A Journey Into Yin Yoga

PRANAYAMA AND MEDITATION 179

diaphragm moves up and down the
torso like a piston inside of a cylinder
(figure 6.1a). When air flows into the
body, the rib cage expands, and the
diaphragm moves downward and
flattens. This pushes the abdomen
out like a balloon (figure 6.1b). On
exhalation, the diaphragm releases.
The abdominal muscles contract and
push the air up. As the air leaves
the body, the intercostal muscles
between the ribs relax and the rib
cage becomes smaller (figure 6.1c).
When this process is impaired
through illness or injury or because
a person habitually takes shallow
breaths, the function of the dia-
phragm is limited, leading to short
or erratic breathing patterns. This
causes the blood to circulate less
oxygen through the body and to the
brain and activates the sympathetic
nervous system, causing the stress
reaction of fight or flight. The heart
pumps erratically, the mind become
anxiety ridden, and the person feels
emotionally depleted.
For someone who breathes deeply
and rhythmically, the opposite is
true. Each breath is full and rich with
oxygen. The diaphragm is strong
and supple and able to fully function
to supply the body with oxygen. The
blood vessels of the body and brain
dilate, allowing oxygen-rich blood
to circulate freely. The parasympa-
thetic nervous system is activated,
producing the relaxation response.
Natural feel-good chemicals such
as endorphins and serotonin are
released. The heart pumps steadily,
the mind is calm, and the person
feels emotionally balanced. I don’t
know about you, but I’m choosing
the second scenario!

FIGURE 6.1 Lungs and diaphragm (a) resting positions,

(b) inspiration, and (c) expiration.

Reprinted by permission from W.L. Kenney, J.H. Wilmore,

and D.L. Costill, Physiology of Sport and Exercise, 5th ed.

(Champaign, IL: Human Kinetics, 2012), 166.

E7122/Eliot/F04.04/598639/pulled-R2

Sternum

Ribs

Diaphragm

Resting positions of the diaphragm

and the thoracic cage, or thorax. Note

the size of the rib cage at rest.

During expiration, the lung volume

decreases, thereby forcing air out of

the lung.

The dimensions of the lungs and

the thoracic cage increase during

inspiration, forming a negative pressure

that draws air into lungs.

Atmospheric pressure =

760 mmHg

Intrapulmonic

pressure

= 760 mmHg

Intrapleural

pressure

= 756 mmHg

Atmospheric pressure =

760 mmHg

Intrapulmonic

pressure

= 758 mmHg

Intrapleural

pressure

= 754 mmHg

Atmospheric pressure =

760 mmHg

Intrapulmonic

pressure

= 763 mmHg

Intrapleural

pressure

= 756 mmHg

b

c

a