Wednesday, June 18, 2008

Review of Scientific Literature on Yoga III

General research on pranayamas

Behanan (1937) reported an increase in oxygen consumption (OC) by 24.5% during ujjayi pranayama and by 18.5% in bhastrika pranayama. Similarly Miles (1964) also measured OC during ujjayi and bhastrika pranayamas and a high frequency yoga breathing called kapalabhati . The OC increased by 32% during ujjayi, 20% during bhastrika and by 14% during kapalabhati. The breath rate decreased by 3 breaths/min following ujjayi, and bhastrika pranayama and an increase of over 4 breaths/min following kapalabhati. In a single subject who practiced ujjayi pranayama at different altitude levels, an increase in OC during ujjayi pranayama by 9% at 520m above sea level was reported (Rao, 1968). An increase of 16% in OC at an altitude of 3800m was also found. Comparisons were made with levels at low altitude.
Bhargava, Gogate & Mascarenhas (1988), studied autonomic responses to breath holding in 20 male healthy volunteers. Breath holding time, heart rate, systolic and diastolic blood pressure, and galvanic skin resistance were recorded when breath was held at different phases of respiration. After initial recordings of the above mentioned parameters, all the subjects practiced nadi-shodhana (alternate nostril breathing) pranayama for a period of 4 weeks. The same parameters were recorded at the end of 4 weeks and the results compared. Baseline heart rate and blood pressure (systolic and diastolic) decreased and were also significantly decreased at breaking point after pranayama breathing. Thus pranayama breathing exercises appear to alter autonomic responses to breath holding probably by increasing vagal tone and decreasing sympathetic discharge. Kumbhak (timed breath holding) is considered as an important phase of the respiratory cycle in pranayama. There are 2 categories of kumbhak viz, short and long kumbhak. Oxygen consumption (OC) was studied using a closed circuit method of breathing through the Benedict-Roth spirometer. Readings were obtained pre, during and post pranayamic breathing period. Results revealed that during the short kumbhak there was a significant increase in OC by 52%, in contrast during long kumbhak there was a significant reduction in OC by 19% (Telles & Desiraju, 1991). In a single subject, heart rate was studied in different types of pranayamas namely, savitri pranayama (SP), nadisuddhi pranayama,(NP), mahatyoga pranayama (MP) and vibhaga pranayama. Ratios of inspiration, kumbhak at the end of inspiration, expiration and kumbhak at the end of expiration differed. Heart rate showed an overall increase during two pranayamas (VP and MP) of the 4 pranayamas, compared to the respective prepranayamic baseline values (Telles & Desiraju , 1992).
A study on middle latency evoked potentials (AEP - MLRs) in subjects practiced ujjayi and bhastrika pranayamas showed that there was an increase in the Na wave amplitude and a decrease in the latency of the Na wave. This is interpreted as a indication of a generalized alteration in information processing at the primary thalamo cortical level during the pranayamas (Telles & Desiraju, 1992). Wood (1993) studied perceptions of physical and mental energy and positive and negative mood states in 71 normal volunteers with ages ranging from 21- 76 years using three different procedures viz, relaxation, visualization and yogic breathing with stretch (pranayamas). He reported that practicing paranayama caused a significant increase in perception of mental and physical energy and feelings of alertness and enthusiasm compared to the other two procedures. Hence, a 30 min program of yogic stretch and breathing exercises which is simple to learn even for the elderly had a markedly `invigorating’ effects on perception of both mental and physical energy and increased high positive mood.

A. Research on uninostril breathing:

The nasal cycle is an ultradian rhythm characterized by alternating patency of the left and right nostrils, with a periodicity of two to eight hours (Keuning, 1968; Shannahoff-Khalsa, 1991). The nasal cycle is controlled by sympathetic/parasympathetic innervation of the nasal mucosa. When sympathetic activity to one side dominates, the result is vaso-constriction and thus decongestion on that side, while the enhanced parasympathetic activity on the other side simultaneously results in congestion (Keuning, 1968; Stocksted, 1953). Hence while the nasal cycle is regulated by the autonomic nervous system, the reverse is also true: the nasal cycle in turn influences the autonomic nervous system. The mechanism for this is as follows: The work by Kristof, Servit & Manas (1981) suggests that the electrographic activity in the cortex is produced by a neural reflex mechanism in the superior nasal meatus. This activating effect could be elicited by air insufflation into the upper nasal cavity without pulmonary exercise. Thus , Stocksted (1953) and Eccles (1978) have proposed that the hypothalamus may be responsible for regulating the cyclical changes in nasal resistance. This lead to further studies on uninostril breathing influencing autonomic status, based on heart rate, plasma catecholamines (Shannahoff-Khalsa & Kennedy 1993, Kennedy, Zeigler & Shannahoff-Khalsa, 1986).
A study done by Backon (1988) shows that right UFNB significantly increases blood glucose levels and left UFNB lowers the blood glucose levels. Similarly studies on intra ocular pressure through the uninostril breathing by Backon, Matamoros & Ticho (1989) showed that right hemisphere activation via left UFNB increases intra ocular pressure by an average of 4.5%, whereas left hemisphere stimulation via right UFNB leads to significant decrease in intra ocular pressure by 25%. On the relationship between the brain rhythm and the nasal cycle the work of Werntz, Bickford, Bloom & Shannahoff-Khalsa (1983) was interesting. They observed an increase in the EEG amplitudes over the hemisphere contralateral to the dominant nostril. Therefore this study suggests that the rhythm alternating cerebral dominance might also be regulated by the autonomic nervous system in a manner similar to the nasal cycle.
Another study by Werntz, Bickford & Shannahoff-Khalsa (1987) on integration of EEG amplitudes and UFNB on 5 subjects who breathed through the more congested nostril for 11-20 min, showed that UFNB produces a relative increase in the EEG amplitudes of the contralateral hemisphere . Correlating EEG changes with functions, a study on spatial and verbal task performance was done on 126 subjects, using breathing through dominant uninostril and forced uninostril breathing (Klein, Pilon, Prosser & Shannahoff-Khalsa, 1986). This showed that there was a tendency for subjects exhibiting baseline right nostril dominance to perform verbal tasks better (relative to spatial performance) than subjects exhibiting left nostril dominance. However there was no effect of forced uninostril breathing on relative verbal and spatial task performance. These results showed that atleast in baseline (not forced breathing) conditions the function of the contralateral hemisphere is enhanced.
It is interesting that an earlier study (Block, Arnott, Quigley & Lynch, 1989) investigated this question correlating performance with gender. Unilateral forced nostril breathing influences spatial and verbal performance in both males and females was studied. In males, they observed that UFNB influences both spatial and verbal tasks ipsilaterally whereas in females, UFNB influenced them contralaterally.
The consistent and selective effect of forced uninostril breathing in normal subjects on the general pattern of EEG activity in the hemispheres suggests the possibility of therapeutic approaches to states of psychopathology where lateralized dysfunction has been shown to occur. Flor-Henry (1983) and others have concluded from numerous studies that schizophrenia is associated with greater left cerebral hemisphere dysfunction and that depression and the other affective disorders are associated with greater right hemisphere dysfunction.
Recently Shannahoff-Khalsa & Beckett (1996) studied the clinical efficacy of yogic techniques in the treatment of 8 adults with obsessive compulsive disorder (OCD) over one year follow up. Left nostril yoga breathing with voluntary nostril manipulation for 31 min was given along with other yoga practices. Five patients were able to complete the study and showed a remarkable improvement in Yale-Brown Obsessive Compulsive scale (Y-BOCS), symptom checklist, Perceived Stress Scale and a significant reduction in medication.

B. Studies on yoga breathing with nostril manipulation:

Studies by other investigators on uninostril breathing (baseline and forced) have shown that these practices alter various autonomic functions, brain rhythm and performance in hemispheric tasks. With this background studies were carried out on 3 types of pranayamas in which nostril manipulation is voluntary not forced, i.e., right nostril yoga breathing (RNYB) , left nostril yoga breathing (LNYB) and alternate nostril yoga breathing (ANYB), practiced over a month for 27 breath cycles, 4 times a day. Oxygen consumption was significantly higher by 37% in RNYB (Telles, Nagarathna & Nagendra, 1994). Following a month of the LNYB similarly practiced ,there was a significant increase in galvanic skin resistance, which can be interpreted as a relaxing effect with reduced sympathetic nervous system activity. The immediate effect of 45 minutes of RNYB was also found to be sympathetic activating, with increased OC, systolic blood pressure and increased cutaneous vasoconstriction (Telles, Nagarathna & Nagendra, 1996).
In a study on 135 school children all yoga breathing practices (irrespective of nostril manipulation), increased spatial memory scores, suggesting a right hemisphere activating effect (Naveen, Nagarathna, Nagendra & Telles, 1997).
Two other studies planned by the guide, on yoga breathing correlated with hand grip strength and heart rate variability have been detailed below under work done by the candidate in this area. Hand grip strength was studied in 130 school children and was found to increase in both hands, irrespective of the nostril breathed through (Raghuraj, Nagarathna, Nagendra & Telles, 1997).
Heart rate variability spectrum studied in alternate nostril breathing pranayama showed a trend of increase in the high frequency, parasympathetic component (Raghuraj, Ramakrishnan, Nagendra & Telles, 1998).

Bibliography in brief:

· Backon, J. (1998) Changes in blood glucose levels induced by different forced uninostril breathing, a technique which affects both hemisphericity and autonomic activity. Medical Science Research, 16: 1197-99.
· Backon, J., Matamoros, N. & Ticho, U. (1989) Changes in intra ocular pressure induced by different forced nostril breathing, a technique which affects both brain hemisphericity and autonomic activity. Graefe’s Archives of Clinical Experimental Ophthalmology, 227: 575-77.
· Behanan, K.T. (1937) Yoga: A scientific evaluation. New York: Dover Publication Inc.
· Bhargava, R., Gogate, M.G. & Mascarenhas, J.F. (1988) Autonomic responses to breath holding and its variations following pranayama. Indian Journal of Physiology and Pharmacology, 32(4): 257-64.
· Block, R.A., Arnott, D.P., Quigley, B. & Lynch, W.C. (1989) Unilateral nostril breathing influences lateralized cognitive performance. Brain Cognition, 9: 181-90.
· Cacioppo, J.T. & Tassinary, L.G. (1990) Principles of psychophysiology: physical, social and inferential elements. New York: Cambridge University Press.
· Eccles, R. (1978) The central rhythm of nasal cycle. Acta Otolaryngologia. 186: 464-68.
· Flor-Henry, P. (1983) Laterality and disorders of affect. Neurobiological and linguistic aspects of the schizophrenic syndrome. John Wright, P.S.G. (Ed) In: Cerebral basis of psychophysiology. Boston. MA. pp 63-90.
· Gertner, R., Podoshin, L. & Fradis, M. (1984) A simple method of measuring the nasal airway in clinical work. Journal of Laryngology and Otology, 98: 351-55.
· Kennedy, B., Zeigler, M.G. & Shannahoff-Khalsa, D.S. (1986) Alternating lateralization of plasma catecholamines and nasal patency in humans. Life Sciences, 38: 1203-14.
· Keuning, J. (1968) On the nasal cycle. International Journal of Rhinology, 6: 99-136.
· Klein, R., Pilon, D., Prosser, S. & Shannahoff-Khalsa, D.S. (1986) Nasal airflow asymmetries and human performance. Biological Psychology, 23: 127-37.
· Kristof, M., Servit, Z. & Manas, K. (1981) Activating effect of nasal airflow on epileptic electrographic abnormalities in the human EEG. Evidence for the reflex organ of the phenomenon.
* Naveen KV, PhD. National Institute of Naturopathy, Pune sponsored this study.
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