Protein Myths Uncovering the Truth About Your Protein

Fitness Solutions
www.fitsol.co.uk

Myth #1: High protein intakes will not affect muscle protein synthesis.

Fact: Greater availability of amino acids means more protein synthesis within muscle cells.1,2,3,4,5,6,7,8

I will concede that experiments have been performed that indicate that a lab animal can survive on a very limited protein intake assuming that fat and carbohydrate intake is adequate. Simply put, the body begins to reduce that amount of amino acid oxidation in order to spare nitrogen containing compounds. Yet can we really apply this kind of example to adult humans trying to build muscle? I think not.

When the body begins getting stingy with amino acids because of low protein intake, non essential functions, such as skeletal muscle protein synthesis, drop to minimal levels. Other functions within the body such as the immune system, which uses glutamine primarily of muscle origin for fuel, also begins to suffer.9 This cripples the body's ability to cope with the stress and tissue damage induced by intense training. Researchers even believe that currently recommended protein intakes may actually predispose people to illness because of the limited reserve of amino acids. Here's what they have to say about current recommendations for protein intake:

"...It seems reasonable to conclude that the lowered rate of whole-body and perhaps muscle protein turnover that appears to occur in healthy adult subjects when intakes of indispensable amino acids approximate the current international figures, would probably diminish the individuals capacity to withstand successfully a major stressful stimulus. Again, for those reasons, we view the significant reduction in the rate of body protein turnover in healthy adults, which permits them to more closely approach or even achieve amino acid balance at currently accepted amino acid requirement intakes, as an accommodation. Thus we further conclude that these international requirement intakes are probably not sufficient to maintain a desirable or adapted state."(Young VR., Marchini JS. Mechanisms and nutritional significance of metabolic responses to altered intakes of protein and amino acids, with reference to nutritional adaptation in humans. Am J Clin Nutr 1990;51:270-89) Emphasis added.

Research clearly shows that by increasing blood levels of amino acids you increase protein synthesis in skeletal muscle. It has also been shown that you can maintain a positive nitrogen balance for extended periods of time and that nitrogen accretion will tend to continue as long as protein intake is high.10 Clearly if you want to maximize your gains in the gym you've gotta get more protein than the average Joe.

Myth #2: You can only assimilate 30 grams of protein at one sitting.

Fact: The body has the ability to digest and assimilate much more than 30 grams of protein from a single meal.

Speaking of high intakes of protein, people have been perpetuating the myth that you can only assimilate ~30 grams of protein at a time, making protein meals any greater than a 6 oz. chicken breast a waste. This is anything but true. For example, the digestibility of meat (i.e. beef, poultry, pork and fish) is about 97% efficient. If you eat 25 grams of beef, you will absorb into the blood stream 97% of the protein in that piece of meat. If, on the other hand, you eat a 10 oz steak containing about 60 grams of protein, you will again digest and absorb 97% of the protein. If you could only assimilate 30 grams of protein at a time, why would researchers be using in excess of 40 grams of protein to stimulate muscle growth?1

Critics of high protein intakes may try to point out that increased protein intake only leads to increased protein oxidation. This is true, nevertheless, some researchers speculate that this increase in protein oxidation following high protein intakes may initiate something they call the "anabolic drive".13 The anabolic drive is characterized by hyperaminoacidemia, an increase in both protein synthesis and breakdown with an overall positive nitrogen balance. In animals, there is a correspondent increase in anabolic hormones such as IGF-1 and GH. Though this response is difficult to identify in humans, an increase in lean tissue accretion does occur with exaggerated protein intakes.14,15

The take home message is that, if you are going to maximize muscle growth you have to minimize muscle loss, and maximize protein synthesis. Research clearly shows this is accomplished with heavy training, adequate calories, and very importantly high protein consumption. This means that meals containing more than 30 grams of protein will be the norm. Not to worry, all that protein will certainly be used effectively by the body.

Myth #3: Protein must be rapidly digested to build muscle. Fact: Both rapidly and slowly digested proteins offer significant benefits to athletes. Recent research has brought up the notion of "fast" and "slow" proteins.11 They are designated as such according to the rate at which they raise blood levels of amino acids after they are consumed. Whey protein for example is considered a fast protein and causes a rapid increase in amino acid levels. Casein on the other hand is considered a slow protein. Both rapid and slow proteins offer benefits to someone trying to build muscle. Research has shown that proteins that enter the blood stream rapidly significantly increase protein synthesis. Proteins that enter the blood stream slowly have a pronounced effect on protein breakdown, significantly inhibiting it even at low quantities. By using a combination of proteins that exhibit both fast and slow properties one should be able not only to jump-start protein uptake into muscle cells during a grueling workout, but also ensure that protein synthesis is jump started and that protein break down is kept at a minimum during the hours following their workout. Take the fast protein before training, and a slow protein after for maximum anabolic effect. In summary, it is a mistake to say that a "fast" protein is better than a "slow" protein. Both types of protein should be used in strategic fashion to alter protein metabolism in favor of net protein deposition (i.e. muscle growth). Myth #4: A protein must have added peptides of specific molecular weights to effectively build muscle. Fact: The body¹s digestive tract makes its own variable molecular weight peptides from the whole proteins you eat. As soon as protein hits the stomach it is attacked by powerful stomach acids. This acid, along with an enzyme called pepsin, serves to change or denature the proteins structure preparing it for further digestion in the small intestine. In the small intestine several other enzymes work to break down the protein into various molecular weight peptides and free amino acids. Each enzyme acts on a specific part of the amino acid chain cleaving it in the appropriate place. Whether you¹ve just eaten a steak, scrambled eggs or a glass of whey protein, the end result of digestion is the same, a full spectrum of molecular weight peptides and a moderate amount of free amino acids perfectly suited for absorption into the body. The small intestine has special transporters which actively pull peptides across the brush border membrane and into intestinal cells. All the various peptide transporters have yet to be clearly identified. As a result of these transporters, peptides can be actively absorbed faster than free amino acids. Within intestinal cells, peptides are further broken down into individual amino acids by enzymes called protease (prote = protein, ase = to split or cleave). It has been shown that a very small percent of digested peptides can enter the blood stream by squeezing between intestinal cells. Even though some peptides make it into the blood stream intact, they are quickly broken down by proteases on the surface of liver and muscle cells. If by some small chance peptides actually make it all the way into these cells, they are rapidly broken down by proteases within the cell. So you see, all this talk about adding various molecular weight peptides simply means that they predigested an already easily digestible protein. This simply adds to the expense of manufacturing the protein. The added cost, of course, is passed on to the consumer. Myth #5: Arguments over whose protein scores highest on various methods of protein assessment will make or break your success in the gym. Fact: As protein intake increases the influence of protein quality decreases. In other words, high quantity can significantly make up for low quality. The quantity of protein in the diet may in fact add importance to the scoring assessment of a given protein. In fact, if you only eat 35- 45 grams a protein a day you better make sure you chose the highest quality protein you can find. On the other hand, if you eat quantities of protein common among bodybuilders, say 1.6 - 1.8 grams per kilogram, the large amount of amino acids overcome slight differences in scoring. Once you achieve a certain levels of quality in a protein supplement, increasing it further will not significantly change it¹s effectiveness when consumed in quantities sufficient to pack on muscle. Here is a quick overview of the various methods used to determine protein quality. Keep in mind that tests used to determine protein quality use the lower threshold of protein requirements. This creates a metabolic environment far different from that seen in a well fed bodybuilder or athlete. Chemical Scoring The most obvious way to determine the quality of a given protein is to break it down into it's individual amino acids. This amino acid profile is then compared to a standard profile. Egg protein is the standard that is used in a Chemical Scoring scale for protein quality and has a rating of 100. Take for example a protein that has a limited amount of a specific amino acid. This amount is then com-pared to the amount found in egg protein. If the amount in the test protein is 75% of that found in egg then the test protein gets a rating of 75. From this you would assume that if you could feed a person an amount of this protein that is exactly his requirement, you would see nitrogen excreted in the urine in the amount of 25 percent of the nitrogen fed. Although it is relatively easy and inexpensive to do a chemical scoring of any protein, it does not always accu-rately predict how well the body can utilize it. So the ad-vantages of chemical scoring in determining the quality of protein are that it is easy and inexpensive. It's drawback is that it cannot tell you anything about the digestibility of the protein. Chemical scoring also involves a procedure that may destroy certain amino acids and this may lead to inaccurate values. It is also insensitive to substances in a given protein that can adversely effect digestibility. To discover this variable the test would have to utilize living animals. Biological value (BV) Biological value (BV) scoring does utilize in vivo testing. To determine the actual amount of a given protein that will be used by the body it is necessary to measure not only urinary, but also fecal losses of nitrogen when that protein is fed to human beings. This method is used inter-nationally. When measuring the BV of a protein source, two nitrogen studies are done. The first study determines how much nitrogen is lost from the body even when no protein is fed. This amount of nitrogen loss is assumed to be inevitable and that the body will naturally lose it regardless of the amount of nitrogen in the diet. In the second study an amount of the protein is fed that is slightly below what is required. As before, the nitrogen losses are then measured, but this time they are compared to the amount of nitrogen consumed. To determine the actual BV of the protein the re-sults are then derived using this formula: NPU = (N retained / N intake) x 100 This method often involves animal test subjects and is more frequently used. It's draw backs are that if a low NPU is obtained, it is impossible to know if it is because of a poor amino acid profile or low digestibility. Protein efficiency Ratio (PER) Protein Efficiency Ratio (PER) is the best known procedure for evaluating protein quality and is used in the United States as the basis for regulations regarding food labeling and for the protein RDA. This method involves rats who are fed a measured amount of protein and weighed periodically as they grow. The PER is expressed as: PER = weight gain (g) / protein intake (g) The benefits of this method are it's expense and simplicity. It's drawbacks are that it is time consuming; the amino acid needs of rats are not those of humans; and the amino acid needs of growing animals are not those of adult animals (growing animals and humans need more lysine, for example). The PER is used to qualify statements about daily pro-tein requirement in the United States. You are assumed to eat protein with a PER that is equal to or better than that of the milk protein casein; if the protein's PER is lower, you must eat more of it to meet the RDA. Food labels have to take protein quality into consideration, using the PER of casein as a reference point. If a food has a protein quality equal or better than that of casein, the RDA is 45 grams. If the protein quality is less than casein you need 65 grams for the RDA. You may be wondering if it makes any difference if you eat your protein from a supplement or from food. Remember that by the time it gets absorbed into the blood stream, all your body knows is how much of each amino acid was present in the food you ate. If you have the money, it is certainly convenient to just drink down a high quality protein supplement. Beyond that, it makes no difference in what form you get your protein from as long as its a complete protein and sufficiently digestible. Protein digestibility-corrected amino acid score (PDCAA) As outlined above, protein quality can be measured by the quantity of indispensable amino acids they contain. If a protein contains all the amino acids essential for life, it is called a complete protein and is given a high score. Because some proteins are not as efficiently digested there arose a need to not only test for the amino acid composition of proteins but also for digestibility. This type of testing is called protein digestibility-corrected amino acid score (PDCAA). It is now a federally accepted standard for determining protein quality for preschool aged children. Some foods however, contain anti-nutritional factors. These factors sometimes occur naturally like in some beans, or are a result of heating and/or cooking, and inhibit the ability of the body to digest and thus absorb certain amino acids. Research has shown the PDCAA method of scoring protein often over estimates the quality of foods containing anti-nutritional factors.12 The take home message from all this is that arguments about who¹s protein scored highest on this test or that test are really meaningless to the average well fed athlete. Conclusion Certainly exposing these myths about protein leaves advertisers with less fodder to bombard you with. Nevertheless, getting rid of these misconceptions will only benefit you the consumer. Knowing the truth about protein will not only save you money but may also open up new opportunities for muscular gains. Knowledge is the key to effective supplementation with protein or any other supplement. Don¹t let your purchasing decisions be controlled by false claims and misleading pseudo science. A wise man once said, ³...know the truth, and the truth shall set you free.² In this case, the truth will give you the freedom to make educated decisions about protein supplementation and the freedom to discern between marketing hype and honest manufacturers offering quality products. From www.hypertrophy-specific.com

Pre/Post Exercise Nutrition Maximize the Training Effect

Fitness Solutions London www.fitsol.co.uk Introduction When implemented properly and consistently, strategic pre- and post-workout supplementation can greatly increase the effectiveness of your training. Without optimum nutritional strategies, the body's response to training can only be considered a compromise at best. From this perspective, training and diet cannot be considered as separate factors. The food and supplements that you take, and the work that you faithfully perform in the gym, are both part of your training. On the day of competition it will not be the athlete who trained harder who wins, it will be the athlete who trained smarter. Exercise causes acute changes in the metabolic environment of muscle tissue. First there is a significant increase in blood flow to working muscles. There is also a sharp increase in catecholamines (e.g. noradrenalin, adrenalin). These changes favor catabolism during exercise, and anabolism immediately after exercise. Because these changes are acute, some lasting only a few hours, the pre and post exercise meals are critical to optimizing the anabolic effect of exercise. This article will discuss pre- and post-exercise nutritional strategies based on current research in this area. BEFORE Pre-workout nutritional strategies are based on providing alternative energy substrates (mainly carbohydrate) to preserve energy stores, and taking advantage of increased blood flow to muscle tissue. Carbohydrates High intensity exercise places great demand on glycogen stores. Glycogen is the sugar stored in the liver and muscles. Because high intensity exercise burns energy at such a high rate, the body is unable to supply sufficient oxygen to be able to use fat for fuel. Instead, it must use sugar both stored in the muscle and brought in from the blood. Consuming simple sugars right before training can reduce the amount of glycogen used during exercise. This can prolong performance. More importantly, higher blood sugar and insulin levels appear to create a hormonal milieu favorable to anabolism (growth). During exercise, cortisol accelerates lipolysis, ketogenesis, and proteolysis (protein breakdown). This happens in order to provide additional fuel substrates for continued exercise. The effects of cortisol may also be necessary to provide an amino acid pool from which the muscle can rebuild new contractile proteins if there are insufficient amino acids delivered from the blood. This ensures that some degree of adaptation can occur regardless of the availability of dietary protein. Over time however, if this process is not balanced with additional dietary protein, the net effect will be only maintenance or even a decrease in functional muscle tissue, as is evident during periods of starvation or prolonged dieting. Fortunately, there is only a non-significant rise in cortisol levels when carbohydrates were consumed during exercise. (Tarpenning, 1998) The net effect is a more rapid increase in the cross sectional area of the muscle fibers with the greatest effect seen in type-II fibers. This may be a less expensive option for those who were thinking of using phosphatidylserine. In this case, carbohydrate administration appears to down regulate the hypothalamic-pituitary-adrenal axis, probably through insulin or perhaps through the presence of carbohydrate itself. This would, in effect, greatly reduce the body's catabolic response to exercise stress. All good news for bodybuilders. Protein Another pre-workout strategy involves taking advantage of increased blood flow to working muscles. Because the availability of amino acids is often the limiting factor for protein synthesis, a pre-workout protein meal will enhance the delivery of amino acids to muscle tissue. Research has demonstrated the effectiveness of a pre-workout protein drink. Delivery of amino acids has been shown to be significantly greater during the exercise bout when consumed pre-workout than after exercise (Tipton, 2001). There is also a significant difference in amino acid delivery in the 1st hour after exercise, with the pre-exercise protein drink providing a significant advantage. Net amino acid uptake across the muscle is twice as high with a pre-workout protein drink as compared to consuming it after. Phenylalanine disappearance rate, an indicator of muscle protein synthesis from blood amino acids, was significantly higher when amino acids were taken pre-workout. These results indicate that the response of net muscle protein synthesis to consumption of a protein solution immediately before resistance exercise is greater than that when the solution is consumed after exercise, primarily because of an increase in muscle protein synthesis as a result of increased delivery of amino acids to the leg. AFTER During exercise muscles use metabolic fuels at an accelerated rate. In order for physical work to be continuous, the body mobilizes stored fuels to make fatty acids, glucose, and amino acids available for oxidation. This is a catabolic process and cannot occur simultaneous to anabolic processes such as glycogen formation and protein synthesis. In order for the body to recover from exercise, the catabolic environment must be quickly changed to an anabolic environment. The food that you eat after training affects the hormonal milieu in your body in order for this to take place. With the rapid introduction of carbohydrate, protein, and fat into the system post exercise, the body is able to begin reparations on damaged tissue and replenish fuel reserves. Carbohydrates Carbohydrates are important for performance and perhaps more importantly for glycogen recovery. Studies have shown an increased ability of muscle tissue to take up serum glucose immediately following strenuous exercise (Goodyear 1998). This is due to what is called, "non-insulin dependant glucose uptake". After a meal, muscle cells transport glucose across the cell membrane in response to the hormone insulin. Insulin binds with its receptors at the cell surface causing a cascade of events that ends with proteins, called glucose transporters, being translocated to the cell surface. Once at the cell surface, these glucose transporters allow glucose to pass through the membrane where they can be phosphorylated and eventually stored as glycogen. Membrane transport of glucose will exhibit saturation kinetics similar to the effect of increasing substrate concentration on the activity of enzymes. The number of glucose transporters limits the rate of glucose entry into your muscle cells. Once all available glucose transporters are associated with a glucose molecule, the rate of glucose entry will go no higher. There are at least 5 different classes of glucose transporter proteins. They are designated GLUT1, GLUT2, GLUT3, GLUT4, and GLUT5. Each class of GLUT protein differs in its kinetic parameters and is found in specific tissues. GLUT-4 is the primary isoform regulated by insulin, and sensitive to muscle contraction. Muscle contractions, much like insulin, cause a separate set of GLUT-4 proteins to be temporarily translocated to the surface of the muscle cell (Sherman 1996). This greatly increases the rate at which muscle tissue can take in glucose from the blood after a bout of exercise. The effects of exercise on glucose uptake last for a few hours into the post exercise period. If the post exercise meal is lacking in carbohydrates, the replenishment of glycogen is delayed. If carbohydrates are lacking in the diet, exercise will cause a glucose deficit and glycogen stores will continue to fall without being replenished to pre exercise levels. There has been some controversy about which type of carbohydrate is best for post exercise glycogen replenishment. Some argue that simple sugars such as dextrose are best after exercise. Others say that drinks with glucose polymers are best. Still others say that there is no need to buy fancy sports drinks and that simply eating a meal high in carbohydrates such as pasta or rice is sufficient. Studies have shown no difference between different types of carbohydrates eaten post exercise and the rate of glycogen replenishment as long as sufficient quantities of carbohydrate are consumed (Burke 1997). Even when the post exercise meal contains other macronutrients such as proteins and fats, the rate of glycogen replenishment is not hindered, given there is sufficient carbohydrate in the meal as well. These studies tell us that the rate-limiting step in glycogen replenishment after exercise is not in digestion or the glycemic index of a given source of carbohydrate. Over a 24-hour period it is the total amount of carbohydrate consumed that is important. The rate-limiting step in glucose uptake during exercise is determined by the rate of phosphorylation once glucose has entered the muscle cell (Halseth 1998). Glycogen synthase activity is also a possible rate-limiting step (Halseth 1998). These processes are not readily influenced by the composition of the "post exercise" meal, but rather by the extent to which glycogen was depleted during exercise as well as the amount of carbohydrate and fat consistently included in the diet. It is recommended that at least 0.7 - 1.0 gram of carbohydrate per kilogram body weight be consumed immediately after exercise and then again 1-2 hours later. If you experience gastric upset try increasing the amount of water you consume with the carbs. Try to shoot for a total of 7-10 grams of carbohydrate per kilogram of body weight over a 24-hour period 3 for maximum glycogen storage. This may well be in excess of caloric needs but it is important to shoot for this intake if glycogen storage is your primary goal. Protein Protein is another critical nutrient post-exercise. Protein is essential to post exercise anabolism. Protein provides amino acids that are used to rebuild damaged tissues as well as provide enzymes and carrier proteins necessary for adaptation to exercise. Without protein, which supplies essential amino acids for endogenous protein synthesis, the body's ability to adapt to exercise is greatly diminished. Studies have shown a 12 to 14 day period after the onset of an unaccustomed exercise program, in which nitrogen balance, the ratio of protein intake to protein loss, is negative (Butterfield 1987). Any study looking at protein needs and exercise must take this into account. Nitrogen balance during this period appears to be insensitive to total caloric intake, but can be improved with a high protein intake if adequate calories are supplied (Gontzea 1975). Even though additional protein intake will prevent nitrogen balance from becoming negative, it will still fall despite high protein intake during the first two weeks of exercise. Muscle specific messenger RNA (mRNA) produced subsequent to training has a half-life of only 4-5 hours. It is so short because mRNA has no "quality control" mechanism built into the coding. By keeping the half-life short, any errors in the sequence won't be able to produce enough defective proteins to do irreparable damage to the cell or organism. This also allows tight control of protein metabolism. The timing of protein intake is important. If the anabolic stimulus from exercise is to be maximized, a steady flow of amino acids must bathe the muscle while mRNA content is high. It should be no surprise that the optimum time for protein intake after your workout is relatively brief compared to frequency of training a particular muscle. Muscle protein synthetic rate (MPS) is elevated in humans by up to 50% at about 4 hours following a bout of heavy resistance training, and by 109% at 24 hours following training. A study done by Macdougall (MacDougall et al 1995) further examined the time course for elevated muscle protein synthesis by examining its rate at 36 hrs following a bout of heavy resistance training. Six healthy young men performed 12 sets of 6- to 12-RM elbow flexion exercises with one arm while the opposite arm served as a control. MPS was calculated from the in vivo rate of incorporation of L-[1,2-13C2] leucine into biceps brachii of both arms over 11 hours. At an average time of 36 hours post-exercise, MPS in the exercised arm had returned to within 14% of the control arm value, the difference being nonsignificant. The following conclusions can be drawn from this study, following a bout of heavy resistance training, muscle protein synthetic rate increases rapidly, is more than double at 24 hours, and then declines rapidly so that at 36 hours it has almost returned to baseline. Current recommendations for total protein intake for athletes is between 1.6-1.8 grams per kilogram body weight, depending on who you read, however, it is not uncommon for bodybuilders to consume in excess of 2 grams per kg of body weight with no ill effects. It should be remembered that the body does not have the capacity to effectively store amino acids. Protein should be eaten at least every 3-4 hours. The evening meal should contain slowly digesting protein that will allow a steady release of amino acids into your system well into the night. Dinner is a perfect time for steak or other meat dishes. Fat Little is known about the effects of fat in the "post-exercise" meal. Total fat intake is probably more important for a bodybuilder than just considering the post-workout meal. Essential fatty acids in sufficient quantities have the ability to alter physiology. Fatty acids such as omega-3s' and omega-6s', when consumed in differing ratios in a consistent and deliberate manner, can alter the composition of cell membranes which alters the production of prostaglandins in working muscles and thereby can modify everything from glucose transport to protein synthesis (Hayashi 1999). These effects are seen after at least 5 days of consuming of these fats in moderate to high doses. Eating them immediately after training and at no other time will most likely not have any dramatic effect. Some forms of fat may delay gastric emptying which theoretically could slow the rate at which nutrients become available to tissues. We can only speculate whether this would have any "long term" effect on gains. Most research indicates that glycogen replenishment is delayed but not reduced when gastric emptying is prolonged. There is some indication that cholesterol may be an important nutrient immediately after high intensity resistance exercise. Total cholesterol has been shown to be significantly lowered for at least 90 hours following a single bout of resistance exercise (Smith 1994). Serum cholesterol may be needed for incorporation into damaged cell membranes after resistance exercise. I'm not implying that you should eat a high cholesterol meal right after training. Taken together, research is still lacking where the optimal levels and composition of post-exercise fats are concerned. Fluids I couldn't really write an article about pre- and post exercise nutrition without at least mentioning fluid replacement. Hydration is extremely important on the cellular level. Muscle growth is inhibited by dehydration. In bodybuilding we tend not to focus on fluid replacement because, unlike runners or cyclists, most bodybuilders do not become dehydrated after a single workout. The rate at which you become dehydrated from training depends on how much you sweat (Gisolfi 1990). Some people sweat a lot when lifting and others don't sweat a drop. A good rule of thumb is to drink 1 ml for every calorie that you need. So, if you eat 3,500 calories a day, try to drink 3 _ liters. If you exercise in hot or humid climates add 2 cups of water for every pound you lose while exercising. It's about synergy As mentioned earlier, macronutrient intake modulates post-exercise protein synthesis in ways that are just beginning to be understood. Yes, protein is required to supply essential amino acids for protein synthesis, but what is the mechanism by which protein is controlling this process? Also, are carbohydrates and fats needed only for fuel replacement, or do they play an "interactive" role in post exercise protein synthesis? Recent research has shed light on these questions. Researchers from the Division of Nutritional Sciences at the University of Illinois examined the effect of post exercise meal composition on protein synthesis. To do this, they looked specifically at the activity of specific proteins known to regulate protein synthesis at the translational level. Initiation of translation (the binding of mRNA to the ribosomal pre-initiation complex) requires group 4 eukaryotic initiation factors (eIFs). These initiation factors interact with the mRNA in such a way that makes translation (the construction of new proteins from the mRNA strand) possible. Two eIFs, called eIF4A and eIF4B, act in concert to unwind the mRNA strand. Another one called eIF4E binds to what is called the "cap region" and is important for controlling which mRNA strands are translated and also for stabilization of the mRNA strand. Finally, eIF4G is a large polypeptide that acts as a scaffold or framework around which all of these initiation factors and the mRNA and ribosome can be kept in place and proper orientation for translation. The researchers in this study looked at the association of the mRNA cap binding protein eukaryotic initiation factor-4-E (eIF4E) with the translational inhibitor 4E-eukaryotic initiation factor binding protein-1 (4E-BP1) in the acute modulation of skeletal muscle protein synthesis during recovery from exercise. Fasting male rats were run on a treadmill for 2 h at 26 m/min and were fed immediately after exercise with saline, a carbohydrate-only meal, or a nutritionally complete meal using Ensure Powder (54.5% carbohydrate, 14% protein, and 31.5% fat). Exercised animals and non-exercised controls were studied 1 h post-exercise. Muscle protein synthesis decreased 26% after exercise and was associated with a fourfold increase in the amount of eIF4E present in the inactive eIF4E.4E-BP1 complex and a concomitant 71% decrease in the association of eIF4E with eIF4G. Refeeding the complete meal, but not the carbohydrate meal, increased muscle protein synthesis equal to controls, despite similar plasma concentrations of insulin. Additionally, eIF4E.4E-BP1 association was inversely related and eIF4E.eIF4G association was positively correlated to muscle protein synthesis. This study demonstrates that recovery of muscle protein synthesis after exercise is related to the availability of eIF4E for 48S ribosomal complex formation, and post-exercise meal composition influences recovery via modulation of translation initiation. The results of this study tell us a few things: 1. Insulin (via carbohydrate intake) alone is not enough to prevent 4E-BP1 from sequestering eIF4E. EIF4E must be free to bind to eIF4G in order for protein synthesis (i.e. recovery from training and net muscle growth) to begin. Insulin as well as amino acids must be present at the same time as indicated by the results from the group that were fed a mixed nutrient meal. So although feeding of the carbohydrate meal resulted in elevated blood glucose and elevated insulin levels, carbohydrates alone are not sufficient to allow protein synthesis to begin. 2. The only group that experienced a significant drop in cortisol levels was the mixed meal group. The carbohydrate-only group showed that neither blood glucose nor insulin had any effect on reducing cortisol levels. In contrast, the mixed meal group showed cortisol levels even below those in the control group who did no exercise and were also fed the same meal. It would have been nice for the authors of this experiment to explore the effect of the fat content in the "mixed meal". From the results we saw that cortisol was lower in the mixed meal group. We can only speculate whether this was due to the protein, the fat, or some combination of protein, fat and carbs. Further research in this area should take into consideration all components of the post exercise meal. One other issue that might be addressed in humans is the time frame during which re-alimentation is critical to "long term" adaptation to exercise. In closing... Pre- and post-exercise nutrition is critical if one wants to maximize the anabolic effects of exercise. The pre-exercise meal should be high in a quickly digestible protein. This will ensure high delivery of amino acids to the muscle tissue. Carbohydrates can also be taken in to minimize glycogen loss and suppress catabolic hormones. Fat should be avoided pre-exercise unless the exercise is for endurance. The post exercise meal should consist of carbohydrate, protein and perhaps a small amount of essential fats, in a form that is easily and quickly digestible. There are many meal replacement products that fit the bill. Just pick the one you like the most. Don't worry about sugar content because right after a workout, fat storage is not a big issue. A liquid meal is the most practical method of post-exercise feeding although it is probably not essential. The ratio of macronutrients depends somewhat on the nature of the training session. An emphasis on high glycemic carbs, complete readily digestible proteins such as whey, egg, or high quality casein, and essential fats such as fish or flax oil will meet the criteria for an effective post exercise meal.

From  http://www.hypertrophy-specific.com