Ujjayi is a closed mouth, vibrational, heating breath we use in Asana (posture) practice and Well yes it does work!
Long and short of it, if you exercise it, it will get stronger! But how is this possible, if something akin to sounding like a growl, a hum, or “Darth Vader”, sounds only like it would make you hoarse, how does it actually work?
1) The heat of the breath: when you breath “heavy” like this it’s hot and humid too- This is actually how we avoid getting dry or hoarse, it’s like a steam breath for our own throat!
2) The duration of the breath: helps to expand the lungs, the more we do this, without even trying, the capacity of our lungs grows. In simplistic terms think of the first time you blow up a balloon, you have to push past the initial resistance but then it expands more easily, same initial theory.
3) The vibration of the breath: literally helps shake “things” loose, in the sense of cleaning out toxins, getting out stale air, and other particles that have settled down into the bottom portion of your lungs.
If these facts still don’t convince you of the benefits, try a little test (on a day when you are not warmed up from any sports or the temp outside, maybe even feeling a little cool in the A/C) crank up your Ujjayi breath for (3) solid minutes breathing deeply against the constriction with mouth closed.
Be Real about it or the test won’t work, and see if after just 3 minutes you haven’t warmed yourself up from the inside maybe even made your nose run, or had to clear your throat!