Even orthodox Astangi's get 25 breaths in Sarvangasana and Sirasasana which can be taken as long, deep and as slow as they like. For the home Ashtangi The complete book of Vinyasa Krama has some nice variations worth considering while your up there.
from Srivatsa Ramaswami's February 2010 Newsletter.
The brain and its nerve pathways form an important system of the human
being and again Yoga has some unique procedures to help the efficacy
of the nervous system. The brain, the spinal cord containing the nerve
fibers, the ganglions, the plexuses and the peripheral nerves form
this system. We have already seen the benefit the yogic technique of
meditation can bring to the brain. It helps to create new neural
connections and reduce disturbances. This Raja Yoga technique works
within the brain and transforms (parinama) it to a better functioning
organ. The Hata Yogis through the Hata Yoga practices such as
Pranayama, viparitakaranis and some mudras help to maintain good
health of the brain. The two postures that really help the brain are,
as you can guess, the inversions, Sirasasana and Sarvangasana.
Many people, when they start to practice Headstand, find that their
faces flush and they feel a rush of blood to the face and the skull.
After some regular practice for a short period of time, the body
adjusts to the new posture and auto regulates the flow of blood. Even
so when one practices this posture for a significant time, the blood
circulation in the brain improves considerably, since the blood
vessels in the brain do not contract or dilate the way other blood
vessels do. This is very refreshing to the brain and normally people
get a cleansed feeling. Equally important is that the cerebro-spinal
fluid, which is a clear and colorless liquid surrounding the brain and
the spinal cord, drains and pools upon the top portion of the brain.
It enters the ventricles and small recesses in the brain and helps in
the nourishment of the brain cells. The third ventricle conveys a
small recess to the posterior portion of the pituitary gland. The
pressure of the CSF, while staying in Headstand, helps the gland to
secrete more of the hormones into the CSF which again is said to
stimulate the sympathetic nervous system. So people who have a weak
sympathetic system may benefit from remaining in Headstand for a
considerable amount of time. The weak sympathetic is considered to be
one of the causes of some ailments like bronchial asthma. Hence this
exercise could be useful for those who suffer from such conditions as
bronchial asthma, its cousin eczema and distant relative, epilepsy y
stimulating the sympathetic.
Sarvangasana is similar to but yet different from Headstand. In this,
instead of the crown, the occipital portion of the head is on the
floor, and the CSF pools into the midbrain and the back of the brain
including the medulla. These areas are really stimulated by a good
stint in Sarvangasana. It is said the Vagas nerve nuclei are
stimulated by this exercise. Thus it results in the activation of the
para sympathetic. It results in reduction in anxiety and insomnia. My
Guru used to say that it helps normalize sexual functions. Thus a
judicious mix of Headstand and Shoulder stand would help to bring
about a healthy balance between sympathetic and parasympathetic
Yoga is particularly directed towards maintaining the integrity of the
spine. The spinal cord is about 45 cm long for men and 43cm for women.
The enclosing bony vertebral column protects the relatively shorter
spinal cord. In fact, the spinal cord extends down to only the last of
the thoracic vertebrae, or the thoracic spine, and then the tail flows
down the lumbar region. The spinal cord is inside the neural canal --
almost the diameter of the thumb-- of the backbone. The nerves from
the spine emanate on either side through openings called neural
foramina and then proceed to the autonomic nervous system and then
various organs. The slightest displacement of the vertebrae will
result in chronic or acute pain. In Yoga, efforts are made to maintain
the spinal column in proper position and mobility. There are fibers of
both the central and autonomic nervous system. When there is some
pressure on the nerves due to even the slightest displacement of the
vertebrae, there is pain which inhibits the various impulses that pass
through the brain, spinal cord, the various organs and muscles. This
can be compared to ‘noise’ in the telephone transmission system. In
such cases the signals do not properly reach the organs or the brain
and spinal cord do not receive the signals properly resulting in the
inefficiency of those organs. So Yogis take special care to see that
the spinal column is properly exercised, mobile and supple. The
exercises are designed to prevent any vertebral pressure on the nerves
by maintaining a healthy inter-vertebral space. And then these spinal
exercises help to circulate blood and CSF to nourish the spinal
nerves. They also suggest strengthening the back muscles so that the
spinal column is well supported. Paschimatanasana, as the name
implies, will meet the requirement admirably.
The movements for the spine include side bending, forward bending,
curving the back, back bending and of course twisting. These may be
done in different postures as is usually done in Vinyasakrama. One of
the simple sequences that helps achieve this is hasta vinyasas and
thoracic exercises in Tadasana, which include all these movements.
(See my book “Complete Book of Vinyasa Yoga, Chapter on Tadasana).
This stretching of the spine will be enhanced if one practices the
scores of vinyasas in inversion poses like Sarvangasana and sirsasana.
The spinal cord is inside the thoracic region of the vertebral column.
So when we move the arms and do the various movements the spine at the
thoracic region does not stretch as the ribcage moves up and down as
one unit. The intervertebral discs in the region of the thoracic spine
are much thinner than in the cervical and the lumbar regions. As a
result there is generally less movement between the vertebrae of the
thoracic spine. The yogis have found a unique way of stretching the
thoracic spine. This is achieved by doing all the movements with deep
breathing, especially inhalation. When we do deep inhalation, the
chest expands side to side, front to back and also up and down which
will help stretch the vertical thoracic spine and maintain a good
intervertebral space for mobility and freedom for the nerves. Hence
the vinyasakrama method of doing asanas with good breathing has this
additional advantage. Again a good stint of Pranayama practice
especially Nadisodhana (nerve cleansing) with an easy, graceful and
secure Jalandharabandha should be very useful for the spinal cord.
Pranayamic deep inhalation and the long breath holding (1:4:2) after
inhalation (antah kumbhaka) directly benefit the nerves inside the
spine.. So when you do deep inhalation, hold the breath and stretch
the spine, the breathing itself acts as an internal traction of the