basskilleronline steroid articles
Egg Whites International
Basskilleronline Menu
Main Page
Anti-estrogen Articles
Antioxidants Articles
Bodybuilding Articles
Bodybuilding DVD's
Cardio Articles
Steroid Conversion Articles
Competition Articles
fatloss Articles
Steroid Profiles
Finaplix Articles
Fitness Articles
Hcg diet, does it work
Health Articles
HGH Articles
IGF-1 Articles
Insulin Articles
Building Muscle Articles
Bodybuilding Message Boards
bodybuilding peptides
Post Cycle Therapy Articles
Powerlifting Articles
Fitness and Diet Recipes
Research Sites
Selective androgen receptor modulator
Sponsors Steroid Articles
Supplement Articles
Women's Fitness Articles
Workout Routines

Research on IGF, Growth Hormone and Insulin

Nearly every athlete knows the critical importance of growth hormone and testosterone for stimulating gains in lean mass. However, not many are aware of insulin's powerful anabolic effects, particularly regarding its synergistic role in producing the body's most potent growth factor, IGF-1 (Insulin-like Growth Factor-1), the muscle builder.

You can buy the best supplements, utilize the best training program and coaches, but unless you control insulin you will fail repeatedly in your quest for muscle mass. How much IGF-1 your body secretes depends on how well you manage insulin. IGF-1 is vital for the correct glucose and protein metabolism that results in muscle growth. IGF-1 is so potent, its presence can reverse many age-related defects such as insulin resistance and reduced muscular force. IGF-1 exerts its potent effects much better when insulin levels are steady.[5]

How it Happens . . .
When humans release growth hormone from their pituitary gland (located at the base of the brain), some goes to muscle and bone to directly initiate tissue growth.[2] Most GH travels to the liver, where it is destroyed within 60-90 minutes. Before this happens the liver uses this material to manufacture somatomedins, also called growth factors. The best studied growth factors are IGF-I and IGF-II. One of growth hormone's main roles is to get to the liver and trigger IGF release.[3]

Insulin interacts with growth hormone at the liver to produce IGF-I. In circulation, both IGF-I and IGF-II have very short lives. IGF-II is mainly responsible for nerve growth. IGF-I exerts powerful growth effects on muscle, however, it needs a steady supply of insulin to work. Unless you've got both insulin and IGF circulating in the right amounts, your muscle growth will be zero. How do we know?

Research on diabetics provided the earliest examples. Insulin-dependant diabetics have low IGF levels and a hell of a job increasing their muscle mass.[4,5] Diabetes is a disease of inconsistent, ineffective insulin secretion by the pancreas. A diabetic's insulin supply is like a yo-yo, constantly going up and down depending on how much they inject and what they eat. It's almost impossible to keep constant. These roller coaster insulin surges kill IGF levels.[4,5]

Weight Training and IGF-1
While previous research shows conflicting results with regard to IGF-1 secretion and exercise, recent research demonstrates that a big squirt of IGF-1 is secreted within the first 12 minutes of intense training.[10]

Carefully designed new research also reveals that muscles used in weight training produce a heap of bioactive IGF-1.[10,11] In fact, IGF-1 circulates in a "system", consisting mostly of a family of six binding proteins, free IGF-1 and an acid-labile unit.[11] These six binding proteins in blood and muscle regulate the biological activity (usability) of IGF-1.[10]

The very latest research on IGF-1 shows that intense weight training creates a signal within muscle to rearrange the ratio of these binding proteins and increase the activity and availability of IGF-1. This appears to be essential to the growth and repair process.

The total amount of IGF-1 secreted is not as important as the rearrangement of the IGF-1 binding protein ratios. [11] Heavy resistance training triggers this rearrangement fantastically well.[11,12] Also, this modulation of the IGF-1 binding proteins to create active IGF-1 is not noticed until six to 12 hours after training. [11] Interestingly, this just about the time that peak muscle protein synthesis rates kick in. Are you starting to see the link?

Growth Hormone Release is Only the Start . . .
To maximize IGF secretion there is a biochemical sequence of events that must be fulfilled, and triggering GH release is the first crucial step.[2] While some athletes inject GH others choose the safer route and enhance its secretion naturally via intense training, increasing sleep frequency and using research-proven nutrients such as GABA, niacin and glutamine.

Using nutrients to spike GH levels is safe. Even the highest endogenous GH spurt consists of bound (inactive) and unbound (active) forms that keep it within tightly regulated physiological levels.[11] However, troubles occur for the big boys 'n' gals that shove in large gobs of artificial GH and IGF-1.

Only precise ratios of protein-bound IGF-I and GH along with the right level of insulin, will exert a synergistic, growth-effect on muscle. Currently, the technology to replicate this information artificially is not yet available, even on the black market. The bodybuilder who sticks one needle under their skin and another in their butt, and hopes for muscle growth is kind of stupid! The body's endocrine system is far too intricate. So do your self a big favor and don't mess with it artificially.

Artificially bombarding the body with random shots of these drugs means the excess has to go somewhere. The surplus binds to receptor sites in organs and intestines. So, for every 1/8th of an inch the "drug boys" add to their arms and shoulders, they also add a good inch to their gut via organ and intestinal growth. The result, as seen at any pro-bodybuilding show, is not a good look.

At the moment, pro-bodybuilding is an ugly sight. Sure, the pros step on stage massive and ripped, but now they also sport hugely distended stomachs due to years of injecting this artificial hormone cascade. Some of them have a gut so big you'd swear if they fell over, they'd rock themselves to sleep trying to get back up!

Injecting growth hormone is a risky business, even in controlled clinical therapy.[6] Several years ago, GH research for replacement therapy among older adults seeking that elusive fountain of youth went dreadfully wrong. The late Dr Daniel Rudman was infamous for promoting this yuppie trend. However, more than half his subjects had to drop out of his research due to serious side effects, such as carpel tunnel syndrome and full-blown diabetes. The latter is more evidence of the imbalance and strain created within the body when a single anabolic is introduced.

Hype vs. Science
Without a steady-state insulin supply, kept within a narrow, physiological range GH levels are quickly destroyed and the active life of IGF-I is short lived.[4] Steady-state insulin levels prolong the active life of IGF and GH secretion so their powerful effects on muscle may last longer.[5]

Natural manipulation of insulin via the diet has become the next exciting frontier for enhancing athletic performance. The intake of key nutrients at the correct time will keep blood insulin where it needs to be. This will promote an optimal anabolic hormone profile that enhances nutrient transport into cells, provides better recovery and faster adaptation to training.

Many athletes have become highly skeptical of claims made by supplement marketers about magical pathways to muscle growth. So I'm going to provide you with the clear-cut science on what we know about enhancing natural anabolic hormone secretion to optimize recovery and muscle growth.

Heavy, intense weight training exercise stimulates GH and IGF secretion fantastically. In fact, the more intense the training (in terms of overload), the higher the concentration of active IGF-1 produced. Best of all, intense weight training enhances the potent effects of IGF-1 in people of all ages, not just athletes.[7,10]

Some endocrinologists suggest that consistent training enhances the GH-IGF axis, resulting in more powerful secretions and an accumulative effect that accelerates adaptive changes to training.[9]

Intensity of exercise appears to be the key factor in GH and IGF-1 secretion. Both high intensity weight and aerobic training create effective GH and IGF-1 release.[9,10]

Heavy, eccentric weight training causes the highest increases in circulating bioactive IGF-1.[11]

Advanced trainers should incorporate some negative-only work into their program. But use this method very sparingly.

Sleep is potent stimulator of GH release and training during the day amplifies its nocturnal secretion.[9]

Remember that spiking GH release via sleep or supplements is useless without enough circulating blood amino acids and insulin. To ensure you have the right building material available, consume a slower absorbing liquid meal such as Ny-Tro Pro-40 before sleep.

While intense training sessions increase testosterone, GH and IGF levels, they also lower insulin levels and increase cortisol (the muscle breakdown hormone).[1] When ever insulin is low the life of GH-IGF secretion is short lived.[1]
In the next article I'll show you how to optimize your anabolic hormone profile with nutritional science.

by Paul Cribb, B.H.Sci HMS
AST Director of Research

1. Kraemer WJ, Volek JS, Bush JA, et al. J.Appl.Physiol.85(4) 1544-1555,1998.
2. Daughaday WH,ed. Endocrine Control of Growth, New York:Elsevier,1981.
3. Tillmann V, Patel L, Gill MS, et al. Clin Endocrinol.53(3):329-336,2000.
4. Philips LS. Metabolism, 34:765-770,1985
5. Carroll PV, Christ ER, Umpleby AM, et al. Diabetes, 49(5):789-96,2000.
6. Zachwieja JJ, Yarasheski KE. Phys Ther. 79(1):76-82,1999.
7. Parkhouse WS, Coupland DC, Li C, Vanderhoek KJ. Mech Aging Dev.
8. Rasmussen BB, Tipton KD, Miller SL, et al. J.Appl.Physiol. 88:386-392,2000.
9. Jenkins PJ. Clin Endocrin. 50:683-689,1999.
10. Bamman MM, et al. Am J Physiol Endocrinol Metab. 280:E383-E390, 2001.
11. Nindl BC, et al. J Appl Physiol. 90:1319-1326, 2001  

Books and Courses

Great Websites

Excellent Stores

Recipe Cook Books

eXTReMe Tracker