Energy Transfer during Short Duration/High Intensity Exercise

Question 1

What causes fatigue?

Answer 1

• Lactic acid
• Depletion of ATP stores
• Myoglobin lost O2
• Depletion of glycogen

Question 2

Why does breathessness occur?

Answer 2

• aerobic energy needed
• Body needs O2 to:
  …replenish ATP-PC stores
  …resaturate myoglobin with O2
  …replenish glycogen levels in liver
  …remove lactic acid
  …maintain high level of temp/metabolic rate
  …energy needed for high HR/breathing rate

Question 3

What is the lactate threshold/OBLA?

Answer 3

• Rest: 1-2mmol/L
• OBLA/Lactate threshold are the same thing - just different ways of measuring lactate
• Intense exercise = lactate accumulates
• OBLA occurs at 4mmol/L lactate
• Gives an indication of endurance levels
• Trained individuals can work at a higher intensity before OBLA and delays when the threshold occurs
• Lactate threshold is expressed as VO2 max
• AVG performer has a lactate threshold pf 50/60% VO2 max
• Elite trained performer has a lactate threshold of 70/90% VO2 max
• We tend to train at a level below the lactate threshold so that performance doesnt deteriorate
• The fitter you are, the higher the threshold hence the harder you work

Question 4

What factors affect the rate of lactate accumulation?

Answer 4

• intensity
• muscle fibre type: slow fibres - less lactate
• rate of blood lactate removal - can be improved w/ training
• respiratory exchange ratio
• fitness of performer - fitter athletes = delayed OBLA

Question 5

Why do elite sprinters have better anaerobic endurance than non elite sprinters?

Answer 5

• body is more tolerant of lactate - work at high intensity for longer
• better at buffering - increased rate of lactate removal
• muscles have adapted to training - higher capillary density, more myoglobin, greater number/size of mitochondria

Question 6

What are the differences in ATP generation between fast/slow twitch muscles?

Answer 6

• slow twitch fibres are used for low/mid intensity and so use aerobic respiration as their main fuel
• fast twitch fibres are used for high intensity and so use anaerobic respiration as their main fuel
• anaerobic respiration is much quicker than aerobic but less efficient only producing 2 ATP per glucose molecule
• muscle also fatigues quicker due to build up of lactic acid