using blood lactate to evaluate sports performance

Question 1

lactate

Answer 1

conversion of pyruvate to lactate by lactate dehyrdogenase
- measure lactate rather than lactic acid in humans
- convserion of lactate is beneficial to us as there is the idea that it prevents greater levels of acidosis

Question 2

lactate and pH

Answer 2

as blood lactate increases, blood pH will drop (more acidic)
as % max exercise increase, blood lactate will increase and blood pH will drop

Question 3

determining blood lactate

Answer 3

rate of lactate clearance in other tissue and rate of lactate production (bneed to be balanced)
lactate can be cleared in t1 muscle- can be oxidised + in other oxidatie tissues, can be cleared in liver and brain
blood lactate is beneficial to brain and may also help in effects of aging
increasing intensity = more lactate produced
(greater accumalation in blood, not all is getting broken down)

Question 4

site of lactate removal

Answer 4

most is oxidised in working muscle (55-70%)
liver + kidneys= 20-25%
cardiac muscle= 10%

Question 5

lactate shuffling

Answer 5

only 50% of produced lactate appears in vascular bed (reflected in blood lactate readings)- lactate produced by fast twitch fibres oxidised in slow twitch fibres (diffusion)
shuttling through vasculature - reperfusion of heart and active muscle
maximising lactate removal after sprinting- active recovery

Question 6

lactate as a fuel

Answer 6

lactate can be converted to pyruvate can be converted to acetyl which entres krebs cycle
(produces NADH which entres ETC)
removing lactate within muscle fibre and utilising it is beneficial
moving to other muscles working aerobically or not working muscles is also beneficial
moving to liver for gluconeogenesis is beneficial

Question 7

why measure blood lactate

Answer 7

can use blood lactate to predict endurance performance, indicates submaximal fitness and as a tool for exercise prescription and monitoring training intensity
once BLa exceeds certain conc during steady state exercise, exercise duration becomes finite

Question 8

determination of lactate thresholds

Answer 8

approx 25 threshold concepts
lactate threshold- 1st significant elevation of lactate level (2mmol)
lactate turnpoint- 2nd lactate increase of at least 0.5mmol from the previous value
working out on threshold graph
- Dmod- maximal distance from BLa curve to the line formed by the point before the first rise in Bla and the value at the cessation of exercise

Question 9

MLSS

Answer 9

maximum lactate steady state
highest blood lactate conmc that can be maintained over time without continual blood lactate accumalation
when determining lactate turnpoint, we want to estimate MLSS

Question 10

lactate turnpoint notes

Answer 10

lactate turnpoint isnt the point where metabolism switches from aerobic to anaerobic - the 2 processed occur simulatenously
at intesnities
at intensities higher than the lactate turnpoint/MLSS, anaerobic processes lead to a gradual build up of H+ and other metabolic products in muscle, ultimately leading to fatigue

Question 11

domains

Answer 11

low intensity domain- Bla <2mmol, <70% vo2 max
moderate domain- between lactate threshold, Bla elevated but stable at 2-8mmol, 70-90% vo2 max
severe domain- above MLSS, Bla >2-8mmol, >90% vo2 max