Exercise MetabolismChapter 4pp 51-66Rest-to-ExerciseAssume standing requires 15 ATP and 0.4 liters/min of oxygenAssume running at 6 mph requires 100 ATP and 1.5 liter/min of oxygenA person can go from standing to running 6 mph in a mater of seconds.But, it takes 2-3 minutes for the oxygen uptake to go from 0.4 to 1.5 liters/minWhere does the energy to run 6 m.p.h come from until adequate oxygen can be supplied?Rest-to-ExerciseOxygen deficitRest-to-ExerciseRecovery from ExerciseLactic Acid RemovalShort-Term, Intense ExerciseATP-PC system when 2-20 seconds Glycolysis 20-45 secondsAnaerobic and Aerobic >45 secondsExample: 70/30 anaerobic/aerobic 60 secProlonged ExerciseAerobic and requires O2 (oxygen demand)O2 transported via cardioplumonary system (oxygen supply)Prolonged ExerciseDeficit: O2 supply < O2 demandSteady state: O2 supply = O2 demandEPOC: O2 supply > O2 demandProlonged ExerciseSteady State ExceptionsHot weatherHigh intensity (>70% of maximal effort)Incremental ExerciseMaximal oxygen uptakeLactate thresholdMaximal Oxygen UptakeLactate ProductionGlycolysis produces NADHLow intensity, most H goes into mitochondria (electron transport chain)Moderate to high intensity, not enough O2 for all HMost H + pyruvate = Lactic AcidInitially lactic acid removed from muscle cellEventually, lactic acid levels increase inside the muscleLactate ProductionLactate ThresholdEstimation of Fuel UtilizationFuel Utilization During ExerciseCarbohydrates and Fats (very little Protein)Fuel Utilization During ExerciseWhich fuel is used more as the exercise intensity increases? Why?What causes the shift towards carbohydrates?Fuel Utilization During ExerciseFuel Utilization During ExerciseWhat fuel is used more as the exercise duration increases? Why?What causes the shift towards fats?Fuel Utilization During ExerciseExercise and Fat MetabolismIs low-intensity exercise best for burning fat? [A Closer Look 4.3]Sources of Carbohydrate During ExerciseMuscle glycogen Liver glycogenLactate as a Fuel During ExerciseSlow twitch muscle fibersHeart muscleLiver via the Cori cycleSources of Fat During ExerciseAdipose tissueTriglycerides to fatty acidsWhy is it not possible to “spot reduce”?Muscle cellsSources of Protein During ExerciseSkeletal muscleAmino acidsDirectlyIndirectly Why is protein not an optimal fuel source?Energy Related FatigueGlycogen depletionWhat is it?Why does it cause fatigue?Low pyruvateHypoglycemiaWhen does it