There are three main energy systems in the body: the phosphocreatine system provides short bursts of energy for up to 12 seconds; the lactic acid system provides moderate power for 45-120 seconds; and the aerobic system provides sustained low-power energy for over 2 minutes. ATP is produced through each system and provides energy to power muscle contractions and cellular processes. Energy is stored and released through different metabolic pathways depending on the intensity and duration of exercise. [/SUMMARY]

1. Energy Systems
By Josh Woodhouse

2. What is Energy.
There are many different forms of energy, a few being; kinetic, thermal
and chemical. Energy is found in carbohydrates and fats, the energy
from these is released through oxidation and carried by ATP. Energy
isn’t made or used up, it is only converted from one form of energy to
another.
(Biology-Online, 2016)
We need energy for:
• Muscular Contractions and Movement
• Circulation
• Transmission of Nerve Impulses
• Digestion of Foods
• Repairing and Replacing tissues

3. ATP
The whole body uses an energy source called ATP to keep everything
working. Adenosine Triphosphate is the body's way of storing and using
energy.
ATP is and Adenine and Ribose molecules with 3 Phosphate molecules.
The energy is stored in the bond of the second and third phosphate
molecules.
The bond is broken when a cell needs energy, creating Adenosine
Diphosphate(ADP) and an extra phosphate molecule.
ATP is formed from ADP when a cell as excess energy.
ATP is needed for any muscles contraction. If the work or the muscles
increases then there would be more ATP used and need to be replaced.
(Writer and Bodybuildingcom, 2015)

4. Energy System
There are 3 energy systems in the body:
• Phosphocreatine system
• Lactic Acid system
• Aerobic Energy system
Calories is a term for energy used by the body. This table is showing the different
amount of calories used by each energy system per minute.
Energy System Calories per minute
Phosphocreatine 36
Lactic Acid 16
Aerobic Energy 10

5. Phosphocreatine System
High power- short duration.
The chemical name is ATP-PC.
This system doesn’t require oxygen and works immediately.
This system works for up to 12 seconds at maximal effort. The ATP supplies
energy for the first few seconds of activity and then PC is used until another
system is needed.
(Breakingmuscle, 2016)
Training and Diet can increase phosphocreatine content in the muscles.
PC+ADP=> ATP+ Cr
(Mackenzie, 2016) Recovery Time (Seconds) PPO recovery (%)
15 68.7
30 73.6
45 78.1
60 81.0
120 88.2
180 92.2

6. Lactic Acid System
Moderate power- moderate duration.
Like ATP-PC oxygen isn’t needed.
The system comes in to pay when the phosphocreatine system cannot
work any longer.
Glucose from the diet is stored as glycogen in the muscle and the liver,
and circulates in the blood.
ATP is created by the breakdown of blood glucose and stored glycogen
through a process called glycosis (Breakingmuscle, 2016)
To remove lactic acid it can take up to 1 hour to get to the original
levels. Walking and jogging as intense exercise can increase the rate
that lactic acid is removes. With the greatest spike of removal
occurring in the frst 10 minutes.
Glucose+2ATP=>Pyruvic Acid=>Lactic Acid+2ATP
(Mackenzie, 2016)

7. Aerobic Energy System
Low power- long duration
Uses oxygen
For the aerobic energy system to reproduce ATP it uses mainly
carbohydrates, fats and if necessary proteins.
More ATP is produced then the other energy systems but not
at a rate fast enough to fuel intense exercise.
The aerobic energy system can be developed using interval
training, continuous training and ‘fartlek’ training.
(Ptdirect, 2016)
Glucose+ Fats+ Amino acids+ Oxygen=> Krebs cycle=>
34ATP
(Mackenzie, 2016)

8. How Much ATP is Made
System Molecule ATP made
Immediate Creatine Phosphate 1
Short Glucose 2
Short Glycogen 3
Long Glucose 38
Long Fatty Acids 129
(Mackenzie, 2016)

9. Energy Systems and Different Sports
Duration Classification Energy Supplied by Sporting Example
1-4 seconds Anaerobic ATP (in muscles) Power lifting
4-10 seconds Anaerobic ATP+PC 50m sprint
10-45 seconds Anaerobic ATP+PC+ Muscle
glycogen
50m swim
45-120 seconds Anaerobic/ Lactic Muscle glycogen 200-400 meter run
120-240 seconds Aerobic+ Anaerobic Muscles glycogen+
Lactic
A round of boxing
240-600 seconds Aerobic Muscle Glycogen+
Fatty acids
1 mile run
(Mackenzie, 2016)

10. Bibliography
(Mackenzie, 2016) Anaerobic and aerobic energy pathways. Available at:
https://www.brianmac.co.uk/energy.htm (Accessed: 17 November 2016).
(The energy systems, 2016) Available at: http://www.coachr.org/energy_systems.htm (Accessed: 17 November
2016).
(Writer and Bodybuildingcom, 2015) ATP: What is it & why is it important? Available at:
http://www.bodybuilding.com/fun/galanis9.htm (Accessed: 17 November 2016).
(Biology-online, 2016) Available at: http://www.biology-online.org/dictionary/Energy (Accessed: 17 November
2016).
(Breakingmuslce, 2016) Available at: https://breakingmuscle.com/learn/understanding-energy-systems-atp-pc-
glycolytic-and-oxidative-oh-my (Accessed: 17 November 2016).
(Ptdirect, 2016) Available at: http://www.ptdirect.com/training-design/anatomy-and-physiology/the-aerobic-
system (Accessed: 17 November 2016).