Aerobic and Anaerobic Exercise (OCR GCSE Physical Education (PE)): Revision Note

Aerobic and anaerobic exercise

• When we exercise, cells of the muscles need to be supplied with sufficient energy for muscle contraction

• Cellular respiration is a reaction which is continuously occurring in living cells to release energy during exercise

• The type and intensity of exercise will determine which processes occur:

  • anaerobic

  • aerobic

Aerobic exercise

• Aerobic exercise takes place in the presence of oxygen

• It occurs when there is a low to moderate demand for energy

• Glucose from carbohydrates and fats supply the energy for the aerobic energy system

• The equation that summarises the chemical reactions of aerobic exercise that release energy from glucose is:

Glucose + oxygen → energy + carbon dioxide + water

• It can be sustained for a prolonged period of time because there is lots of glucose available and no build-up of lactic acid

Anaerobic exercise

• Anaerobic exercise is performed in the absence of oxygen

• It occurs during high-intensity activities when the heart and lungs cannot supply blood and oxygen to the muscles as fast as the respiring cells need them

• This system uses glucose stored in our muscles as glycogen as fuel to produce short-term bursts of energy very quickly

• The equation that summarises the chemical reactions of anaerobic exercise that release energy from glucose is:

  Glucose → energy + lactic acid

• The build-up of lactic acid causes muscle fatigue and pain; therefore it can only be sustained for a short period of time