Blood Lactate response to exercise

Question 1

What type of glycolysis does lactate come from?

Answer 1

Anaerobic

Question 2

What determines whether aerobic or anaerobic glycolysis takes place?

Answer 2

The rate of energy demand

NOT OXYGEN AVAILABILITY

Question 3

What enzyme converts pyruvate into lactic acid and then lactate?

Answer 3

Lactate Dehydrogenase (LDH)

Question 4

What leads to fatigue?

Answer 4

Accumulation of protons from lactic acid

Question 5

True/False: Pyruvate is converted to lactic acid by LDH then lactic acid dissociates into a proton and a molecule of lactate

Answer 5

True

Question 6

True/False: We can measure levels of lactic acid

Answer 6

False, it dissociates into lactate and a proton almost immediately

Question 7

True/False: The more blood lactate present, the more hydrogen ions are present causing the pH of the blood to decrease and be more acidic

Answer 7

True

Question 8

What is the range of blood lactate at resting level?

Answer 8

0.5 - 1.5mmol/L

Question 9

What determines blood lactate concentration?

Answer 9

• Rate of lactate production, mainly from type IIb fibres
• Rate of lactate clearance in other tissues

Question 10

Where are the main sites of lactate removal?

Answer 10

• Working muscles (~55-70%)
• Liver & Kindeys (~20-25%)
• Cardiac muscle (~10%)

Question 11

Explain the process of lactate shuttling

Answer 11

Only ~50% of lactate appears in the bloodstream that can be used by further away muscles, the rest diffuses into nearby fibres within the same muscle and used closer to the site of production

Question 12

How is lactate used as energy?

Answer 12

• Pyruvate is converted to lactate
• This can be oxidised within muscles to produce ATP
• It can be transported to the liver, where it’s turned back into glucose which can be released into the bloodstream

Question 13

Why do we measure BLa?

Answer 13

• To predict endurance performance, indicate submaximal fitness and as a tool for exercise prescription and monitoring training intensity
• Once BLa exceeds a certain concentration during steady state exercise, exercise duration becomes finite as we’re using glycogen supplies rapidly

Question 14

What is lactate threshold?

Answer 14

The first sudden increase in blood lactate

Question 15

What is lactate turnpoint?

Answer 15

The second inflection/Increase

Question 16

What does MLSS stand for?

Answer 16

Maximum lactate steady state

Question 17

What is MLSS?

Answer 17

The highest lactate concentration that can be maintained over time without a continual lactate accumulation, this is the lactate turnpoint

Question 18

What happens at intensities higher than the MLSS?

Answer 18

Anaerobic processes lead to a build up of H+ and other metabolic products in muscle, leading to fatigue

Question 19

What intensity of exercise is before lactate threshold? ~ < 70% VO2max

Answer 19

Regenerative/Low-intensity endurance training

Question 20

What type of exercise occurs after the MLSS? ~ > 90% VO2max

Answer 20

Interval training sessions

Question 21

When does Moderate-High intensity endurance trianing and the aerobic-anerobic transition occur? ~ 70 - 90% VO2max

Answer 21

Between the LT and MLSS