In many yoga classes, the poses are paired with the breath and instructors will often tell you to inhale or exhale before or as you move into and through poses.
For many reasons, students of yoga may want to understand why and when to inhale versus exhale; perhaps you are a curious science yogi type, or your practice could benefit from more breath, or your yoga instructor has stopped cuing verbally and you have to maintain the breath on your own.
Yoga poses try to pair the inhale or the exhale with the anatomical changes that occur during the respiratory change.
Inhaling
Mindfully: Sit in a comfortable position and deeply inhale. Listen. Feel. What happens to your body? Air fills the lungs, fills the belly, you sit up a bit taller, your rib cage expands, your chest puffs up, and so on.
Anatomically: A muscle (diaphragm) and muscle group (intercostals) are primarily responsible for some of these changes.
The diaphragm, the dome-shaped muscle at the base of the lungs and ribcage contracts and pulls down, allowing the lungs to expand, and subsequently air flows inward. The intercostal muscles, situated between rib bones, also contract and pull the ribcage outward, increasing the lung volume.
Asana-ically: What kinds of poses pair well with the anatomical changes that occur during inhale? Poses that have you expanding your chest, sitting up taller, and reaching your arms overhead like Urdhva Hastasana, rising into Warrior I, or sitting up tall during Seated Spinal Twist.
Exhaling
Mindfully: Sit in a comfortable position and deeply exhale. Listen. Feel. What happens? The lung volume decreases as the ribcage moves inward, your shoulders may drop, your back and spine relax, and so on.
Anatomically: The diaphragm relaxes, reforming a tight concave dome, pushing the lungs upward and pushing air up and out. The intercostal muscles relax, allowing the ribcage to compress, also pushing the air out by decreasing lung volume.
Asana-ically: What kinds of poses pair well with the anatomical changes that occur during an exhale?
Well, consider poses that do what your body naturally does during an exhale. Poses that have you folding inward, curling, and twisting like Uttanasana, Downward Facing Dog, or any pose in which you are deepening a twist (Chair Twist, Low Lunge Twist).
Additional Tips
If in doubt, try to remember that in general, inhales are for length and opening, while exhales are for deepening folds and twists.
And, if you find yourself lost and out of sync with your inhale and exhale, an important thing to remember is that you have already been mindful of your breath—don’t worry, it will come back.