1 Nutrition and Sport Study Guide 21. Define post-absorptive and postprandial states and explain how each of the macronutrients is absorbed into the system.- Post-absorptive state for Carbohydrates: Once in the body, glucose is stored either in the liver or the muscle of glycogen. The process of glucose to glycogen is called glycogenesis. Then when the body need glucose, it undergoes glycogenolysis or gluceoneogenesis to replenish the blood glucose.- Post-Prandial state for Carbohydrates: Post-prandial means after feeding, so you ingest the carbohydrate and it is storedas glycogen. Remember that glucose is the main fuel for almost all the muscles, so the cells are continuously removing glucose from the body stores. Also fructose and galactose are mostly converted to glucose before storage, but some fructose is preferred to storage as glycogen, and with fructose the glycogen synthesis rate is faster. - Absorption of Carbohydrates: Basically the end product is glucose, fructose, and galactose once the carbohydrates reach the small intestine. Then they are absorbed into the capillaries, with glucose and galactose undergoing active transport with Na, and fructose undergoing facilated diffusion- Post-absorptive state for lipids: Well once you ingest lipids, they are mostly stored as adipose cells. - Post-Prandial state for lipids: After feeding, most lipids are stored as adipose, and the intramuscular stores vary between 5-35%. They can also become lipoproteins (chylomicrons, LDL, HDL, VLDL) - Absorption of lipids:Tony Berardi2 Lipids are hydrophobic (not soluble in water) so they have to form a micelle to beabsorbed into the body. We didn’t really go over the absorption in detail.- Post-absorptive state of protein: Didn’t really go over, but stored in skeletal muscles mostly- Post-Prandial state of protein: Stored in muscle- Absorption state of protein: Didn’t go over the exact way it is absorbed, but protein can also be metabolized to glucose in gluconeogenesis. 2. Which hormones control blood glucose and how? How does exercise influence these responses? The hormones the control the blood glucose are insulin, glucagon, epinephrine, and norepinephrine. Insulin and glucagon are antagonist hormones where one controls the uptake and the other controls the release. So once the body has justingested glucose, the pancreas releases insulin from its beta cells and this helps the cells uptake the glucose. Then once the body needs energy, glucagon is released for the pancreas by its alpha cells and this releases the glucose to increase the blood glucose level.  Now for the sympathetic hormones, when blood glucose is low, receptors in the hypothalamus are activated and epinephrine and norepinephrine are released bythe adrenal glands. These increase glycogenolysis and increase blood glucose. - Exercise influence: With insulin, less seems to be released as the duration increases. It is opposite with glucagon. And norepinephrine and epinephrine increase with duration. 3. What factors influence carbohydrate use during exercise and how?Tony Berardi3- Use during exercise is dependent on the intensity, duration, your initial levels of glycogen, and your training status. It seems with a light intensity exercise, the body doesn’t use too much of its glycogen stores, but it increases with moderate and heavy exercise. This also correlates with duration, with moderate lasting 120 minutes until glycogen is depleted, and high only lasting up to 60 min.4. What is the recommended timing for carbohydrate feeding before exercise?- With feeding before exercise, the ideal time seems to be 3-4 hours before. There is some evidence that feeding 30 min before just spiked their blood glucose, then fell within 10 min of exercise. Now when they looked at the intensity affect of the feedingtime, they found that high intensity had a decrease in performance and moderate intensity actually had no difference. 5. What are the general guidelines for a pre-competition meal?- Going along with the ideal time for feeding, which is 3-4 hours, one should consume about 100-300g of carbohydrates. These should be either solid or liquid form, and themeal should contain little fat, fiber, and protein. Also, foods with a low GI work best6. When is it most beneficial to feed carbohydrates during exercise? What are the guidelines?- Feeding during exercise is only effective when the effort is longer than 90 min. Ingesting an outside source of carbohydrates will spare the muscle glycogen and maintain the blood glucose. Now this only works if you have a modest amount (2-6%) carbohydrate, otherwise you have GI problems. Feeding doesn’t have any effect when the subject is hyperthermic, or if the limiting factor is a H+ buildup (lactic acid, burning sensation) or if the duration is under 60 min (thus people “carbo loading” for a 5k is stupid)7. How does carbohydrate feeding during recovery influence muscle glycogen?Tony Berardi4- Feeding after exercise helps replenish the depleted glycogen stores. When you exercise, your body undergoes glycogenolysis to breakdown its glycogen stores and supply glucose, depleting its stores. Ingesting carbohydrates will then increase the blood glucose level, stimulate insulin and glycogenesis and build up its stores again8. What factors enhance glycogen synthesis and how?- The main enzyme that drives synthesis is Glycogen Synthase, or GS. There are two forms of this enzyme, called D-form and I-form, with the I-form being the more active form. This I-form is activated be exercise, insulin, or just general glycogen depletion. - Now the factors that affect the synthesis: the timing of the ingestion (sooner is better), the type of carbohydrate, the amount, dependent on other nutrients, what type of exercise was done9. What are the guidelines for enhancing glycogen storage on recovery?- The guidelines for feeding after exercise are to consume 1-1.5 g/Kg each hour for the first 4 hours, high GI foods work best to maximize the glucose. If food doesn’t work with the athlete, they can also take a drink with 70-90g carbohydrate immediately after. TIMING IS THE KEY WITH ALL RECOVERY. - Now for feeding over a day, feeing amount should coincide with the training. So heavy training, eat more carbs. Usually more carbs yields better performance.10. How does muscle damage influence glycogen resynthesis?- The eccentric phase