Cardio-respiratory system - WJECLung volumes

Vital capacity is the maximum amount of air that can be breathed out after breathing in as much air as possible. Taking part in regular aerobic exercise has been shown to increase a person's vital capacity.

Breathing rate (frequency, BR) is the number of breaths in a minute. The average breathing rate is 12 breaths per minute.

Tidal volume is the amount of air breathed in with each normal breath. The average tidal volume is 0.5 litres (500 ml).

Minute ventilation (VE) is the total volume of air entering the lungs in a minute. The average minute ventilation is 6 litres per minute.

Minute ventilation = breathing rate × tidal volume

VE = BR × TV

6 litres per minute = 12 × 0.5

During exercise, tidal volume increases as does the depth of breathing and the rate of breathing. This has the effect of taking more oxygen into the body and removing more carbon dioxide.