Scientific Research in Medical Applications of Yoga
To date large number of publications are available studying various aspects of yoga in health and disease. Let us look at these under two major categories namely (a) application of yoga in disease including rehabilitation and (b) in promotion of positive health at physical, mental, social and
Yoga in Stress Related Diseases
The increasing awareness that many of the common psychiatric and psychosomatic problems have stress as the basic underlying factor, has led to many studies trying to apply techniques of stress management in these ailments with encouraging results. 'Yoga', which is an
experiential science provides a systematic methodology with its firm roots in a holistic philosophy
which is in total harmony with nature. This science is the offshoot of thousands of years of internal
research by Indian sages.
Yoga in Respiratory Allergies
There are several publications to demonstrate the role of emotions in asthma and also to validate
the efficacy of different yoga practices in bronchial asthma. Some are well designed controlled
studies whereas many of the earlier studies were observations on uncontrolled groups.
Negative emotions and psychosocial pathology are found to be related to severe asthma (Friedman,
1984; Carswell, 1985; Carson and Schauer, 1992). Miller et al (1994) demonstrated that sadness was
associated with greater heart rate variability and instability of oxygen saturation compared with
happiness. There was mixed results for mixed happiness and sadness. Self-rated hostility and
depression (Schmaling et al. 1997) and higher degree of frustrating situations in their life (Berezin et
al. 1997) were found to be associated with decreased pulmonary function, blood immunoglobulin
levels and clinical state of the disease. Alexander (1972) demonstrated the effect of systematic
relaxation on flow rate in asthmatic children in whom emotional factors were prominent. Wilson etal (1975) evaluated 21 asthmatics after the practice of TM for 6 months with crossover at 3 months, indicating that transcendental meditation is an useful adjunct in treating asthma. Goyeche (1982) published his work on the integrated yoga approach to asthma with beneficial results. Singh et al
(1990) studied 18 subjects with mild bronchial asthma after 2 weeks of practice of yogic pranayama
by the use of a breathing device called pink city lung exerciser (PCL). Slow mouth breathing through
this devicesimulates yogic pranayama with a ratio of 1:2 between inhalation and exhalation. This
was compared with breathing through a placebo device. In this randomised, double blind, crossover
placebo controlled study they observed greater degree of improvement in PCL group than the
control group on FEV1, PEFR, symptom score and inhaler usage. Fluge et al (1994) in a controlled
study on 36 asthmatics followed up for 4 months concluded that breathing exercises had an
additive effect when used in combination with Albuterol inhalation therapy. Vedanthan et al (1998)
studied the effect of yoga practices on 17 students in the age group of 19-52 years in an university
set up. Daily symptom score, medication score, AM and PM PEFR, weekly questionnaires and lung
functions were measured. The subjects in yoga group reported significant degree of relaxation,
positive attitude and tendency for lesser usage of inhalers.
Yoga in Anxiety Neurosis
Various yoga practices such as asanas, meditation, pranayama, savasana are now recognised as
relaxation techniques comparable to many behavioral modification techniques like biofeedback and
progressive muscular relaxation based on the famous work of Wallace (1970) who showed that the
practice of Transcendental Meditation (TM) brings about signs of overall psychophysiological
relaxation. Anxiety neurosis recognized as an exaggerated form of stress response with sympathetic
hyperreactivity, could therefore benefit through any one of these relaxation therapies. (Udupa,
1972; Rapp et al. 1984), Norton & Johnson (1983), DeLuca & Holborn (1984), Tarrier & Main (1986)
have demonstrated the comparative efficacy of different types of muscle relaxation therapies
(taped instructions or applied relaxations) in different types of anxiety of both cognitive and
somatic type such as snake phobia, nail biting, hair pulling, panic attacks as well as general anxiety.
Tyrer et al (1988) in their randomised control study on 210 subjects demonstrated that self help
group fared better than the diazepam group and consumed less psychotropic drugs. Further Rabat
et al (1992) showed the effect of mindful meditation to reduce stress, anxiety, depression, panic
and also the panic of agrophobia. Gagne (1990) compared the effect of therapeutic touch &
relaxation and concluded that they could be palliative adjuncts in anxiety. Khalsa et al (1996) tried
the efficacy of a specific yoga breathing pattern in 8 subjects with obsessive compulsive disorder
with significant improvement on OCD, as measured by anxiety and global severity indices. Crisan
(1988) observed reduction in scores on Max Hamilton's a anxiety scale, general health
questionnaire, heart rate, urinary level of VMA and a rise in galvanic skin resistance in 19 patients
with generalised anxiety neurosis after 8 weeks of pranayama practice.
Yoga in Diabetes
In both IDDM and NIDDM physiologically demanding stressful situations like infection, pregnancy
etc. are known to increase the demand for insulin. Similarly emotional stresses also contribute to
the irregular control of diabetes. Relaxation therapies using biofeedback or taped instructions have
been reported to be useful in better control of diabetes (Me grady et al. 1991). Jobson et al (1991)
in a well planned controlled study showed that although there was demonstrable physiological rest
(reduced muscle activity and skin resistance) the progressive relaxation training and biofeedback
given once a week did not help in improving diabetic control in 20 patients with type II diabetes.
Monro et al (1992) carried out a controlled trial on 21 subjects with NIDDM. Fasting blood glucose
and glycosylated haemoglobin reduced significantly [p < 0.05] in the group of 11 who practised the
integrated programme of yoga as compared to a matched control group of 10 who did not practice
yoga. Several other studies (Sahay et al 1986, Jain et al 1993) have shown the beneficial effects of
yoga in NIDDM through reduction in hyperglycemia and the need for oral hypoglycemic agents. Rice
et al (1992) observed increased peripheral blood circulation in lower extremities as measured
through toe temperature and blood volume pulse in 40 diabetes in the age range of 17 to 73 years
after biofeedback assisted relaxation training.
Yoga in Hypertension
As early as nineteen thirties Swami Kuvalayananda of Kaivalyadhama started studying the effects of
yogic practices on blood pressure, heart rate etc, in yogis. Datey and his coworkers (1969) showed
the beneficial effect of savasana in mild hypertensives who were not taking medication. Patel
(1973,75) has shown the beneficial effects of savasana in hypertension in her year long follow-up
control study. In an open study comprising 23 hypertensive patients Sachdeva et al (1994) observed
reduction in systolic blood pressure from 134.5 ± 16.01 to 125.1 ± 9.60mm of Hg and diastolic blood
pressure from 88.5 ± 9.42 to 81.62 ± 6.48mm of Hg respectively after 2 months of yogic life style
Talukdar (1994) noted statistically significant changes in cell membrane enzymes after yoga
practices in hypertensives. 10 to 12 weeks of practising certain yogasanas increased serum HDL
levels and caused a trend of reduction in serum cholesterol, triglycerides, LDL and VLDL
(Bhaskaracharyulu et al, 1996). Though its beneficial role in mild hypertension has been
demonstrated, more in-depth study is required to document the effect of different forms of yoga
on patients with moderate and severe hypertension and also the mechanisms have to be worked
out through studying autonomic status, renin-angiotensin mechanism and platelet aggregation etc.
Yoga in Coronary Heart Disease
Coronary heart disease being one of the major killers of mankind even today, the role of life style
modification to take care of all the risk factors to prevent CHD cannot be overlooked.
Greenwood et al (1996) reviewed the literature and showed that both social support and life
stresses influence the incidence and mortality of coronary heart disease, the latter more so than
the former. The emotion support had the largest effect. Orth Gomer et al (1997) analysed the heart
rate variability from a bolter record during transient myocardial ischeamia and observed
suppression of the efferent vagal activity and suggested that this vagal blockage may be a
forerunner to onset of ischaemia. Winneberg (1997) found positive correlation between collagen
induced platelet aggregation and outwardly expressed anger as measured by anger expression
scale. The work of Ornish et al has become a major land mark on this path of preventive cardiology.
Gould, Ornish and coworkers (1995) studied the changes in myocardial perfusion by positron
emission tomography (PET) after 5 years of intense risk factor modification. The experimental group
of 20 followed a programme of very low fat vegetarian diet, mild to moderate exercise, stress
management and group support. The abnormalities on rest-dipyridamol PET abnormalities of
ventricular perfusion showed significant change in the experimental group (-5.1 ± 4.8% normalised
counts) while the control group who continued under family physicians care with antianginal
therapy had worsening of size, severity of PET abnormalities (10.3 * 5.6%). Although there was a
significant degree of improvement observed in the percent diameter stenosis on coronary
angiography in the experimental group as compared to control group, greater degree of changes
were observed in ventricular perfusion and the measurement of area of LV with less than 60%
activity in PET.
Yoga in Rheumatoid Arthritis
Stress could be a major triggering or aggravating factor for the autoimmune inflammation in
rheumatoid arthritis has been understood. Haslock (1994) reported the beneficial effect on grip
strength and Stanford health assessment questionnaire disability index in 10 severe rheumatoid
arthritis subjects, as compared to 10 matched controls who participated in a programme of IAYT.
Role of yoga in mechanical back pain, carpel tunnel syndrome, cervical spondylosis, fibromyalgia
and chronic pain have been studied by many workers.
Yoga in Rehabilitation
Yoga practices have been tried in the rehabilitation of various socially disadvantaged groups like
inmates of jails, drug abusers, alcoholics, congenitally blind, mentally retarded and children from
community (remand) homes. In all these socially disadvantaged groups, either due to repressed
anger or depression or anxiety, a heightened state of mental arousal could be a common underlying
factor, that can interfere with their efficiency in any new learning for better living or for improved
Yoga in Community Homes
Children in community homes although physically normal were socially and emotionally
traumatized (Ahvenainen, et al 1990) Significantly higher level of sympathetic arousal as seen by
heart rate, respiratory rate, skin resistance was seen in community home girls in Bangalore
compared to regular school children (Telles, Naveen & coworkers 1997). In a comparative study, we
(Narendran & Raghuraj, 1997; Raghuraj & Telles 1997) showed significant reduction in breath rate,
skin resistance, performance on muscle power, dexterity skill and visual perception in the yoga
group compared to the group practising games in 14 pairs of girls in the age group 12-16 years,
from a community home.
Yoga for the Blind
Naveen et al (1996) on repeated recording of middle latency auditory evoked potentials (AEPMLR)
demonstrated that the information processing in the auditory pathways was much better in the
congenitally blind than normally sighted children showing better sensitivity in hearing enabling
them to use echoes to perceive spatial position. Greater anxiety and higher heart rates were noted
in the blind compared to matched normal children (Ollendick et al. 1985 & Wycherley 1970).
Yoga for Mentally Retarded
Special education for the mentally retarded has now been well streamlined and these children are
getting integrated into general education. Yoga has been tried out as an adjunct in education of
children with mental retardation, learning disabilities and attention deficit hyper activity
syndromes. Krishnamacharya yoga mandiram (1983) documented and reported subjective
improvements and also described the practices of yoga adopted for these children. We (Uma et al
1989), in our matched control study
on 90 retarded children practising IAYT for one hour daily for one academic year as an adjunct to
the standard techniques of special education have shown significant improvement in IQ (Binet
Kamat's test) and social adaptation (Vineland social maturity scale) in addition to improvement in
locomotor skills (Siguine form board) in those with mild and moderate degree of retardation.
Improved attention span after IAYT may be the mechanism that promotes learning.
Yoga for Psychosis and Chemical Abuse
There are several reports of the use of TM in the rehabilitation of drug abusers and alcoholics
(Shafi, 1974; Brautigam, 1972; Benson et al. 1972). We observed the beneficial effect of IAYT in the
rehabilitation of schizophrenics (Telles, 1997) in a long stay home.
Yoga for Promotion of Positive Health
Application of yoga for the first component (absence of disease) of the WHO definition of health
has been highlighted. Let us now look at the other components namely promotion of positive
health at the physical, mental, social and spiritual level.
Yoga for Positive Physical Health
Positive health at physical level includes normalcy of body mass index (Height weight ratio),
flexibility of joints, supple but strong muscles, skill in motor performance, resistance in infections
and tolerance to environmental variations.
Large number of studies were reported by the TM group demonstrating improved physical health
measured by motor and perceptual ability, athletic performance and reaction time (Shaw & Kole,
1971), and also by better performance of perceptual motor tasks (Karene, 1971). Six months of
yogic asanas was shown to increase hip and shoulder flexibility in the middle-aged men whereas
physical exercises had no such effect (Ray et al. 1983).
Yoga in Physical Education
Nayar et al. (1975) demonstrated improvement in cardiorespiratory functions in NBA cadets trained
in yogic practice as compared to those undergoing physical training, The body flexibility and the
muscular efficiency improved after six months of yogic training (Ray et al. 1986). The improvement
in muscular efficiency was reflected as an increase in endurance time probably due to alternate
recruitment of motor units. Telles et al (1993) studied 40 senior physical education school teachers
who were doing diverse physical activities for 8.9 ± 5.8 years after 3 months of integrated yoga
programme. There was a significant increase in PFR (6%),,FEV1 (16%), FVC (18%), breath holding
time (40%) and a significant reduction in heart rate, respiratory rate, blood pressure, body weight
and the number of errors made in the steadiness test reduced significantly. The galvanic skin
resistance increased reflecting reduction in sympathetic tone.
Yoga and Immune System
Psychological stress is thought to undermine host resistance to infection through neuroendocrine
mediator changes in immune competence. 236 preschool children in the age group of 3 to 5 years,
were studied by Boyce et al (1995). They compared the effect of laboratory stress of performing
developmentally challenging task with two measures of environmental stress at the child care
center and assessed the cardiovascular reactivity, incidence of respiratory illnesses, CD4, CDS &
CD19 cell counts, lymphocyte mitogenesis and antibody response to pneumococcal vaccine. They
showed that the incidence of illness was related to an interaction of child care stress and mean
arterial pressure reactivity (measure of psychobiologic reactivity to stress). They also observed an
interaction between stressful life events and CD19 reactivity during stress of entering school.
Klemons (1972) in their controlled clinical study assessed the degree of gingival inflammation (GI) in
46 TM meditators compared with 26 non meditators. Improvement of GI was noted in 74% of the
meditators Vs 15% in non meditators. Practice of IAYT by patients with open tuberculosis in a
sanatorium through controlled studies showed faster recovery in their general health, X-ray
changes and sputum positivity. Allergies, autoimmunity and cancer are other immune system
disorders where the role of yoga has been experimented upon.
Yoga for Positive Mental Health
A positive mental health would be achieved by sharpening of perception of information arriving to
the brain through all our special senses, better analytical faculty (IQ), sharper memory and on the
overall improvement in personality characteristics. Emotions being the major component of human
behavior, mastery over the upsurges of emotion is considered as the sign of better health rather
than just a sharpening of emotions. The capacity to replace instinctual violent emotions like anger
or fear by soft emotions like love, sympathy, peace and contentment indicates higher levels of
Yoga for Perception
Meditation has been described as a training in awareness, which when kept over long periods
produces definite changes in perception, attention and cognition (Brown, 1977). Significant changes
were reported in the visual perception of advanced meditators, who were able to distinguish subtle
differences in color and shade. They were more perceptually sensitive to detect shorter light flashes
and required a shorter interval to differentiate between successive flashes correctly (Brown et al.
1980,1984). It has also been shown that processing of sensory information at the thalamic level is
facilitated during the practice of pranayama (Telles et al. 1992) and meditation (Telles & Desiraju,
1993). These two practices, along with IAYT were found to bring about an improvement in hand
steadiness in college students following 10 days of
practice (Telles et al. 1993). This improvement was believed to be due to improved eye-hand
coordination, better attention, concentration and relaxation.
We (Telles et al 1995) tested the visual discrimination in two groups of 18 college students (age 17-
22 years) each, by their ability to detect intermittent light of fixed luminance at varying frequencies
on a Critical Flicker Fusion apparatus. The initial values were 37.6±0.7 and 37.9±0.6 which changed
to 42.6±1.6 [p < 0.01] and 36.4 ± 0.7 [p < 0.5] in Yoga and control groups respectively demonstrating
sharper perceptual ability after yoga. In another study (Ramanavani 1997) in adults (25 to 39 years),
we observed that the improvement in Critical Flicker Fusion in yoga group occurred after 20 days of
yoga instead of 10 days unlike in children where the changes were demonstrable within 10 days.
It has been shown that training in focusing the gaze on the stimulus reduces the optical illusion by
79% (Hochberg 1984). The degree of illusion was measured on Muller Lyer apparatus where the
lines although of equal length, appear unequal due to the two different types of arrows drawn at
both ends of the line (<—>), the close ended (<—>) or open ended (<—>). There was a 86%
reduction (Tukey test, p<0.001) in degree of illusion in the group of 30 subjects after 30 days of
integrated yoga practice where as the control group did not show significant change (Telles et al.
Yoga for Learning and Intelligence
Shecter (1975) showed significantly greater improvement on measures of creativity (match problem
test), Intellectual performance (Raven progressive matrices) and personality (Jackson personality
inventory) with a reduction in their anxiety (Lickert scaled questionnaire) after practice of
transcendental meditation (4 days ) and science of creative intelligence (14 weeks) Program in 60
high school students. Collier (1973) and Heaton et al (1974) demonstrated the improvement in
performance and achievement in university students after transcendental meditation. In 1989 we
(Uma et al) demonstrated the role of integrated approach of yoga in improving IQ in special
Yoga in Memory
Improved information processing at thalamo-cortical pathway, better attention, concentration and
emotional stability forms the basis for better registration and retrieval. Abrams (1972) showed a
direct relationship between transcendental meditation, quicker acquisition and higher recall
performance in 14 subjects. Effect of breathing through a particular nostril on selective memory
test for 'right' (spatial) and 'left' (verbal) brain functions (Telles et al 1997) were studied. 108 school
children with an age range of 10 to 17 years were randomly arranged to 4 groups. Each group
practiced a specific yoga breathing technique namely (a) right nostril breathing (SAV), (b) left nostril
breathing (CAV), (c) alternate nostril breathing (NS), (d) breath awareness without manipulation of
nostrils. Yoga training caused an increase in verbal and spatial memory scores within 10 days. For all
groups there appeared to be more marked improvement in right brain functioning. A marginal
difference was obtained between the scores of the SAV and the CAV groups, suggesting an
ipsilateral beneficial effect.
Yoga for Emotional Stability
Modern day living style in laden with the ill effects of stress. Stress according to yoga is an
uncontrolled surge of emotions like intense desire, anger, anxiety etc. When the stress is prolonged,
the person loses his capacity to come out of the clutches of the loop of intensely heightened activity
that shows up as imbalances in the function of the autonomic nervous system. This shows up as
generalised complaints like anxiety, fatigue, addictions etc. or as localised problems (asthma). Role
of yoga to reduce the force and speed of these violent surges of emotions has been validated by
many workers through psychophysiological studies.
In early 1970's, the epoch making study of Wallace (1970) showed that the practice of
Transcendental Meditation brings about a unique "hypometabolic physiologic wakeful state" with
overall signs of psychophysiological relaxation. A study from DIPAS (Delhi) showed that six months training in asanas (physical postures), pranayama (breathing practices), and meditation brought about definite physiological changes in normal volunteers, viz. an increase in orthostatic tolerance and an overall shift in the autonomic equilibrium towards parasympathodominance, as was shown.
during Transcendental Meditation (Selvamurthy et al. 1983). Further studies (Telles et al 1995) on
OM meditation showed significant reduction in heart rate with an increase in cutaneous peripheral
vascular resistance which is a sign of increased mental alertness even while physiologically relaxed.
Telles et al (1994) published their interesting observation that breathing exclusively through right
nostril (Surya anuloma viloma) showed a 37% increase in basal oxygen consumption, as compared
18% and 24% increase after alternate nostril (nadi suddhi) or left nostril (Chandra anuloma viloma)
breathing. This suggested that breathing through right or left nostril breathing may have activating
or relaxing effect on the sympathetic nervous system. This was supported (Telles 1997) by changes
in systolic blood pressure and digit pulse volume suggesting the sympathetic stimulating effect of
right nostril breathing.
Yoga for Social Health
Better adaptability when exposed to varying sociocultural situations is an important faculty which is
generally measured through various personality tests. According to yoga the most important
parameter of positive social health is "Tatsukha Sukhitwam" which means joy in the joy of others.
Movement from selfishness to selflessness is considered as the measure of growth of social health.
At the negative spectrum of the social health one could consider antisocial behaviors like crimes,
accidents etc. that show up because of increasing degree of selfishness with total lack of social
awareness and civic sense.
In 1976 Borland et al. published their interesting paper on "Maharshi effect" wherein they
demonstrated a sudden downward shift in the trend of increasing crime rate when about 1% of the
city population had begun the TM technique. A comparison of 11 US cities with population over 25,
000 with 0.97% or more of their population practising TM with 11 matched control cities showed
that the mean change in crime rate from 1972-1973 among the control cities had increased by 8.3%
as compared to a decrease of 8.2% in cities with 1% meditators, the difference being statistically
Yoga for Spiritual Health
Texts on Yoga and Upanishads describe the criteria of spiritual health as self awareness of one's
natural state of contentment. The joy or happiness is independent of any external agency. Such a
person's activities are not motivated by the need for material gains of money, name or fame and
they function in the society totally in tune with cosmic order charecterised by simplicity,
truthfulness and confidence. This is a state of eternal bliss and contentment, undisturbed by the
ups and downs of the life.
The nearest measure of such a state described by the modern psychologists could be that of "self
actualization". Many studies were conducted on transcendental meditators to show improved
scores on self actualization values, spontaneity, self regard, self acceptance, synergy, acceptance of
aggression, capacity for intimate contact in meditation as compared to non meditators (Hielle 1974,
Davis et al. 1984 and Nidich et al. 1973). This was measured by Shostrom's personal orientation
inventory of self actualization.
Triguna questionnaire which is based on Satva, Rajas, and Tamas type of personality described in
Bhagavad Gita and other Indian texts may prove to be a good tool for measuring the spiritual
growth of the individual. Studies on higher states of consciousness (Orme Johnson 1976), new
theories in physics defining consciousness as the base of all being (Goswami 1993), research in ESP,
telepathy, rebirth and Psychoneuroimmunology are all opening up newer avenues of understanding
of the subtler aspect of positive health, which were not in the perview of science until recently.