2. What is energy?
• Energy is a property of objects which can be transferred to other
objects or converted into different forms. (Reference: Wikipedia)
• We gain energy through a long chain, it originates from the sun as
light energy. The sun then causes plants to grow and the energy is
transferred into chemical energy and makes chemical carbohydrates.
Animals then eat the plants and take on chemical carbohydrates and
gain chemical energy. We then eat animals and plants, then convert
the chemical energy into kinetic energy, this helps us perform exercise
at well and sometimes at long periods of time. This is known as
thermodynamics, the law of thermodynamics is that energy can not
be created or destroyed but can just change in to different forms.
3. What do we need energy for?
• We need energy to be able to digest food, our body uses energy to break down foods and give our
body the key things it needs, when digesting food our body turns chemical energy into
mechanical energy and then into thermal energy, these changes of energy help the breaking
down of the foods.
• We also need energy to repair and replace tissues, this means if we get injured, for example pull a
muscle, our body will help repair the muscle by using energy. Our body uses proteins, fats and
carbohydrates to be able to replace and repair tissues, if we do not eat enough fat and
carbohydrates our body will mainly use proteins to repair the tissues.
• Energy is also needed for muscular contractions, to help us move, the source of energy used for
this is ATP. When muscular contractions start to occur ATP has to be made at quite a quick rate as
it is not stored in the body at a large extent.
• We need energy for circulation, energy is key for healthy blood flow, this is because we need
energy for our heart to be able to contract properly and keep the blood flowing around the body
properly.
• We also need energy to be able to transmit nerve impulses around our body, we need nerve
impulses, as it is the way the cells communicate with one another, this helps us move and also
helps us to react quickly.
4. ATP-Adenosine Triphosphate
• ATP is a bond between adenine, ribose and phosphate, there a 3
phosphates which are all joined by energy rich phosphate bonds. If our
body needs energy immediately and energy needs to be released into the
cells very quickly, for example to be able to keep your muscles contracting
when sprinting, one of the triphosphate bonds are broken in the ATP.
Energy is released into the cells when the bond is broken. ATP then
becomes ADP+P+Energy, this is because the phosphate is by itself when it
splits and it creates energy. Therefore the Adenosine Triphosphate
becomes Adenosine Diphosphate. ATP is made in the mitochondria of cells
and is produced by many different energy systems.
• ATP is needed by our cells as energy for, muscular contractions, building up
proteins, transmission of nerve impulses and cell division.
5. Phosphocreatine
• Phosphocreatine is an energy source which is used for muscular contraction it is present
in the skeletal muscle tissue. It enables explosive power in the muscles, but it does not
last much longer than 12 seconds. It is also known as the anaerobic alactic system, it is
anaerobic as it does not need oxygen to function. It is a molecule that gives off high
energy phosphates in the brain and skeletal muscles. This system is used during high
intensity exercises, this is because it gives you short quick bursts of energy. The equation
for this is ADP + PCr -> ATP + Cr.
• It brings back small amounts of ATP very quickly, ATP is very important for movement,
therefore as you get the ATP in small and quick amounts, phosphocreatine is better for
short burst exercises such as 100m sprints and weightlifting. However, this would not be
good for athletes who run long distances or perform for a long period of time as they will
not be getting enough ATP from the phosphocreatine throughout the activity.
• The recovery time after using the phosphocreatine energy system is around 3 minutes,
for example after running 100 metres sprint your phosphocreatine system will take 3
minutes to regain energy and therefore you will not be able to use this energy system for
3 minutes, therefore you could not run 100m then straight after another 100m .
6. Lactic Acid System
• Lactic Acid is a waste product that is made whilst exercise and it causes your
muscles to lock up and because it is an acid it causes your muscles to experience
a burning feeling. It is produced during intense levels of exercise when oxygen
demands of the muscle fibres goes beyond what the blood is capable of .
• The lactic acid system is an anaerobic energy system, as it does not use oxygen,
this is when ATP is made from the breakdown of glucose to pyruvic acid in muscle
cells. The lactic acid system can be used for around 2 minutes, but it does not
produce as much energy as phosphocreatine. The lactic acid system is dominant
from about 10-30 seconds during intense exercise, it produces 2 ATP molecules
per glucose molecule. It has a recovery time of around 8 minutes, therefore if you
run a long distance you will have to wait quite a while to be able to get more
energy from the lactic acid system after completing the event.
• This system is used in a variety of sports, such as 200m and 400m as you need
lost of energy but phosphocreatine does not last long enough so this system is
used, it is also used in swimming events for the same reason.
7. Aerobic Energy System
• The aerobic energy system produces more ATP than either of the other
energy systems but it produces it much more slowly, therefore it cannot
fuel intense exercise that demands the fast production of ATP. Aerobic
refers to all exercise that requires oxygen to help produce energy. The
aerobic energy system can continue to supply energy for over 2 hours, but
it does not produce as much as the others. Therefore sports such as long
distance running, cycling, boxing and swimming use this system.
• If glucose is used to produce the ATP then 38 ATP is made, and if fatty acids
are used then 129 ATP is made. The recovery time can vary, it depends how
much ATP is replenished it can range from 30 seconds recovery time if 50%
ATP is replenished up to 3 minutes recovery time if 98.5% ATP is
replenished.
8. Analysis
Below is a graph showing the changes in velocity for the 100 metres runner Mo.
9. Analysis-Continued
• At the start of the race the graph shows that Mo accelerated for the first 40 metres, therefore he is getting
quicker. From 40 metres and onwards he goes at a continuous rate which means he is not getting any faster or
slower, he manages to maintain this for the rest of the race. This means he is more likely to win the race as he
maintained his speed and others may become slower and fall behind.
• At the start of the race your body uses the ATP system to gain its energy but this only lasts for a few seconds, so
after the first 20 metres you run out of energy from this system. So your body then uses the ATP-CP system to get
energy as it produces it reasonably quickly and then runs at after 10 seconds, so at the 80 metre mark your body
starts to use the lactic acid system to produce the energy. This does not produce the energy very quickly so this is
why for the last 20 metres sprinters start to slow down as lactic acid is building up.
• In a 1500m race various energy systems are also used, for the first 100 metres it is quite a quick pace as people
try to get in the best position possible, this means the ATP system and the creatine phosphate system are used to
gain energy as you gain it quickly and it only lasts a few seconds which means it is perfect as they only run quickly
for 10-15 seconds. From 100 metres to 1,100 metres the pace slows down and goes the same pace throughout
this means the lactic acid system is used to produce the energy this why throughout the race you can feel the
lactic acid building up in your legs. Throughout this distance the energy from the aerobic system increases as
your body needs more and more oxygen throughout the race as you are working for a long period of time. Then
for the last 400 metres the pace begins to pick up therefore the energy comes mainly from the lactic acid system
as you body is tired and you have to maintain that distance for quite a while so the ATP system and the ATP-CP
system will not be able to work for long enough. However, for the last 100 metres the athletes go flat out to the
finish line therefore your body uses the ATP system and the ATP-CP system to produce energy as it only lasts for
10-15 seconds and also because you are sprinting.
