesser extent most other cells, make proteins called somatomedins in response to GHexposure. It turns out that most, but not all, of the actions of GH are actually brought about by thesesecondary messengers. Many of the ac-tions of the somatomedins are similar to insulin, so they also havethe name “insu-lin-like growth factors,” or IGF. At least four IGFs have been characterized. The mostimportant of these seems to be IGF-1. Some dwarfs actually have adequate GH levels, but have a geneticdefect that does not allow them to make IGF-1.

This highlights the importance of these mol-ecules in mediating GH actions . It is interesting to note thatthe life span of growth hormone in the blood is very short. Its half-life (the time required for itsconcentration to drop by one-half) is about 20 minutes. We might think at first that GH would have veryshort-lived effects, based on its short half-life, or perhaps that we would have to secrete it continuously inorder to get much of an effect. Neither is true. Since most of the actions of GH are brought about by IGF-1and other somatomedins, one might say that the function of GH is to stimulate somatomedin production .The half-life of IGF-1 is about 20 hours. So the IGF-1 “smooths out” the effective-ness of a single burst ofGH release. The emerging picture? Most of the anabolic actions of GH are mediated by IGF-1 and GH has adirect catabolic effect on lipid metabolism (3). The primary factor in determining overall GH secretion isundoubtedly age. Growth hormone levels are highest during childhood. Gradually GH levels decrease toabout 25 percent of the initial level in the elderly. The second major GH factor is body composition (2).Excessive bodyfat seems to decrease GH levels. GH is nor-mally released in a pulsatile (pulsation) fashion:the biggest spike occurs about two hours after deep sleep. So this means sleep is a stimulus for GH release.Other factors which increase GH release include exercise, excitement, stress, malnutrition and some specificnutrients. Malnutrition is an interesting one to consider. Protein malnutrition turns out to be a powerfulstimulus for GH release. Does this mean we want to deprive ourselves of protein in order to increase GHlevels? Certainly not. During protein malnutrition the body loses muscle mass, so more GH is re-leased in anattempt to counteract this; the body fights to preserve muscle and does so by promoting the utilization offat as energy instead of amino acids. Although starvation will increase GH levels, it won’t help you gainmuscle.

Exercise is a relatively potent stimulus for GH release. Many studies seem to be in agreement that intenseexercise, particularly anaerobic exercise resulting in glycolysis and lactic acid formation, are the mosteffective forms of exercise for increasing GH (2,4,5,6). This is prob-ably why intense exercise, such asweight lifting, results in greater changes in body composition than low intensity exercise, such as walking. Ifyou look at people who only perform low intensity exercise, you can see that they’re able to lose weight andget smaller, but not lean and muscular . Compare marathon runners to sprinters. Both utilize the sameexercise (running), but sprinting has much higher intensity . The marathon runners are thin and sleek whilethe sprinters are much more muscular. Is there a connection? Most likely. This also explains why you shouldal-ways include some sets with higher reps. It is certainly possible to pick a heavy weight and train to failureafter five reps, but this does not result in lactic acid ac-cumulation. This style of training is an excellent wayto increase strength but by itself does not result in optimal size in-creases. Train to failure with higher reps,as many as 20-25 reps, to really feel an intense burn. And just because you’re us-ing a lighter weight formore reps doesn’t mean it’s a wimpy set. You can and should push the set to absolute failure. Training withmoderate (and even light) weights can be very intense if you do it right. We do 100 rep sets with the beltsquat, and believe me, it’s brutal. For op-timal muscular development you need to do some training withvery heavy weights in the 3-5 rep range, some training in the 8-10 rep range, and some training in the 20rep range, until you really feel a burn. It is these higher rep sets, carried to failure, that stimulate GH releasemost effectively. You’ve heard you should do low reps for mass and high reps for definition.

An oversimplification to be sure, but with an element of truth. Most people explain it this way: The high repwork burns more calories so helps you get more cut . This isn’t what’s really happening. In reality, you don’tburn many calories (relatively) lifting weights even with high rep sets. The main factor is that the high repsets trigger GH release. If done consistently, over time, this use of high rep sets will change bodycomposition. How do you take advantage of this knowledge and spur GH release? It depends. A roughguideline might be 25 percent of your sets in the 3-5 rep range, 50 percent in the 8-10 rep range, and 25percent in the 20-25 rep range. Try this for six weeks and see what happens. Many bodybuilders have thisidea that if they do more than 12 reps they’re wasting their time, and should just increase the weight. Not so.Doing work with higher reps is very beneficial. Just remember you have to take it to failure even if you’redoing high reps. Plus, if you have never trained above 12 reps, the change will undoubtedly stimulate yourprogress . Another exercise parameter which seems to enhance GH release is to use shorter rest intervals. Todo this, of course, you have to use lighter weights (and more reps). A difficult protocol which works well toincrease GH levels is to train to failure at 10 reps (use 10 rep maximum weight) combined with one minuterest intervals (5). If you’re used to resting 3-5 minutes between sets, shortening up the rest interval to oneminute or less; it will work wonders. Sometimes bodybuilders get into a rut; they plateau and can’t figure outthe problem. It might be that they’re training like powerlifters: very heavy weights, very low reps with longrest intervals. If you haven’t made good gains in awhile try to incorporate some of these GH-releasing ideas .In 1993 a scientific study compared the GH-release of 20 sets of one rep each (done maximally) to 10 sets of10 reps (also maximum) and found the 10 sets of 10 reps resulted in greater GH release (6).

Why? Probably the larger volume of work, done with enough reps to result in some lactic acid production,combined with short rest intervals, is the best way to trigger GH release. It may prove ben-eficial to includesome high intensity aerobics as part of your cardiovascular training. There seems to be theoreticaljustification to include sprinting for better results . You can also optimize GH release through nutrition andsupplementation . A diet higher in protein seems to promote GH release. Another piece of advice is to not eatfor two hours before a workout. Exercise seems to result in more GH re-lease if performed on an emptystomach. What you should do just depends on your goals. If your goal is to be as strong as possible in thegym, lifting the heaviest weight you can, some ProCarb™ and CapTri® an hour beforehand will give you moreenergy and help you be stron-ger. But if your goal is to train for maxi-mal GH release, you should probablywait for two hours before you train. Certain nutrients have also been shown to increase GH levels (2,7,8,9).Certain combinations of specific amino acids, such as found in Enhanced GH Formu-la™, are shown toenhance GH release (8).

Probably the best way to use these is on an empty stomach, first thing in the morning, right before aworkout, and before bed. We were impressed to learn that MCTs, like CapTri®, can be a potent stimulus forGH release (9). As far as we know, this has only been examined in one study, but this study demonstrated a900 percent increase in plasma GH levels two hours after MCT ingestion that was maintained for three hours.If you eat every three hours, that would keep GH levels up all day. We wonder if this is part of the wayCapTri® works, in addition to it’s unique metabolic properties. We know that a high protein diet, medium incarbohydrates and containing one to two tablespoons of CapTri® each meal, consumed every two an a half tothree hours, helps most people get lean and muscular. I wonder how much of this ef-fect is mediated by GH.Try these modifi-cations in your diet and exercise program Growth Hormone Physiologyand let me knowwhat kind of results you get. Transform your metabolism into a muscle-building, fat-burning mode by us-ing these GH-stimulating techniques. You might see a remarkable transformation in a relatively short time.Using Parrillo Performance principles, real people get real results real fast!


1. Guyton AC and Hall JE. Textbook of Medical Physiology. W.B. Saunders Com-pany, Philadelphia, 1996.

2. Vance ML. Nutrition, body composition, physical activity and growth hormone se-cretion. Journal ofPediatric Endocrinology & Metabolism 9 suppl 3: 299-301, 1996.

3 . Shils ME, Olson JA, and Shike M . Mod-ern Nutrition in Health and Disease. Lea & Febiger, Malvern, PA,1994.

4. Roemmich JN and Rogol AD. Exercise and growth hormone: does one affect the other? Journal ofPediatrics: 131, S75-80, 1997 .

5. Kraemer WJ, Fleck SJ, et al. Changes in hormonal concentrations after differ-ent heavy resistance exerciseprotocols in women. Journal of Applied Physiology 75: 594-604, 1993 .

6. Hakkinen K and Pakarinen A. Acute hormonal responses to two different fa-tiguing heavy resistanceprotocols in male athletes. Journal of Applied Physiology 74: 882-887, 1993 .

7. Vance ML, Hartman ML, and Thorner MO. Growth hormone and nutrition. Hor-mone Research 38: suppl. 1:85-88, 1992.

8. Isidori A, Lo Monaco A, Cappa M. A study of growth hormone release in man after oral administration ofamino acids. Current Medical Research and Opinion. 7: 475-481, 1981 .

9. Valls E, Herrera F, Diaz M, Barreiro P, and Valls A. Modification in plasmatic insulin and growth hormoneinduced by medium chain triglycerides . Span . Ana . Ped. 11: 675-682, 1978.

2018-03-13T11:10:32-04:00 June 16th, 2009|Technical Supplement Bulletins|

Already familiar with Parrillo Products? Click Here - New Quick-Order Form! Dismiss