Breathing frequency, tidal volume and minute ventilation

Overview

Breathing frequency, tidal volume and minute ventilation at rest, the minute ventilation equation with worked examples, the tidal volume plateau, and minute ventilation before, during and after submaximal and maximal exercise.

What you need to know

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Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Define breathing frequency and give a typical resting value.

   Model answer

   Breathing frequency is the number of breaths taken per minute. A typical resting value is 12–15 breaths per minute.

2. 2

   Define tidal volume and give a typical resting value.

   Model answer

   Tidal volume is the volume of air breathed in or out per breath. A typical resting value is about 0.5 litres.

3. 3

   Define minute ventilation and give a typical resting value.

   Model answer

   Minute ventilation is the volume of air breathed in or out per minute. A typical resting value is about 6–7.5 litres per minute.

4. 4

   State the equation for minute ventilation.

   Model answer

   Minute ventilation equals tidal volume multiplied by breathing frequency. The equation is VE = TV × f.

5. 5

   A performer at rest has a tidal volume of 0.5 L and a breathing frequency of 14 breaths per minute. What is the minute ventilation?

   Model answer

   The minute ventilation is 7 L/min. Tidal volume × frequency = 0.5 L × 14 = 7.0 L/min.

6. 6

   A resting minute ventilation of 6 L/min comes from 12 breaths per minute. What is the tidal volume?

   Model answer

   The tidal volume is 0.5 L, or 500 ml. Minute ventilation ÷ frequency = 6 L/min ÷ 12 = 0.5 L.

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