energy systems

Question 1

What fuels are involved in resynthesis of ATP?

Answer 1

Glycogen: Stored in the muscle and liver. It is converted into glucose before being used for ATP resynthesis. This can be done both aerobically and anaerobically.
Fats: At rest 2/3 of energy requirements are met through breaking down fatty acids. Rich in energy, but require large amounts of 02 to be broken down. Transport in fats is slow so it’s only used in low intensity.
Protein: Contribute the least to the energy yield (only 15%). Used when carbohydrates and fats stores are low.
Phosphocreatine: A chemical stores within the muscle cell. Used within the first 10 seconds of intense exercise.

Question 2

What is the difference between the fuels of glucose, fats and protein in the aerobic system?

Answer 2

Glucose is the most efficient way of resynthesis ATP, as it’s oxidation produces 38 molecules of ATP.

When fats (fatty acids) are broken down, they’re reduced to the molecule acetyl coenzyme A. This molecule enters the krebs cycle.

When the proteins (amino acids) are broken down, they too are reduced to the molecule acetyl coenzyme A. This molecule enters the krebs cycle

Question 3

What occurs in glycolysis? (Oxidative system)

Answer 3

Takes place in the sarcoplasm of the muscle cell.
Breaks glucose down into pyruvic acid via the enzyme phosphofructokinase (due to 02 present).
During glycolysis, every 1 molecule of glucose produces 2 molecules of ATP.
Pyruvid acid is then converted into acetyl coenzyme A as 02 is present.
If there isn’t sufficient oxygen present, it will turn into lactic acid.
Acetyl coenzyme A is carried into the Krebs cycle.

Question 4

What occurs in the Krebs cycle?

Answer 4

Takes place in the mitochondria which produces high levels of energy.
As a result of the Krebs cycle, the acetyl groups are carried in combine with oxaloacetic acid.
This forms citric acid: citric acid is produced and then undergoes oxidative carboxylation.

As a result, the following are produced: C02, H20, H+ions and 2 ATP.
The hydrogen atoms enter the third stage of the aerobic system.

Question 5

What occurs in the electron transport chain?

Answer 5

Takes place in cristae of the mitochondria.
Hydrogen atoms enter the electron transport chain where lots of energy is produced - enough to resynthesis 32-34 more ATP.
Consequently, that 1 molecule of glucose/fat/protein has produced 36-38 ATP which is a really high energy yield.

Question 6

What is beta oxidation?

Answer 6

Stored fats can be used in a very similar way to glucose.
Firstly, they must be broken down from triglycerides into glycerol and free fatty acids.
The glycerol and free fatty acid go through the process of beta oxidation (glycolysis for fats).
This forms oxaloacetic acid which combines with Acetyl Coenzyme A.
Once combined with Acetyl Coenzyme A, it can now enter krebs

Question 7

Positives of the oxidative system?

Answer 7

1 molecule of glucose/fat/protein has produced 36-38 ATP
a really high energy yield
lots of energy over a long period of time
no fatiguing by-products
high stored of glycogen and triglyceride meaning exercise lasts for a long time

Question 8

Negatives of aerobic system?

Answer 8

system can only be used during submaximal activities
energy production is not rapid, will take minutes
fatty acid transportation in muscles is low
fatty acids require 15% more oxygen to be broken down

Question 9

Positives of the anaerobic glycolytic system?

Answer 9

ATP resynthesised quickly due to fewer reactions
Lasts longer than ATP-PC system
If oxygen present, lactic acid is converted back to glycogen
Used during a sprint finish for extra bursts of energy

Question 10

Negatives of anaerobic glycolytic system?

Answer 10

Lactic acid is the by-product
Accumulation of lactic acid denatures enzymes
Prevents the rate at which chemical reactions can take place
Small energy yield (2ATP)
Energy from anaerobic conditions is low (5%) compared to energy from aerobic conditions (95%)

Question 11

Positives of ATP-PC system?

Answer 11

energy released quickly
ATP resynthesised quickly
allows high intensity to be completed again in a short space of time
no waste by-products formed
can extend duration of system through creatine supplementation

Question 12

Negatives of ATP-PC system?

Answer 12

limited phosphocreatine stores
can only be completed for 8-10 seconds
full recovery takes 2-3 minutes
PC resynthesis can only take place in the presence of oxygen
only one molecule of ATP can be resynthesised for every one molecule or PC (poor energy yield)

Question 13

What is the anaerobic glycolytic/aerobic threshold?

Answer 13

The point at which the anaerobic glycolytic system is exhausted and the aerobic system takes over.
This happens at 3 minutes

Question 14

What is oxygen consumption at rest?

Answer 14

0.3-0.4 li/min

Question 15

What is the average maximal oxygen consumption?

Answer 15

3-6 li/min

This is our VO2 max

Question 16

Define EPOC

Answer 16

Post-exercise oxygen consumption

this is our recovery phase
when we recover from any activity, we go into EPOC

Question 17

How is lactic acid removed in the slow component?

Answer 17

4 ways:
- When O2 present: Lactic acid → pyruvate → CO2 +H2O in the inactive muscles and organs - this can then be used by the muscles as an energy source.

Cori cycle: Transported in the blood → liver, then converted into blood glucose and glycogen
Converted into protein
Removed in sweat and urine

Question 18

What is OBLA

Answer 18

Onset of blood lactate accumulation

Also known as the accumulation of lactate in the blood

Question 19

How does gender affect VO2 max?

Answer 19

Men generally have approx. 20 per cent higher VO2 max than women.

Question 20

What are the measurements of energy expenditure?

Answer 20

Indirect Calorimetry
Lactate sampling
Respiratory exchange ratio
VO2 max test

Question 21

What is indirect calorimetry and how does it work?

Answer 21

It measures the production of CO2 and the consumption of O2.
Provides an accurate estimate of energy expenditure through gas exchange.
Measures the production of CO2 and O2 at both rest and during exercise.
Enables the performer to find the main fuel being used (e.g. fats/carbohydrates).
It is an accurate test which provides a precise calculation of VO2 and VO2 max.

Question 22

What is lactate sampling and how does it work?

Answer 22

Involves taking blood samples to measure the level of lactic acid in the blood.

Provides accurate and objective measures by measuring OBLA/lactate threshold which occurs at 4mmols.
The higher the intensity at which OBLA occurs, the fitter the athlete.
Ensures training is at the correct intensity, gives an idea of fitness levels and enables the coach to monitor improvements over time.

Question 23

What is respiratory exchange ratio and how does it work?

Answer 23

Measures the ratio of CO2 released compared to O2 used by the body.

Estimates the use of fats and carbohydrates used during exercise/calculates energy expenditure.
Requires the performer to be attached to a gas analyser while on a treadmill or cycle ergometer.
Enables accurate readings.
Tells if performer is working aerobically or anaerobically and indicates which energy system is being used.