Wellness - Homeostasis through Yoga
Pratiti Ghosh*
Department of Physiology, West Bengal State University, India
Submission: March 23, 2022; Published: May 6, 2022
*Corresponding author: Pratiti Ghosh, Department of Physiology, West Bengal State University, India
How to cite this article: Pratiti G. Wellness - Homeostasis through Yoga. J Yoga & Physio. 2022; 9(5): 555774. DOI:10.19080/JYP.2021.09.555774
Abstract
Adoption of yogic practice beneficially modulates homeostasis from the holistic organismic as well as reductionist cellular approach. It subtly affects not only the physical body but also other kosh or sheaths, thus imparting psychophysiological well-being and spiritual growth. Every physiological system has been shown to be nurtured with optimal conditions for its functioning near set-point, thus conserving the fine-tuning at large. Often an analogy may be drawn between the medical science of today and the Vedantic science of ancient times, thus asserting that even minor attempts to imbibe yogasanas in routine life would benefit the practitioner. Not everything can be tested or measured, as the so-called-imperceptible things are beyond our ability to sense or comprehend. Though physiological and anatomical changes may be monitored, the achievement of mental tranquility may also be the marker for yoga as the alternative medicine.
Keywords: Yoga; Psychophysiological well-being; Alternative medicine
Abbreviations: PET: Positron Emission Tomography; MRI: Magnetic Resonance Imaging; FMRI: Functional MRI; EEG: Electroencephalography
Introduction
practice is a form of lifestyle encompassing bridled thoughts, words and actions for realization of the Brahman or Self within individual human beings. The sincere seeker requires to lead a spiritual life which will endow him/her with bliss which again shall psychosomatically enhance his/her physiological well-being. This is furthered by intake of fresh food as ‘prasadam’ which retains all nourishment, thus enhancing the ‘prana’ or life-force of the consumer yogi. This body comprises of Annamay kosh which is gross and thus can be dealt with by materialistic science. The effect of asanas, pranayama, dhyan can be monitored only at this level as it is devoid of instruments or yardsticks beyond this kosh. Psychosomatic expression includes all the koshas together Annamay, Pranmay, Manomay and Vijnaymay kosh and we in sthula sharira are thus affected by distortions in subtle or causal body. Allopathic medicines act on this kosh (gross body) superficially treating the disease but it cannot access the root cause of the deviated homeostasis settled in other kosh. Alternative modalities of treatment viz., homeopathy, music-colour-aromatherapy or placebo probably partially affect the subtle body or Manomay kosh. Practice of the eight limbs of yoga positively modulates the five pranas which in turn renders a strong body, mind, memory, intellect and beneficially directed ego, which effectively control the brain (sahasrar) and nervous system.
This ultimately distributes bliss to all organs thus maximizing homeostasis.
Methodology
The article has been compiled primarily from references from original scientific research articles, review materials from internet sites viz., Pubmed, ScopeMed, ResearchGate, Cochrane Library, related to physiological interpretation of yogasanas. These have been correlated with philosophy of Vedantic sutras with tangible extension into the spiritual realm.
Review
Scientific evidence proves beyond doubt that yoga has the potential to promote homeostasis, preventing and curing stress. Heyam Sukham Anagatam implies that the ‘purpose of yoga is to stop the misery before it arises’. Yoga is an experiential science for medical professionals, healthy beings and patients. It is highly recommended as a lifestyle adjunct in non-pharmacological alternate therapy, to reduce drug dosage and enhance quality of life. It is most effective in prevention and management of stress, chronic degeneration, old age and lifestyle related disorders. Stress adversely affects immune functions and neuroendocrine axis, leading to pathophysiological state. Reactive oxygen species or toxic metabolites of oxygen are implicated in aging and in the etiology of cardiovascular disease, diabetes, cancer, neurodegenerative disorders, etc. [1] Yogic practice plays a pivotal role in revival from trauma, stroke and infections [2,3]. It favourably modulates the nervous system by promoting relaxation in cohesion with attention and cognition. Meditation entrains purity of heart, clarity of thought and spontaneity in action. This leads to satisfaction and less repentance which in turn increases concentration. The objective and subjective quality of sleep is also thus enhanced [4] Practice of yoga reduces performance anxiety, mood disturbance [5] and depression [6] compared to patients only on anti-depressants [7]. It boosts self-confidence, improves interpersonal relationship, increases attentiveness, lowers irritability levels ultimately endowing efficiency and optimism [8]. There is better adjustment to the environmental and internal stressors so that these practitioners with calm disposition show improved performance. Dhyan and shavasan improve attentiveness [9,10] with reduction in visual and auditory reaction times [11] indicating improved visual scanning abilities by ignoring extraneous stimuli through refined processing of the central nervous system [12] Other cognitive functions also improve, viz, eye-hand co-ordination, speed, accuracy, reversal ability [13,14] and increase in critical flicker fusion frequency, i.e., persistence of vision [15].
In yogic practitioners, the modulation in brain blood flow and metabolism are in favour of optimization of sensory-motor abilities along with induction of tranquility through alteration in higher-order cognitive functions, brain structures and activity. Spatial functioning of brain may be detected by its higher glucose metabolism whereas long-term enhancement of brain functioning capacity may be determined by its increase in grey matter. Such spatial cerebral metabolic response to glucose metabolism alter in response to external or mental stimulation as observed from positron emission tomography (PET) analysis, [16] especially after yoganidra meditation [17]. PET scans analyze body functions whereas Magnetic Resonance Imaging (MRI) shows body structures. MRI brain images show that meditators have more concentration of gray matter in the right anterior insula, which is involved in interoceptive awareness arising from the body [18] in the left inferior temporal gyrus and right hippocampus, which are deeply involved in meditation; in the right orbito-frontal cortex, right thalamus, left inferior temporal gyrus, right hippocampus [19] all of which are involved in habits that inculcate positive stable emotions and mindful behavior. The temporal processing of brain stimuli through Functional MRI (fMRI) helps detect brain areas with high metabolic activity by measuring minute increase in blood flow. Heightened activity has been observed in the anterior cingulate cortex, frontal, prefrontal cortex and dorsomedial prefrontal area during Zen, Vipassana and transcendental meditation [18]. Such overactivity has also been observed in the cingulate cortex amygdala, temporo-parietal junction and right posterior superior temporal sulcus circuitry in meditators practising “compassion meditation” or emotional sounds. This also indicates that they are more sensitive to positive emotional expression [20]. The frontopolar cortex or Brodmann area 10 is primarily related to meta-awareness; whereas the sensory and insular cortex are concerned with body awareness; the hippocampus with memory reconsolidation anterior cingulate and orbitofrontal cortex with emotional regulation which all ultimately improve self-regulation and attentiveness leading to association and execution. These brain structures of the meditators show changes in the grey and white matter [21]. Despite increasing age of the long-term meditators, substantial retention of grey matter is observed in the putamen, which show slower decline in their learning ability, attentiveness and cognitive flexibility [22] They are also more tolerant to pain, [23] psychophysiologically, as evident from the changes in their somatosensory cortices [24]. Regular practice of yoga and meditation favorably alter the levels of various brain neurotransmitters that link neurons thus helping form the networks. Gamma amino butyric acid or GABA, a neurotransmitter used as antidepressant, is released after a single session of yoga proving its role in amelioration of depression and related anxiety disorders [25]. PET scan shows 65% increase in endogenous dopamine (feel good factor) release during yognidra meditation and decreased blood flow in prefrontal, cerebellar and subcortical regions, which subserve executive control over cognitive processes [26]. Monitoring of brain waves that are akin to those in deep sleep closely mimic a meditative state, where the subject is free from any form of stress. Neuroscience and psychology have analyzed brain trait and state alterations in meditators through electroencephalography (EEG). Analyses from such recordings of brain neuron frequencies give a temporal insight into the neuronal dynamics depicting the state of the mind, which is modified by the practice of meditation. Such practitioners show temporally distinct EEG recording pattern through delta, theta and alpha frequency bands differentially characterizing various phases of meditation, apart from sleep. Less activation in the amygdala of brain denotes achievement of a steady focus, after attaining the state of focused attention. Parasympathetic activity reduced hippocampal density of gray matter and monoamine secretion are contributory to stress-mediated depression. With practice of meditation, these levels are altered thus enhancing the ability to handle emotional fluctuations, cognition, hormonal and autonomic controls. A long-term meditator with sharp awareness may be distinguished from his/her sleep by lower frequency of alpha waves and theta waves, [27] decreased alpha blocking and increased frontal lobe-specific theta activity [28-30]. So, the coherence and percentage of alpha waves are quantitatively higher in meditators [31] especially Sahaj Yoga practitioners, [32] along with enhancement of cognitive processing [33].
The autonomic nervous system plays the most vital role in inducing relaxation. It consists of the sympathetic and the parasympathetic nervous system. The ida and pingla nadis are probably superimposed on the sympathetic and parasympathetic nervous system, whereas the susumna nadi possibly corresponds to the spinal cord area, all probably in different kosh. Yoga balances the two by inducing a state of parasympathetic dominance and restoring autonomic regulatory reflex mechanisms [34,35] The uninostril breathing or anulom vilom pranayama optimizes autonomic functions [36,37] balancing the activity of the left and right brains [38]. There is deep psychophysiological relaxation, improved somatic steadiness [39] relaxation in peripheral autonomic tone, sweating and cutaneous circulation [40] all characteristics of pranayama practice. Alternate nostril breathing induces fewer errors. Left nostril breathing improves spatial cognitive tasks whereas, right nostril breathing enhances verbal tasks [41]. Yogasanas affect the vascular system. The arteriovenous vascular system is responsible for channelizing nutrients and energy to the body, which may vaguely be akin to the invisible 72,000 nadis or channels. The source and extension of the prana channels probably extend beyond the gross body to the subtle and causal forms which might explain the unidentified power behind meagre intake of food, sparse sleep, yet indomitable energy in the yogis (spiritual practitioners). Regularity in yogasana practice improves cardio-respiratory efficiency as evident from lowered sweating response, increased respiratory pressures, endurance, maximum inspiratory / expiratory pressure, improved ventilatory function viz., prolongation of breath holding time, etc. [42,43] and hand grip strength [44,45]. Even brief intervention by yogic techniques considerably boosts overall performance and work capacity, contributing to better management of lifestyle diseases [46] compared to walking or exercise [47]. Yogic practice optimizes heart rate, blood pressure and oxygen consumption [48]. This is achieved by decrease in the frequency and intensity of internal and environmental signals reaching the hypothalamus, resulting in deep psychosomatic relaxation [49,50] Yogasana improves exercise tolerance by increasing cardiovascular endurance, anaerobic threshold and thus the cardiac recovery index [51,52] It delays onset of fatigue and enables one to perform work at reduced maximal oxygen ventilation [53] The increased heart rate returns to normal pre-stress level earlier in meditators than in relaxed subjects [54]. Cardiac disease risk factors are modified through yoga with decrease in unhealthy serum lipid markers [55] Baroreflex sensitivity (involved in cardiovascular regulation) [56,57] renin-angiotensin and sympatho-adrenal activity (involved in blood pressure automation) are reduced favourably through yogic practice in essential hypertensives [58]. Besides reduction of the age-induced deterioration in cardiovascular functions, the coronary lesions and myocardial perfusion which are determinants of quality of the heart, improve with yogic lifestyle [59-61]. Yogic techniques involving isometric contraction increase skeletal muscle strength. These isometric exercise postures assumed during yoga practice improve dexterity, strength and neuro-musculo-skeletal coordination, improve orthostatic tolerance and gait with upright posture and balance, strengthen bones and prevent age-related weakening. During yoga practice, stimuli to respiratory centers are consciously changed, thus controlling respiration, which is said to exert an effective control over the mind and its flow of thoughts. Practice of pranayama has been observed to lower exertion-induced supranormal level of blood lactate which cause exhaustion and pain in the athletes [53,62]. Yogic practice also boosts immunity. Asana postures that open the chest and throat stimulate the thymus gland which induce production of progenitor cells to combat infection. Headdown poses improve circulation of lymph and immune cells to all parts of the body twisting and opening poses activate the spleen which acts as a filter for the damaged cells. In general, asanas improve nutrient, gas, drug circulation and expulsion of excretory products from skin, lungs, liver, kidney and large intestine. It also rejuvenates internal organs and activates energy pathways for efficient healing. Stress induces inflammatory markers and boosts procytokines which compromise immunity, whereas yogic practice reverses this trend to release only immune-enhancing factors [63]. Practice of Sudarshan kriya pranayama by cancer patients has been shown to activate their innate immune system through increased production of natural killer cells [64]. There is also overall decline in perceived stress and trait anxiety or obstetric complications in yogasana practicing pregnant women. Doctors presently recommend prenatal yoga to pregnant women to help them combat pregnancy stress, ease parturition, reduce pain from baseline to post intervention and increase birth weight with least complications [65,66]. Yoga thus orchestrates fine tuning of aggregate homeostasis. It uniquely balances the neuro-endocrine axis, superseding the brain. Reduction in stress hormones, viz., serum cortisol levels [67] reduced or absence of urinary excretion of dopamine, aldosterone, adrenaline, noradrenaline, serum testosterone, luteinizing hormone [68-70] synergistically denote the endocrine efficiency through yogasansas. Plasma melatonin level, which chronobiologically rises with darkness thus inducing sleep, have been observed to increase in experienced meditators after meditation than on a corresponding night [71].
Conclusion
Yoga is thus the auto reset button of the body within healthy limits. It accelerates the reboot mechanism by a holistic approach, similar to Ayurveda and Homeopathy. Its practice affects every human organ and cell for better neuro-effector communication. The asanas improve musculoskeletal strength, optimizing homeostasis, enhancing resistance power, and relieving stress. It primarily endows the practitioner with tranquility, equanimity, and positive attitude for a purposeful healthier life. Medical research perceives the ‘glimpse of the infinity’ as an imperceptible phenomenon as it is beyond the scope of its measurement or assessment. Further, the inability to obtain proper control samples for the complete yogic practice, makes it difficult to decipher the changes. Ideally, the EEG, fMRI, etc. should be assessed before a person adopts this 8-fold path of life which will lead him/ her to dharana, pratyahara, dhyan and ultimately to Samadhi.
Unfortunately, that intermittent assessments have not yet been possible with a statistically significant group. Impact of Yogic practice is not within the purview of technology except partially for the asanas and meditation. Ideally, experimental subjects are to be measured under severely stringent conditions which cannot ever be subserved on any group of dedicated practitioners who passionately melt into these processes encompassing all the eightfold path in accordance with Patanjali’s yogasutras. Similarly, the previous data of good practitioners cannot be obtained. Here it is worth reiterating that uncaptured by the realms of technology, does not assert or imply nonexistence of the Vedic statements, as only invisible tools can assess the invisible. Though “Jat pinde tat brahmande,” had been inscribed in the scriptures thousands of years ago, in a technology-bereft world, it is well interpretable today, by the understanding that the body is made up of only the five elements of the environment. It may also be said that the alignment and movement of all molecular subatomic particles are in coherence with that of the Solar system in the Milky Way of our universe. It is also to be remembered that communication in the animal-fish-bird-insect and plant world, is mediated by light of imperceptible rays (ultraviolet, infra-red), human incognizant incomprehensible sounds (ultra-audible and infraaudible), with a range of perceptibility which is quite beyond our arena of capability. So ungraspable by the human mind does not necessitate obliteration of facts. If this age-old verdict could be translated into truth today, then the benefits of yoga should not remain an apprehension but should be strongly believed as the yet unprovable path to the relief of mundane physical and mental misery, by merely asserting on the ‘feel-good factor’ of the practising individuals.
References
- Anand A, Kaur G, Bammidi S, Mathur D, Battu P, et al. (2020) Primer for main streaming mind-body techniques for extreme climates-insights and future directions. Medicines (Basel) 7(3): 12.
- Yadav RK, Ray RB, Vempati R, Bijlani RL (2005) Effect of a comprehensive yoga-based lifestyle modification program on lipid peroxidation. Indian J Physiol Pharmacol 49(3): 358-362.
- Gupta S, Shankar V, Lal H (2015) Effect of sahaja yoga on mda and blood thiol levels in healthy volunteers. Intl J of Basic and Appl Med Sci 5: 27-32.
- Patra S, Telles S (2009) Positive impact of cyclic meditation on subsequent sleep. Med Sci Monit 15(7): 375-381.
- Khalsa SB, Shorter SM, Cope S, Wyshak G, Sklar E (2005) Yoga ameliorates performance anxiety and mood disturbance in young professional musicians. Appl Psychophysiol Biofeedback 34(4): 279-289.
- Woolery A, Myers H, Sternlieb B, Zeltzer L (2004) A yoga intervention for young adults with elevated symptoms of depression. Altern Ther Health Med 10(2): 60-63.
- Sharma VK, Das S, Mondal S, Goswami U, Gandhi A (2005) Effect of sahaj yoga on depressive disorders. Indian J Physiol Pharmacol 49(4): 462-468.
- Malathi A, Damodaran A (1999) Stress due to medical exams role of yoga. Indian J Physiol Pharmacol 43(2): 218-224.
- Madanmohan, Thombre DP, Balakumar B, Nambinarayanan TK, Thakur S, et al. (1992) Effect of yoga training on reaction time, respiratory endurance and muscle strength. Indian J Physiol Pharmacol 36(4): 229-233.
- Malathi A, Parulkar VG (1989) Effect of yogasanas on the visual and auditory reaction time. Indian J Physiol Pharmacol 33 : 110-112.
- Bhavanani AB, Madanmohan, Udupa K (2003) Acute effect of Mukhbhastrika (a yogic bellows type breathing) on reaction time. Indian J Physiol Pharmacol 47(3): 297-300.
- Sarang SP, Telles S (2007) Immediate effect of two yoga-based relaxation techniques on performance in a letter-cancellation task. Percept Mot Skills 105(2): 379-285.
- Telles S, Nagarathna R, Vani PR, Nagendra HR (1997) A combination of focusing and defocusing through yoga reduces optical illusion more than focusing alone. Indian J Physiol Pharmacol 41(2): 179-182.
- Telles S, Praghuraj P, Ghosh A, Nagendra HR (2006) Effect of a one-month yoga training program on performance in a mirror-tracing task. Indian J Physiol Pharmacol 50(2): 187-190.
- Vani PR, Nagarathna R, Nagendra HR, Telles S (1997) Progressive increase in critical flicker fusion frequency following yoga training. Indian J Physiol Pharmacol 41(1): 71-74.
- Herzog H, Lele VR, Kuwert T, Langen KJ, RotaKops E, et al. (1990) Changed pattern of regional glucose metabolism during yoga meditative relaxation. Neuro psycho biology 123(4): 182-187.
- Lou HC, Kjaer TW, Friberg L, Wildschiodtz G, Holm S, et al. (1999) A 15O-H2O PET study of meditation and the resting state of normal consciousness. Hum Brain Mapp 7(2): 98-105.
- Holzel BK, Ott U, Hempel H, Hackl A, Wolf K, et al. (2007) Differential engagement of anterior cingulate and adjacent medial frontal cortex in adept meditators and non-meditators. Neuroscience Letters 421(1): 16-21.
- Luders E, Toga AW, Lepore N, Gaser C (2009) The underlying anatomical correlates of long-term meditation: larger hippocampal and frontal volumes of gray matter. Neuroimage 45(3): 672-678.
- Lutz A, Brefczynski-Lewis J, Johnstone T, Davidson RJ (2008) Regulation of the neural circuitry of emotion by compassion meditation: effects of meditative expertise. Ploso One 3: e1897.
- Fox KCR, Nijeboer S, Dixon ML, Floman JL, Ellamil M, et al. (2014) Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuro imaging in meditation practitioners. Neuroscience Bio behavioral Reviews 43: 48-73.
- Pagnoni G, Cekic M (2007) Age effects on gray matter volume and attentional performance in Zen meditation. Neurobiology of Aging 28(10): 1623–1627.
- Grant JA, Rainville P (2009) Pain Sensitivity and Analgesic Effects of mindful states in zen meditators: a cross-sectional study. Psychosomatic Medicine 71(1): 106–114.
- Grant JA, Courtemanche J, Rainville Pierre (2011) A non-elaborative mental stance and decoupling of executive and pain-related cortices predicts low pain sensitivity in zen meditators. Pain 152(1): 150–156.
- Streeter CC, Jensen JE, Perlmutter RM, Cabral HJ, Tian H, et al. (2007) Yoga asana sessions increase brain GABA levels: a pilot study. J Altern Complement Med 13(4): 419-426.
- Kjaer TW, Bertelsen C, Piccini P, Brooks D, Alving J, et al. (2002) Increased dopamine tone during meditation-induced change of consciousness. Brain Res Cogn Brain Res 13(2): 255-259.
- Cahn BR, Polich J (2006) Meditation states and traits: EEG, ERP and neuro imaging studies. Psychol Bull 132(2): 180-211.
- Kasamatsu KH, Hirai T (1966) An electroencephalographic study on the zen meditation (Zazen). Psychiatry and Clinical Neurosciences 20(4): 315-336.
- Stigsby B, Rodenberg JC, Moth HB (1981) Electroencephalographic findings during mantra meditation (transcendental meditation). A controlled, quantitative study of experienced meditators. Electroencephalogr Clin Neurophysiol 51(4): 434-442.
- Becker DE, Shapiro D (1981) Physiological responses to clicks during zen, yoga, and TM meditation. Psychophysiology 18(6): 694-699.
- Khare KC, Nigam SK (2000) A study of electroencephalogram in meditators. Indian J Physiol Pharmacol 44(2): 173-178.
- Sharma VK, Das S, Mondal S, Goswami U, Gandhi A (2007) Comparative effect of sahaj yoga on EEG in patients of major depression and healthy subjects. Biomedicine 27: 95-99.
- Sarang SP, Telles S (2006) Changes in p300 following two yoga-based relaxation techniques. Int J Neuro Sci 116(12): 1419-1430.
- Vempati RP, Telles S (2002) Yoga based guided relaxation reduces sympathetic activity judged from base line levels. Psychol Rep 90(2): 487-494.
- Vijayalakshmi P, Madanmohan, Bhavanani AB, Patil A, Kumar Babu P (2004) Modulation of stress induced by isometric handgrip test in hypertensive patients following yogic relaxation training. Indian J Physiol Pharmacol 48(1): 59-64.
- Telles S, Nagarathna R, Nagendra HR (1994) Breathing through a particular nostril can alter metabolism and autonomic activities. Indian J Physiol Pharmacol 38(2): 133-137.
- Shannahoff-Khalsa DS, Kennedy B (1993) The effects of unilateral forced nostril breathing on heart. Int J Neurosci 73(1-2): 47-60.
- Stancák AJr, Kuna M (1994) EEG changes during forced alternate nostril breathing. Int J Psychophysiol 18(1): 75-79.
- Telles S, Nagarathna R, Nagendra HR, Desiraju T (1993) Physiological changes in sports teachers following 3 months of training in Yoga. Indian J Med Sci 47(10): 235-238.
- Sharma VK, Das S, Mondal S, Goswami U (2008) Effect of sahaj yoga on autonomic patients in healthy subjects and patients of major depression. Biomedicine 28: 139-141.
- Joshi M, Telles S (2008) Immediate effects of right and left nostril breathing on verbal and spatial scores. Indian J Physiol Pharmacol 52(2): 197-200.
- Makwana K, Khirwadkar N, Gupta HC (1988) Effect of short term yoga practice on ventilator function tests. Indian J Physiol Pharmacol 32(3): 202-208.
- Joshi LN, Joshi VD, Gokhale LV (1992) Effect of short term ‘Pranayam’ practice on breathing rate and ventilator functions of lung. Indian J Physiol Pharmacol 36(2): 105-108.
- Madanmohan, Thombre DP, Balakumar B, Nambinarayanan TK, Thakur S, et al. (1992) Effect of yoga training on reaction time, respiratory endurance and muscle strength. Indian J Physiol Pharmacol 36(4): 229-233.
- Madanmohan, Mahadevan SK, Balakrishnan S, Gopala Krishnan M, Prakash ES (2008) Effect of six weeks yoga training on weight loss following step test, respiratory pressures, handgrip strength and hand grip endurance in young healthy subjects. Indian J Physiol Pharmacol 52(2):164-170.
- Sharma R, Gupta N, Bijlani RL (2008) Effect of yoga based lifestyle intervention on subjective well-being. Indian J Physiol Pharmacol 52(2): 123-131.
- Oken BS, Zajdel D, Kishiyama S, Flegal K, Dehen C, et al. (2006) Randomized, controlled, six-month trial of yoga in healthy seniors: effects on cognition and quality of life. Altern Ther Health Med 12(1): 40-47.
- Madanmohan, Rai UC, Balavittal V, Thombre DP, Gitananda (1983) Cardiorespiratory changes during savitri pranayama and shavasan. The Yoga Review 3: 25-34.
- Datey KK, Deshmukh SN, Dalvi CP, Vinekar SL (1969) Shavasana: A yogic exercise in the management of hypertension. Angiology 20(6): 325-333.
- Patel C, North WRS (1975) Randomised controlled trial of yoga and biofeedback in management of hypertension. Lancet 19: 93-95.
- Muralidhara DV, Ranganathan KV (1982) Effect of yoga practice on cardiac recovery index. Indian J Physiol Pharmacol 26(4): 279-283.
- Bera TK, Rajapurkar MV (1993) Body composition, cardiovascular endurance and anaerobic power of yogic practitioner. Indian J Physiol Pharmacol 37(3): 225-228.
- Ray US, Mukhopadhyaya S, Purkayastha SS, Asnani V, Tomer OS, et al. (2001) Effect of yogic exercises on physical and mental health of young fellowship course trainees. Indian J Physiol Pharmacol 45(1): 37-53.
- Goleman DJ, Schwartz GE (1976) Meditation as an intervention in stress reactivity. J Consult Clin Psychol 44(3): 456-466.
- Mahajan AS, Reddy KS, Sachdeva U (1999) Lipid profile of coronary risk subjects following yogic lifestyle intervention. Indian Heart J 51(1): 37-40.
- Murugesan R, Govindarajulu N, Bera TK (2000) Effect of selected yogic practices on the management of hypertension. Indian J Physiol Pharmacol 44(2): 207-210.
- Selvamurthy W, Sridharan K, Ray US, Tiwary RS, Hegde KS, et al. (1998) A new physical approach to control essential hypertension. Indian J Physiol Pharmacol 42(2): 205-213.
- Barnes VA, Davis HC, Murzynowski JB, Treiber FA (2004) Impact of meditation on resting and ambulatory blood pressure and heart rate in youth. Psychosom Med 66(6): 909-914.
- Ornish D, Brown SE, Scherwitz LW, Billings JH, Armstrong WT, et al. (1990) Can life style changes reverse coronary heart disease? The Life style Heart Trial. Lancet 336(8708): 129-133.
- Manchanda SC, Narang R, Reddy KS, Sachdeva U, Prabhakaran D, et al. (2000) Retardation of coronary atherosclerosis with yoga lifestyle intervention. J Assoc Physicians India 48(7): 687-694.
- Yogendra J, Yogendra HJ, Ambardekar S, Lele RD, Shetty S, et al. (2004) Beneficial effects of yoga lifestyle on reversibility of ischaemic heart disease: caring heart project of International Board of Yoga. J Assoc Physicians India 52: 283-289.
- Raju PS, Madhavi S, Prasad KV, Reddy MV, Reddy ME, et al. (1994) Comparison of effects of yoga & physical exercise in athletes. Indian J Med Res 100: 81-86.
- Venkatesh HN, Ravish H, Wilma Delphine Silvia CR, H Srinivas (2020) Molecular signature of the immune response to yoga therapy in stress-related chronic disease conditions: an insight. Int J Yoga 13(1): 9-17.
- Kochupillai V, Kumar P, Singh D, Aggarwal D, Bhardwaj N, et al. (2005) Effect of rhythmic breathing (Sudarshan Kriya and Pranayam) on immune functions and tobacco addiction. Ann N Y Acad Sci 1056: 242-252.
- Narendran S, Nagarathna R, Narendran V, Gunasheela S, Nagendra HR (2005) Efficacy of yoga on pregnancy outcome. J Altern Complement Med 11(2): 237-244.
- Beddoe AE, Paul Yang CP, Kennedy HP, Weiss SJ, Lee KA (2009) The effects of mindfulness-based yoga during pregnancy on maternal psychological and physical distress. J Obstet Gynecol Neonatal Nurs 38(3): 310-319.
- Kamei T, Toriumi Y, Kimura H, Ohno S, Kumano H (2000) Decrease in serum cortisol during yoga exercise is correlated with alpha wave activation. Percept Mot Skills 90: 1027-1032.
- Chaya MS, Ramakrishna G, Shastry S, Kishore RP, Nagendra H, et al. (2008) Insulin sensitivity and cardiac autonomic function in young male practitioners of yoga. Natl Med J India 21(5): 215-221.
- Manjunatha S, Vempati RP, Ghosh D, Bijlani RL (2005) An investigation into the acute and long-term effects of selected yogic postures on fasting and post prandial glycemia and insulinemia in healthy young subjects. Indian J Physiol Pharmacol 49(3): 319-324.
- Schmidt T, Wijga A, VonZurMühlen A, Brabant G, Wagner TO (1997) Changes in cardiovascular risk factors and hormones during a comprehensive residential three-month kriya yoga training and vegetarian nutrition. Acta Physiol Scand Suppl 640:158-162.
- Tooley GA, Armstrong SM, Norman TR, Sali A (2000) Acute increases in night-time plasma melatonin levels following a period of meditation. Biol Psychol 53(1): 69-78.