Nutrition and Sports PET3361 EXAM II REVIEW 1 Define postabsorptive and postprandial states and explain how each of the macronutrients is absorbed into the system glycogenolysis gluconeogenesis in the liver after overnight fast when blood glucose is maintained by Postabsorptive Glycogenolysis 65 75 of glucose released Gluconeogenesis 25 35 of glucose released Muscle glycogen cannot be converted to blood glucose b c glucose 6 phosphate cannot be converted to glucose in muscle Postprandial after a meal absorbed glucose being stored as glycogen in skeletal muscles liver glucogenesis most cells removing glucose for energy glycolysis adipose cells remove glucose to form glycerol needed for triglycerides formation from fatty acids 2 Which hormones control blood glucose and how How does exercise influence these responses Insulin Glucagon Epinephrine Nor epinephrine Lowers Blood Glucose Raises Blood Glucose Raises Blood Glucose Raises Blood Glucose Exercise increases response of all except Insulin 3 What factors influence CHO use during exercise and how Exercise intensity high intensity more dependent on CHO mod less CHO dependent CHO is only fuel during anaerobic exercise Exercise duration longer duration less dependent on CHO FA as a main source of energy during prolonged exercise Initial glycogen levels higher glycogen levels allow for longer hours of running before exhaustion chart on slide 24 Training status higher trained athletes have higher PNS activity higher trained athletes more efficient with energy use for marathon runners may be more efficient at dipping into FA sooner Metabolic primer role of carbs glycogen fat catabolism ketone 4 What is the recommended timing for the feeding of CHO before exercise CHO feeding 3 4 hours before endurance exercise has shown improvements in performance 3 5 g kg BW 5 What are the general guidelines for a pre competition meal 3 4 hours before 150 300g CHO 3 5g kg Solid or Liquid Relatively little fat or fiber Limit Protein 6 When is it most beneficial to feed CHO during exercise What are the guidelines Good for exercise lasting more than 60 mins Spares muscle glycogen Maintains blood glucose levels High conc Of glucose during exercise can cause GI distress Feeding guidelines o not necessary for less than 45 mins o 45 75 mins small amount mouth rinse o 1 2 5 hours 30 60 g hr o More than 2 5 hours 60 90g hr o 2 1 glu fru may allow for enhanced intestinal absorption 7 How does CHO feeding during recovery influence muscle glycogen High levels of CHO during recovery showed better Adding protein with CHO doesn t really make a big results difference High CHO feeding will help restore depleted glycogen as well as increase stored glycogen due to activation of GSI CHO insulin glucose into the cells glycogen synthesis 8 What factors enhance glycogen synthesis and how Glycogen depletion increases percentage of activated GS I form the more active form of glycogen synthase enzyme with stimulates muscle glycogen growth Presence of Insulin enhances glycogen synthesis After Exercise there is more GLUT 4 present at the cell membrane fructose Glucose is better than sucrose and much better than Med high levels of glucose are better than low levels Timing of carbohydrate ingestion CHO feeding immediately rather than delayed improves glycogen synthesis presence of insulin enhances glycogen synthesis Type of carbohydrate fed medium levels 0 7g kg BW of glucose sucrose have higher effect on glycogen synthesis than medium levels of fructose Amount of carbohydrate fed medium levels 0 7g kg BW of glucose has a higher effect on glycogen synthesis than high levels 1 40g kg BW of glucose both had greater effect than low levels 0 35g kg BW Presence of other nutrients with CHO protein carbs has no significant effect on muscle glycogen synthesis Effect of exercise type eccentric exercise causing muscle soreness damage is accompanied by reduced muscle glycogen resynthesis Effect on subsequent performance runners who received 6 3 gCHO kg ran significantly less time than on day 1 while the runners who received 8 8 gCHO kg were able to run slightly longer 9 Know the recovery feeding guidelines for enhancing muscle glycogen storage Feed approximately 1 0 1 5 g of carbohydrate per kg body weight each hour for the first 4 hours after exercise for fast recovery Within the first 6 hours after exercise high glycemic index foods or simple carbohydrates glucose sucrose maltodextrin provide the best glycogen replacement These foods increase insulin levels in the blood which stimulate both glucose transport into the cells and glycogen synthesis Provide CHO replenishment beverage containing 70 90g CHO immedatly after exersice if athletes are eating self selected diets are unable to eat w in 2 hours or don t feel like eating 10 How does muscle damage influence glycogen resynthesis Eccentric exercise causing muscle soreness and damage is accompanied by reduced muscle glycogen resynthesis May be due to damage to the sarcolemma and interference with glucose transport into the muscle fiber May also be due to the inflammatory response and increased glucose oxidation by neutrophils 11 What are the guidelines for daily CHO intake Get 45 to 65 percent of your daily calories from carbohydrates Carbohydrates have 4 calories a gram Based on a 2 000 calorie a day diet this amounts to 900 to 1 300 calories a day or about 225 to 325 grams Emphasize natural nutrient dense carbohydrates from fruits and vegetables beans and legumes and whole grains Limit less healthy sugar sweetened beverages desserts and refined grain products For moderate or heavy endurance training or competition your recovery diet should include 7 12 g carbohydrate kg per day Extreme exercise training 4 6 hours day diet should include at least10 12 g carbohydrate kg per day How is performance daily moderate and high intensity influenced by CHO intake Over a 24 hr period feed 5 7 g carbohydrate per kg body weight for moderate duration low intensity training For moderate or heavy endurance training or competition your recovery diet should include 7 12 g carbohydrate kg per day Extreme exercise training 4 6 hours day your diet should include at least10 12 g carbohydrate kg per day 12 No need for strict timing patterns or types Daily low CHO intake 45 of daily cal leads to progressive reduction of muscle glycogen high CHO intake 70 of daily cal normalized muscle glycogen stores Moderate fatigue in shuttle run test High intensity high CHO