Physiology of Pranayama

Oxygen consumption during pranayamic type of very slow-rate breathing

To determine whether the yogic Ujjayi pranayamic type of breathing that involves sensory awareness and consciously controlled, extremely slow-rate breathing including at least a period of end-inspiration breath holding in each respiratory cycle would alter oxygen consumption or not, ten males with long standing experience in pranayama, and volunteering to participate in the laboratory study were assessed. These subjects aged 28-59 years, had normal health appropriate to their age. Since Kumbhak (timed breath holding) is considered as an important phase of the respiratory cycle in the pranayama, they were categorised into two groups of five each, one group practising the short Kumbhak varieties of pranayama, and the other the long Kumbhak varieties of pranayama. The duration of Kumbhak phase was on an average 22.2 per cent of the respiratory cycle in the short Kumbhak group and 50.4 per cent in the long Kumbhak group. The oxygen consumption was measured in test sessions using the closed circuit method of breathing oxygen through the Benedict-Roth spirometer. Each subject was tested in several repeat sessions. Values of oxygen consumption of the period of pranayamic breathing, and of post- pranayamic breathing period, were compared to control value of oxygen consumption of the pre- pranayamic breathing period of each test session. The results revealed that the short Kumbhak pranayamic breathing caused a statistically significant increase (52%) in the oxygen consumption (and metabolic rate) compared to the pre-pranayamic base-line period of breathing. In contrast to the above, the long Kumbhak pranayamic breathing caused a statistically significant lowering (19%) of the oxygen consumption (and metabolic rate). The values returned to near normal in the post-pranayamic periods. The data provide a basis to indicate that different types of pranayamic breathing may lead to different types of alterations in the oxygen consumption and metabolic rate.


Alterations of auditory middle latency evoked potentials during yogic consciously regulated breathing and attentive state of mind

Middle latency auditory-evoked potentials (AEP-MLRs) of 10 healthy male subjects in the age range of 21-33 years, were assessed to determine whether yogic pranayamic practice would cause changes in them. The pranayama type assessed here is an exercise of consciously-controlled rhythmic breathing involving timed breath-holding in each cycle of breathing, while the subject holds utmost attention and experiences the touch of inhaled air in the nasal passage. The results revealed that the Na-wave amplitude increased and latency decreased during the period of pranayamic practice, whereas the Pa-wave was not significantly altered. The change is interpreted as an indication of a generalized alteration caused in information processing at the primary thalamo-cortical level during the concentrated mental exercise of inducing modifications in neural mechanisms regulating a different functional system (respiratory). Further researches are required to understand the operational significances of such changes. Read More...

BREATHING THROUGH A PARTICULAR NOSTRIL CAN ALTER METABOLISM AND AUTONOMIC ACTIVITIES
Abstract : There is increasing interest in the fact that breathing exclusively through one nostril may alter the autonomic functions. The present study aimed at checking whether such changes actually do occur, and whether breathing is consciously regulated. 48 male subjects, with ages ranging from 25 to 48 years were randomly assigned to different groups. Each group was asked to practice one out of three pranayamas (viz. right nostril breathing, left nostril breathing or alternate nostril breathing). These practices were carried out as 27 respiratory cycles, repeated 4 times a day for one month. Parameters were assessed at the beginning and end of the month, but not during the practice. The ‘right nostril pranayama’ group showed a significant increase, of 37% in baseline oxygen consumption. The ‘alternate nostril pranayam’ a group showed an 18% increase, and the left nostril pranayama group also showed an increase, of 24%. This increase in metabolism could be due to increased sympathetic discharge to the adrenal medulla. The ‘left nostril pranayama’ group showed an increase in volar galvanic skin resistance, interpreted as a reduction in sympathetic nervous system activity supplying the sweat glands. These results suggest that breathing selectively through either nostril could have a marked activating effect or a relaxing effect on the sympathetic nervous system. The therapeutic implications of being able to alter metabolism by changing the breathing pattern have been mentioned.

Physiological Measures of Right Nostril Breathing

Abstract : This study was conducted to assess the physiological effects of a yoga breathing practice that involves breathing exclusively through the right nostril. This practice is called surya anuloma viloma pranayama (SAV). Twelve volunteers (average age 27.2 years ± 3.3 years, four males) were assessed before and after test sessions conducted on two consecutive days. On one day the test session involved practicing SAV pranayama for 45 minutes (SAV session). During the test period of the other day, subjects were asked to breathe normally for 45 minutes (NB session). For half the patients (randomly chosen) the SAV session was on the first day and the NB session on the next day. For the remaining six patients, the order of the two sessions was reversed. After the SAV session (but not after the NB) there was a significant (P < .05, paired t test) increase in oxygen consumption (17%) and in systolic blood pressure (mean increase 9.4mm Hg) and a significant decrease in digit pulse volume (45.7%). The latter two changes are interpreted to be the result of increased cutaneous vasoconstriction. After both SAV and NB sessions, there was a significant decrease in skin resistance (two factor ANOVA, Tukey test). These findings show that SAV has a sympathetic stimulating effect. This technique and other variations of unilateral forced nostril breathing deserve further study regarding therapeutic merits in a wide range of disorders. Read More...


EFFECT OF TWO SELECTED YOGIC BREATHING TECHNIQUES ON HEART RATE VARIABILITY
Abstract : The heart rate variability (HRV) is an indicator of the cardiac autonomic control. Two spectral components are usually recorded, viz. high frequency (0.15- 0.50 Hz), which is due to vagal efferent activity and a low frequency component (0.05- 0.15 Hz), due to sympathetic activity. The present study was conducted to study the HRV in two yoga practices which have been previously reported to have opposite effects, viz, sympathetic stimulation (kapalabhati, breathing at high frequency, i.e., 2.0 Hz) and reduced sympathetic activity (nadisuddhi, alternate nostril breathing). Twelve male volunteers (age range, 21 to 33 years) were assessed before and after each practice on separate days. The electrocardiogram (lead 1) was digitized on-line and off- line. analysis was done. The results showed a significant increase in low frequency (LF) power and LF/HF ratio while high frequency (HF) power was significantly lower following kapalabhati. There were no significant changes following nadisuddhi. The results suggest that kapalabhati modifies the autonomic status by increasing sympathetic activity with reduced vagal activity. The study also suggests that HRV is a more useful psychophysiological measure than heart rate alone.

AMPLIFIER SETTINGS AND THE RECORDING OF THE ENDOSOMATIC SYMPATHETIC SKIN RESPONSEAbstract : The sympathetic skin response (SSR) is a measure of the electrodermal activity recorded by an endosomatic method, i.e., without using external current. It correlates with exogenous (e.g., a sound) and endogenous (e.g., a deep breath) stimuli. This paper describes the variations in the SSR waveform with varied amplifier filter settings (low cut filter settings 0.1 Hz, 0.3 Hz, and 5.0 Hz and high cut filter settings 15 HZ, 35 Hz, and 75 Hz) in 25 healthy male volunteers (aged between 20 and 40 years); under different physiological conditions (e.g., deep breathing and with successive sound stimuli). The optimal amplifier settings for psychophysiological studies using the SSR are discussed.