YOGA : The Physiological Effects of Pranayama

Dr. KK Deepak

Our heritage has given us several life style based principles of keeping our body and mind in good shape. Yoga is one such way of life style that our ancestors have given us. The beauty of yoga is that it takes care of our entire personality - the physical, mental, spiritual and social aspects. The physical part is trained by the rhythmic yogic asanas, the mental aspect is trained by meditation and pranayama and above all the spiritual aspect has been taken care by concentration on the Divinity. There is interdependence among various components of yogic approaches so far as benefits are concerned.
The most prevalent tradition of yoga is Hath Yoga. It basically involves eight steps: Yam, Niyam, Pranayama, Pratyahara, Dharana, Dhyana and Samadhi. Pranayama is one of the most important steps. Pranayama is regulation of breath. It is scientifically and beautifully designed to give extensive exercise not only to our lungs, but to other several body systems and organs. The systems which are influenced are cardiovascular system, central nervous system, respiratory system. This may also influence gut, renal, lymphatic system and other systems, however, they have been less studied.
The process and types of Pranayama
Pranayama is a unique technique of regulation of breathing cycle. Since respiration is under control of volition and it is an automatic act. It can be precisely altered although within limits. We can change the frequency (rate) and the amplitude (depth of respiration). We can breathe through three openings (mouth, left nostril, right nostril and different combinations) in many ways. Pranayama can be classified into various types depending on the frequency (rate), degree of depth used, types of openings used and accompanying physical manipulations. Fortunately, we are privileged that 5000 years ago our ancestors thought of altering breathing patterns in very precisely scientific manner.
The knowledge about some types of Pranayama is common place knowledge such as Anulom-Vilom Pranayama, right nostril breathing and left nostril breathing. There are several other types which are listed in the Table :
There are many other types of breathing practices such as Sudarshan kriya, Sukh Pranayama, Savitri Pranayama, Pranav Pranayama and several others types. They use different maneuvers and different states while performing breathing exercises.
The effect of Pranayama on physiology:
Since it is connected to regulation of vital gases (oxygen and carbon-di-oxide), it has capability to alter the regulation of circulation. Breathing induces pressure variations in the thorax (chest cavity) where heart, major vessels and lungs are housed. Therefore, changes in thoracic cavity pressures cause changes in availability of blood to heart and big arteries. Thus breathing influences activity of heart. Activity of heart influences the blood circulation which, in turn, influences the circulation to brain. In fact, alteration of breathing pattern virtually shakes up the regulating and regulated variable points within normal limits.
The most important health indicator is the status of heart and blood vessels. The Pranayama is best known stimulus to influence and improve these vital parameters.
Breath causes heart beat to fluctuate:
It is well established fact that when we inhale our heart rate increases and when we exhale the heart rate slows down. This happens with every respiratory cycle (breath in-breath out). This coupling is inbuilt into our system and fairly hard wired. The coupling is not under our voluntary control but under autonomic
control. The extent of this coupling is an indicator of our autonomic health and, henceforth, our cardiovascular health. Children have greater heart rate fluctuation in response to breathing. As age advances this coupling between breathing and heart gradually decreases. Our respiratory act is automatic; however, we have great degree of voluntary control. Perhaps our ancestors knew this fact. More than 5000 years ago our sagas utilized this fact and they devised breathing practices that could influence the potential connection between respiration and heart for the benefit of overall human health.
Breath causes blood pressure to oscillate:
As stated earlier that our breathing alters heart beat every time, in a similar way the breathing generates fine oscillation in our blood pressure profile. This coupling is a sign of good health. Breathing induced oscillations in blood pressure is generated by complex mechanism. First, the breathing cycle induces pressure changes in our thorax and thus this will be reflected in bold pressure and large amount of blood is housed in our thoracic cavity. Secondly, respiration may also induce oscillation in blood pressure through influencing heart beats.
Slow and deep breathing synchronizes beating of heart and blood pressure:
We found in our study that when we breathe at slower pace, the heart rate shows similar rhythm at the same frequency. The blood pressure also starts oscillating at newer frequencies. The analysis suggests that a change in heart rhythm causes the changes in blood pressure. The changes in heart rhythm and blood pressure oscillations are linked to each other for the purpose of providing effective circulation.
 
Slow breathing Techniques
 
Type of Breathing Practice
Anulom-Vilom (Alternate breathing)
Manoeuvre       
Inhalation with left then exhale with right nostril and continue
Known Principle Physiological effects
Cardiovascular and autonomic effects
 
Type of Breathing Practice
Right nostril breathing
Manoeuvre       
Breathing with right nostril while left nostril is closed
Known Principle Physiological effects
Excitatory effect, increased metabolism
 
Type of Breathing Practice
Left Nostril Breathing
Manoeuvre       
Breathing with left nostril while right nostril is closed
Known Principle Physiological effects
Relaxing effect, decreased metabolism, activates brain
 
Type of Breathing Practice
Slow Bhastrika
Manoeuvre       
Slow and deep exhalation, use both nostrils
Known Principle Physiological effects
Autonomic effects
 
 
Fast breathing Techniques
Type of Breathing Practice
Kapalbhati
Manoeuvre       
Fast and forceful exhalation followed by passive inhalation (use both nostrils)
Known Principle Physiological effects
Increased circulation to brain, cognitive excitation, respiratory effects
 
Type of Breathing Practice
Bhramari
Manoeuvre       
Exhalation with humming sound  ( use both nostrils)
Known Principle Physiological effects
Increased circulation to brain, cognitive excitation
 
Type of Breathing Practice
Shitali
Manoeuvre       
Inhalation through mouth with folded tongue (use both nostrils for exhalation)
Known Principle Physiological effects
Respiratory effects
 
Type of Breathing Practice
Bhastrika (Fast & Mukha )
Manoeuvre       
Fast exhalation
Known Principle Physiological effects
Altered circulation to brain, cognitive excitation, respiratory effects
 
In our study we tried to find out whether respiration influences the synchrony between heart rhythm and blood pressure rhythm. We found that slow breathing results in better coupling in breathing, heart rhythm and blood pressure oscillation. Our study provides mechanism which explains the effect of slow breathing on our cardiovascular health. Our research has also shown that the breathing induced changes in autonomic controls are linked to psychological betterment. One Indian study from JIPMER Pudduchery found that both type of Pranayama (slow and fast) are useful for improving mental function, but for improving cardiovascular effect, the slow breathing is useful.
Several studies have suggested that breathing practices can be treated as part of interventional strategies for functional illness. Functional illnesses are those which do not have definite structural defects in the body concerning the disease. We ourselves have carried out studies to document the autonomic changes during Sudarshan Kriya (a well defined sequence of rhythmic breathing with paced breathing at varying rates and depths interspersed with definite pauses). Several beneficial effects have been reported consequent to rhythmic rapid breathing accompanied by adequate pauses at varying degrees of breathing rate. The literature describes several positive changes.
In order to understand the mechanism of breathing effect on heart and blood vessels we suggested one mechanism in 2002 as hypothesis. Our physiological systems have immense capacity to adapt any intense physiological stimuli during tolerable limits. The body system over a period attempts to blunt the response. This theory is largely evidenced by physiological system when they are exposed to altered environmental adverse situations like high altitude, chronic hypoxia, and chronic thermal changes in the environment.
The daily practice of breathing practice beyond normal limits may have potential to induce immediate changes and long term changes. It was hypothesized that repeated episodes of breathing beyond normal limits results in sympathetic excitations. This Sympatho-exicitation helps to build better system next time. We tested this hypothesis by measuring the autonomic excitation levels during slow breathing. We found that during acute experiments there is increment in sympathetic activity.
Beneficial effects of Pranayama in health and disease:
The slow type of Pranayama is most beneficial in hypertension, a well know silent killer of today. It has been reported by several studies that slow breathing reduces heart rate and blood pressure in hypertensive patients. The anulom-vilom (alternate nostril breathing) has been shown to reduce blood pressure. Therefore, it is very much effective in hypertension patients.
There have been several reports to show the positive effect of Pranayama on brain functions. It influences both cognition and behaviour. Pranayama is useful for improving memory, concentration and problem solving. Pranayama are also useful for alleviating anxiety, and helping in patients of depression. The various type of Pranayama have stress alleviating effect and thus, useful in various disease where stress is component in causing or aggravating factor in diseases. Thus, different types of Pranayama have different capabilities to influence different body functions. It means that they have specific effects on human physiology. They are useful in different types of disease.
To conclude, the slow pranayamic exercises help in cardiovascular and autonomic conditioning while fast breathing benefits in activation of central nervous system. The combination of the pranayamic exercises provides mixed benefits.
Dr. KK Deepak is Prof. and Head, Dept of Physiology, AIIMS, New Delhi 110029
e-mail : kkdeepak@gmail.com
Image: Courtesy Google