Fatigue and Recovery

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Fatigue and Recovery
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Defining fatigue

• How would you describe fatigue?
• A reduction in muscular performance or a
  failure to maintain expected power output
• Muscular tiredness
• Shortness of breath
• Vary depending on activity

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Causes of fatigue

• Insufficient ATP
• Lactic acid
• Glycogen depletion
• Fluid loss- low blood pressure

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Recovery Process after Exercise

• Why does a 400m sprinter take the same deep
  breaths as a marathon runner after the race, even
  though they have run different distances?
• Why do we take deep breaths?

5
Recovery Process is needed to.

• Rebuild muscular stores of ATP and PC that were
  used during exercise.
• Remove lactic acid.
• Replenish the myoglobin O2 stores (Myoglobin has
  an important , if small scale, role in carrying
  O2 from haemoglobin to the mitochondria thus
  ensuring the provision of energy in muscles.
• Complete restoration is thought to be complete by
  the time needed to recover the alactacid debt
  component.
• Replace Glycogen.

• There are many other processes involved in
  recovery. Processes such as restoration of
  cardiac/pulmonary functioning to resting values,
  return to normal body temperature etc. all
  require additional O2 ( although substantially
  less than that used during the alactacid and
  lactacid components) and therefore adds time to
  paying back the O2 deficit to reach the pre
  exercise level.

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The oxygen debt

• Oxygen Debt the amount of oxygen consumed
  during recovery above that which normally would
  have been consumed at rest in the same period of
  time
• Excess Post-exercise oxygen consumption (EPOC)
  The need for O2 to rapidly replace ATP and
  remove lactic acid.

• Oxygen debt will occur if anaerobic activity has
  occurred
• Debt can be measured by analysing oxygen
  consumption before and after exercise.
• Oxygen debt used to compensate for oxygen
  deficit..

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Oxygen Deficit

• Oxygen deficit is the difference between the O2
  required during the exercise and the O2 actually
  consumed during the activity
• O2 is not available for the first few mins
  approximately, so an oxygen deficit will always
  occur.

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Oxygen debt has 2 components 1Alactacid Debt

• It is the volume of oxygen required to restore
  phosphogens used in the alactic or ATP-PC energy
  system.
• fast replenishment
• 1st component of oxygen debt to be replaced

• 2-3 mins to replenish phosphocreatine
• 2-3 litres of 02 consumed to provide energy
• Intense work- this recovery process can occur to
  allow for another set of reps.
• Interval training doesnt allow full recovery

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Effects of training on the Alactacid Component

• Increased stores of ATP and PC in muscle cells.
• Improved ability to provide O2.
• Increase in size of alactic component

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2 Lactacid Debt

• It is the volume of oxygen consumed during
  recovery used to remove lactic acid from muscles,
  which has accumulated during anaerobic work
• slow replenishment

• Most lactic acid is
• -removed into blood -oxidised in mitochondria
  via aerobic system to give CO2 and H20
• -converted into muscle and liver glycogen,
  glucose and protein
• -excreted from body as sweat or urine.
• Lactic acid removal takes approx 1 hour

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The Effect of Lactic Acid Accumulation

• During high intensity exercise, muscle fatigue
  occurs at a pH of 6.4 and noticeably affects
  muscle function. It is thought that protons
  dissociate from lactic acid and associate with
  glycolytic enzymes, thus making them acidic.
• In this state, the enzymes lose their catalytic
  ability and energy production through glycolysis
  ceases. This coupled with the inhibition of the
  transmission of neural impulses impairs muscle
  contraction

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Fate of the Lactic Acid

• 65 is oxidised to form carbon dioxide and water.
• 20 is converted back into glucose by the liver
  (gluconeogenesis). This is returned to the liver
  and muscles to be stored as glycogen.
• 10 is converted in the liver to form protein.
• 5 is converted into glucose.