Blood Lactate

Question 1

Glycolysis

Answer 1

Provides ATP at a 2x rate of oxidative from carbohydrates and a >3x rate of oxidative from fat

Question 2

Lactate

Answer 2

Not independently produced in hypoxia-dependent on the rate of energy demand
Reflective of fatigue mechanisms - H+ causes a decrease in PH, ADP and Pi concentrations and reflects elevated glycogen utilisation and depletion

Question 3

What determines blood lactate concentration?

Answer 3

It’s a balancing act between rate of lactate clearance in other tissues and the rate of lactate production.
Even at rest we are working a little anaerobically hence the slight build up of blood lactate levels

Question 4

Sites of Blood lactate removal

Answer 4

Most is oxidised in the working muscle
Liver and kidneys (20-25%)
Cardiac muscle (10%)

Question 5

What is lactate shuttling?

Answer 5

Only approximately 50% of the produced lactate appears in the vascular bed - lactate produced by fast twitch fibres oxidised in slow twitch fibres (diffusion).
Shuttling through vasculature is the reperfusion of heart and active muscle

Question 6

How to maximise lactate removal?

Answer 6

Do cool down to actively oxidise the molecules of lactate - working in an oxidative fashion and using it as a fuel source

Question 7

How can lactate be used as a fuel?

Answer 7

Moving the lactate within the muscle fibre and utilising it is beneficial
Moving it to oth3er muscles working aerobically (or not involved in the exercise) is beneficial
Moving it to the liver for gluconeogenesis may be beneficial

Question 8

Why measure blood lactate?

Answer 8

We can use BLa to predict the endurance performance, indicate submaximal fitness an as a tool for exercise prescription and monitoring training intensity
Once BLa exceeds a certain concentration during steady state exercise duration becomes finite

Question 9

What is Maximum Lactate Steady State (MLSS)?

Answer 9

The highest blood lactate concentration that can be maintained over time without a continual lactate accumulation

Question 10

How to determine the lactate turnpoint?

Answer 10

We really want to estimate the MLSS
The lactate turnpoint/MLSS is NOT the point where metabolism ‘switches’ from aerobic to anaerobic

Question 11

What happens at intensities higher than the lactate turnpoint?

Answer 11

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