Energy
Respiration
Respiration is a chemical reaction that happens in all living cells. It is the way that energy is released from glucose, for our cells to use to keep us functioning.
Remember that respiration is not the same as breathing (which is properly called ventilation).
Aerobic means with oxygen. Some oxygen is used by the body and muscles to release energy.
Anaerobic means without oxygen this is often when exercising maximally/intensely/flat out.
Aerobic respiration
The glucose and oxygen react together in the cells to produce carbon dioxide and water. The reaction is called aerobic respiration because oxygen from the air is needed for it to work.
This is the equation for aerobic respiration:
glucose + oxygen → carbon dioxide + water (+ energy)
Carbon dioxide and water are the by-products of aerobic respiration.
Anaerobic respiration
Anaerobic respiration is a type of respiration that does not use oxygen. It is used when there is not enough oxygen for aerobic respiration. It can be summarised by the following equation:
glucose → lactic acid (+ energy released)
The lack of oxygen will reduce the length of time energy can be produced for and, therefore, the length of time a performer may exercise for at that intensity.
Lactic acid (also known as lactate) is the by-product of anaerobic respiration.
Sources of Energy
Energy sources: fats as a fuel source for aerobic activity; carbohydrates as a fuel source for aerobic and anaerobic activity
Carbohydrates are a fuel source for aerobic and anaerobic activity which provide the athlete with energy for exercise and movement. Energy from carbohydrates is released more rapidly.
Carbohydrates are stored as glycogen and converted into glucose during exercise.
Fats are a fuel source for aerobic activity only.Energy from fats is released more slowly.
Fats should form smaller part of diet than carbohydrates
Fats are stored as triglycerides and converted to free fatty acids when required.
Carbohydrates and fats are the main energy providers, and the intensity and duration of exercise plays a key role in determining which of these are used. The breakdown of fats to free fatty acids requires more oxygen than is required to break down glycogen, so during high-intensity exercise, when oxygen is in limited supply, glycogen is the preferred source of energy
Stores of glycogen are much smaller than stores of fat and it is important during prolonged periods of exercise not to deplete glycogen stores, as some needs to be conserved for later when the intensity could increase, for example the last kilometre of a marathon.