Breathing is the endless alternation of two movements:
- breathing in (inhaling): the chest expands and air flows in through nose or mouth;
- breathing out (exhaling): the chest relaxes and air flows back out.
At rest, the pair repeats about times a minute — faster in babies, faster in effort — without your ever needing to think about it.
Examples
Example 26.2 (Watching the movements)
Hands flat on your ribs: breathing in, the rib cage rises and widens under your palms; breathing out, it sinks back. A sleeping cat’s flank shows the same rise and fall. The movements never stop — awake, asleep, from first cry to last day.
Example 26.6 (Why running takes your breath)
Sprinting, your legs burn energy fast — so they need oxygen fast. Breathing obliges: from about calm breaths a minute to or more, deep ones, while the heart (Chapter 27 tells its side) races to speed the deliveries. The panting after the race is the body settling its oxygen accounts.