All living cells need to breath (think about an image here)
Breath in, extend your spine, bring the power of fresh energy into the nose, throat, diagphram pushing into the digestive organs – deepen the inhalation thru the upper torso into the deep back muscles, hamstrings, and calf muscles.
On the exhalation the diaphragm permits a release that lulls the stetching muscles into deeper stretches and relaxation.
The body is folded upon itself. The inhalation takes a little energy. The exhalation tends to be resisted a little, keeping even lengths. Active inhale requires energy to expand and active exhale requires a little resistance. Breathing should be nice and easy, flowing, soothing, and relaxing.
Pose is semi inverted, the diaphragm presses the abdominal organs towards the ceiling when inhaling and the diaphragm eccentrically resists the fall of the abdominal organs against the underside of the diaghram, exhaling a little more completely than ususal.