Lecture 9 Alkalisers and Buffers Flashcards
State 3 reasons for fatigue in repeated sprints
Glycogen depletion
Phosphocreatine depletion
Muscle acidosis
List 3 ways we can buffer lactate
- 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
Disturbances with which ion causes the most issues with the membrane potential?
- Sodium
- Potassium
- Calcium
- Chloride
Potassium
What happens if K+ levels are disrupted?
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
How high to K+ levels get for force generation to decrease?
10mM, at 12mM no force generated
Name 4 intercellular buffers
PCr
Bicarbonate
Protein
Carnosine
Name 1 extracellular buffer
Bicarbonate
What situations might sodium bicarbonate aid performance?
When you get high anaerobic glycolysis; repeated sprints, sprint finish, 1-7 minutes high intensity exercise
What was found by Eggar 2014?
Increase TTE with the use of sodium bicarbonate as oppose to placebo
Explain the contrast in acidosis and alkalosis
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%
Who benefits the most from sodium bicarbonate supplementation and why?
Untrained. Trained athletes already have an improved buffering capacity from training alone
Explain effects of sodium bicarbonate as a training aid
Increased VO2max
Increased lactate threshold
Increased TTE at pre VO2max level
Side effects of sodium bicarbonate
Vomiting
Light headed
Diarrhoea
GI distress
How can you minimise GI distress?
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
What is advised dose of sodium bicarbonate?
0.3-0.5g.kgBW
What is the resting membrane potential?
-70
What is the rate limiting factor of carnosine
Beta alanine
State 3 functions of carnosine
Hydrogen buffering - hydrogen soaked up by nitrate in the carnosine
Antioxidant - protects against oxygen radicals
Glycation and Carboxylation prevention
Explain differing levels are carnosine in the muscle
More carnosine in fast twitch fibres due to increased buffering capacity
Explain factors that may influence carnosine levels
Aging decreases carnosine
Higher in men than women
Higher in high meat diets or with beta alanine supplementation
Low in vegetarians
How should we dose beta alanine
Either high dose for short time or low dose for a long time
More beta alanine consumed, more carnosine produced
How long should performance be to seen impact of carnosine
Greater than 60 seconds
Optimal between 1-4 mins
Still events above 4 mins but not as great an effect
How long does increased carnosine evident after beta alanine supplementation
16-20 weeks
Side effects of beta alanine supplementation
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
