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Chapter 7

Chapter 7. Integration & Regulation of Metabolism & the Impact of Exercise & Sport. Interrelationship of Carbohydrate, Lipid, & Protein Metabolism. Any energy nutrient can fuel the body in the short term TCA cycle = amphibolic pathway Lipogenesis CHO spares lipolysis - promotes gain

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Chapter 7

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  1. Chapter 7 Integration & Regulation of Metabolism & the Impact of Exercise & Sport 2009 Cengage-Wadsworth

  2. Interrelationship of Carbohydrate, Lipid, & Protein Metabolism • Any energy nutrient can fuel the body in the short term • TCA cycle = amphibolic pathway • Lipogenesis • CHO spares lipolysis - promotes gain • Glucose is precursor for glycerol & fatty acids 2009 Cengage-Wadsworth

  3. Interrelationship of Carbohydrate, Lipid, & Protein Metabolism • Gluconeogenesis • Glycerol portion only from fat • Fatty acids with odd # of C atoms • Glucogenic amino acids • Conversion among energy nutrients favors lipogenesis 2009 Cengage-Wadsworth

  4. Interrelationship of Carbohydrate, Lipid, & Protein Metabolism • TCA cycle & electron transport chain - common to all 3 • This catabolic pathway also: • Produces CO2 for carboxylation & C for other needs • Provides common intermediates • Provides citrate & malate for lipogenesis 2009 Cengage-Wadsworth

  5. The Central Role of the Liver in Metabolism • Key processor & distributor • Glycogenesis & glycogenolysis • Protein synthesis, catabolism, conversion to other compounds • Lipoprotein synthesis 2009 Cengage-Wadsworth

  6. Tissue-Specific Metabolism during the Fed-Fast Cycle • Stages of fed-fast cycle • Fed state - lasts 3 hours after meal ingestion • Postabsorptive/early fasting state - 3 to 12-18 hours after meal • Fasting state - 18 hours to 2 days after meal when nothing else eaten • Starvation/long-term fast - fully adapted to deprivation (weeks) 2009 Cengage-Wadsworth

  7. Carbohydrate & Lipid Metabolism • The fed state • Glucose  glycogen & fatty acids • Glucose used by nervous tissues, RBCs, adipose & muscle tissues • The postabsorptive or early fasting state • Glycogenolysis • Gluconeogenesis 2009 Cengage-Wadsworth

  8. Carbohydrate & Lipid Metabolism • The fasting state • Amino acids (primarily), glycerol, lactate used for gluconeogenesis • Ketone formation • The starvation state • Fatty acids used to greater extent • Glycerol major glucose source • Ketosis after oxaloacetate depletion 2009 Cengage-Wadsworth

  9. Amino Acid Metabolism • Fed state - used for proteins or degraded • Fasting • Catabolism for energy produces quantities of N • Excreted in urea • Gluconeogensis in liver & kidneys 2009 Cengage-Wadsworth

  10. System Integration & Homeostasis • Major regulatory systems • Nervous system • Endocrine system • Vascular system • Endocrine function in fed state • GIP, CCK, gastrin, secretin • Insulin 2009 Cengage-Wadsworth

  11. System Integration & Homeostasis • Endocrine function in postabsorptive or fasting state • Glucagon • Epinephrine & norepinephrine • Low levels of insulin 2009 Cengage-Wadsworth

  12. Metabolic Syndrome • Cluster of risk factors for CVD, CKD & T2DM • Insulin resistance • Weight loss & insulin insensitivity 2009 Cengage-Wadsworth

  13. Sports Nutrition • Energy for physical activity comes from nutrients • Energy demands during physical exertion in athletes similar to fed-fast cycle 2009 Cengage-Wadsworth

  14. Biochemical Assessment of Physical Exertion • Types of muscle • Type I (“red”) - oxidative • Type IIa (“white”) - hybrid of I & IIb • Type IIb (“white”) - fewer mitochondria & active glycolytic pathway • Common measurements • Respiratory quotient (RQ) • Maximal oxygen consumption (VO2 max) 2009 Cengage-Wadsworth

  15. Energy Sources during Exercise • The ATP-CP (phosphagen) system • Muscles use high-energy creatine phosphate with ATP • The lactic acid system • Anaerobic glycolysis • The aerobic system • TCA cycle 2009 Cengage-Wadsworth

  16. Energy Sources during Exercise • Fuel sources during exercise • Muscle glycogen • Plasma glucose • Plasma fatty acids • Intramuscular triacylglycerols 2009 Cengage-Wadsworth

  17. Energy Sources during Exercise • Exercise intensity & duration • Low intensity - plasma fatty acids • Moderate intensity - increased fatty acid oxidation (due to muscle TG) • High intensity - CHO oxidation & lactate production increase 2009 Cengage-Wadsworth

  18. Energy Sources during Exercise • Level of exercise training • Training increases muscle glycogen & TG stores • Initial muscle glycogen levels 2009 Cengage-Wadsworth

  19. Carbohydrate Supplementation (Supercompensation) • Classical regimen • 2 sessions of intense exercise, 2 days of low-CHO diet, 3 days of high-CHO diet + rest • Modified regimen • Exercise tapered over 5 days, 1 day of rest • 3 days of 50%-CHO diet, then 3 days of 70%-CHO diet 2009 Cengage-Wadsworth

  20. Diets for Exercise • Macronutrients • Meal frequency • Pre-event meal • Glycemic index 2009 Cengage-Wadsworth

  21. Nutritional Ergogenic Aids • Amino acids • Arginine • Ornithine • Aspartate salts • Branched-chain amino acids • Antioxidants 2009 Cengage-Wadsworth

  22. Nutritional Ergogenic Aids • Herbs • The ginsengs • Caffeine • Intermediary metabolites • Bicarbonate • Carnitine • Coenzyme Q10 • Creatine • Other 2009 Cengage-Wadsworth

  23. Perspective 7 Diabetes: Metabolism Out of Control 2009 Cengage-Wadsworth

  24. Diabetes • Type 2 diabetes • Insulin resistance in peripheral tissues due to lack of functional glucose transporters • Type 1 diabetes • Lack of insulin due to autoimmune response against pancreatic -cells 2009 Cengage-Wadsworth

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