Alkalisers and buffers Flashcards Preview

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Flashcards in Alkalisers and buffers Deck (38)
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1

During repeated sprints, why does our mean power output fall?

• An increase in metabolites
• Glycogen depletion
• PCr depletion
• Muscle acidosis
o Not lactate- H+ associated accumulation
o pH <7 = acidosis

2

Give a simple overview of muscle contraction key steps

action potential --> neurotransmitter release --> Ca --> powerstroke/cross bridge formation

3

What molecule causes acidosis

protons

4

What can we do to lactate to prevent proton accumulation

Buffer it

5

H + Pyruvate --> ?

Lactate + H

6

HC03 + H --> ?

Co2 + H20

7

Give 3 ionic changes which occur extracellularly during fatigue

o ↓K
o ↑Ca
o ↑H
o ↑Lactate
o ↑Na
o ↑Cl

8

Give 3 ionic changes which occur interstitially during fatigue

o ↓Na
o ↓Cl
o ↑K
o ↑H
o ↑Lactate

9

State 2 exchange channels the body has to alter ionic concentrations

• Na/H exchange channel
• H/lactate monocarboxylate
• Na/HCO3 transporter
• Na/K ATPase

10

Why are changes in K the most important ionic variation?

K is the key ion for the generation of action potentials

11

How many K in for Na out of the Na/K ATPase

2 K in
3 Na out

12

What is the resting membrane potential disturbed to during exercise

-70mv to -50mv.

13

Why is there a disturbance in resting membrane potential during exercise?

The Na/K pump is ATP dependent, and as during exercise ATP levels decrease, K+ rises extracellularly

14

True or False: The disturbance in resting membrane potential during exercise means a smaller change is required in MV to cause an action potential

True- This means there is a smaller force generation, which effects Ca2+ release.

15

What process may attenuate K increase, preventing the change in H ions

Alkalosis

16

HCO3 is an extracellular buffer. How does it work?

It decreases H and therefore K but doesn’t change blood lactate

17

Why is buffering beneficial

allows the body to work harder i.e. generate more lactate for longer

but without the performance decrements normally associated with increased lactate.

18

Give an example of an alkaliser

-sodium bicarbonate
-sodium citrate

19

How do alkalisers work?

increases blood HCO3 pool, and therefore the muscle.
They can increase time to exhaustion.

20

What type of events may alkalisers be beneficial for

They are useful for anaerobic glycolysis events, or those effected by a reduced pH.

21

True or False: alkalisers cause an increase in H

True, but though more H were produced (increased Bla),

NaHCO3 and NaCitrate buffered it with HCO3 so effects weren’t felt

22

What is a beneficial effect of chronic bicarbonate supplementation?

pH reduced and there was an increased buffering ability and power seen, with high supplementation for 5 days prior

23

Describe alkalisers effectiveness as a training aid

 There is a ceiling effect- increased buffering in untrained athletes
 Increases VO2 max
 Increases lactate threshold
 Increase exercise at pre-training VO2max
 Increase exercise duration
 Increases stress on body, so greater adaptions seen

24

Give 2 side effects of alkalisers

• Vomiting
• Diarrhoea
• Dizziness
• GI distress

25

What is the optimum timing for alkaliser supplementation

• 120-150 mins prior to exercise
o Or 60 mins prior if in capsule form

26

What should alkalisers be co-ingested with

a light meal or fluid such as orange juice

27

What is the optimum dose of alkalisers

0.3-0.5g/kg/BW of bicarbonate

28

Give 2 examples of intracellular buffers

PCr, Protein, Carnosine or Bicarbonate

29

What is carnosine

A dipeptide found in animal flesh, made up of L-Histidine and Beta-Alanine

30

How does carnosine work

It acts as a buffer, antioxidant and prevents glycosylation or carbonylation.

The N group removes H+ after exercise, decreasing H+ accumulation.