S1L5 Blood Lactate

Question 1

How is lactate formed?

Answer 1

Pyruvate –>lactate via LDH
Traditional view = lactic acid –>H+ and lactate

Question 2

What is the relationship between lactate and pH?

Answer 2

an increase in lactate decreases pH - more acidic

Question 3

What determins blood lactate concentration?

Answer 3

• rate of lactate clearance
• rate of lactae production

Question 4

What are the site of blood lactate removal?

Answer 4

• Working Muscles (most)
• Liver (20-25%)
• Cardiac muscle (10%)

Question 5

What is lactate shuffling?

Answer 5

Lactate produced by fast twitch fibres is oxidised in slow twitch fibres.

Question 6

How is lactate used as a fuel?

Answer 6

Lactate converted back to pytuvate - can use as a fuel source:
- used in muscle fibres
- used in other muscles
- used in liver for gluconeogenesis = Cori cycle–> lactate converted to new glucose molecules for fuel for further exercise

Question 7

What are the training zones for each exericse domain?

Answer 7

• Low intensity = Below LT. BLa <2mmol/L; <70%Vo2 max
• Moderate intestity –> between LT MLSS. BLa 2-8mmol/L; 70-90% VO2max
• Severe intensity –> above MLSS. BLa >2-8mmol/L; >90% VO2max

Question 8

Why would you measure blood lactate?

Answer 8

• to predict endurance performance
• to indicate submax fitness
• tool for exercise prescription

Question 9

What is Lactate Threshold and Lactate Turnpoint?

Answer 9

Lactate Threshold = 1st significant elevation of lactate level (~2mmol/L)
Lactate Turnpoint = 2nd lactate increase of at least 0.5mmol/L from previous value.

Question 10

What is MLSS?

Answer 10

Maximum Lactate Steady State = highest blood lactate concentration that can be maintained over time w/o a continual BLa accumulation.
- above MLSS = incrased anaerobic metabolism so increase in H+ accumulation so leads to fatigue