Oxygen Debt & Anaerobic Exercise (AQA GCSE Physical Education (PE))

Excess Post-exercise Oxygen Consumption (EPOC)/ Oxygen Debt

• EPOC (excess post-exercise oxygen consumption) also known as an oxygen debt is an increased rate of oxygen intake following strenuous exercise

• This can occur during anaerobic exercise

  • During anaerobic exercise much less energy is released to the muscles than during aerobic exercise

  • It also results in the formation of lactic acid as glucose is incompletely broken down

• Lactic acid can cause muscle fatigue and pain and needs to be broken down into safe chemicals

• To do this “extra” oxygen is needed to react with the lactic acid and repay the oxygen debt

  • This is why an individual still breathes heavily at an increased rate (with a higher heart rate than usual) after exercising anaerobically, more oxygen is required to rid the body of lactic acid

• Depending on the intensity and duration of the exercise, an oxygen debt can last up to several hours

Oxygen debt diagram

Heavy breathing after strenuous exercise is required to pay back an oxygen debt