stiebs
Contributor
Your lungs may not be muscles, but their usable capacity is dictated by the muscles via the diaphragm. And just like with any other muscle, you can train your diaphragm to make your lungs suck in more air than they usually would.
When I did my first lung capacity test as an adult, my lung capacity was measured at just over 6 litres. A few years later after a three year break from apnea based sports (spearfishing (snorkelling) and underwater hockey) my lung capacity was measured at 5.2 litres. It is now back up to 5.7 litres.
