1 Nutrition and Sport Study Guide 2 1 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 stored as 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 Berardi Lipids are hydrophobic not soluble in water so they have to form a micelle to be absorbed into the body We didn t really go over the absorption in detail 2 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 just ingested 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 by the 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 Berardi 3 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 feeding time 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 the meal should contain little fat fiber and protein Also foods with a low GI work best 6 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 Berardi 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 again 4 8 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 done 9 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 muscle lengthening causes the soreness and the damage is accompanied by the decrease in muscle glycogen resynthesis The reason for this might be due to damage on the sarcolemma and this could potentially affect glucose muscle uptake Another guess is it might be due to