okay basically i'm going to lay down a whole load of quoted stuff some with sources, some without
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"There are some instances, however, where a food has a low glycemic value but a high insulin index value. This applies to dairy foods and to some highly palatable energy-dense "indulgence foods." Some foods (such as meat, fish, and eggs) that contain no carbohydrate, just protein and fat (and essentially have a GI value of zero), still stimulate significant rises in blood insulin."
The New Glucose Revolution (New York: Marlowe and Company, 2003, pages 57-58
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Regulation of GLUT4 protein and glycogen synthase during muscle glycogen synthesis after exercise.
Ivy JL, Kuo CH.
Department of Kinesiology, The University of Texas at Austin, 78712, USA.
The pattern of muscle glycogen synthesis following its depletion by exercise is biphasic. Initially, there is a rapid, insulin independent increase in the muscle glycogen stores. This is then followed by a slower insulin dependent rate of synthesis. Contributing to the rapid phase of glycogen synthesis is an increase in muscle cell membrane permeability to glucose, which serves to increase the intracellular concentration of glucose-6-phosphate (G6P) and activate glycogen synthase. Stimulation of glucose transport by muscle contraction as well as insulin is largely mediated by translocation of the glucose transporter isoform GLUT4 from intracellular sites to the plasma membrane. Thus, the increase in membrane permeability to glucose following exercise most likely reflects an increase in GLUT4 protein associated with the plasma membrane. This insulin-like effect on muscle glucose transport induced by muscle contraction, however, reverses rapidly after exercise is stopped. As this direct effect on transport is lost, it is replaced by a marked increase in the sensitivity of muscle glucose transport and glycogen synthesis to insulin. Thus, the second phase of glycogen synthesis appears to be related to an increased muscle insulin sensitivity. Although the cellular modifications responsible for the increase in insulin sensitivity are unknown, it apparently helps maintain an increased number of GLUT4 transporters associated with the plasma membrane once the contraction-stimulated effect on translocation has reversed. It is also possible that an increase in GLUT4 protein expression plays a role during the insulin dependent phase.
Publication Types:
Review
Review, Tutorial
PMID: 9578375 [PubMed - indexed for MEDLINE]
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Dietary strategies to promote glycogen synthesis after exercise.
Ivy JL.
Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX, USA.
Muscle glycogen is an essential fuel for prolonged intense exercise, and therefore it is important that the glycogen stores be copious for competition and strenuous training regimens. While early research focused on means of increasing the muscle glycogen stores in preparation for competition and its day-to-day replenishment, recent research has focused on the most effective means of promoting its replenishment during the early hours of recovery. It has been observed that muscle glycogen synthesis is twice as rapid if carbohydrate is consumed immediately after exercise as opposed to waiting several hours, and that a rapid rate of synthesis can be maintained if carbohydrate is consumed on a regular basis. For example, supplementing at 30-min intervals at a rate of 1.2 to 1.5 g CHO x kg(-1) body wt x h(-1) appears to maximize synthesis for a period of 4- to 5-h post exercise. If a lighter carbohydrate supplement is desired, however, glycogen synthesis can be enhanced with the addition of protein and certain amino acids. Furthermore, the combination of carbohydrate and protein has the added benefit of stimulating amino acid transport, protein synthesis and muscle tissue repair. Research suggests that aerobic performance following recovery is related to the degree of muscle glycogen replenishment.
Publication Types:
Review
Review, Tutorial
PMID: 11897899 [PubMed - indexed for MEDLINE]
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Amino acids stimulate translation initiation and protein synthesis through an Akt-independent pathway in human skeletal muscle.
Liu Z, Jahn LA, Wei L, Long W, Barrett EJ.
Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA.
zl3e@virginia.edu
Studies in vitro as well as in vivo in rodents have suggested that amino acids (AA) not only serve as substrates for protein synthesis, but also as nutrient signals to enhance mRNA translation and protein synthesis in skeletal muscle. However, the physiological relevance of these findings to normal humans is uncertain. To examine whether AA regulate the protein synthetic apparatus in human skeletal muscle, we infused an AA mixture (10% Travesol) systemically into 10 young healthy male volunteers for 6 h. Forearm muscle protein synthesis and degradation (phenylalanine tracer method) and the phosphorylation of protein kinase B (or Akt), eukaryotic initiation factor 4E-binding protein 1, and ribosomal protein S6 kinase (p70(S6K)) in vastus lateralis muscle were measured before and after AA infusion. We also examined whether AA affect urinary nitrogen excretion and whole body protein turnover. Postabsorptively all subjects had negative forearm phenylalanine balances. AA infusion significantly improved the net phenylalanine balance at both 3 h (P < 0.002) and 6 h (P < 0.02). This improvement in phenylalanine balance was solely from increased protein synthesis (P = 0.02 at 3 h and P < 0.003 at 6 h), as protein degradation was not changed. AA also significantly decreased whole body phenylalanine flux (P < 0.004). AA did not activate Akt phosphorylation at Ser(473), but significantly increased the phosphorylation of both eukaryotic initiation factor 4E-binding protein 1 (P < 0.04) and p70(S6K) (P < 0.001). We conclude that AA act directly as nutrient signals to stimulate protein synthesis through Akt-independent activation of the protein synthetic apparatus in human skeletal muscle.
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Determinants of post-exercise glycogen synthesis during short-term recovery.
Jentjens R, Jeukendrup A.
Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
The pattern of muscle glycogen synthesis following glycogen-depleting exercise occurs in two phases. Initially, there is a period of rapid synthesis of muscle glycogen that does not require the presence of insulin and lasts about 30-60 minutes. This rapid phase of muscle glycogen synthesis is characterised by an exercise-induced translocation of glucose transporter carrier protein-4 to the cell surface, leading to an increased permeability of the muscle membrane to glucose. Following this rapid phase of glycogen synthesis, muscle glycogen synthesis occurs at a much slower rate and this phase can last for several hours. Both muscle contraction and insulin have been shown to increase the activity of glycogen synthase, the rate-limiting enzyme in glycogen synthesis. Furthermore, it has been shown that muscle glycogen concentration is a potent regulator of glycogen synthase. Low muscle glycogen concentrations following exercise are associated with an increased rate of glucose transport and an increased capacity to convert glucose into glycogen.The highest muscle glycogen synthesis rates have been reported when large amounts of carbohydrate (1.0-1.85 g/kg/h) are consumed immediately post-exercise and at 15-60 minute intervals thereafter, for up to 5 hours post-exercise. When carbohydrate ingestion is delayed by several hours, this may lead to ~50% lower rates of muscle glycogen synthesis. The addition of certain amino acids and/or proteins to a carbohydrate supplement can increase muscle glycogen synthesis rates, most probably because of an enhanced insulin response. However, when carbohydrate intake is high (>/=1.2 g/kg/h) and provided at regular intervals, a further increase in insulin concentrations by additional supplementation of protein and/or amino acids does not further increase the rate of muscle glycogen synthesis. Thus, when carbohydrate intake is insufficient (<1.2 g/kg/h), the addition of certain amino acids and/or proteins may be beneficial for muscle glycogen synthesis. Furthermore, ingestion of insulinotropic protein and/or amino acid mixtures might stimulate post-exercise net muscle protein anabolism. Suggestions have been made that carbohydrate availability is the main limiting factor for glycogen synthesis. A large part of the ingested glucose that enters the bloodstream appears to be extracted by tissues other than the exercise muscle (i.e. liver, other muscle groups or fat tissue) and may therefore limit the amount of glucose available to maximise muscle glycogen synthesis rates. Furthermore, intestinal glucose absorption may also be a rate-limiting
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Scientists Close In On Trigger Of Insulin Resistance
Extra sugar can cause insulin resistance in cells. Now scientists have an explanation.
In experiments with fat cells, Johns Hopkins scientists have discovered direct evidence that a build-up of sugar on proteins triggers insulin resistance, a key feature of most cases of diabetes.
The results underscore the importance of glycosylation - attachment of a sugar to a protein -- as a way cells control proteins' activities, the scientists report in the April 16 issue of the Proceedings of the National Academy of Sciences. The scientists found that at least two proteins involved in passing along insulin's message were unlikely to work properly when coated in extra sugar.
Type 2 diabetes, the most common form in adults, occurs when muscle, fat and other tissues stop responding to insulin's signals to mop up sugar from the blood. The resulting high blood sugar, if uncontrolled, can lead to blindness, amputation and death. Understanding sugar's precise influence on insulin's activity may help improve treatment and prevention, scientists hope.
"Cells don't respond to insulin itself. Instead, a whole cascade of events, set in motion by insulin, eventually causes cells to take in sugar," explains Gerald Hart, Ph.D., professor and director of biological chemistry in the school's Institute for Basic Biomedical Sciences. "We now have an explanation of how sugar can affect these signals, and even a hypothesis for how high blood sugar could cause tissue damage in diabetes -- by improperly modifying proteins."
Hart's lab discovered 18 years ago that sugar is used routinely inside cells to modify proteins, turning them on and off. The more commonly known protein-controller, phosphate, actually binds to some of the same building blocks of proteins as sugar does. If proteins have too many sugars on them, they can't be controlled properly by the cell and are unlikely to work correctly, suggests Hart.
"We think we've come across a major mechanistic reason for insulin resistance," says Hart. "These cells developed insulin resistance simply because their proteins, and specific proteins in fact, had more than the normal number of sugar tags."
If key proteins laden with sugar are present in patients with diabetes, the findings may provide a target for developing new strategies to deal with this growing public health threat, says Hart. While diabetes can be fairly well controlled by diet and carefully monitoring one's blood sugar levels, finding a way to remove extra sugar tags may help treat or prevent diabetes someday, the researchers suggest.
"Textbooks frequently and incorrectly show glycosylation only happening to proteins on the cell surface," says Hart. "Complex sugars are added only to proteins outside the cell, but simple sugars are used all the time in the nucleus and cytoplasm to modify proteins. It's this glycosylation that happens inside the cell, involving simple sugars, that is the key in insulin resistance."
The "simple sugar" to which he refers is O-linked beta-N-acetylglucosamine, a complex name that condenses to a difficult acronym -- O-GlcNAc -- with an ugly pronunciation -- "oh-gluck-nack." But in many ways, O-GlcNAc is a beautiful and mysterious thing, says Hart.
"O-GlcNAc is a modifier on many proteins, but if you didn't know to look for it, you'd never find it," he says. "Instruments and the usual laboratory methods have a hard time measuring it, so we developed the techniques to detect it."
O-GlcNAc is added to proteins by one enzyme and removed from proteins by another. By selectively blocking that removal, the scientists hoped to load up proteins with sugar without adding extra sugar (the way other scientists have created insulin resistance). "We wanted to see the effect of glycosylation itself, so we used a molecular sledgehammer to increase the amount of sugar bound to proteins," says Hart, whose lab proved the ability of the blocker, a molecule called PUGNAc.
Not only did the blocker increase the amount of O-GlcNAc bound to proteins, but that increase caused the cells to stop responding to insulin, say co-first authors and postdoctoral fellows Lance Wells and Keith Vosseller.
Looking for proteins in the insulin-signaling pathway that were more glycosylated than normal, Vosseller and Wells found two: beta-catenin and insulin receptor substrate-1 (IRS-1). The crucial role these proteins play in passing along insulin's messages is likely to be adversely affected by the extra sugars they carry, the researchers say.
"Our experiments show that increasing O-GlcNAc on proteins is, by itself, a cause of insulin resistance, rather than an effect or a coincidence," says Vosseller.
In the body, sugar (glucose) is changed into glucosamine, which is changed into O-GlcNAc. Other scientists have shown that giving cells or animals excessive amounts of sugar or glucosamine, along with extra insulin, leads to insulin resistance. The new findings provide an explanation for others' experience with animal and laboratory models of insulin resistance.
There has been little study of glucosamine, a commonly used dietary supplement, in people. It is suggested that people taking glucosamine consult their doctors if they are concerned about the possibility of increasing their risk of developing diabetes.
Funding was provided by grants and National Research Service Awards from the National Institutes of Health. Professor of biological chemistry Daniel Lane, Ph.D., is also an author.
Under a licensing agreement between Covance Research Products and The Johns Hopkins University, Hart is entitled to a share of royalty received by the university on sales of the antibody used to detect O-GlcNAc on proteins. The terms of this arrangement are being managed by The Johns Hopkins University in accordance with its conflict of interest policies.
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I think the reason why everyone consumes high GI carbs post workout is to replenish their muscle glycogen levels and to combat the insulin level post workout. U have a small window of opportunity post workout when your body is most primed to absorb nutrients. I think worrying about consuming high vs. low GI carbs post workout is rather trivial. To simplfy it (for those of U unfamiliar) glycogen is in muscle and glucose floats around in the blood (at a very small amount). The glycogen only lasts about 10 min, so like AT said, you should be more concerned about pre-workout complex carbs IMO. They would be much more beneficial.
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Also people think the faster you replenish glycogen stores the faster rate of synthesis will occur and thats just not true.
The oatmeal is not even for the first phase of glycogen replenishment because that phase is insulin independent. It's more for the second insulin dependent stage which is much more prolonged.
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exercise in itself makes you extremely insulin sensitive therefore just about any form of carb will immedietly be put to use
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Catabolism post workout is highly exaggerated. ANY insulin response stops any form of catabolism not to mention GH secretions last up to 60 minutes post exercise.
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Physiological hyperinsulinemia stimulates p70(S6k) phosphorylation in human skeletal muscle.
Hillier T, Long W, Jahn L, Wei L, Barrett EJ.
Department of Internal Medicine, Division of Endocrinology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA.
Using tracer methods, insulin stimulates muscle protein synthesis in vitro, an effect not seen in vivo with physiological insulin concentrations in adult animals or humans. To examine the action of physiological hyperinsulinemia on protein synthesis using a tracer-independent method in vivo and identify possible explanations for this discrepancy, we measured the phosphorylation of ribosomal protein S6 kinase (P70(S6k)) and eIF4E-binding protein (eIF4E-BP1), two key proteins that regulate messenger ribonucleic acid translation and protein synthesis. Postabsorptive healthy adults received either a 2-h insulin infusion (1 mU/min.kg; euglycemic insulin clamp; n = 6) or a 2-h saline infusion (n = 5). Vastus lateralis muscle was biopsied at baseline and at the end of the infusion period. Phosphorylation of P70(S6k) and eIF4E-BP1 was quantified on Western blots after SDS-PAGE. Physiological increments in plasma insulin (42 +/- 13 to 366 +/- 36 pmol/L; P: = 0.0002) significantly increased p70(S6k) (P: < 0.01), but did not affect eIF4E-BP1 phosphorylation in muscle. Plasma insulin declined slightly during saline infusion (P: = 0.04), and there was no change in the phosphorylation of either p70(S6k) or eIF4E-BP1. These findings indicate an important role of physiological hyperinsulinemia in the regulation of p70(S6k) in human muscle. This finding is consistent with a potential role for insulin in regulating the synthesis of that subset of proteins involved in ribosomal function. The failure to enhance the phosphorylation of eIF4E-BP1 may in part explain the lack of a stimulatory effect of physiological hyperinsulinemia on bulk protein synthesis in skeletal muscle in vivo.
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This is where your wrong. Speed is not the key, in terms of glucose. THere is no evidence sating that increased glycogen storage equals a greater rate of synthesis. In fact it states the oppisite in that you can have a large quick spike or a slower spike and the rate stays the same. Its aminos that are the trigger and key to increased rate of synthesis, not insulin.
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Since exercise alone increases a cell's sensitivity to insulin, dextrose isn't neccessary to replace glycogen. Glycogen can be restored via other methods. You've increased insulin sensitivity already via anaerobic exercise; you are increasing the possibility for spillage by introducing dextrose/malto......the rate of glycogen restoration isn't the same as the rate of protein synthesis.
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Conventional thinking helped by numerous marketing ads tell us we need to replenish glycogen as fast as we can and we need to creat a large spike to accomplish this. They are totally wrong. They have zero studies supporting this. The studies they use say there is a greater glycogen replenishent (which DOES NOT increase the RATE)with high GI and that is it. They conclude in no way that the rate of protein synthesis is increased and just recently studies have shown that aminos, NOT insulin, are what triggers protein synthesis. The point is that a large spike, or faster spike, is NOT needed.
Exercise induces sensitivity meaning that a lower GI carb will have a more pronounced insulin spike [than normal] BECAUSE of the sensitivity. A high GI source will have the same effect. Since there is an insulin INDEPENDENT stage and studies clearly show that not all glucose is being utlilized by the exercise (study clearly states that as well) the need for such a large spike is not needed. Insulin, even hyperinsulinemia, post exercise does not cause a significant increase in protein synthesis (study clearly states).
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High G.I. carbs work great and most of what Berardi says is correct. But what he may not understand himself (as he is a writer first and a lifter second), is that low G.I. is the better choice, accomplishing the same goal (anabolism) while leaving rollercoaster ride of up and down blood sugar levels in the past. With a pre-workout meal, steak, chicken, whey protein shake, etc combined with about 50 gms of carbs (oatmeal, sweet potato, etc) your muscles will be supplied with a constant supply of aminos throughout the workout, and will not be "screaming" for a protein fix by workout's end. Thus there is just NO NEED for a huge and dramatic insulin spike here.
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there is no need to spike insulin when glycogen synthesis can occur without it
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Signalling to glucose transport in skeletal muscle during exercise.
Exercise-induced glucose uptake in skeletal muscle is mediated by an insulin-independent mechanism. Although the signalling events that increase glucose transport in response to muscle contraction are not fully elucidated, the aim of the present review is to briefly present the current understanding of the molecular signalling mechanisms involved. Glucose uptake may be regulated by Ca++-sensitive contraction-related mechanisms possibly involving protein kinase C, and by mechanisms that reflect the metabolic status of the muscle and may involve the AMP-activated protein kinase. Furthermore the p38 mitogen activated protein kinase may be involved. Still, the picture is incomplete and a substantial part of the exercise/contraction-induced signalling mechanism to glucose transport remains unknown."
http://www4.infotrieve.com/newmedlin...take&count=713
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ANY insulin spike eliminates cortisol. It doesn't have to be a big one. Your body is highly responsive to any nutrient taken post workout. Do you think your body sits there and thinks whether it should release insulin or not? Do you think a low GI sources will not produce an insulin response?
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