In contemporary medical science motor activity is what in Yoga we understand as vāyu, while the contemporary concept of sensory activity, which gives rise to sensations, perceptions and knowledge is understood in Yoga as prāna. In Ayurveda, vāta refers to two functions: kriyā or chestā and jñāna.
With reference to breathing or respiration we usually talk about the “exchange of gases” (O2–CO2), “quality of air and its pollution” as well as “collection and analysis of breath”, “composition of breath”, various “volumes and capacities”, etc. Empirical aspects of these breathing processes are studied in laboratory in an empirical manner.
At the center of these studies is “air” as a material substance of breathing. Medical science also refer to the “mechanics of breathing”, “control and regulation of breathing”, and thoracic, diaphragmatic and abdominal breathing. These aspects of breathing are also studied empirically with the help of suitable instruments.
However, these results are directly related with the “individual” who is breathing. There is a complex of variables on both internal and external spectrum of individually recognized reality, affecting internality and exteriority of the individual. Both individuality and environmental processes influence the individual and the energy system can thus get disturbed. That is the reason why measured breathing parameters show variations.
Traditional education in Yoga gives importance to the subjectively developed awareness of the movements of the body, “air” (svāsa, “breath”) and “energy” (Shakti), related with involuntary and voluntary breathing in particular during the practice of prānāyāma.
In traditional Yoga literature, there is no mention of diaphragm, diaphragmatic breathing, and understandably also of O2, CO2, and other gases. Instead, we read about vāyus, prāna and prānāyāma while working with breath and breathing.
We also find terms like ten vāyus, five prānās, “main pathways” (mārga) of vāyu and prāna, “six lotuses” or chakras as well as pūraka–kumbhaka–rechaka along with “inhalation–retention–exhalation of breath” in relation to the practice of prānāyāma.
Traditional concepts of Yoga are based on the experiential knowledge and awareness of the movements of the body and breath during breathing through the internal sensing mechanisms (manas).
Experiencing movements of the trunk, related with natural inhalation and exhalation on the four sides with the help of the hands during a state of good relaxation practiced after a session of āsanās can make us aware of the “lotus flower as if opening and closing” movements of the trunk segment (prāna–apānavāyus).
The awareness of these multidirectional opening and closing type of movements (prāna–apānavāyus) is different from that of the linear, balancing and vertical movements of the body (vyāna, samāna and udāna vāyus), often used in various training and education programs including Yoga.
Internalizing our attention while experiencing these opening-closing movements (prāna–apānavāyus) can help us to recognize and appreciate the presence and activity of an “internal force” (Shakti) as being responsible for them during involuntary breathing.
Movement of the thoracic diaphragm, which is not mentioned in traditional Yoga texts, is responsible for the phenomenon called Shakti, “force”. There is a general misconception that the air movement is responsible for the body movements during breathing. This incorrect notion has to be corrected for taking advantage of prānāyāma used for the maintenance of health.
Objectively, medical profession measures the volume of air moving in and out of the lungs and calls it “breath” or “tidal volume”. It can be collected in a suitable container and sent to a laboratory for an analysis of different gases, alcohol content, etc.
In Yoga, svāsa-prasvāsa is the “awareness of inward-outward air-movement” developed through the touch sensations (sparshasamvedanā) arising inside the nasal passages (nāsikyaprāna) and the mouth cavity (mukhaprāna). Subjectively felt and experienced knowledge of svāsa and prasvāsa in Yoga cannot be collected in a container and analyzed, like the “breath” of medical science. Therefore, objectively studied and understood “breath” should not be equated and compared with the Yogic term svāsa, even though both are related with “air”.
Beginners in Yoga are guided to recognize and appreciate the concept of prāna–apāna vāyus while working with breathing in different areas of the trunk during the practice of prānāyāma.
Breathing movements can be initiated in the areas that are physically and energetically blocked with the help of suitable āsanās and kriyas. Thus also incorrect type of body movements have to be corrected (vāyusuddhi) in order to make progress in prānāyāma and Yoga possible.
Possible implications of such type of practice with breath and breathing along yogic lines has been attempted in relation to various brain functions. During the practice of prānāyāma, we essentially work in the area of the trunk and the vertebral column in a stabilized and relaxed psycho-physical state. Therefore, the traffic of sensory-motor nerve impulses in these areas will be maximal. Due to this there should be a better development of these areas in the cortex and other areas of the brain and the nervous system.
In conclusion, while in ordinary life we use our body and senses like transparent glass panels to see and perceive external objects and events, in Yoga the same structures and faculties are made to function as mirrors reflecting the existing condition or state of the Self. Accordingly, corrective measures can be taken to get established in a balanced and integrated condition (samādhi).