Carbohydrate;low intensity and high intensities physical activities

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  • adapted from; Melvin H Williams 2010; Nutrition for Health, Fitness and Sport.
  • Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th ed, McGraw HillMelvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th ed, McGraw Hill


  • 1. 4-utilization of carbohydratesduring exerciseSport NutritionPrepared by De. Siham GritlyDr. Siham Gritly
  • 2. objectives• At the end of the lecture student should be ableto understand;*Utilization of Carbohydrate diets duringendurance performance* Utilization Carbohydrate diets and highintensity exercise*Concepts of Glycemic Index and GlycemicloadDr. Siham Gritly
  • 3. Carbohydrate Needsthe diet for athletes and active people is that it should includemore carbohydrate-containing foods that recommended by thehealth professionals.Dr. Siham GritlyTheir diets should be about 60-70% of their dailyenergy intake obtained from carbohydrates, 30 %or less from fat and 10 to 15 % from proteinsAdequate carbohydrate intake also helps preventprotein from being used as energyIt also fueling the central nervous system (CNS)and brainDuring heavy training kcal must be increasedspecially from carbohydrates (CHO), to meet theenergy demands. Low intake may result in:Chronic muscular fatigue.Weight and muscle mass loss Ellie Whitney and Sharon RadyRolfes; Under standing Nutrition,Twelfth Edition. 2011, 2008
  • 4. Carbohydrates utilized by the body indifferent ways;• *for the immediate energy needs throughoxidation to carbon dioxide and water via theprocesses of glycolysis and tri-carboxylicacid cycle or Kerb cycle• *stored as glycogen in the liver and musclestissue through the process glycogenesis.Dr. Siham Gritly
  • 5. • *converted to fatty acids and stored astriglyceride.• *convert to other necessary CHO such as ribose,fructose and deoxyribose which is necessary forthe formation of genetic material DNA.• *some become the carbon skeletons forproduction of essential amino acidsDr. Siham Gritly
  • 6. • Carbohydrates can produce nearly 20 times moreenergy (in the form of ATP) per gram whenmetabolized in the presence of adequate oxygen(aerobic oxidation).• CP, creatine phosphate (also calledphosphocreatine): a high-energy compound inmuscle cells that acts as a reservoir of energy thatcan maintain a steady supply of ATP. CP providesthe energy for short bursts of activityDr. Siham Gritly
  • 7. Carbohydrates come in two sources duringexercises ;Carbohydrates utilization during Exercise1-Simple sugar glucose2-Storage form of glucose –glycogen; Glycogenis stored in Muscles and LiverDr. Siham Gritly
  • 8. Muscle glycogen store is the first source ofglucose for the exercising muscleDr. Siham Gritlywhen no glycogen;- the process ofglycogenolysis started and follow bygluconeogenesis in the liver to makeglucose available (main function ofthe liver is to release glucose throughglycogenolysis and gluconeogenesis )if no enough glucose after 3 hours ofheavy exercise athletes enter to acondition known as hoypglycemia(low glucose level in the blood)
  • 9. Muscle glycogen breakdown duringexercise• It is needed for any short, intense short period ofexercise from sprinting (running) to weight lifting• Two main factors lead to the Muscle GlycogenDepletion1- intensity of exercise2-duration of exerciseDr. Siham Gritly
  • 10. Aerobic physical activityand carbohydrate• Aerobic physical activity: activity in which thebody’s large muscles move in a rhythmicmanner for a sustained period of time.Aerobic activity, also called endurance activity,improves cardiorespiratory fitness. Brisk(fast)walking, running, swimming, and bicycling areexamplesDr. Siham Gritly
  • 11. Carbohydrate diets and endurance performanceEndurance performance such as (cycling,swimming or running• aerobic ExerciseDr. Siham Gritly
  • 12. • The endurance capacity of an individual on ahigh-CHO diet is approximately 3 timesgreater than on a high-fat diet.When CHO intake is low, several days of exacttraining will deplete muscle CHO (glycogen)stores and eventually impair performance.CHO should supply 60 -65% of the totaldaily kcal intakeDr. Siham Gritly
  • 13. Moderate-intensity physical activity:• moderate-intensity physical activity: physicalactivity that requires some increase inbreathing and/or heart rate and expends 3.5to 7 kcalories per minute.• Walking at a speed of 3 to 4.5 miles per hour(about 15 to 20 minutes to walk one mile) isan exampleDr. Siham Gritly
  • 14. Low- to moderate-intensity aerobic exercises thatcan be sustained for a long time (more than 20minutes) use some glucose, but more fat for fuel.Dr. Siham GritlyNutrient Density A healthful diet isbased on nutrient-dense foods—foodsthat supply adequate vitamins andminerals for the energy they provide.Active people need to eat both fornutrient adequacy and for energy. Adiet that is high in carbohydrate (60 to70 percent of total kcalories),moderate in fat (20 to 35 percent), andadequate in protein (10 to 20 percent)ensures full glycogen and othernutrient stores
  • 15. Carbohydrate diets and high intensityexercise intensity exercise such as( soccer,hockey, tennis, basketball and rugby)• Muscle glycogen provides the maincontribution of energy during high-intensityexercise that lasts more than about 30 seconds.• As the exercise duration increases, the muscleglycogen stores are diminished, and the ATPcomes from the contributionof fatty acid oxidation.Dr. Siham Gritly
  • 16. CHO for Strength Training(weight lifting)• CHO are required for strength training becausethe exercises rely on muscle glycogen stores forenergy.• CHO should supply 55-60% of the total dailycaloric intake. This is slightly lower than therequirements for endurance activities becausethe total amount of energy expended is less.Dr. Siham Gritly
  • 17. vigorous-intensity physical activity: physicalactivityIntensity refers to the rate at which the activity is beingperformed• vigorous-intensity physical activity: physicalactivity that requires a large increase inbreathing and/or heart rate and expends morethan 7 kcalories per minute.• Walking at a very brisk pace (>4.5 miles perhour) or running at a pace of at least 5 milesper hour are examples.Dr. Siham Gritly
  • 18. Anaerobic exercise• Anaerobic exercise include, strength-basedactivities, such as sprinting or bodybuilding,Dr. Siham Gritly
  • 19. Anaerobic exercise is high in intensity and shortin durationRef.• Anaerobic exercises may last only two minutesor less, but this type of workout actually burnsmore calories than aerobic exercise.• Unlike aerobic exercise, anaerobic exerciseburns a higher percentage of calories fromglycogenDr. Siham Gritly
  • 20. Intense activities; such as a quarter-mile race—useglycogen quickly. In such activities, the muscles breakdown glucose to pyruvate anaerobically, producing ATPquickly. (anaerobically glycolysis)Lactate is the product of anaerobic glycolysisDr. Siham Gritlysprinting, strength/resistance trainingand other intense activities thatrequire more energy than can beprovided in a lower intensity aerobicactivity would be anaerobic (nooxygen).
  • 21. Lactate• Lactate; When the rate of glycolysis exceeds thecapacity of the mitochondria to accept hydrogenswith their electrons for the electron transport chain,the accumulating pyruvate molecules are converted tolactate.• At low intensities, lactate is readily cleared fromthe blood, but at higher intensities, lactateaccumulates.• When the rate of lactate production exceeds the rateof clearance, intense activity can be maintained foronly one to three minutes (as in a 400- to 800-meterrace or a boxing match).Dr. Siham Gritly
  • 22. • Working muscles may produce lactate andexperience fatigue, but the lactate does not causethe fatigue.• Lactate quickly leaves the muscles and travels in theblood to the liver.• liver enzymes convert the lactate back into glucose.• Glucose can then return to the muscles to fueladditional activity. (The recycling process thatregenerates glucose from lactate is known as the Coricycle)Dr. Siham Gritly
  • 23. The Cori cycle (also known as Lactic acid cycle), refers to themetabolic pathway in which lactate produced by anaerobicglycolysis in the muscles moves to the liver and is converted toglucose, which then returns to the muscles and is converted backto lactate.Dr. Siham GritlyThe cycles importance isbased on the preventionof lactic acidosis in themuscle under anaerobicconditions
  • 24. Hypoglycemia• During intensity of exercise and longduration;• Glycogen supplies energy within the first fewminutes of any sport, If no glucose withinhours athletes enter a condition known ashypoglycemiaDr. Siham Gritly
  • 25. Hypoglycemia and the development ofFatigues during exercise• Hypoglycemia occurs when a persons bloodsugar levels are low, the normal blood glucoselevel is usually ranges from 80-120 mg ofglucose per 100 ml of blood• Usually hypoglycemia occur during highintensity aerobic exercise when no glycogenstorage in the liverDr. Siham Gritly
  • 26. • blood glucose is very short supply duringexercise, and should be replenish from glycogenstorage in the liver• ATP that supply the muscle decreased thusathletes become fatigue• The symptoms of hypoglycemia rarely developuntil the level of sugar in the blood falls below 60milligrams per deciliter of bloodDr. Siham Gritly
  • 27. • Hypoglycemia impair the function of central nervoussystem (brain and spinal cord) thus acute feeling ofdizziness, muscular weakness, sweating and fatiguedeveloped• severe hypoglycemia causes symptoms such asconfusion, seizure, and coma• Symptoms of hypoglycemia are treated by consumingsugar in any form.• the sugar levels in the blood become too high, acondition called hyperglycemia.Dr. Siham Gritly
  • 28. Major hormones involved in regulation ofblood glucose levelsadapted from; Melvin H Williams 2010; Nutrition for Health, Fitness and Sport.hormone Gland stimulus actionInsulin PancreasIncrease in bloodglucoseHelps transport glucose intocells; decrease blood glucoselevelsGlucagon PancreasDecrease in bloodglucose; exercisestressPromotes gluconeogenesis inliver; helps increase bloodglucoseEpinephrine Adrenal Exercise stress;decrease in bloodglucosePromote glycogen breakdownand glucose release from theliver; helps increase bloodglucose levelscortisol adrenal Exercise stress;decrease in bloodglucosePromotes breakdown of proteinand resultant gluconeogenesis;helps increase blood glucoselevelsDr. Siham Gritly
  • 29. Glycemic Index (GI)• Glycemic index represents a ranking systemrelative to the effect that consumption of 50grams of particular carbohydrates thatinfluence blood glucose within 2 hours.In other words;-• glycemic index; Carbohydrates which producea large increase in blood glucoseconcentration, in response to a standardamount of carbohydrate (50g), are classified ashaving a high glycemic indexDr. Siham Gritly
  • 30. Glycemic Index values• The values that used to rank glycemic index of food asfollows;-*70 or more------high GI*69-55------------medium GI foods*55 or less--------low GI foodsFactors other than CHO might influence the GI;-*physical form (coarse or fine)*serving mode (raw or cooked)A glycemic index GI value tells you only how rapidly aparticular carbohydrate turns into sugarDr. Siham Gritly
  • 31. • The carbohydrate in watermelon or grapes, forexample, both have a high GI (food which have refinedsugars). Foods high in fiber such as beans have low GI• GI in fructose has a low GI used as primary source insports drinks. Why?• the low glycemic index carbohydrate improveendurance capacity more than the high glycemic indexfood. Why?.Dr. Siham Gritly
  • 32. Glycemic load (GL)• The glycemic load represents a ranking systemrelative to the effect that eating acarbohydrates food has on the blood glucoselevel, but also includes the portion size• The glycemic load (GL) is a relatively newway to assess the impact of carbohydrateconsumption that takes the glycemic index intoaccount, but gives a fuller picture than doesglycemic index aloneDr. Siham Gritly
  • 33. Glycemic index and glycemic load• glycemic index is the rate at which food isconverted into glucose, glycemic load is thetotal amount (load) of glucose provided by thefood. Glycemic index is an absolute value• while glycemic load depends on the servingsize of the food in question. Glycemic loadvalues are always quoted in reference to aserving size in grams.Dr. Siham Gritly
  • 34. Glycemic load values• Values are used to rank the glycemic loadfood;-*20 or more----high GL*19-11----------medium GL food*10 or less------low GL foodsFoods that have a low GL almost always have alow GI is more healthful source of CHO.Dr. Siham Gritly
  • 35. • The glycemic load of a food is calculated bymultiplying the absolute GI value by the gramsof available carbohydrate in the serving, andthen dividing by 100.Dr. Siham Gritly
  • 36. • The glycemic load can be calculated by thefollowing equation;-• GL= GI gms of CHO in one serving 100• Note that Available Carbs is equal to the totalcarbohydrate content minus the fiber content.• For example, a 225 g (1 cup) serving of Bananaswith a GI of 52 and a carbohydrate content of 45.5g (51.4 g total carbohydrate - 5.9 g fiber) makes thecalculation GL = 52 * 45.5 / 100 = 24, so the GL is24.• Adapted from; Siham Gritly
  • 37. Exercise;- calculate the Glycemic Load of thefollowing carbohydrates;-adapted from; Melvin H Williams 2010; Nutrition for Health, Fitness and Sport.COH Glycemic index CHO in grams Gycemic loadL1-baked potato 1 cup 85 57 ?2-white bread 1 slice;- 70 10 ?3-orange 1 medium 44 15 ?4-fructose 1 tsp 23 5 ?5-wafers (5 cookies) 77 15 ?Dr. Siham Gritly
  • 38. Carbohydrate diets and Recovery fromexercise• recovery from exercise by resynthesize of thebodys carbohydrate stores & rehydration• Recovery of muscle glycogen can be achieved in24h when sufficient dietary carbohydrate isingested• Within 30 minutes of completing an extended orintense exercise session, consumption of at least50 grams of CHO (roughly 200 kcals) isrecommended .Dr. Siham Gritly
  • 39. • Some expertise suggested that; the optimal amountof carbohydrate is about 1 to 1.5 g ofcarbohydrate/kg body weight, consumedimmediately after exercise and at 2-h intervals untilthe next meal• The most important effect of such a diet is tomaximize the stores of glycogen in the muscles.• recover of muscle glycogen stores may take longerwhen exercise causes muscle damage and painDr. Siham Gritly
  • 40. • Rehydration• Immediately after exercise most athletesgenerally prefer to drink fluids rather than toconsume solid foods.• Drinking fluids helps rehydrate the athlete,which is an essential part of the recoveryprocessDr. Siham Gritly
  • 41. references*Ellie Whitney and Sharon Rady Rolfes; Under standing Nutrition, TwelfthEdition. 2011, 2008 Wadsworth, Cengage Learning*Sareen Gropper, Jack Smith and James Groff, Advanced Nutrition andHuman Metabolism, fifth ed. WADSWORTH*Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th ed,McGraw Hill*Heymsfield, SB.; Baumgartner N.; Richard and Sheau-Fang P. 1999. ModernNutrition in Health and Disease; Shils E Maurice, Olson A. James,Shike Moshe and Ross A. Catharine eds. 9th edition*Guyton, C. Arthur. 1985. Textbook of Medical Physiology. 6th edition,W.B. CompanyDr. Siham Gritly
  • 42. *LEMON, P. W. R. Protein and exercise: update 1987. Med Sci.Sports Exerc., Vol. 19, No. 5*FAO FOOD AND NUTRITION TECHNICAL REPORTSERIES 1*Human energy requirements Report of a JointFAO/WHO/UNUExpert Consultation Rome, 17-24 October2001*Burke LM et al. (2004). Carbohydrates and fat for training andrecovery. J Sports Sci 22:15-30Dr. Siham Gritly
  • 43. • *Power sports;- Olympic weight lifting• *Very high-intensity sports;- 100-meter dash• *High-intensity, short duration sports;- 5,000-meter run• *Intermittent high-intensity sports;- soccer• *Endurance sports;- marathon running• *Low-endurance, skill sports;- golf• *Weight-control and body image sports;- bodybuildingDr. Siham Gritly