I found this in researching more of this issue, and it supports dextrose/malto/etc. pwo and gives reasoning as well. Just curious of what you think Bobo, or anyone else for that matter.
Q: What are the properties of glycogen? And why are these properties so vital post workout?
A: Glycogen is a polysaccharide, (C6H10O5)n that is the main form of carbohydrate storage in animals and humans and occurs primarily in the liver and muscle tissue. It is readily converted to glucose as needed by the body to satisfy its energy needs (21), such as during intense training.
To enhance the progress of muscular strength and size with heavy-resistance body building programs, optimal conditions for recovery from training sessions are imperative, primarily glycogen re-synthesis (22).
Recovery occupies the coordinated operation of multiple physiological processes that are heavily influenced by the accessibility and actions of exclusive hormones and nutrients (16, 17).
Both qualitative and quantitative modifications in skeletal muscle contractile proteins are all supported and signaled by a horde of systematic -trophic influences from hormones to nutrient availability (18, 19).
Markedly, concentric and eccentric contractions disrupt or damage certain muscle fibers that must undertake a remodeling restoration process. Dietary nutrients, hormones, and growth factors interact to regulate this remodeling of skeletal muscle proteins (5).
One primal factor associated with muscular fatigue is depletion of muscle glycogen (1).
These stores must be replaced rapidly during the post-workout initial recovery phase in order for performance to be reproducible in a subsequent exercise bout(s).
Glycogen synthesis may be restricted by blood glucose concentration, glucose transport, and the activity of the enzymes involved in the pathway, particularly glycogen synthase (10).
Body building training programs provide conditions within skeletal muscle to support the rapid synthesis of glycogen.
Glycogen synthase action is inversely relative to glycogen intensity (23); as a result of the glycogen-depleted state post-training, skeletal muscle (24) and hepatic glycogen synthase activity are raised (13).
Basal glucose transport within skeletal muscle occurs via GLUT-4 (A powerhouse effect of insulin is the stimulation of glucose transport via the translocation of the insulin responsive glucose transporter, GLUT4, to the plasma membrane) (14).
Nevertheless, the ability of skeletal muscle to take up glucose is relative, due to adjustments in the GLUT-4 content of the sarcolemal membrane.
Image 1. Atrophic muscle fibers. The sarcolemal membranes of these two atrophic fibers have a wavy appearance. Courtesy: Department of Pathology; Virginia Commonwealth University;
There are hypothesized to be one or more intracellular pools of GLUT-4 proteins, which are translocated to the sarcolema in response to both increased insulin concentration (20) and prior exercise (9); these effects are additive (6).
In the post-workout period, therefore, muscle membrane permeability to glucose is high, thus favoring the accretion of glycogen replacement. However, if rapid carbohydrate distribution is not provided during recovery, glycogen synthesis will be limited because the rate of endogenous glucose production from gluconeogenic precursors such as alanine and glycerol is inadequate to support maximal rates of glycogen synthesis (15).
The ingestion of high GI carbohydrates increases glycogen synthesis in two ways.
The first (12) is increased substrate availability through the increased blood glucose concentration, which results in an increased glucose uptake due to mass action.
Moreover, the resultant increase in systemic insulin concentration stimulates the translocation of GLUT-4 transporters from an intracellular pool to the sarcolemal membrane (7).
The hormone insulin is also a powerful activator of glycogen synthase and inhibitor of glycogen phosphorylase (2).
The effectiveness of a specific carbohydrate in encouraging resynthesis of the carbohydrate stores is reliant on the insulin and glucose response to the carbohydrate load (4).
This is directly linked to gastric emptying and intestinal absorption rates. It is also associated with the insulinogenic potential of the carbohydrate, as indicated by the glycemic index (GI) of a carbohydrate.
The development of glycogen synthesis relies upon the accessibility of glycogenic substrate (8) and the activity of the enzymes implicated in glycogen synthesis. These include hexokinase and glycogen synthase.
Prior exercise enhances skeletal muscle glucose transport (3) because of the translocation of GLUT-4 transporters from an intracellular pool to the sarcolemal membrane.
The inclination for skeletal muscle to extort blood glucose will thus be increased, and the glucose will tend to be directed toward glycogen synthesis because glycogen synthase is activated during recovery due to the low intramuscular glycogen concentration (23).
These conditions favoring the resynthesis of glycogen can be exploited (8) by the provision of a quality carbohydrate source.
The consequential amplification in glucose availability and the insulin response to the glucose load would tend to stimulate (7) a further increase in the GLUT-4 content of the sarcolemal membrane.
Research has demonstrated (11) that there is a direct correlation between the rate of glycogen storage during recovery and total muscle GLUT-4 protein content.
On a side note, observational and empirical evidence makes it plainly obvious that the endocrinal state of the body builder post-workout is nothing like that of a sedentary individual.
A red herring argument is an attempt to offer evidence to support one proposition by arguing for a different one entirely, or dodging the main argument by going off on a tangent.
Oftentimes opponents of high GI carbohydrate supplementation post-workout will point to the dangers of excess insulin-spiking and glucose intake; however, this is a red herring argument. This claim is like comparing apples to oranges.
~SC~
Not a bad article but way too many generalizations and speculations just not based on accurate interpretations of available studies.
1. Glyocgen resynthesis has nothing to do with how fast glucose is made readily availalble. Big misconception. IT occurs at the saem rate regardless of CHO.
Carbohydrate nutrition before, during, and after exercise.
Costill DL.
The role of dietary carbohydrates (CHO) in the resynthesis of muscle and liver glycogen after prolonged, exhaustive exercise has been clearly demonstrated. The mechanisms responsible for optimal glycogen storage are linked to the activation of glycogen synthetase by depletion of glycogen and the subsequent intake of CHO. Although diets rich in CHO may increase the muscle glycogen stores and enhance endurance exercise performance when consumed in the days before the activity, they also increase the rate of CHO oxidation and the use of muscle glycogen. When consumed in the last hour before exercise, the insulin stimulated-uptake of glucose from blood often results in hypoglycemia, greater dependence on muscle glycogen, and an earlier onset of exhaustion than when no CHO is fed. Ingesting CHO during exercise appears to be of minimal value to performance except in events lasting 2 h or longer.
The form of CHO (i.e., glucose, fructose, sucrose) ingested may produce different blood glucose and insulin responses, but the rate of muscle glycogen resynthesis is about the same regardless of the structure.
2. Insulin does increase Glut4 permeability but exercise in itself does this quite efficiently. Also the role of insulin in increasing Glut4 receptors during post exercise does not react in the same fashion as it would in normal feeding patterns. Muscle contraction in itself producing the initla increase in Glut 4 permeability followed by an insulin dependent phase.
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
3. THis statement is completey wrong. All of the follwing studies contradict this. This is what WAS thought but has recently been proven false.
"The effectiveness of a specific carbohydrate in encouraging resynthesis of the carbohydrate stores is reliant on the insulin and glucose response to the carbohydrate load (4)"
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.
Effect of different post-exercise sugar diets on the rate of muscle glycogen synthesis.
Blom PC, Hostmark AT, Vaage O, Kardel KR, Maehlum S.
Department of Physiology, National Institute of Occupational Health, Oslo, Norway.
Comparison of carbohydrate and milk-based beverages on muscle damage and glycogen following exercise.
Wojcik JR, Walber-Rankin J, Smith LL, Gwazdauskas FC.
Department of Human Nutrition, Foods, and Exercise at Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
Type and timing of protein feeding to optimize anabolism.
Mosoni L, Mirand PP.
Effect of different types of high carbohydrate diets on glycogen metabolism in liver and skeletal muscle of endurance-trained rats.
Garrido G, Guzman M, Odriozola JM.
Department of Human Performance, National Institute of Physical Education, Madrid, Spain.
Simple and complex carbohydrate-rich diets and muscle glycogen content of marathon runners.
Roberts KM, Noble EG, Hayden DB, Taylor AW.
Faculty of Physical Education, University of Western Ontario, London, Canada.
4. Another completely false statement:
"The development of glycogen synthesis relies upon the accessibility of glycogenic substrate (8) and the activity of the enzymes implicated in glycogen synthesis"
Amino's are the substrate, not glucose. It is also the nutrient signal for ptein synthesis after exercise.
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.
[email protected]
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.
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 factor for muscle glycogen synthesis when large quantities (>1 g/min) of glucose are ingested following exercise.
5. Here is another one not based on the lit.
"Oftentimes opponents of high GI carbohydrate supplementation post-workout will point to the dangers of excess insulin-spiking and glucose intake; however, this is a red herring argument. This claim is like comparing apples to oranges."
Well it might be apples to oranges to him but not according to the lit.
"
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.
6. THis statement is true to an extent but glycogen stores are not that depleted.
"One primal factor associated with muscular fatigue is depletion of muscle glycogen (1)."
Thats something seem more in a ketogenic state to where the purpose is to depletd glycogen stores. This takes usually around 48 hours to accomplish, not a an hour workout with resistance training. Highly exaggerated.
7. The basis for his theory is the presumption that hyperinsulinemia increases glycogen and protein synthesis. His findings are based on in vitro studies and for some reason everyone likes to quote these studies withouth knowing the complete difference in effets amino's and/or peptides have when given in vitro compared to a natural physiological response. This study is a clear explample.
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.
So he basically tried to give you a physioliogy lesson using studies that don't support his case. This looks more like a marketing tactic and supp companies tend to this this a lot. It never ceases to amaze me how one can distort studies to try and make a case. You would think I'm back in law school. Leave the distoring of cases to the lawyers