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Physiology of long pranayamic breathing: Neural
respiratory elements may provide a mechanism
that explains how slow deep breathing shifts the
autonomic nervous system
Ravinder Jerath *, John W. Edry, Vernon A. Barnes, Vandna Jerath
Augusta Women’s Center, 2100 Central Avenue, Suite 6 & 7, Augusta, GA 30904, United States
Received 20 January 2006; accepted 23 February 2006
Summary Pranayamic breathing, defined as a manipulation of breath movement, has been shown to contribute to a
physiologic response characterized by the presence of decreased oxygen consumption, decreased heart rate, and
decreased blood pressure, as well as increased theta wave amplitude in EEG recordings, increased parasympathetic
activity accompanied by the experience of alertness and reinvigoration. The mechanism of how pranayamic breathing
interacts with the nervous system affecting metabolism and autonomic functions remains to be clearly understood. It is
our hypothesis that voluntary slow deep breathing functionally resets the autonomic nervous system through stretch-
induced inhibitory signals and hyperpolarization currents propagated through both neural and non-neural tissue which
synchronizes neural elements in the heart, lungs, limbic system and cortex. During inspiration, stretching of lung tissue
produces inhibitory signals by action of slowly adapting stretch receptors (SARs) and hyperpolarization current by
action of fibroblasts. Both inhibitory impulses and hyperpolarization current are known to synchronize neural elements
leading to the modulation of the nervous system and decreased metabolic activity indicative of the parasympathetic
state. In this paper we propose pranayama’s physiologic mechanism through a cellular and systems level perspective,
involving both neural and non-neural elements. This theoretical description describes a common physiological
mechanism underlying pranayama and elucidate the role of the respiratory and cardiovascular system on modulating
the autonomic nervous system. Along with facilitating the design of clinical breathing techniques for the treatment of
autonomic nervous system and other disorders, this model will also validate pranayama as a topic requiring more
research.
c2006 Published by Elsevier Ltd.
Introduction
Pranayama: a brief review
‘‘Pranayama’’ (the practice of voluntary breath
control, consisting of conscious inhalation, reten-
0306-9877/$ - see front matter
c2006 Published by Elsevier Ltd.
doi:10.1016/j.mehy.2006.02.042
*Corresponding author. Tel.: +1 706 736 5378; fax: +1 706 738
9922.
E-mail address: RJ605R@aol.com (R. Jerath).
Medical Hypotheses (2006) x, xxx–xxx
http://intl.elsevierhealth.com/journals/mehy
ARTICLE IN PRESS
tion and exhalation) is often practiced in conjunc-
tion with ‘‘dhyana’’ (meditation), and ‘‘asanas’’
(physical posture) [1]. Versions of pranayama vary
from single nostril breathing to belly breathing.
Pranayama consists of three phases: ‘‘puraka’’
(inhalation); ‘‘kumbhaka’’ (retention) and ‘‘rec-
haka’’ (exhalation) that can be either fast or slow
[2]. Although all pranayama has three phases, dif-
ferent forms of pranayama evoke dissimilar and
sometimes opposite responses in the subject
depending on variables such as which nostril is used
or the speed of the respiration. Pranayama has
been researched mostly for its beneficial applica-
tions in treatment of cardiovascular diseases such
as hypertension [2–4], pulmonary disease such as
asthma [5–7], autonomic nervous system imbal-
ances [8], and psychologic or stress related disor-
ders [4,9].
Pranayama is known to improve pulmonary func-
tion [10] and cardiovascular profile [2–4]. A But-
eyko breathing device, which mimics pranayama,
was shown to improve symptoms and reduce bron-
chodilator use in asthma patients [5,7]. Pranayama
has also been shown, over time, to reduce oxygen
consumption per unit work [11]. ‘‘Kapalabhati’’,
a fast breathing pranayamic technique, has been
shown to promote decarboxylation and oxidation
mechanisms in the lungs which is believed to
‘‘quiet’’ the respiratory centers [12]. Alteration
in information processing at the primary thalamo-
cortical level inducing modification in neural mech-
anisms regulating the respiratory system [13] may
contribute to pranayama’s beneficial pulmonary
effects. In studies that examined pranayama as a
form of exercise, nostril breathing was shown to in-
crease hand grip strength of both hands [14]. Pra-
nayama, by reducing risk factors associated with
cardiovascular disease [15], has shown that it is
not only theraputic but also preventative. Reduc-
tion in oxidative stress levels with increased super-
oxide dismutase and decreased number of free
radicals may explain in part the beneficial long-
term impact pranayama has on the cardiopulmo-
nary system [16].
Pranayama is known to increase neural plasticity
and to alter information processing making it a pos-
sible treatment for psychological and stress disor-
ders or improving one’s psychological profile
[4,9]. Higher improvement in IQ and social adapta-
tion parameters were noticed in mentally retarded
children after yogic training including pranayama
[17]. Sudarshan Kriya Yoga, which includes pranay-
ama, has been used as a public health intervention
for treatment of post traumatic stress disorder,
depression, stress related medical illnesses, sub-
stance abuse, and rehabilitation of criminal
offenders for its ability to enhance well being,
mood, attention, mental focus, and stress toler-
ance [9]. In conjunction with other yogic tech-
niques, pranayama has been shown to decrease
symptoms of irritable bowel syndrome by enhanc-
ing parasympathetic activity of gastrointestinal
tract and by reducing effects of stress [18]. It has
been mentioned as a possible treatment for symp-
toms of epilepsy [1] and has been shown to in-
crease plasticity of motor control indicating that
it might have applications in rehabilitation pro-
grams [19].
Different forms of pranayama activate different
branches of the autonomic nervous system effect-
ing oxygen consumption, metabolism and skin
resistance. Pranayamic breathing, characterized
by brief breath retention, caused significant in-
creases in oxygen consumption and metabolic rate
while pranayamic breathing, characterized by long
breath retention, caused lowering of oxygen
consumption and metabolic rate [20]. This demon-
strates that slow breathing enhances parasympa-
thetic activation. In another study using breathing
exercises mimicking pranayama, slow breathing
over a period of three months was shown to im-
prove autonomic function while fast breathing did
not have an effect on the autonomic nervous sys-
tem [8]. Slow breathing pranayamic exercises show
a strong tendency of improving or balancing the
autonomic nervous system through enhanced acti-
vation of parasympathetic nervous system. In con-
trast to slow pranayamic breathing, nostril
breathing, both through right nostril, left nostril,
and both nostrils, has been shown to increase base-
line oxygen consumption indicative of sympathetic
discharge of the adrenal medulla [21]. Contradicto-
rily, left nostril breathing has been shown to in-
crease volar galvanic skin resistance interpreted
as a reduction in sympathetic nervous activity
[21]. Although nostril breathing and short pranaya-
mic breathing practices are capable of altering the
autonomic nervous system, more research is re-
quired to fully understand their clinical benefits
[21].
Pranayama may also affect the immune system.
Inhibition of the sympathetic nervous system has
been shown to enhance function of the immune
system in several forms of meditation including
mindfulness meditation, Qigong, and Transcenden-
tal meditation [22–25]. Since pranayama has been
shown to shift the autonomic nervous system away
from sympathetic dominance [8,26] it is probable
that pranayama may have beneficial immune ef-
fects similar to meditation. More studies are
needed to elucidate pranayama’s direct effect on
immune function.
2 Jerath et al.
ARTICLE IN PRESS
Although many studies show pranayama is a ben-
eficial technique, there have been studies that
indicate possible risks especially associated with
fast breathing versions. If done improperly, fast
breathing pranayama can cause hyperventilation
and may hyperactivate the sympathetic nervous
system [27] which may stress the body. Pneumo-
thorax has been attributed to fast breathing
‘‘Kapabhati’’ pranayama in one case study [28].
Some studies indicate that deep breathing similar
to slow breathing pranayama may agitate symp-
toms of bronchial hyperactivity. Deep breathing in-
duced parasympathetic activity is correlated with
bronchial hyperactivity in asthmatics [29]. It is pos-
sible that pranayamic parasympathetic activity
may elicit bronchial hyperactivity in asthmatics as
well.
Pranayamic breathing has been shown to be a
beneficial clinical application in the treatment
of psychological disorders as well as physiological
diseases. Research has revealed pranayamic
breathing to be a low risk, cost effective adjunct
treatment that can be potentially applied to im-
prove symptoms associated with cardiovascular
disorders, autonomic disorders, and psychological
disorders including those involving stress [9].
Although slow pranayamic breathing is said to
be one of the most practical relaxation tech-
niques [2] and holds a great deal of potential in
the treatment of autonomic and psychological
disorders, two problems exist in present research
that prevent full application and understanding of
this practice. The first is that there is no coher-
ent model for the mechanism underlying slow
pranayamic breathing. A physiological description
of the pranayamic mechanism would provide in-
sight into the cellular physiology of deep breath-
ing and the dynamic connection between the
nervous system and respiration. Secondly, many
studies report only the effects of pranayama, yo-
gic postures, and meditation collectively. In fu-
ture research, pranayama needs to be studied
exclusively without meditation or postures in or-
der to fully understand the pranayamic mecha-
nism. Within the research conducted on the
many different types of pranayama, slow rhyth-
mic pranayamic breathing seems to be the most
practical and hold the most physiological benefit.
Slow pranayama, a treatment for autonomic
disorders
Slow pranayamic breathing, characterized as regu-
lar slow frequency respiration with long periods of
breath retention has been known to cause short-
term and long-term changes in physiology. One
long-term effect of pranayamic breathing is the
improvement in autonomic function [3]; specifi-
cally, with slow breathing pranayama there is a
noted increase in parasympathetic activity and a
decrease in sympathetic dominance [8]. It has been
suggested that the cardio-respiratory system can
be normalized through rhythmic breathing exer-
cises [30,31] such as slow pranayama.
Short-term effects of slow pranayamic breathing
include increased galvanic skin resistance (a non-
neural response) [21], decreased oxygen consump-
tion [20], decreased heart rate, decreased blood
pressure [3], and increased amplitude of theta
waves [32]. Increase theta amplitude and delta
waves during breath retention and slow breathing
is indicative of a parasympathetic state while alpha
and beta waves signify activity. Both the short-
term and long-term effects of pranayamic breath-
ing indicate a dynamic alteration of the autonomic
system.
There are several chemical and non-chemical
mechanisms that may account for some of the
physiologic phenomena experienced by pranayama
practitioners. No significant changes in arterial
blood gases were noted after pranayama practice
indicating a neural mechanism for pranayama’s ef-
fect [33]. Increased melatonin production after a
regimen of slow breathing pranayamic exercises
has been attributed to pranayama’s tendency to
create a sense of relaxation and well being in the
subject [4]. Breath holding, an essential part of
pranayama, is shown to induce theta waves [32].
A decrease in breathing frequency can increase
synchronization of brain waves eliciting delta wave
activity [34] indicating parasympathetic domi-
nance. Although these mechanisms provide some
clues to pranayama’s mechanism, the neural mech-
anism that causes this body-wide autonomic shift is
largely unknown [3]. It has been proposed that cer-
tain voluntary breathing exercises can modulate
the parasympathetic and sympathetic nervous sys-
tem bringing their levels of activation into a normal
range [35]. Some have proposed that pranayama al-
ters autonomic responses to breath holding per-
haps by increasing vagal tone and decreasing
sympathetic discharges [26]. It has been suggested
that pranayama ‘‘balances’’ the autonomic ner-
vous system through stretch-induced inhibitory sig-
nals of abdominal muscles (specifically the
diaphragm) and even nerve endings in the nose
[32]. It is abundantly evident that respiration and
the parasympathetic response are intricately con-
nected. What is not clear, however, is the cellular
mechanism that integrates respiration and the
parasympathetic response.
Physiology of long pranayamic breathing 3
ARTICLE IN PRESS
Hypothesis
The general cellular mechanism of
pranayama
It is our hypothesis that voluntary, slow, deep
breathing functionally resets the autonomic ner-
vous system through stretch-induced inhibitory sig-
nals and hyperpolarization currents propagated
through both neural and non-neural tissue which
synchronizes neural elements in the heart, lungs,
limbic system, and cortex.
It is suspected that deep pranayamic breathing,
by voluntary control, dynamically modulates the
autonomic nervous system by heightening genera-
tion of two physiologic signals: (1) Pranayama
increases frequency and duration of inhibitory
neural impulses by activating stretch receptors
of the lungs during above tidal volume inhalation
(as seen in the Hering Breuer’s reflex). (2) Pranay-
ama heightens generation of hyperpolarization cur-
rent by stretch of connective tissue (fibroblasts)
localized around the lungs (see Fig. 1). It is recog-
nized that inhibitory impulses, produced by slowly
adapting receptors (SARs) in the lungs during infla-
tion [36], play a role in controlling typically auto-
nomic functions such as breathing pattern, airway
smooth muscle tone, systemic vascular resistance,
and heart rate [37]. Stretch of connective tissue
fibroblasts are capable of effecting the membrane
potential of nervous tissue [38]. Both hyperpo-
larization and inhibitory impulses generated by
stretch of neural and non-neural tissue of the lungs
are the likely agents of autonomic shift during pra-
nayamic breathing.
Inhibitory current synchronizes rhythmic cellular
activity between the cardiopulmonary center [39]
and the central nervous system [40]. Inhibitory cur-
rent regulates excitability of nervous tissues [41]
and is known to elicit synchronization of neural ele-
ments which typically is indicative of a state of
relaxation [42]. Synchronization within the hypo-
thalamus and the brainstem [43] is likely responsi-
ble for inducing the parasympathetic response
[44] during breathing exercises. The strongest car-
dioventilatory coupling, a parasympathetic-type
phenomenon, occurs when there is decreased
Slow pranayamic
breathing
Generation of
inhibitory impulses in
neural tissue
Generation of
hyperpolarization
current
Inhibitory impulses
in neural tissue
synchronize tissue
Synchronization of
neural tissue
includ ing
hypothalamus and
brainste
m
Decreased action
potentials in
neural tissue
Increased
Par asympath etic
dominance
Activation of slowly adapting
stretch receptors (SARs)
Decreased BP,
heart rate, O2
consumption
Stretch of fibroblasts
surrounding lungs
Resting membrane
potential polarity
increases in
surrounding tissue
decreasing metabolic
act ivit
y
Figure 1 Diagram of the series of events that occur during the autonomic shift present in pranayamic slow breathing.
4 Jerath et al.
ARTICLE IN PRESS
breathing frequency [45] similar to that found in
slow pranayama. Cardioventilatory coupling, found
during deep breathing exercises, indicates a syn-
chronization mechanism that coordinates neural
and non-neural activity. It is likely that inhibitory
synchronized activity between the lungs and brain
elicits parasympathetic-like states.
Hyperpolarization affects the autonomic ner-
vous system by modulating neuronal excitability
[46], resting membrane potential [39], and gener-
ating rhythmic brain activity [40]. It is well docu-
mented that hyperpolarization of tissues
manifests itself in parasympathetic-like changes
[47]. Hyperpolarization is generated during stretch
of fibroblasts in tissue surrounding the lungs [38].
Similarly, in some neurons, hyperpolarization cur-
rent inhibits unsynchronized neuronal input [46]
thereby increasing the dominance of synchronized
input. Stretch of lung fibroblasts likely contributes
to the generation of the slower wave brain activity
and the parasympathetic autonomic shift present
during slow pranayamic breathing exercises.
There are several ways to test the hypothesis
that voluntary slow pranayama functionally resets
the autonomic nervous system through stretch-
induced inhibitory signals and hyperpolarization
currents propagated through both neural and non-
neural tissue. Simultaneous, intracellular, in vivo
recordings of fibroblasts and endothelium in the
lungs and heart during slow pranayamic breathing
would show that hyperpolarizing currents, originat-
ing in the lungs, are being propagated long dis-
tances affecting the cellular metabolism as well
as nervous system excitability. Blockade of inhibi-
tory signals during activation of lung stretch recep-
tors would likely show a decrease in the
parasympathetic effect of slow pranayamic breath-
ing consistent with our model. A recording measur-
ing autonomic indicators such as respiratory sinus
arrhythmia (RSA), the frequency of heart rate var-
iability, and EEG during the practice of pranayama
would also suggest that this deep breathing tech-
nique resets the autonomic nervous system through
parasympathetic shift and causes increased syn-
chronization of neural elements with the heart,
lungs, and cortex.
This hypothesis presents a common physiological
mechanism underlying several forms of breathing
exercises and elucidates the role of the respiratory
and cardiovascular system on modulating the auto-
nomic nervous system. Revealing the cellular
mechanisms that shifts the autonomic nervous sys-
tem towards parasympathetic dominance is impor-
tant for the general understanding of yogic
breathing practices and breathing physiology. The
cooperative action of pulmonary slowly adapting
stretch receptors, heart and lung fibroblasts, vas-
cular endothelium, nervous system glia and neu-
rons during voluntary deep breathing needs to be
further investigated at the cellular level.
Conclusion
Slow pranayamic breathing generates inhibitory
signals and hyperpolarizing current within neural
and non-neural tissue by mechanically stretching
tissues during breath inhalation and retention. It
is likely that inhibitory impulses in cooperation
with hyperpolarization current initiates the syn-
chronization of neural elements in the central ner-
vous system, peripheral nervous system, and
surrounding tissues ultimately causing shifts in
the autonomic balance towards parasympathetic
dominance. Further experimental research of the
cooperative cellular mechanisms of pranayama is
needed to confirm this theory.
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