Lecture 9 Alkalisers and Buffers

Question 1

State 3 reasons for fatigue in repeated sprints

Answer 1

Glycogen depletion
Phosphocreatine depletion
Muscle acidosis

Question 2

List 3 ways we can buffer lactate

Answer 2

• Sodium/hydrogen exchange - Release hydrogen, bring in sodium
• Monocarboxylase transporters - remove both hydrogen and lactate from the cell
• Sodium bicarbonate transporters - bicarb enters cells, buffers hydrogen by breaking it don into CO2 and H20

Question 3

Disturbances with which ion causes the most issues with the membrane potential?

• Sodium
• Potassium
• Calcium
• Chloride

Answer 3

Potassium

Question 4

What happens if K+ levels are disrupted?

Answer 4

When K+ levels are disrupted, the resting membrane potential increases from -70 towards 0. An action potential will still take place, however the size of change is less meaning less force can be generated

Question 5

How high to K+ levels get for force generation to decrease?

Answer 5

10mM, at 12mM no force generated

Question 6

Name 4 intercellular buffers

Answer 6

PCr
Bicarbonate
Protein
Carnosine

Question 7

Name 1 extracellular buffer

Answer 7

Bicarbonate

Question 8

What situations might sodium bicarbonate aid performance?

Answer 8

When you get high anaerobic glycolysis; repeated sprints, sprint finish, 1-7 minutes high intensity exercise

Question 9

What was found by Eggar 2014?

Answer 9

Increase TTE with the use of sodium bicarbonate as oppose to placebo

Question 10

Explain the contrast in acidosis and alkalosis

Answer 10

Acidic conditions: Buffering capacity reduced, lower pH and reduced lactate due to less work done. Decrease in buffering capacity reduced performance by 1.7%

Alkali conditions: Increased buffering capacity, increased pH, increase lactate due to more work done. Increase in buffering capacity improved performance by 1.7%

Question 11

Who benefits the most from sodium bicarbonate supplementation and why?

Answer 11

Untrained. Trained athletes already have an improved buffering capacity from training alone

Question 12

Explain effects of sodium bicarbonate as a training aid

Answer 12

Increased VO2max
Increased lactate threshold
Increased TTE at pre VO2max level

Question 13

Side effects of sodium bicarbonate

Answer 13

Vomiting
Light headed
Diarrhoea
GI distress

Question 14

How can you minimise GI distress?

Answer 14

Take in capsule form
Spread doses out by 60 mins
Take with fluid an light meal
Take with orang juice
Do not take with alcohol
Do not take just before competition

Question 15

What is advised dose of sodium bicarbonate?

Answer 15

0.3-0.5g.kgBW

Question 16

What is the resting membrane potential?

Answer 16

-70

Question 17

What is the rate limiting factor of carnosine

Answer 17

Beta alanine

Question 18

State 3 functions of carnosine

Answer 18

Hydrogen buffering - hydrogen soaked up by nitrate in the carnosine
Antioxidant - protects against oxygen radicals
Glycation and Carboxylation prevention

Question 19

Explain differing levels are carnosine in the muscle

Answer 19

More carnosine in fast twitch fibres due to increased buffering capacity

Question 20

Explain factors that may influence carnosine levels

Answer 20

Aging decreases carnosine
Higher in men than women
Higher in high meat diets or with beta alanine supplementation
Low in vegetarians

Question 21

How should we dose beta alanine

Answer 21

Either high dose for short time or low dose for a long time

More beta alanine consumed, more carnosine produced

Question 22

How long should performance be to seen impact of carnosine

Answer 22

Greater than 60 seconds
Optimal between 1-4 mins
Still events above 4 mins but not as great an effect

Question 23

How long does increased carnosine evident after beta alanine supplementation

Answer 23

16-20 weeks

Question 24

Side effects of beta alanine supplementation

Answer 24

Paraesthesia - Tingly hands, numbness, itchiness, pins and needles in extremities
Beta alanine and taurine use same transporter, too much beta aniline means taurine doesn’t get to the muscle resulting in;
- poor performance
- hypertension
- mood issues
- weight gain
- disturbed vision

Question 25

How do you prevent paraesthesia?

Answer 25

Use slow release capsules

Question 26

What did Sale et al 2011 report about sodium bicarbonate and beta alanine supplementation?

Answer 26

Combination of beta alanine and sodium bicarbonate saw biggest performance improvements

Question 27

What did Danaher 2011 report about sodium bicarbonate and beta alanine supplementation?

Answer 27

Beta alanine and combination of BA and SB saw improvements in performance, single use of SB didn’t see performance benefits.

Question 28

What does beta alanine supplementation increase?

Answer 28

Carnosine

Question 29

Beta alanine improves performance in high intensity exercise through which of the following mechanisms:

• Reduced buffering
• Improved calcium handing
• Reduced pH
• Reduced glycogen depletion

Answer 29

Improved calcium handling

Question 30

How much carnosine recommended with 6 weeks supplementation?

Answer 30

4.8g/day

Question 31

How much carnosine recommended with 9 weeks supplementation?

Answer 31

3.2g/day

Question 32

How much carnosine recommended with 18 weeks supplementation?

Answer 32

1.6g/day

Question 33

How much histidine and beta alanine are in carnosine?

Answer 33

Histidine - 50uM

BA - <2uM

Question 34

Explain carnosine synthesis

Answer 34

The body doesn’t absorb carnosine well, therefore breaks it down into histidine and beta alanine.
Then transported back to the muscle where it forms carnosine