A2 PE Aerobic Energy System

Question 0

Explain now VO2Max is related to performance in a marathon?

Answer 0

Endurance event so a higher VO2Max results better performance or quicker time
Oxygen used in ATP production so less/no lactic acid as it involves Krebs cycle and ETC
Delayed OBLA

Question 1

Define the term VO2Max

Answer 1

Maximal volume of oxygen consumed/used by the muscles per minute

Question 2

What factors can affect a person’s VO2Max?

Answer 2

Lifestyle choices, aerobic training (altitude/O2 tents), age, physiology (muscle fibre type), genetics (inherited factors), gender, body composition.

Question 3

How does aerobic training affect a person’s onset of blood lactate accumulation (OBLA)?

Answer 3

OBLA will start at a higher percentage of a persons VO2Max if they are trained.
OBLA is delayed as 4mmols of blood lactate will take longer to accumulate
Can train at higher intensity for longer without becoming fatigued

Question 4

VO2Max is dependent on an effective oxygen delivery system as well as aerobic-friendly muscle structure, which fibres are more suitable for a higher VO2Max and why?

Answer 4

Slow twitch fibres (Type I)
Large mitochondrial density for aerobic respiration
Large capillary density to deliver O2
High myoglobin content to deliver O2 to mitochondria
Triglyceride (fat) stores for aerobic respiration

Question 5

How can an athlete measure their VO2Max?

Answer 5

Multi stage fitness test (bleep test) - increase intensity by speeding up pace of shuttle.
Direct gas analysis - increasing intensity of performance on a treadmill and analysing the gases inspired and expired (similar to RER)

Question 6

What fuels are used by the body to re-synthesise ATP for muscular contractions?

Answer 6

Phosphocreatine (PC)
Glycogen (carbohydrates CHO)
Triglycerides
Proteins

Question 7

Briefly outline the main stages of the aerobic energy system

Answer 7

Glucose broken down by PFK into pyruvic acid (2ATP)
Pyruvic acid converted by PDH into acetyl co-enzyme A
Fatty acids converted into acetyl co-enzyme A
Acetyl co-enzyme A fed into krebs cycle (2ATP + CO2)
Hydrogen ions removed and fed into the ETC (34 ATP + H2O)

Question 8

What is produced as a result of the aerobic energy system?

Answer 8

38 ATP (2 from glycolysis, 2 from Krebs, 34 ETC)
CO2
H2O

Question 9

What duration of exercise would predominantly use the aerobic energy system as the body’s main source of energy production? Give examples.

Answer 9

Longer than 3 minutes and lasting many hours
Marathon
Cross country ski
Triathlon
1500m

Question 10

Where do the Krebs cycle and electron transport chain take place within the muscle cell?

Answer 10

In the mitochondria;
Krebs - matrix of mitochondria
ETC - Cristae of the mitochondria

Question 11

What is beta oxidation?

Answer 11

Fat equivalent of glycolysis

Fats are broken down into fatty acids and converted into Acetyl co-enzyme A to enter kerbs cycle

Question 12

What is EPOC?

Answer 12

Excess post-exercise oxygen consumption

Question 13

What are the two stages of EPOC?

Answer 13

Fast component (alactacid stage)
Slow component (lactacid stage)

Question 14

How many litres of oxygen required for the fast and slow stages of EPOC and how long does each take to complete?

Answer 14

Fast; 2-3 minutes, up to 4litres of oxygen

Slow; up to 2 hours 5-10 litres of oxygen

Question 15

What are the functions of the fast component of EPOC?

Answer 15

Resynthesise muscle ATP and PC

Re-saturate myoglobin and haemoglobin with oxygen

Question 16

What are the functions of the slow component of EPOC?

Answer 16

Remove lactic acid
Replenish muscle and liver glycogen stores
Maintain elevated heart and breathing rate
Maintain elevated body temperature

Question 17

Why is there always an oxygen deficit even if intensity of exercise is low?

Answer 17

All activities will be anaerobic for the first 3 minutes.
This is because there is not sufficient oxygen available for aerobic respiration to occur until after 3 minutes (oxygen transport takes time!)

Question 18

What is the Cori cycle?

Answer 18

The process where lactic acid is converted into glucose and glycogen in the liver

Question 19

What can reduce the time it takes an athlete to return blood lactate levels to normal levels?

Answer 19

An active cool down (active recovery)

It can take 1 hour to remove lactic acid if completing an active recovery (2 hours if passive)

Question 20

What is the carbohydrate window?

Answer 20

The optimal time to take on a high carbohydrate meal following exercise. The window is within the first 45-60 minutes following exercise and should contain 200-300g of CHO.

Question 21

What are the advantages of the aerobic energy system?

Answer 21

No fatiguing by products produced.
Triglyceride and glycogen stores allow for slow release energy over a prolonged period.
It is efficient - 38 ATP molecules can be resynthesised.
Glycogen loading can prolong aerobic capacity for activities lasting 90 mins or more.

Question 22

What are the disadvantages of the aerobic energy system?

Answer 22

It takes 3 minutes for enough oxygen to be available to work aerobically.
There are many chemical reactions which need to take place so it can only be used at low to moderate intensities.