Central to Zen meditation (zazen) is maintaining attention on the breath in the lower abdomen (hara). With patient, persistent practice, this cultivates both a stabilizing & energizing force - anchor, ballast & power plant - not just during meditation, but throughout life. This practice is central to all Chinese, Japanese, & other Eastern martial arts & is the basis of "core strength" in gymnastics, diving, dance, figure skating etc.
A baby sleeping on her back will breathe slowly, regularly, the chest remaining still, the abdomen slowly rising & falling. This is normal, healthy abdominal (diaphragmatic) breathing. When a deep breath is taken, first the abdomen rises (due to the diaphragm bowing towards the stomach, thus displacing the abdominal organs outwards), then near the end of the inhalation, the (intercostal) muscles between the ribs become activated, expanding the chest. On exhalation, the intercostal muscles relax, the chest returns to normal, then the diaphragm relaxes, allowing the abdomen to return to normal.
This is very efficient breathing and is naturally slower than the way many today breathe - chest breathing - which is intentionally (self-consciously) holding the abdomen in, and breathing primarily in the upper chest.
James Nestor wrote a very interesting short article (based on his book: "Breath: The New Science of a Lost Art"): https://www.theguardian.com/lifeandstyle/2020/jul/26/every-breath-you-take-the-lost-art-of-breathing?utm_source=pocket-newtab In it he writes about the benefits of abdominal breathing:
"But lest we forget, nature is simple but subtle. For me, the perfect breath is this: inhale for about 5.5 seconds, then exhale for 5.5 seconds. That’s 5.5 breaths a minute for a total of about 5.5 litres of air. You can practice this perfect breathing for a few minutes, or a few hours. When we breathe like this, breathing practitioners suggest that circulation in the brain and body will increase while the burden on the heart decreases. All the while the diaphragm – that umbrella-shaped muscle in our chests – will drop lower and rise higher, allowing more air to enter the lungs and assisting in pushing blood throughout the body. For this reason, the diaphragm is sometimes referred to as 'the second heart', because it not only beats to its own rhythm but also affects the rate and strength of the heartbeat."
A key component needs to be added - the quality of our relationships. A surprising number of us relate to our own breath much like the new owner of a car who has absolutely no interest in or affection for their car other than to use it to go places. Disconnection / dissociation from not only our own breath, but also from the rest of our body, from our own deepest values, from our family, friends & co-workers, from our community, from the environment, from nature, from the present moment, from our very life - is more common than we realize AND is profoundly alienating, lonely & unhealthy.
A small but important step towards re-establishing a healthy, normal relationship with life is through our breath. A normal healthy relationship is modeled by our hands. How do our left & right hands naturally relate to each other? That's a deep question to silently ponder - and then bring to ALL of our relationships.
We can all use a breath of fresh air in our lives.