Respiration is influenced in very interesting ways in headstand. Since we’ve shifted the effect of gravity upon the body by turning upside down, we’ve done the same to our breathing. Right side up the diaphragm pushes the abdominal organs down and flattens out from it’s bowl shape to open the base of the rib cage. This vacuum helps pull air into the lungs. Upside down however the abdominal organs are now putting pressure on the diaphragm and the muscle has to work against gravity to lift the abdominal organs. Essentially, you’re making it workout.
The exhale in headstand is smooth, easy and not forced. As you relax the diaphragm releases and air smoothly flows out of the lungs as the abdominal organs press down helping force air out of the lungs. Combined with the usual ujjayi breathing that’s common in yoga you have a one two punch that strengthens, tones and refines the musculature of breathing. After years of practice, even when at rest, a yogi’s breathing is still full and strong from strengthening these areas.
Headstand also allows freedom to the legs and spine to move in many directions. Your hips are now free to move within whatever range of motion feels good. Upside down isn’t so bad.
I always say headstand is a yogic cup of coffee. I feel calm, alert, energized and focused after doing the pose.