LO5: Energy Systems

Question 1

Aerobic

Answer 1

With oxygen
It needs oxygen to produce energy
Produces lots of lower-level energy
Lactic acid is not a by-product
Athletes can keep working (hours)

Question 2

Anaerobic?

Answer 2

Without oxygen
It doesn’t need oxygen to produce energy
Produces some high-level energy
Lactic acid my be a by-product
Athletes can only work for short periods

Question 3

ATP-PC System (Alactic system)

Answer 3

An anaerobic system, doesn’t require oxygen to produce energy, produces enough energy to resynthesise one ATP.
It releases a high amount of energy which can make muscle fibres contract quickly producing a lot of force/power.
The problem is that the muscle only stores a small amount of PCr, enough to last approx 10 seconds.
Creatine Phosphate (or Phosphocreatine) is a high energy compound found stored in the sarcoplasm of the muscle cells.
It is affected by the enzyme creatine kinase. When we exercise the breakdown of the high energy bonds between Phosphate and Creatine increases, which releases stores energy (exothermic reaction).
This energy is used to resynthesise ADP back into ATP (endothermic reaction).

Question 4

Advantages of ATP-PC System (Alactic system)

Answer 4

​No fatiguing by-products
Energy is stored in the muscle
Energy is provided immediately
It doesn’t need oxygen to provide energy.
Fewer reactions are involved

Question 5

Disadvantages of ATP-PC System (Alactic system)

Answer 5

It only lasts 10 seconds.
The ratio of reynthesise 1:1
There are limited stored of CP that cannot be greatly increased.
The ATP-PC system is only highly effective in the use if short, high-intensity exercises and sport. E.g., 100m, a hockey penalty or a gymnastics vault

Question 6

Lactic Acid System (Anaerobic Glycolysis)

Answer 6

An anaerobic system, doesn’t require oxygen to produce energy, produces enough energy to resynthesise 2 ATP.
When the ATP-PC system starts to fade at around 10 second, the process of anaerobic glycolysis (the break down of glucose) begins.
The lactate system is a high energy system. Glucose is a more complex compound than the PCr and as such stores more energy producing 2 ATP.
Important in events like: 200m sprint, 400m sprint, 100m swim, which require all out energy for up to approx 60-90 secs.

Question 7

Advantages of Lactic Acid System (Anaerobic Glycolysis)-

Answer 7

It has a fast speed of reaction for fast work.
Few reactions are involved in the production of energy.
Provides more ATP than the PCr system (2 ATP for every one glycogen molecule)
It doesn’t require oxygen to provide energy.

Question 8

Disadvantages of Lactic Acid System (Anaerobic Glycolysis)

Answer 8

Lasts between 30 seconds and 3 mins depending on intensity.
The by-product of this system, lactic acid, is fatiguing to muscles.

Question 9

Aerobic System

Answer 9

An aerobic system, does require oxygen to produce energy, produces enough energy to resynthesise 38 ATP.
Long-term energy system.
When plenty of oxygen is available (everyday movements and light exercise) glycogen and fatty acids break down to allow us to resynthesise the greatest amount of ATP.
Side effects = carbon dioxide and water.
This DOES NOT affect the muscle contracts or our ability to keep exercising, unlike the lactate system.

Question 10

Aerobic glycolysis

Answer 10

It converts carbs (glucose or glycogen) into pyruvic acid using oxygen.
This breakdown requires 10 chemical reactions (another reason this system is slower than the anaerobic systems).
The first stage resynthesises 2 ATP.

Question 11

Krebs cycle/citric acid cycle

Answer 11

Takes place in the Mitochondria.
The Pyruvic Acid produced in Stage 1 enters the mitochondria and is converted into Citric Acid.
Carbon dioxide and Hydrogen are waste products at this stage.
The carbon dioxide is breathed out.
Hydrogen is used in the 3rd stage of the aerobic energy system.
The second stage resynthesises 2 ATP.

Question 12

Electron Transport Chain

Answer 12

The hydrogen is released in stage 2 is VITAL in the production of energy.
The ETC is the MOST important step in energy production and is where the majority of ATP is created.
The hydrogen created in Stage 2 as part of the Krebs cycle is accepted by the hydrogen acceptor found in the mitochondria where ATP can be produced, where oxygen is available. This third stage resynthesises 34 ATP.

Question 13

Advantages

Answer 13

No fatiguing by-products.
It has almost limitless energy production potential.
It’s very efficient at producing energy (38 ATP for every molecule of glycogen and 138 ATP for every palmitic acid molecule).
It uses fats an an energy store.

Question 14

Disadvantages

Answer 14

Only suitable for low to moderate intensity activities.
It takes time to transition to this system.
It takes 20 mins to start using fats as energy source.

Question 15

EPOC

Answer 15

EPOC is the result of an elevation in oxygen consumption which occurs after exercise as the body recovers, repairs, and returns to its pre-exercise state. This can happen for up to 24 hours. The extent and duration of EPOC are dependent on the workout intensity.

Question 16

Fast EPOC

Answer 16

This deals with the resynthesise of phosphocreatine (PC).
Here, the aerobic system provides the energy needed to reverse the original exothermic reaction where energy was released.
The reason why PC recovery is called the fast component is because it is possible to resynthesise 50% of the PC in our body in the first 30 seconds, 75% in the first 60 seconds, and 98% in 3 minutes.

Question 17

Slow EPOC

Answer 17

This is specifically concerned with the removal of lactic acid.
Rather than lactic acid being the ‘unwanted’ by-product which causes cramp, and the muscles to stop contracting, here we see it being used as an energy source, especially for the heart during exercise.
The removal of lactic acid from the muscles can happen through a series of different methods:
With a surplus of oxygen being available, the body is now able to convert lactic acid back into Pyruvic acid.
In a reversal of glycolysis, the pyruvic acid can then be converted back into glucose and glycogen.
Lactic acid can be removed to the liver, through the cori cycle. It can be converted back to glycogen and returned to the muscle. The whole process of removing the lactic acid is a lengthy process compared to the restoring the PC system.
It can take two or more hours depending on how intense the exercise was and if a cool down was completed.