The Efficiency of the Respiratory System (OCR GCSE Physical Education (PE)): Revision Note

Breathing rate, tidal volume & minute ventilation

• Performance of the respiratory system is assessed by measuring how much air is inspired or expired each minute

• Breathing rate (or frequency, f) is the number of breaths taken in one minute

  • The average resting breathing rate is approximately 12-15 breaths in a minute

• Tidal volume (TV) is the amount of air inspired or expired in a normal breath

  • The average resting tidal volume is approximately 500 ml

  • This can increase but up to 5-9 times during exercise

• Minute ventilation (VE) is the amount or volume of air inspired or expired in one minute

  • This can be calculated using the following equation:

    Minute ventilation (VE) = Breathing frequency (f) x tidal volume (TV)

• During exercise, the muscles need more oxygen to produce energy for muscle contractions and more carbon dioxide is produced as a waste product

  • This means our breathing rate (f) and tidal volume (TV) both increase and therefore VE also increases to make more oxygen available for the working muscles and remove carbon dioxide from the lungs