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 By: Anssi Manninen
"[To a student] Dear Miss ---, I have read about 16 pages of your manuscript ... I suffered exactly the same treatment at the hands of my teachers who disliked me for my independence and passed over me when they wanted assistants...keep your manuscript for your sons and daughters, in order that they may derive consolation from it and not give a damn for what their teachers tell them or think of them... There is too much education altogether." -Albert Einstein, The World as I See It
Traditionally, it's been recommended that athletes ingest high-glycemic carbs (e.g., sugars, white bread) after exercise. High-glycemic carbs are broken down easily and increase rapidly the flow of glucose into the bloodstream. This glucose can then be converted to glycogen in your muscles ("filling your tank"). Unfortunately, high-glycemic carbs increase risk of obesity, diabetes and heart disease. A recent study by Dr. Stevenson and co-workers investigated the metabolic responses to high-glycemic or low-glycemic meals consumed during recovery from prolonged exercise. Meals were provided 30 minutes and two hours following cessation of exercise. The authors concluded,
"The glycemic index of the carbohydrates consumed during the immediate post-exercise period might not be important as long as sufficient carbohydrate is consumed."
Although endurance athletes may benefit from high-glycemic carbs, bodybuilders and other strength-power athletes should eat mainly low- and moderate-glycemic carbs such as unprocessed whole grains, fruits and legumes.
We Have Four Ways To Get Amino Acids Into The Blood:
Protein can be hydrolyzed, producing small chains of amino acids called peptides. This process mimics our own digestive actions thus making it an ideal way to process protein.
Several studies have shown that protein hydrolysates containing mostly di- and tri-peptides are absorbed more rapidly than free form amino acids and much more rapidly than intact proteins. Obviously, this is a desirable trait for serious athletes who wish to maximize amino acid delivery to muscle.
At zero, 30, 60, and 90 minutes, the subjects received a beverage 3.5 mL/kg to ensure a given dose of 0.8 g/kg carbohydrate (50 percent as glucose and 50 percent as maltodextrin) and 0.4 g/kg of an amino acid and protein hydrolysate mixture every hour. The results of this study indicate that oral ingestion of some amino acid mixtures in combination with carbohydrates can produce strong insulinotropic effects. Hydrolysates Vs. Intact Proteins:
This resulted in an insulin response not significantly different from that found with the control trial (30 percent greater) and tended to be less than the responses observed after ingestion of the protein hydrolysates. After ingestion of the intact protein, blood amino acid responses over this two-hour period were in general lower than the responses observed after ingestion of the protein hydrolysates. Conclusions:
The authors concluded that oral intake of protein hydrolysates and amino acids in combination with carbohydrates can result in an insulinotropic effect as much as 100 percent greater than with the intake of carbohydrates only.
In another excellent study by Dr. van Loon and co-workers, after an overnight fast, eight male cyclists visited a laboratory on five occasions, during which a control and two different beverage compositions in two different doses were tested. After they performed a glycogen-depletion exercise, subjects received a beverage (3.5 mL/kg) every 30 minute ensure an intake of 1.2 g/kg/h carbohydrate and zero, 0.2 or 0.4 g/kg/h protein hydrolysate and amino acid mixture.
Further, a dose-related effect existed because doubling the dose (0.2-0.4 g/kg/h) led to an additional rise in insulin response. Blood leucine, phenylalanine and tyrosine concentrations showed strong correlations with the insulin response.
This suggests that tissue amino acid uptake and post-exercise muscle protein anabolism were increased after the ingestion of protein hydrolysate-amino acid-mixture.
They concluded that whey protein hydrolysates are absorbed at a faster rate from the small intestine than are whole milk proteins delivered as a milk solution, as reflected by the rapid increase in the blood concentration of branched-chain amino acids in peripheral blood. Furthermore, the whey protein hydrolysate elicited the greatest availability of amino acids during the 3-h postprandial period. According to Drs. Calbet and MacLean, the association of high levels of blood amino acids and insulin might explain a superiority of protein hydrolysates over whole proteins in promoting better nitrogen utilization (i.e., greater anabolism), especially when administered in combination with glucose.
A recent study by Dr. Koopman and colleagues at the Maastricht University was designed to determine post-exercise muscle protein anabolism following the combined ingestion of carbs with or without protein and/or free leucine.
Eight Male Subjects Were Randomly Assigned To Three Trials In Which They Consumed Drinks Containing Either:
Following 45 minutes of resistance exercise. As expected, blood insulin response was higher in the carbs+protein+leucine group compared with the other groups. In addition, muscle protein synthesis rates were higher when protein and free leucine were co-ingested compared with the ingestion of carbs only. Ingestion of carbs and protein resulted in intermediate muscle protein synthesis rates, so this study clearly shows that the combined ingestion of protein and leucine with carbohydrate stimulates protein anabolism. The authors concluded,
"The present data indicate that the additional ingestion of free leucine in combination with protein and carbohydrate likely represents an effective strategy to increase muscle anabolism following resistance exercise."
4-hydroxyisoleucine, an amino acid that isn't found in mammalian muscle tissue, has unique insulinotropic properties. Because the insulin is a strong potentiator of glycogen synthesis in the muscle, the recent study by Dr. Ruby and colleagues at the University of Montana determined the effects of 4-hydroxyisoleucine with a glucose beverage on rates of post-exercise muscle glycogen re-synthesis in trained male cyclists. Following an overnight fast, subjects completed a 90-minute glycogen depletion ride after which a muscle biopsy (the removal of muscle tissue) was obtained from the vastus lateralis.
  Click To Enlarge. The Vastus Lateralis. Immediately & Two Hours After The Muscle Biopsy, Subjects Ingested Either:
With a second muscle biopsy four hours after exercise. The main finding of this study was that in combination with large simple carb feeding, the added 4-hydroxyleucine promoted a 63 percent higher rate of post-exercise glycogen re-synthesis compared to carbs alone. Interestingly, there were no significant differences in blood insulin concentration between carbs and carbs+4-hydroxyleucine trials at any time point, so 4-hydroxyleucine appears to enhance glycogen re-synthesis without altering insulin. References
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Peptides differ from proteins, which are also long chains of amino acids, by virtue of their size. Traditionally, those peptide chains that are short enough to make synthetically from the constituent amino acids are called peptides rather than proteins.
Van Loon Study:
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