L3 BTEC Sport - Unit 1 - LA E - Aerobic System

Energy systems

Energy systems

These need to be used to resynthesise ATP to allow us to keep exercising. The intensity, duration, fuel source and availability of oxygen depends which one we use.

Adenosine Triphosphate (ATP)

A high-energy compound which is the only immediately available source of energy for muscular contractions.

Aerobic

System requires oxygen to produce energy.

Aerobic metabolism

The breakdown of food into energy using oxygen. It has 3 stages, so produces ATP slowly.

Mitochondria

A structure within the cell where aerobic respiration and energy production occur. Also known as the powerhouse of every cell.

Aerobic glycolysis

Converts glucose into pyruvic acid with the enzyme Phosofructokinase catalyzing the reaction, yielding 2 moles of ATP. Pyruvic acid is taken into the next stage of aerobic metabolism due to the presence of oxygen.

Site of aerobic glycolysis

Muscle sarcoplasm

Krebs Cycle

Pyruvic acid combines with CoA to form Acetyl CoA, which then combines with Oxaloacetic acid to form Citric Acid. The reaction yield 2 ATP. Hydrogen produced is passed onto the next stage of aerobic metabolism.

Site of the Krebs Cycle

Matrix of the mitochondria

Electron Transport Chain (ETC)

Receives hydrogen from the Krebs Cycle which are passed through the ATP, producing 34 molecules of ATP. Water (H20) is a by-product of this process.

Site of the Electron transport train

Cristae of the mitochondria

Glycogen sparing

Fats can be metabolised aerobically, providing a preferred and huge potential fuel store which conserves glycogen for higher-intensity sections

Duration

Low to moderate intensity exercise for longer than 3 minutes.

Recovery

It takes 24-48 hours for the body to replenish muscles with glycogen stores.

Waste products

Carbon dioxide and water

Sporting example

Endurance events - e.g. marathon

ATP yield

38 molecules of ATP from 1 mole of glucose

Advantages

High ATP yield, no harmful waste products produced and can provide energy for a long period of time.

Disadvantages

Delay for oxygen delivery, complex series of reactions, and slow energy production means it can only provide energy for moderate to low intensity exercise.