Proposed physiological mechanisms of pranayama: A discussion

Abstract

Background

Pranayama, or yogic breathing technique, is now well-known worldwide by ordinary people, doctors, and scientific communities for its immediate and long-term physiological effect. However, no comprehensive physiological mechanisms explained pranayama. The present study proposed these physiological mechanisms to interpret the underlying science behind pranayama.

Method

The author searches PubMed/Medline internet sources for authentic scientific data and articles to acquire evidence following specific keywords. The author reviewed a total of seventy-three papers, following PRISMA guidelines. 17 full articles, including seven systematic reviews, five clinical trials, two observational studies, and three randomized control trials, have been selected to discuss proposed physiological mechanisms.

Discussion

This study proposes physiological mechanisms of pranayama. It is commenced from Step 1. Activation of mechanoreceptors and chemoreceptors in the respiratory system; then Step 2. Activation of mechanoreceptors and chemoreceptors in the circulatory system, followed by Step 3. Activation of brain respiro-circulatory control centre; Step 4. Activation of the cerebellum; Step 5. Activation of the limbic system and finally end with; Step 6. Activation of the cerebral cortex. The physiological adjustment and adaptation mechanisms due to pranayama of all these six proposed areas have been discussed. Authentic scientific evidence has also been presented to support these proposed physiological mechanisms of pranayama. The author stated the study's limitations and suggested future specific scientific experiments in this area of proposed physiological mechanisms of pranayama.

Conclusion

These prospective proposed physiological mechanisms of pranayama in the future may provide the best scientific background for therapeutic rehabilitation and for the healthy population to maintain their general wellness.

1. Introduction

Pranayama is an ancient Bharatiya (Indian) yogic breathing technique invented by age-old sages, the then yoga scientists, by their solid observations and experiments. They discovered that the respiratory system can be controlled involuntarily and voluntarily and has a strong relationship with mental functions. Various ancient yogic texts explained the relationship between pranayama and psychophysiological functions. In the ‘Ananda Sutra,’ Bhagavan Buddha said, “Form the development, from the repeated practice, of respiration and mindfulness concentration, there comes to the neither wavering nor trembling of the body nor wavering nor trembling of mind” [1]. In the ‘Yoga Sutras’, sage Patanjali described that “through these practices and processes of pranayama, the mind acquires or develops the fitness, qualification or capability for true concentration” [2]. In the ‘Hatha Yoga Pradipika,’ Swami Svatmaram explained, “When the breath wanders, the mind is unsteady. But when the breath is calmed, the mind too will be steady” [3]. Most yogic breathing techniques positively influence neuropsychological abilities [4]. Yogic practices (meditation, yogasana, pranayama) were even used in clinical settings with beneficial effects [5].

Pranayama is a yogic breathing technique. The word pranayama combines ‘prana’ and ‘ayama.'Prana means ‘vital energy’ or ‘life force.''Ayama’ is defined as ‘extension’ or ‘expansion.'So, the meaning of pranayama is ‘extension or expansion of the dimension of prana.'Pranayama is a set of yogic breathing techniques that aim to act directly and intentionally regulating (stop/control) one or more parameters of respiration (e.g., frequency, deepness, inspiration/expiration ratio) [6]. During the time of pranayama, one has to perform focused inhalation (puraka) and then energetic exhalation (rechaka) [5, 7, 8]. The main difference between normal breathing and pranayama is that in pranayama, the breathing follows smooth, systematic, step-by-step, and scientific yogic sub-techniques, i.e., puraka (inhalation), rechaka (exhalation), and antah kumbhaka (internal breath retention) or bahih kumbhaka (external breath retention). In some cases (kapalbhati), strong exhalation is followed by automatic inhalation. However, there is some automatic, spontaneous breath retention (kevala kumbhaka) in higher and advanced pranayama practice [2,3].

After a review of various pranayama, a group of scientists reported that pranayama might modulate ventricular performance by decreasing sympathetic activity and increasing parasympathetic activity, strengthen cardiorespiratory coupling, enhance baroreflex sensitivity, and have a unique effect on the brain stem cardiorespiratory centre. Left uni nostril breathing is associated with the parasympathetic response by activating the right hemisphere. Right uni nostril breathing is associated with a sympathetic response by activating the left hemisphere. Dynamic and smooth, both nostril breathing may balance both hemispheres. However, they concluded that the mechanisms behind the effect of various pranayama still need to be improved [9].

Earlier, the present author identified physiological classifications and proposed theoretical mechanisms of yogasana [10]. After completing many yoga-related research projects and mechanisms identification [[11], [12], [13], [14], [15], [16], [17], [18], [19], [20]], this experienced researcher proposed physiological mechanisms of pranayama for debate, discussion, and future scientific experiments.

2. Methodology

For this proposed pranayama mechanisms article, the present author searched only PubMed/Medline online databases to acquire authentic and scientific evidence up to November 2022. The search keywords were: I. Pranayama mechanism II. Mechanism of pranayama III. Yogic breathing mechanism IV. Mechanism of Yogic breathing. A total of seventy-three articles were identified. The studies that are only on pranayama or Yogic breathing and in English were included. Abstract only and duplicate studies were excluded. The author screened the remaining articles with the following inclusion criteria i. systematic review (SR) ii. randomized control trial (RCT) iii. clinical trial (CT), and iv. observational study (OS). Seventeen full-text articles (three RCT, five CT, two OS, and seven SR) were included in the final discussion (Fig. 1).

Fig. 1.

PRISMA chart for searching procedure for literature review.

3. Discussion

3.1. Proposed physiological mechanisms of pranayama

Respiratory rhythms generate from the brainstem, the respiratory centres in the medulla oblongata, and the pons. Also, these centres have both afferent and efferent associations with the limbic system and the higher brain. The receptors in the superior nasal meatus, sensitive to mechanical and chemical stimuli, can modulate both the autonomic system and brain activity. There is a direct relationship between brain activity and nasal stimulation [6].

The primary respiratory control centre is the medulla oblongata in the brain stem. The respiration has been controlled by the two regions in the medulla. The ventral region stimulates expiratory movements, and the dorsal region stimulates inspiratory movements. Underneath the medulla, the pons is the other respiratory centre that controls the rate or speed of respiration.

A unique adjustment, adaption, and new homeostasis have been established during pranayama. In the following, the present author proposes physiological mechanisms step by step to explain the underlying science behind pranayama: Step-1 Activation of Mechanoreceptors and Chemoreceptors in the Respiratory System; Step-2 Activation of Mechanoreceptors and Chemoreceptors in the Circulatory System, Step-3 Activation of Brain Respiro Circulatory Control Centre; Step-4 Activation of Cerebellum; Step-5 Activation of Limbic System; and Step-6 Activation of Cerebral Cortex (Fig. 2).

Step-1

Activation of Mechanoreceptors and Chemoreceptors in the respiratory system:

Fig. 2.

Proposed physiological mechanisms of pranayama (yogic breathing).

3.2. Mechanoreceptors

In the practice of pranayama, smooth-focused inhalation (puraka), exhalation (rechaka), and breath-retention (kumbhaka) has been taken place, and all the stretch receptors (mechanoreceptors) inside the nasal area and another part of the respiratory tract and also inside the lungs are activated. These particular types of sensations reach the respiratory centre in the brainstem. Due to those focused activities, the stretch receptors in the intercostal muscles and the diaphragm are also activated. This information, too, goes to the voluntary control centre of respiration in the pons and medulla. The normal breathing process has been overlapped by the readjusted yogic breathing (pranayama) pattern, and the control has been started initially from the respiratory centre in the brainstem area.

The following scientific reports have been presented to support this mechanoreceptors activation in the proposed pranayama mechanisms Step-1: i. Stretch Receptors Activation, ii. Mucociliary Clearance.

• I.Stretch Receptors

In the time of pranayama, involvement of lung stretch receptors (i.e., Hering-Breuer reflex) and pulmonary connective tissues (fibroblasts) stretching has been postulated. These stretching tissues contribute inhibitory signals, and hyperpolarization currents propagated through neural and non-neural tissues, coordinating neural elements in the lungs, heart, limbic system, and cortex. Inhibitory influence and hyperpolarization lead to decreased metabolic activity, indicating parasympathetic activity activation [21]. Inhibitory impulse synchronizes rhythmic cellular activity between the circulorespiratory centre and the central nervous system. Cardiac vagal and respiratory mechanisms are combined in the pranayama process. The brain stem and hypothalamus are probably answerable for inducing the parasympathetic response [22].

• II.Mucociliary Clearence

A research group concluded that anuloma and viloma pranayama (AVP) provides a modified way of nasal breathing and improve ciliary oxygenation by enhancing ciliary surface O₂ availability and boosting the production of NO, which has mucociliary enhancement properties. AVP may enhance the hypoxia state of the cilia of the nasal cavity, paranasal sinuses, and the rest of the respiratory tract. AVP helps satisfy the ciliary need for oxygenation by increasing surface and systemic oxygen concentration levels [23].

Mechanoreceptors found in the pulmonary vessels, lungs, trachea, and airways send sensory information to the respiratory centre in the brain about airways stretch, vascular congestion, and lung volume. Lung pulmonary stretch receptors (mechanoreceptors) during pranayama, when the lung expands, initiate the Hering- Breuer reflex, which reduces the respiratory rate. Vegas nerve transmitted this signal. Increased firing from these receptors may enhance the production of pulmonary surfactant. The techniques of pranayama may influence all these factors.

3.3. Chemoreceptors

During the time pranayama, a smooth and convincing inhalation (puraka) and exhalation (rechaka) or kumbhaka (breath-holding), are conducted, more oxygenated and deoxygenated air interacts with the respiratory tract, including the lungs. So, the chemoreceptors in the respiratory system should be activated, and the impulse should reach the respiratory control centre in the lower brain and then the sensory cortex. The respiratory control centre in the brain stem has initiated information on breathing readjustment during pranayama.

In support of chemoreceptors' activity in the proposed pranayama mechanism, some authentic scientific documents of i. Hypoxia ii. Molecular biomarkers are presented here.

• i.Hypoxia

Kumbhaka (breath holding) is the easiest way to cultivate brief intermittent hypoxia, may intensify erythropoietin and vascular endothelial growth factor, induce nitric oxide synthesis, and help stem cell migration [24].

• ii.Molecular Biomarker

In the yogic breathing group, the levels of interleukins and monocyte chemotactic protein were significantly decreased. Also, the salivary nerve growth factor could be cajoled, and the salivary proteome could be altered by yogic breathing [25].

Chemoreceptors are particular types of nerve cells that understand the changes in chemical composition and send information to the brain to control respiratory function. The respiratory system has two types of chemoreceptors: arterial and central in the brain. Both are activated in the time of pranayama may be due to the changes in partial pressure of oxygen, carbon dioxide, and blood pH.

Step-2

Activation of Mechanoreceptors and Chemoreceptors in the circulatory system:

In the process of pranayama, due to more amount of gas exchange, the time of inhalation and exhalation, and breath holding, mechanoreceptors and chemoreceptors, which are present in the circulatory system, including the heart, are activated and send the information to pons and medulla (circulatory control centre) for rearrangements of respiro-circulatory information processing and adjustment.

To support this proposed pranayama mechanism Step-2, mechano and chemoreceptors adjustment in the circulatory system following reports of experimental works i. Baroreflex sensitivity ii. Valsalva maneuver is presented here.

• i.Baroreflex sensitivity

Yogic breathing weakened chemoreflex sensitivity and upgraded baroreflex sensitivity through mechanisms involving both afferent and efferent vagal nerve activity. Pranayama broadens vagal modulation and augments endogenous nitric oxide production [5,8,26,27].

• ii.Valsalva Maneuver

Valsalva maneuver produces an expanded intrathoracic pressure and shortened pre-load to the heart. The prolonged exhalation phase of pranayama mocked the Valsalva maneuver resulting in a curtail in venous return, cardiac output, and blood pressure [27].

Stretch-sensitive mechanoreceptors are found in the pulmonary circulations, heart, and adjoining coronary. Baroreceptors are a type of sensory neuron that is activated by the stretch of the blood vessels. Also, juxta capillary receptors are activated, which respond to pulmonary events. During pranayama, the vessels may be stretched, and the firing rate of machono receptors increases.

Aortic and carotid bodies are the main chemoreceptors in the circulatory system. They transmit signals to the cardiac centres in the brainstem when they sense low oxygen and high carbon dioxide or decreases in the blood pH. The oxygen and carbon dioxide pressure may be changed regularly during pranayama and after that. That may be one of the adaptation pathways of the circulatory system after regular pranayama practice.

Step-3

Activation of brain respiro-circulatory control centre:

Pons and medulla control respiro-circulatory activities in the brain stem during normal and adjusted breathing patterns. In pranayama, the regular breathing pattern has been changed and rearranged. A smooth, convincing, and systematic new breathing pattern has been replaced voluntarily with specific yogic breathing techniques. It is just the opposite of a regular and standard breath-controlling system. So, for the time being, these controlling centres slow down their electrical and chemical information system to readjust the situation. Therefore, immediately after pranayama, the breath rate is slower than average. After completion of the pranayama practice, the standard breathing rate is lower and below the standard rate and has been continued for at least a few minutes. The brain's respiro-circulatory centre actively participates in breathing readjustment during the pranayama process. Also, this centre relays the information to the hind, mid, and higher brain for further adjustment.

The following scientific experiments may support the proposed pranayama mechanism of step- 3: i. Locus Coeruleus Function, ii. Cardio-Respiratory Coherence. iii. Respiratory Sinus Arrhythmia.

• i.Locus Coeruleus Function

Locus coeruleus (LC) is a small bilateral nucleus in the pons that influences arousal and attention and helps optimize cognitive states. The anterior cingulate cortex, an integral part of the all-attention system, is known to modulate LC activity precisely. Also, LC plays an integral part in the brain stem respiratory chain, especially CO₂ sensitivity. With pranayama practice, the respiratory rate decreased frequency, reduced CO₂ sensitivity, and modulated arousal. It alters and regulates focus attention due to LC's shared responsibility [28].

• ii.Cardiorespiratory Coherence

Cardiorespiratory coherence (CRC) modulates the autonomic nervous system and brainstem, leading to suppression of the amygdala and thalamus. High levels of CRC are correlated with parasympathetic rule and curb the intrinsic excitability of cells. Pranayama techniques inflect visceral afferent signaling, which modifies the function of ANS, brain stem, limbic and cortical areas of the brain [29].

• iii.Respiratory Sinus Arrhythmia

Respiratory Sinus Arrhythmia (RSA) is a non-invasive sensitive index of parasympathetic cardiac control. RSA coordinates homeostasis and improves pulmonary gas exchange and oxygen uptake during pranayama. Researchers observed a significant increase in RSA after pranayama and interpreted that the increases were mediated more by changes in the respiratory centre rather than the pulmonary stretch receptors. RSA is mainly guided by two mechanisms (a) abate of intrathoracic pressure during inhalation, which in turn is registered by stretch receptors, and (b) blockage of vagal cardiac efferent activity due to the stimulation of pulmonary afferents fibers [30,31].

In the pons apneustic centre give signals for long and deep breaths. It also controls the intensity of the breath rate. The stretch or mechanoreceptors of the pulmonary muscles inhibit this centre's activity. The pnuemotaxic centre of pons releases signals to inhibit inspiration, allowing it to control the respiratory rate globally. In the time pranayama, both the apneustic and pnuemotoxic centre and medulla are activated differently, controlling or slowing down respiratory rate. The chemoreceptors of the respiratory centre detect pH levels in the blood. High carbon dioxide is linked to higher hydrogen ions in the blood, causing high pH. During the time of pranayama, the changes in oxygen and carbon dioxide level in the body may impact the function of the brain's respiro-circulatory control centre.

Step-4

Activation of Cerebellum:

The primary function of the cerebellum is control of balance, posture, muscle tone, coordination, motor movements, etc. Various mechanoreceptors like a. Meissner's corpuscles, b. Pacinian corpuscles, c. Perkel's disks, and d. Ruffini's corpuscles participate in feedback mechanisms with the cerebellum. From the pons and medulla, the pranayama-related signal reaches this area, and it slows down all functional activities by withdrawing impulses from the muscles (muscle tone drop and relaxation) and waiting for the higher signal.

Multiple Regulation scientific report has been presented to support this proposed pranayama mechanism of step-4:

• I.Multiple Regulation

The basic need for O₂ diminishes after pranayama breathing. However, the CO₂ level in the blood increases in pranayama. However, it always remains below the maximum acceptable level. This procedure has a psychophysiological effect. Voluntary control by attentive pranayama effort on thoracic and abdominal muscles alters the blood gas concentration. Persuasive breath out reduces the PCO₂, which acts on the chemoreceptor and customizes the activity of the respiratory centre. Pranayama breathing can modify adrenocortical activity and release opioids that give pleasurable sensations. Short-term and speedy excitation on the respirocirculatory system during pranayama acted with numerous regulatory mechanisms like mechanical coupling, baroreflex, and central mechanisms [32,33].

It is well known that the cerebellum's role is high when respiration is challenged. The Cerebellum connects the higher brain to the spinal cord and monitors autonomic functions like breathing, heart rate, etc. The deep cerebellum nuclei are involved in neural activities necessary for breathing. During pranayama, breathing has been challenged due to its special techniques. The participation of the cerebellum may be evident and necessary.

Step 5

Activation of the limbic system:

The limbic system consists of the hypothalamus, thalamus, hippocampus, amygdala, etc. The hypothalamus controls the autonomic nervous system and endocrine system. Experimental literature indicates that vagal nerve afferent synapse in the medulla on the nucleus tractus solitaries, which in turn communicates via the parabrachial nucleus to the thalamic nucleus, leading to modulatory effects on frontal, parietal, and occipital cortices and the limbic system.

The limbic system is at the border of the brain stem, and the cerebrum is associated with emotions, memory, pleasure, arousal, etc. From the brain stem (pons and medulla), the respiratory adjustment signal of pranayama travels to the limbic system and slows down its functional activities. For that, after pranayama practices, one has experience of low level of arousal and emotional expression calm down, the feeling of pleasure and memory increases.

This researcher presented the following scientific reports to support the proposed pranayama mechanisms Step-5: i. Thalamo cortical function, ii. Neuro-Hormonal Pathway, iii. Autonomic nervous system.

• i.Thalamocortical Function

During Yogic breathing, changes in middle latency and auditory evoked potentials have been detected, and it is explained as the modification in the neural mechanisms. The adjustment in the information processing at the primary thalamocortical level has been interpreted [7].

• ii.Neuro-Hormonal Pathway

Pranayama collaborates with somato-neuroendocrine mechanisms, affecting the autonomic nervous system and metabolic function [31,34]. Yogic breathing boosts the release of prolactin, vasopressin, oxytocin, and brain-derived neurotrophic factor and decreases cortisol levels [35].

• iii.Autonomic Nervous System

Pranayama increases high-frequency heart rate variability (HRV) in the reflection of enhancement of parasympathetic nervous system tone. Parasympathetic (nucleus ambiguous) and sympathetic (locus coeruleus) efferent nerves conceive in the brain stem. The pons, medulla, and hypothalamus are concerned with the homeostasis of autonomic control. The brain stem innervates the discharge of neurotransmitters to the limbic system and hypothalamic-pituitary-adrenal axis. Also, the midbrain periaqueductal gray area modulates autonomic nervous system activity due to the parasympathetic nervous system awaking after pranayama. Also, for that, metabolic rate and oxygen consumption have been curtailed.

Yogic breathing stimulates the vagus nerve and acts on the limbic system, which impresses the thalamic nucleus resulting in delivery of the frontal cerebral cortex and temporoparietal cortex area. The vagus nerve sends interceptive information from the gastrointestinal, cardiovascular, and pulmonary systems to the central nervous system through the nucleus of the tractus solitarius which transmits it to the thalamus and limbic system via the parabrachial nucleus [6,[35], [36], [37]].

The respiratory system is controlled finally by a smooth interaction between the brainstem, higher cortical structures, and limbic system. Emotion, memories, and arousal are the three primary functions of the limbic system. Respiration is essential in balancing physiological homeostasis and co-exists with emotions. The regulation of breath by the limbic system generates emotional repercussions. After pranayama practice, one experiences low arousal, higher memories, and balanced emotion. The present researcher concluded that the limbic system might be directly involved in the controlling mechanism process during pranayama.

Step-6

Activation of Cerebral Cortex:

From the brain stem, cerebellum, and limbic system, the pranayama-related respiratory signal reaches the cerebral cortex. The cerebral cortex is composed of four lobes: frontal, parietal, temporal, and occipital. The cerebral cortex is mainly involved in consciousness. Its functional areas: the sensory cortex receives sensory impulses, the motor cortex control voluntary muscle movements, the premotor cortex executes planning and coordination of movement, and the prefrontal cortex control executive function, behavior, personality, etc. In pranayama, these higher brain areas send the order to all their control areas to slow down their functional activities, at least for the time being. So, all the psychophysiological function slows down, and the consciousness becomes more and more active to counter-adjust the situation, which leads to increased concentration and focused attention. The same one may experience after pranayama practice.

The following author presented some authentic scientific reports supporting this proposed pranayama mechanism Step- 6: i. Cortical Activity ii. Brain Blood Oxygen Level iii. Top-Down Process iv. Combined Physiological Pathway v. Psychophysiological Correlation.

• I.Cortical Activity

The link between the pranayama technique and consciousness is associated with the olfactory bulb by the mechanical stimulation of the olfactory epithelium. Pranayama may balance the activity of the piriform cortex, somatosensory cortex, prefrontal cortex, amygdala, and hippocampus [6].

• II.Brain Blood Oxygen Level

Slow and deep breathing raises the level of oxygenated hemoglobin in the anterior part of the prefrontal cortex and blood oxygen level-dependent activity in many brain areas. The energized cortical brain areas are motor, supplementary motor, and parietal cortices. The sub-cortical brain areas are: the dorsal length of the pons; thalamic regions; cerebellum; striatum; sub-parabrachial nucleus; parabrachial nucleus; locus coeruleus; periaqueductal gray; hypothalamus; hippocampus [38,39].

• iv.Top-Down Process

Slow breathing techniques of yoga may engage top-down components of brain organization such as attention, working memory, cognition, executive function, etc. These functions are associated with the central executive network, including dorsolateral prefrontal; posterior parietal cortices; frontoparietal network; anterior cingulate cortices; interior frontal junction; pre-supplementary motor area, and intraparietal sulcus [6].

• v.Combined Physiological Pathway

Mechanisms underlying the effect of yogic practices (such as pranayama) on human physiology can be accepted by four major pathways i. nervous system activity (central and peripheral); ii. Humoral factors (melatonin, Dehydroepiandrosterone, growth hormone/insulin-like growth factor- I, arginine vasopressin, nitric oxide, inter-leukin 6, C- reactive protein, etc.); iii. Cell trafficking (macrophages, lymphocytes, monocytes, natural killer cells, hematopoietic stem, and mesenchymal stem cell) and IV. Bio electromagnetism (electrical conduction) [[5], [7], [8]].

• vi.Psychophysiological Correlation

Slow breathing increases cortical and subcortical activity. These modifications may correlate with the following psychological output: increased comfort, relaxation, pleasantness, vigor, and alertness and reduced symptoms of arousal, anxiety, depression, anger, and confusion. Two hypothetical mechanisms may analyze these slow breathing-related changes i. voluntary regulation of internal bodily states by interoceptors and ii. role of mechanoreceptors within the nasal vault in modulating olfactory bulb activity, which activates the entire cortical areas [6].

The involuntary regulation of breathing depends on three components of the respiratory system: i. control centres ii. the sensors and the effector organs. The brainstem is the control centres for the automaticity of breathing. The brain stems respiratory centre comprises three critical neuronal groups in the brain: the dorsal respiratory group in the nucleus tractus solitarious (NTS), the ventral respiratory group in the medulla, and pontine respiratory group in the pons. NTS is the primary integrative centre for autonomic functions like respiration in the central nervous system.

Whereas the promoter and motor cortex within the cerebral cortex control voluntary respiration. Voluntary respiration is any respiration under conscious control, like blowing out candles. Pranayama, or yogic breathing, is voluntary respiration. So, the involvement of the motor cortex is essential. By the ascending respiratory pathway, the motor cortex controls muscular movement related to respiration. Different parts of the cerebral cortex control different forms of voluntary respiration. The phrenic nerves, vagus nerves, and posterior thoracic nerves continue the signal of ascending respiratory pathway from the spinal cord to the respiratory muscles. The cerebral cortex also involves many high-level functions like reasoning, thought, and consciousness. After practicing pranayama, one may feel that the reasoning power thought process improved and consciousness increased. This study puts forward that in pranayama, the physiological controlling mechanism starts from down to the top, but finally, the control comes from the top (cerebral cortex) to the down (respiratory nerve ending) and vice versa.

4. Conclusions

The article proposed comprehensive physiological mechanisms of pranayama, outlining the activation process from the respiratory and circulatory apparatus to the cerebral cortex. The proposed physiological mechanisms of pranayama commence from the mechano and chemoreceptors in the respiro-circulatory apparatus. Then the activation reaches the brain stem's respiro-circulatory control centre, followed by the cerebellum, limbic system activity, and ultimately extent up to the cerebral cortex. A smooth physiological mechanism evolves for readjusting the delicate, unique, systematic, and scientific yogic breathing pattern created by the pranayama methods. Limited systematic reviews, very few randomized control trials, and a missing link in the mechanism analysis kinds of literature are the limitation of this article. Each of the six proposed physiological mechanisms could be the empirical study area in the future. Future scientific experiments may include different types of pranayama and their physiological mechanism. These proposed pranayama mechanisms support that they can be used for rehabilitation purposes in various clinical populations and for promoting general health and wellness.

Sources of funding

Nil.

Conflict of interest

Nil.

Use of generative AI in writing

Nil.

Author contribution

The author confirms sole responsibility for the following: study conception, collection of literature sources, analysis & interpretation, and manuscript preparation.