Lesson 6: Cardiovascular Drift and Arterio-venous difference.

Question 1

What is cardiovascular drift?

Answer 1

The progressive increase in heart rate that begins after approximately 10 min of prolonged steady state exercise.

Question 2

Why does your HR climb during steady state?

Answer 2

• SV and arterial pressure progressively decrease.
• A progressive rise in HR.

Question 3

Dedpite the exercise being steady state SV and arterial pressure progressively decrease. Why?

Answer 3

• SV progressively decreases due to hot tempereature. Due to the temp, fluid is lost as sweat resulting in a reduced plasma voluma and redcued venous return.
• HR progressively increases because cardiovascular drift occurs after a period of exercise.
• Cardiac output also increases due to more energy needed to cool body/sweat.

Question 4

What do you do as an athlete to minimise cardiovascular drift?

Answer 4

Maintain high fluid consumption before and after exercise.

Question 5

Cardiovascular drift memory tool:

Answer 5

Cardiovascular drift occurs in after a period of exercise - HR increases - SV decreases - because od fluid lost as sweat - resulting in a reduced plasma volume - reduced venous return - cardiac output also increases due to more energy needed to cool body/sweat.

Question 6

What is an arteriole?

Answer 6

• An arteriole is a very small blood vessel that branches off from your artery and carries blood away from your heart to your tissyes and organs.
• They link with capillaries - very thin walled, your capillaries act like an exchange station where oxygen and nutrients trade places with waste from your tissues.
• Your smallest veins (venules) also link to your capillaries to make this exchange.

Question 7

What do arterioles do?

Answer 7

• Control blood flow and BP throughout your body.
• They supply 80% of your blood vessels’ resistance to blood flow in your body.

Question 8

What is arterio-venous difference (A-VO2 diff)?

Answer 8

• The difference between the oxygen content of the arterial blood arriving at the muscles and the venous return of blood leaving the muscles.
• At rest, the arterio-venous difference is low as not much oxygen is required.
• During exercise, more oxygen is needed so the arterio-venous difference is high.
• This increase will affect gaseous exchange: more oxygen is taken in and more CO2 is removed.
• Training also increases the arterio-venous difference as trained performers can extract a greater amount of oxygen from the blood.

Question 9

What happens when arterio-venous difference is high?

Answer 9

• It results in more blood being pumped to working muscles (especially slow-twitch)
• Muscle fibres better at extracting and processing oxygen as a result of increased mitochondria numbers, more oxidative enzymes and increased levels of myoglobin.