BIO-MECHANICS  OF YOGA

The bio -mechanics of Yoga is  a intricate subject.   The human body is constantly in movement not only externally  but also internally.  Every single organ, tissue cell is constantly active.  During sleep the factory called the human body is supposed to get rest but yet the various parts are working.  Over the years, the regional circulation falls down and the various parts of the factory' start malfunctioning.  This results in a Myocardial Infarct if the coronary circulation is poor, a Stroke if the cerebral circulation is poor and so on.  If the blood flow to these organs were kept up, no disorder would have resulted.  Yoga bio -mechanics help in this.

The biodynamics of yoga also helps in realignment of various mechanical disorders like slipped disc, hiatus hernia, umbilical hernia, arthritis, cervical spondylitis, etc.  In hiatus hernia, for example, the stomach is pulled away from the diaphragm and the herniation is thus adjusted.

Consider diseases of the skeletal system like arthritis, slipped disc, etc.  The mechanical realignment in the knee by rejuvenating the cartilage, pulling the tibia and fibula away from the femur relieves arthritis.  For a slipped disc, the bony column and muscles are pulled apart so that the disc is not pressurized.

In order to benefit various medical problems, various asanas (postures) have been given.  We shall review the use of various postures in stages.  The asanas can be done sitting, standing, lying down, upside down, etc.  All of these, place varied stresses and strains on the organs ,muscles bones ligaments nerves etc. The advantage of the yogic system is the very availability of innumerable geometric shapes .

Standing postures:

There are a variety and I have illustrated a few of them:
 
 
  
                Trikonasana    (trikona=triangle)                                            Parivrtta Trikonasana (parivrtta=rotation)
 

 
                       Trikonasana with a prop                                                  Dog pose (as it resembles a dog arching its spine)
 

 There are many standing postures like Trikonasana(trikona = triangle and one can notice three triangles in the posture illustrated). Parivrtta (rotation) Trikonasana, dog pose, Uttanasana etc. (refer Light on Yoga by BKS Iyengar) .The most obvious effects of the standing poses are on the musculo skeletal system.

All standing postures are meant to strengthen the ankle, knee joint, the hip-joint, the arch of the foot, the spinal joints, etc.
Decompression of the inter-vertebral joints takes place allowing relief for a prolapsed disc.  Relief from sciatic pain thus occurs.  Because of the stretch of the paraspinal muscles and the inter-vertebral ligaments, any fusion or arthritic change in the spinal joints can be arrested.  Patients may have to use a prop as shown above. This helps them perform the poses accurately and ensures quick relief . Later they may practice as a normal person does.
 

Standing poses cause a natural traction to the spinal column thus restoring the intrinsic strength of the muscle so that a future disc prolapse is avoided.  This is in direct contra-distinction to medical traction which only is an external force.  Once the external force is removed, the problem surfaces.

Unless the muscle retains its resilience which keeps the inter-vertebral spaces apart preventing compression of the disc, the problem will recur. All musculo-skeletal problems which are mechanical, have to be dealt with mechanically. Bone strength increases.

Realignment is given to the para-spinal muscles which removes the altered stresses and strains on the spinal nerves thus re-establishing their anatomical relationship. Other problems like listhesis, calceneal spurs, low back pain, compartment syndromes in the leg, nocturnal cramps, plantar fascitis, hamstring tears, vascular claudication without obstruction, neuralgic pain etc. can all be benefited by standing poses as they help improve sluggish circulation in the lower limbs, tone up the nerves, improve venous return, strengthen the bones etc. Regular practice of such postures will prevent formation of varicose veins for those who are required to stand for long hours.
 

On the CVS

Standing poses tone up the cardio-vascular system.  As the poses are maintained for a certain period of time the cardiac muscle is strengthened by a feed back mechanism without any increase in the bulk of the muscle. The lateral wall of the heart is completely stretched and toned up so that the blood flow on the lateral walls are healthy. As standing poses are static and not dynamic very minimal lactic acid is formed in the muscles so fatigue of the circulatory system does not occur the way it happens in other exercises.

Without a reflex change in skin blood flow as happens in other exercises, standing poses improve the blood supply to all parts of the body depending on the pose used. This is because the body is not used like aerobics or jogging in a dynamic manner yet the blood flow to different parts is improved The main factor is time. As the poses are maintained for several minutes blood can remain in those areas without strain and the effect of such changes persist for a longer period.

In the usual type of exercises, there is no time for blood to pool in any area of the body though the blood flows to different parts of the body with speed. Hence any benefit would be transient.
 

On the RS
The walls of the lungs are also toned up as these poses expand the intercostal muscles so that ventilation of the lungs is better, every alveolus is opened up so that perfusion of the lung is improved. Dog pose ( illustrated above ) improves the vital capacity and gives the effect of having run for a prolonged period though without strain and usage of vital biochemical parameters of the body. This has to be done to be experienced.  
 
 

On the GI tract

The abdominal organs are fully toned up in all standing poses. When Trikonasana is done, the liver and spleen are fully stretched and their cells are toned up.  Any sluggishness in the organs is removed.    All the abdominal and pelvic organs are prevented from herniating or prolapsing.  Sluggishness in the intestines is removed due to the massaging activity of the pose and peristaltic activity is stimulated owing to better blood circulation. Elasticity and blood supply of the skin on the abdominal area is kept up.
 

Inverted poses :

There are three main poses - Sirasasana ( Head stand -below left), the same done on ropes (below -center), and Sarvangasana (Shoulder stand- below right) and Halasana with and without a prop.
 

  
       Headstand  (Sirasasana)                        Headstand on ropes                          Sarvangasana ( Shoulder stand)
 
 

 
                                  Halasana                                                                                      Half Halasana (with prop )
 

These are peculiar only to the yogic system. Throughout our life as we stand straight and gravity acts on the body to tire us- when we feel like lying down to relax. Inverted poses refresh the system as the glandular and circulatory systems get rest from the strain of gravity.

On the CVS

Inverted poses improve body circulation by Laplace's Law. The venous and lymphatic system of the legs and the muscles that serve to pump the blood and lymph upward get rest.  This is essential, as in life the body remains erect all the time.  Inverted poses thus prevent the formation of varicose veins unless one is deficient in valves by birth.  The circulation to the brain is kept up so that the tissues do not degenerate. An ischemic stroke never results for those who practice this regularly as the blood supply is kept up par excellence.

Contrary to popular thought both amongst medical and non medical persons, standing on the head dose not increase the pressure in the cerebral arteries. Trans-cranial dopplers have revealed that with the right method the pressure actually decreases and the caliber of the vessel doubles. Even a hypertensive , after the pressure has been controlled by medication and  other yogic poses  can safely use the ropes to perform  the pose. It is important that every hypertensive does this pose as this alone can bring back ( or maintain) the lost  capacity of auto-regulation of the cerebral blood vessels. If this auto regulation is maintained, the elasticity of the vessels being healthy , a sudden rise in systemic pressure will not result in a cerebral rupture as the blood vessels can adapt and expand. This capacity is provided for only by head stand.
 
 
All this has to be learnt in a medically rational way. One must know how much strain the carotid arteries can be subjected to without ill effects.  Patients can safely do Head stand on the rope as shown in the fig . above. The weight of the body is taken by the  ropes at the pelvic girdle and this prevents pressure on the diaphragm and brain. In addition, the bandage on the eyes prevents any rise in intra ocular pressure. As the patient is suspended , there is no subconscious fear and the systemic pressure does not rise.  The head is supported by pillows and this prevents pressure on the brain.

Tissue changes of strokes, dementia, pseudo bulbar palsy, diffuse cerebral atherosclerosis (DCA) etc., are all due to reduced cerebral perfusion. Practice of inverted poses like Head Stand (Sirsasana) and shoulder stand (Sarvangasana) prevent this completely.  It can also prevent the occurrence of atherosclerotic Parkinson's disease.

Fatigue of the brain cells which occurs as part of everyday life will not occur with regular daily practice of Head stand.  This is due to the rejuvenation of the brain cells with fresh blood and O2. Regarding the LV function in inverted poses, the Ejection fraction rises upto 70.4% in Sarvangasana.

In Setu Bandha Sarvangasana   ( illustrated below left) the cardiac stroke volume is 124 ml, the ejection fraction being 88.5% all without an increase in pulse rate or blood pressure.  In Halasana, the stroke value is 63.17% and the ejection fraction is 71.4%. There was no change in the heart rate and the inter-ventricular septum did not thicken.
 
 
 

 Setu Bandha Sarvangasana on prop (setu=a bridge-the humanbody forms a bridge)

 The conclusion that can be drawn is that there is a progressive reduction in the end diastolic and end systolic dimension but the difference between both dimensions was maintained in all the poses.  There was a significant increase in the ejection fraction in Setubandha Sarvangasana (upto 10%). This helps us to understand how asanas are beneficial for Ischemic heart disease and cardio myopathies.

As the circulation is purged in a gentle manner no stagnation can occur throughout the body.  

RS
The inversion rests the lungs which feels refreshed. The vital capacity increases as the lungs learn to breathe against the strain of the body organs resting on it in the posture.

GI tract
The inversion releases congested blood in the jejunum and colon. Fresh warm blood invigorates the cells . The change in posture enhances peristaltic contractions and aids good elimination. Constipation is eliminated provided the water and fiber content of the diet are normal.

Pelvic Organs
The uterus and bladder are exercised. Women with dysmenorrhoea get relief with regular practice of head and shoulder stand. This is due to the inversion and relief from the constant pressure of blood in the uterine cells providing a relative "drying "of the Sterus every day..

Even though the body is later in the erect position, the effects of what has been done is not lost. Just as a drug has to be taken on a constant basis, the asanas too have to be done regularly to ensure constancy of benefits. Regular practice prevents cellular bleeding and congestion of the uterine cells as they get used to being inverted every day.

It is very good for pregnancy as the baby is kept in the erect position for periods of time. Prolapse of the uterus is easily corrected up to the second degree. The perineal and other supports of the uterus are strengthened. Immediate relief is given to the patient as far as pain and heaviness are concerned.
 

Cystocele and rectocele up the second degree can also be reversed by inverted poses and controlled.  The lightness in the organs can be felt at once. Surgery can be avoided.
 

The eye

The eye is nourished with blood and senile macular degeneration will never occur. Age related optic atrophy will not occur as the blood supply is kept up. The nerves of the eye are soothed. The pressure in the ocular arteries and veins do not increase in a correct head stand. Hence there be no fear. Even for a patient with glaucoma, head stand done with the bandage  around the eyes on the ropes does not increase the intra-ocular pressure.
 

The CNS

The most important aspect of inverted poses is to soak the brain with blood for a fixed period of time which never happens in other systems of exercises. This rejuvenates the brain cells and prevents age related cerebral atrophy. Senile changes in brain are prevented. And as mentioned before ischemic strokes can be completely prevented as the blood supply is enhanced without pressure.

The immediate change felt after performing this pose is an enhanced alertness which lasts through the day. Again, the quality of sleep also improves . This does not mean it cures insomnia. Assuming one has a normal stress level, and controlled attitudes in daily living, head stand ensures good sleep. A cooling effect is felt on the face in the pose.  
 

Musculo skeletal system

The bones of the neck are strengthened as are the cervical muscles.  Just because the cervical vertebrae are smaller dose not mean that it cannot bear the weight. In fact the weight in Head stand does not fall on the neck  at all but on the trapezius and biceps and the forearms. This method has to be learnt. Space has to be created between the trapezius and the nuchal area to avoid pressure on the neck. Cervical and lumbar spondylitis are prevented.

Skin
The skin on the face remains healthy with a glow so long as one practices head stand. This is due to healthy fresh blood pooling in the area every day.

Head stand and shoulder stand are "nourishing poses " according to yoga as they promote cellular soothing . In addition they also provide extra energy by anti gravity effects.
 
 
 

Forward bending poses :

These include a variety -Janu Sirsasana, Paschimottanasana,  etc.

 
                   Janu sirasasana   (janu =knee)                                                                      Janu sirasasana with pillows
 
 

Paschimottanasana (paschima=the western aspect of the body =the spinal muscles area)
 
Effects on the musculo-skeletal system

They stretch the paraspinal muscles, inter vertebral joints so that their blood supply increases and owing to the self-induced traction in these poses, spinal problems do not occur.  But they cannot be used initially for therapy. In the long run they are a panacea for low back problems provided standing poses are perfected before this. A forward bend is not actually a " bend" but a stretch and hence it is safe for a patient to perform it under guidance . Maximum elasticity of the spine is provided for in these poses. The pelvic joints are made supple as are the sacro iliac joints. The spine has to be moved right from the sacro- iliac muscles and not from the lumbar which is harmful.

Whatever spinal length one has in an erect position (of standing )has to be retained in all forward bends -done standing or sitting- this is the key to a correct stretch of the spine.

Effects on the CVS and RS

Due to the horizontal position of the spine the sympathetic nerves are quieted and blood pressure regulation occurs.   When there is perfect relaxation of the nervous system the metabolic rate of the body is brought down.  The body cells go into a temporary state of hibernation.  This is essential as in daily life we only use the body without replenishing the same. The organs of action and the senses of perception need to be kept rested for a few hours daily so that the mind is calm and energy levels in the body are optimized. As the mind is always outgoing these poses draw it inward and refresh it. The effect can be felt when one performs them.   Rest is given to the sympathetic nervous system due to the horizontal position of the body in the forward bending poses and the practitioner feels refreshed. The heart and lungs are rested and refreshed. Blood pressure reduces  though patients perform this in a different manner. The posterior part of the lungs get a healthy stretch and are well ventilated.
 

GI system

Owing to the massage of the intra-abdominal organs, the organs function better.  The appetite increases with such poses and one can actually feel the hunger pangs after a prolonged practice of forward bends.

The CNS

 The neuro endocrine circuit is energized. These poses are a cure for different kinds of headaches- migraine, cluster , etc. They act by an effect of decompression on the brain in the pose. This has to be felt when one practices them The illustration of Janu sirasasana above  with an elastocrepe bandage over the face is how patients with chr headaches perform these poses with the head resting on a pillow. As the mind is rested and the brain is kept in an introverted position headaches are relieved . Regular practice of these , prevent completely ,  the occurrences of migraine headaches.
The tension in the eyeball, facial skin are totally released in these poses.

On The Skin
The skin on the posterior aspect of the body is completely elasticized . This provides a healthy blood supply . Softness and suppleness are thus retained.

Energy levels

I have mentioned this as a separate entity as forward bends replenish chronic fatigue and are a cure for Chr Fatigue syndrome. Gravity weakens us as we are an erect species the positioning of the body in a horizontal position for several minutes( 30)  , brings back an enormous energy and freshness in the system - done to be experienced. When we are tired we feel rested when we lie flat. Yogic poses are an extension of this natural principle but keeps the body in a different level of positioning. A practice of half hour as mentioned above of different types , makes one very alert, calm and refreshed in contrast to backbends listed below which energize the body to make us feel bright.
 
Sitting poses:
I have illustrated just one important asana :

The pelvic organs are massaged and toned up particularly by baddha konasasana illustrated  below:

                             Baddha Konasana
 
The above pose is invaluable for health of the pelvic organs especially for women. The pelvic floor is made elastic. This facilitates easy delivery. This also, for reasons yet to be understood -prevents recurrent UTI in women. The same pose done lying down is invaluable for relieving the abdominal pain of menstruation., lifting up  a prolapsed bladder and uterus. It also keeps the hip joints supple and healthy. 
 
 

Supine Poses- I have just highlighted a couple of them:
 

 
             Supta Virasana (supta =supine)                                            Supta Baddha Konasana (the heels are at the perineum)
                                                                                                                                   8th month of pregnancy
 
 
 

Supta virasana is a very good poses of refreshing chronic  leg fatigue. Particularly invaluable for surgeons who stand for long hours. The pose massages the neuro-lymphatic-circulatory systems in the legs. This removes accumulated toxins of prolonged standing and makes the cells light again. A good five minute stay in the pose makes one capable of standing for long hours again. The pose prevents formation of varicose veins and in patients with established varicosity's, provides great relief.  Unless there is gross damage to the skin and joint due to long standing varicosities, one never need to operate on such patients as the pose prevents progression of the pathology due to the regular massaging effects. It is superior to the elastocrepe bandage in this. It also relieves and prevents arthritic ankle pain and plantar fascitis  and calceneal spur pain. It is very good for cardiac patients to get relief from angina. Good deep breathing done in this pose ventilates the lungs very well. The pose also relieved general body fatigue of daily activities. The heart and lungs are rested. The pose is very good if done post prandially to relieve  fullness in the stomach.  It relives lower abdominal pain of dysmenorrhoea.
 
 Supta Baddha konasana is a pose designed for women. The pelvic floor is stretched and can be done throughout pregnancy as illustrated above. It relieves menstrual cramps very well. It lifts up prolapsed pelvic organs. Particularly valuable for cyctocele and grade two uterine prolapse - it is better than Baddha konasana . It provides great relief from menstrual fatigue .
 

 
 Twisting Postures :
 

 
Marichyasana (Marichya= a name of an Indian sage)                         Bharadwajasana on chair (bharadwaja = a name of a sage)
 
Musculo-Skeletal system

In postures which involve rotation of the spine, i.e.  lumbar and thoracic rotation,  (which are normally never done in daily life) the paraspinal muscles are made flexible and the emerging spinal nerves are freed from their " physiological adhesions " which commonly occurs as one grows older.  Disorders like lumbago and slipped disc syndrome are relieved as in the former case the lumbar muscles have been very stiff  (and rotational movements are good to soften them) and in the latter, enough room is given for the herniated disc so that pressure effects are avoided.

 In most cases , surgery is better avoided as recurrences are very common with secondary arthritic changes in the spine. Even after surgery yoga is very useful in failed cases.  The disc slipping is an effect of a certain situation and not the cause of the pain. The pain can easily be relieved by elasticising the muscles. The inter vertebral joints are well maintained and the nutrition of the disc is kept up as the spinal muscles are made soft and elastic, yet strong. Hence age related degeneration does not occur.
 

In a slipped disc problem, the root cause is lack of resilience of the spinal muscles which have to bear the stresses and strains the body is subjected to.  As the disc loses its support from the ligaments and muscles, the rupture occurs.  Fortunately, in yoga, by strengthening and realigning the muscles, one can prevent further leakage of the disc contents.  So  long as the patient practices yoga , recurrences do not occur. Of course,
if there occurs a cauda equina situation, surgery is a must. If one carefully notices, children do not suffer from low back disorders.  This is because their spinal muscles are supple.  If this suppleness were retained, no one would suffer from low back disorders.

The discal nutrition is maintained as the surrounding spinal muscles benefit with excellent blood flow by these poses. These poses help the disc retain the osmotic forces that serve nutrition for the disc.

In my experience, even for patients with established foot drop or a radiculopathy motor or sensory , surgery has been avoided in the long run by correct practice of yoga. The foot drop remained but the condition never progressed further.  Invariably it never progresses but we are always in a hurry to cut the patient.

Standing poses which stretch the spinal muscles laterally like Trikonasana are invaluable for this and done with the prop as illustrated in the beginning of the article- relieves pain easily. In fact , patients need a prop as shown above where I am using a chair ( above , right) to get the same effects of a floor twist ( photo  above on the left).
 

CVS AND RS
The heart and lungs are made to work in a constrained atmosphere as the twisting poses squeeze one side of the body . Thus cardio-respiratory capacity improves. The intercostal muscles are made elastic - a feature unique to yoga. No other system can do this.
 

The resiliency of the abdominal organs is maintained. All abdominal organs are alternatively squeezed and flushed with blood.  This drying and rinsing action is important for health of the cell.   No deposits are allowed to form in the walls of the arteries so that the regional circulation does not fail as one grows older.  As the intestines are stimulated, constipation is relieved.
 

Balancing Poses:
 

 
Pincha Mayurasana  (Mayur =peacock)                                        Galavasana (Galava =a name of a sage)
 
Musculo skeletal effects
 
 Yoga has not neglected the strengthening of the muscles and bones. Due to different shapes of the balancing postures, different parts of the body are toned up. Weight bearing is provided so that osteogenesis is stimulated.  In Pincha Mauyrasana , ( above left) the inner and outer deltoids are made healthy. In Galavasana ( right) the inner deltoids and inner biceps are strengthened.  One lifts one's own body weight in yoga . The action of the body muscles in these poses are quite different than gymnastics as alignment and angulations are accurate and a peculiar "sucking " action of the muscles are used to maintain the body in the pose. This brings the flesh closer to the bone which massages the latter.
 
 
Regarding the effects on the heart  and lungs, these poses tone up the same . So are the abdominal organs. The most important effect  is the tremendous lightness and agility provided for .
 
 Backward bending poses :
 

  Viparita Dandasana( viparita =reverse)                                        Urdhva Dhanurasana 1 ( correct pose) (urdhva=raised-the spine is raised)
the spine is moved in a reverse direction

 
The same as above on a prop-
There is not strain to the heart and lungs; no rise in BP or                    Urdhva Dhanurasana 2 -note the incorrect spinal arch
respiratory rate -easy for any patient of any age group
 
 

These poses are one of the finest to tone and energize the body akin to aerobic types.

Musculo-Skeletal effects

Though one would label them medically  as spinal extension in reality they are not a bend as it appears but a stretch of the spine.  I have shown the incorrect pose of Urdhva Dhanurasana which appears like a table top . Done this way , it can promote spinal compression. The body should take a dome shape as in Urdhva Dhanurasana 1 which prevents spinal compression. This takes time to learn as one has to stretch the spine vertebra by vertebra. The entire spine is strengthened.  The posterior muscles are squeezed and massaged and the anterior parts of the body stretched out . This improves blood circulation in the anterior parts. One need not label them as hyper- extension as we medical professionals have never explored the limits of the human body. So long as anatomical tenets are followed in the poses injury never occurs.

The tenets in these poses are never to lose the length of the body in the pose and one must never be a table top- one can clearly notice that the spine appears longer in Urdhva Dhanurasana 1 than type 2. Backaches never occur with regular practice. The agility of a child is maintained. As we age, we lose vitality due to spinal stiffness. These poses retain the inner vitality of our framework which is nothing but the musculo -skeletal system.

The arms are fully elasticized and frozen shoulders can never occur. The blood supply to the axillae are enhanced. The vitality given to the spine is to be experienced when one finishes the poses. Any tendency for inguinal hernia is prevented as the openings are made narrow like a slit in these poses due to angular upward pull exerted.

CVS and RS

The most important aspect is the application In IHD. As the spine is bent backward, the entire septum of the heart is stretched out along with the left ventricle.  This can be seen echocardiographically.  It is well known that exercises improve blood supply to the myocardium but this has to be done without strain .  Primary muscle disorders of the heart like cardiomyopathy can be greatly benefited as the flabby cardiac muscle is toned up so that the pump efficiency becomes better and the patient can have a longer lease of life.  Just like the skeletal muscles can be toned up, the cardiac muscle can also be toned up by moulding the supporting structures of the heart which is the dorsal spine with its surrounding musculature.
 
  It ha been borne by experience that myocardial infarction does not  occur in a person who practices yoga.  When effort angina occurs , cessation of any strain gives relief to the anginal pain because any disparity between demand and supply of blood and oxygen is removed.  Drugs reduce angina by reducing the heart rate or dilating the cardiac vessels.  Asanas promote vasodilatation by reduction in sympathetic stress on the system without a rise in any parameters.  In Prinzmetal Angina, asanas give complete relief in a few days unless the particular case is very terminal with extensive muscle damage.
 

Backbends are particularly used to treat IHD patients. The moment these poses are done. angina reduces or disappears. Effort tolerance improves.  If any other poses are used there is no improvement. The mechanisms by which they work are still to be evaluated . The yogic hypothesis is that these asanas enhance blood flow into the thoracic bed and improve the elasticity of the arota. Because the intra thoracic organs are made supple, their blood supply improves and the intense massaging action of these poses can be felt on the heart as one does them. As any exercise improves angina tolerance yoga does too; but in a different manner. The arterial massage is absent in other systems . Yoga also works without straining the system yet improving hemodynamics.

It is possible to thus avoid surgery in pts with IHD provided yoga is instituted early enough and appropriate dietary changes are made to correct other parameters.  In the long run medication can be discontinued.  The benefits of these poses is appreciated when one uses them as a preventive. Patients practice these asanas for IHD only with props as shown above. There are may such props. When the condition improves they revert to normal practice .
 

Mitral valve prolapse can be symptomatically treated by asanas as the tendency for the valve herniation to worsen with age is checked by the practice of back bending postures. LV function does not deteriorate in such patients.

As we grow older, the elasticity of the thoracic cage  and the intercostal muscles diminishes.  Vital capacity reduces  along with the vitality of the body systems. Back bending movements prevent this change by maintaining the suppleness of the thoracic organs due to the stretch and the squeezing effect  given to them. These poses increase the blood supply of the organ systems by reducing the tension of the supplying arteries. The lungs are worked to the maximum in yoga only in the backbends. One can get the effect of a mile race from such poses. Yet the strain is different. An asana known as Viparita  Chakrasana where one does reverse backward flips like gymnastics though very slowly, is excellent for preserving lung vitality. Moreover as maximum elasticity is gained in the lungs; excellent O2 and CO2 dynamics are retained with age. 

As we age, we pant easily. Backbends prevent this. The poses also allow very deep systematic , complete breathing to occur. This percolates O2 properly than in normal life with more conservation than wastage as happens in other systems where there is an O2 deficit. This never occurs in yoga yet the system is energized.

The two gates of life are the CVS and RS . The inhaled air has to be absorbed by healthy lungs and circulated by a healthy heart . Yoga effectively works on this .

GI tract and Pelvic organs
Hunger is reduced due to the stretch of the vagus nerve. These asanas are  very useful in dyspepsia as the stomach and duodenum are regulated in their motility. Hiatus hernia is relieved by these poses as the tendency for prolapse is checked. The cardiac sphincter is toned up and strength is provided in that junction . The stomach is pulled away from the esophagus and repeated practice of such exercises checks the tendency to herniate.

 As the retro-peritoneal area is  stretched intensively excellent blood flow is retained with age. This prevents organ aging.  Aging of the abdominal arota is prevented. Atheroma cannot form as the blood vessels are literally stretched. Venous return is enhanced and this removes congestion in the intestines preventing constipation. It also improves their mechanical contractions. The water content of the tissues forming the lining the intestines are well preserved . As proper organ circulation is maintained digestion is well preserved.  Pelvic pain due to dysmenorrhoea is relieved as the congestion in the uterus is relieved. Tendency  for prolapse of the pelvic organs is also prevented due to the upward pull of the organs.

The Skin

The skin on the anterior abdominal wall is stretched intensively and it retains the youthfulness of a child. The anterior abdominal muscles are well toned up.

Thus it can be seen that Yogic biodynamics is a holistic science because it acts according to the physio-biochemical laws of the human body and since it works along with the Anatomical and Physiological pathways, it is thus a rejuvenative science of our biological organism.
 
 I have high- lighted as much of yoga as space will permit. In the next  article I will try to show specific case histories treated by both yoga and western medicine .