Alkalisers and buffers

Question 1

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

Answer 1

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

Question 2

Give a simple overview of muscle contraction key steps

Answer 2

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

Question 3

What molecule causes acidosis

Answer 3

protons

Question 4

What can we do to lactate to prevent proton accumulation

Answer 4

Buffer it

Question 5

H + Pyruvate –> ?

Answer 5

Lactate + H

Question 6

HC03 + H –> ?

Answer 6

Co2 + H20

Question 7

Give 3 ionic changes which occur extracellularly during fatigue

Answer 7

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

Question 8

Give 3 ionic changes which occur interstitially during fatigue

Answer 8

o	↓Na
o	↓Cl
o	↑K
o	↑H
o	↑Lactate

Question 9

State 2 exchange channels the body has to alter ionic concentrations

Answer 9

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

Question 10

Why are changes in K the most important ionic variation?

Answer 10

K is the key ion for the generation of action potentials

Question 11

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

Answer 11

2 K in

3 Na out

Question 12

What is the resting membrane potential disturbed to during exercise

Answer 12

-70mv to -50mv.

Question 13

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

Answer 13

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

Question 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

Answer 14

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

Question 15

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

Answer 15

Alkalosis

Question 16

HCO3 is an extracellular buffer. How does it work?

Answer 16

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

Question 17

Why is buffering beneficial

Answer 17

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

but without the performance decrements normally associated with increased lactate.

Question 18

Give an example of an alkaliser

Answer 18

• sodium bicarbonate

- sodium citrate

Question 19

How do alkalisers work?

Answer 19

increases blood HCO3 pool, and therefore the muscle.

They can increase time to exhaustion.

Question 20

What type of events may alkalisers be beneficial for

Answer 20

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

Question 21

True or False: alkalisers cause an increase in H

Answer 21

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

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

Question 22

What is a beneficial effect of chronic bicarbonate supplementation?

Answer 22

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

Question 23

Describe alkalisers effectiveness as a training aid

Answer 23

 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

Question 24

Give 2 side effects of alkalisers

Answer 24

• Vomiting
• Diarrhoea
• Dizziness
• GI distress

Question 25

What is the optimum timing for alkaliser supplementation

Answer 25

• 120-150 mins prior to exercise

o Or 60 mins prior if in capsule form

Question 26

What should alkalisers be co-ingested with

Answer 26

a light meal or fluid such as orange juice

Question 27

What is the optimum dose of alkalisers

Answer 27

0.3-0.5g/kg/BW of bicarbonate

Question 28

Give 2 examples of intracellular buffers

Answer 28

PCr, Protein, Carnosine or Bicarbonate

Question 29

What is carnosine

Answer 29

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

Question 30

How does carnosine work

Answer 30

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

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

Question 31

Which muscle fibre type has the greatest amount of carnosine in

Answer 31

Type II

Question 32

Describe the synthesis of carnosine in the body

Answer 32

Carnosine (from diet) –> histidine and B-alanine (in blood) –> carnosine (in skeletal muscle)

Question 33

What does B alanine share a transporter with

Answer 33

taurine

Question 34

What are the benefits of B alanine

Answer 34

decreases neuromuscular fatigue, improves ca handling, and increases exercise duration

Question 35

What is the wash out period of carnosine

Answer 35

16-20 weeks

Question 36

What is the wash out period for PCr and Cr

Answer 36

4 weeks

Question 37

Give 2 side effects of carnosine

Answer 37

•	Paraesthesia
•	Hypertension
•	Double vision
•	Weight gain
•	Because uses same transporter as taurine
o	May be decreased performance
o	Effects mood

Question 38

What type of exercise may B alanine be beneficial for

Answer 38

exercise >60 secs