Breathing patterns and body oxygenation
Do we notice that our breathing is heavy?
Usually, people notice that their breathing is heavy when they breathe more than 25 l/min at rest (or 4-6 times the norm!).
Why is this? Air is weightless, and breathing muscles are powerful. During rigorous physical exercise we can breathe up to 100-150 l/min. Some athletes can breathe up to 200 l/min. So it is easy to breathe "only" 10-15 l/min at rest (only 10% of our maximum capacity), throughout the day and night and not be aware of this rate of breathing.
However, in health, we should breathe only about 3-4% of our maximum breathing rate.
It is nevertheless normal during rigorous exercise to breathe, 50 or more l/min since, while exercising, CO2 and O2 concentrations in the arterial blood can remain nearly the same as at rest.