Evaluating Yoga Research

To date only a little research has been done to scientifically and conclusively prove the value and effectiveness of yoga in our lives. However, many people have experienced positive and beneficial effects for themselves. The claims that yoga can make us healthier, more peaceful, more alert and better people as a whole, demand that more research be made into the various techniques and their application to our lives. This is especially so since no one has claimed that, practiced properly and under expert guidance, yoga has any deleterious effects. Certainly no scientific evidence has shown this.

To gain a correct perspective of the effects of yoga we must view the practices in their totality. It is not correct to take one asana and to research only a few physical parameters. We have to study as much data as we can in order to draw definite and repeatable conclusions. Comparison of the mental and physical correlates as well as the personality before and after is required. That is, we must judge our objective data in relation to the subjective experience of the practitioner.

An example of the opposite of this approach to research would be that of a scientist who finds certain biochemical results in a certain asana. If this result seems to be deleterious purely from the point of view of the data, for example, an increase in stress hormones, then we may be justified in supposing that we should not practice such an asana. However, what if the practitioner feels better afterwards despite what the chemical data states? Then the data has to be judged in this light.

Asanas and pranayama have a wide range of effects on the mind and body and have to be selected according to individual needs. Some people need their hormones turned up, some need them turned down. Machine data is only a reflection of the psychophysiology we are experiencing. One parameter may have two opposite, yet valid, interpretations. Thus we have to view the whole picture. In this way we can better judge and evaluate yoga's role in order to lay down guidelines as to the best techniques in a wide variety of situations, both in health and disease.

The work of K. N. Udupa, director of the Institute of Medical Sciences, Benares Hindu University, Varanasi (India) is an important step in terms of coming close to the criteria of whole research. He states:

"The practice of yoga in general influences both the body as well as the mind. Therefore the methodology of evaluation of the effects of yogic practices needs an evaluation of these aspects."*1

Udupa has conducted several studies into asanas and pranayama, meditation, and the combinations of these practices in terms of their effects on the body and the mind.


When studied in terms of the effects of a large group of asanas practiced over 6 months, the following data was obtained:*2

  1. There was a decrease in body weight and abdominal girth. This was especially evident in obese people.
  2. The respiration was beneficially affected. The rate of breathing decreased from approximately 17 to 13.5 breaths per minute. This is correlated with relaxation and increased longevity. The amount taken in each full breath (vital capacity) increased from approximately 3500 to 4500 millilitres. The ability to hold the breath increased from approximately 75 to 100 seconds.
    Physical stress (running) upset the breathing less after the 6 months and there was less increase in pulse rate, indicating that the body had adapted and increased its stress handling ability.
  3. The amount of fat in the blood (serum cholesterol) decreased from approximately 150 to 134 milligrams per 100 millilitres of blood (mg %). The ramifications of this finding for arterial diseases such as atherosclerosis and coronary heart disease, the largest killers in the world today, could well be profound.
  4. There was a large decrease in the blood sugar level from approximately 75 to 63 mg%. The authors interpret this as a vitalising influence on insulin activity decreasing the percentage of glucose needed in the blood. The advantages to diabetics are obvious.
  5. Increase in serum proteins occurred (from approximately 5.7 to 6.0 mg %) because of the drop in blood glucose.
  6. The adrenal cortical activity increased with an increase in plasma Cortisol, urinary corticoids and testosterone. This was interpreted as a greater resistance to stress. The practices stress the body by stretching various components and the body responds. The increase in testosterone excretion was interpreted as indicating improved vitality and sexual vigour.
  7. A decrease in plasma acetylcholine and cholinesterase indicated tranquillity in the brain.

Psychological testing was also performed and the following results were found:

  1. A lowered neuroticism index
  2. Decreased rate of mental fatigue, even after stress
  3. Increased feelings of well being
  4. Increased memory
  5. Dominant alpha waves correlating with enhanced relaxation and feelings of creativity.

Specific asanas were also tested individually so as to ascertain whether there were any specific benefits to be gained.*3 These included sirshasana, sarvangasana, halasana, bhujangasana, shalabhasana, mayurasana and paschimottanasana. Of these, sarvangasana had the most dramatic effects:

  1. The thyroid function and adrenocortical function showed more pronounced changes. An increased PBI level (a measure of thyroid function) indicated that this asana activates the thyroid gland to function.
  2. Respiratory function showed improvement such as increased chest expansion, better breath holding ability and a wider range of inhalation and exhalation (vital capacity).
  3. Again, there was an increase in the adrenocortical activity with increased levels of Cortisol and corticosteroids and decreased levels of catecholamines.

All the asanas measured individually showed that they had the capacity to lower blood sugar and blood fat levels.


Ujjayi was practiced for only 7 minutes and this was followed by 5 minutes of rest before starting 10 minutes of bhastrika. This regime was practiced over 6 months and showed:

  1. Improved cardio-respiratory function. Breath holding increased from 85 to 110 seconds and there was a slight rise in blood pressure from a low systolic value of 104 to a more normal level of 110 millimetres of mercury.
  2. Adrenocortical activity increased indicating increased resistance to stress and the catecholamine levels decreased indicating bodily tranquillity.
  3. Blood sugar and fat levels decreased.


Measurements were made at a 10 day Buddhist vipassana meditation course where practitioners meditated for 8 to 10 hours per day. The following was found:

  1. Adrenocortical activity decreased with lower levels of Cortisol, corticoids and urinary nitrogen. This was interpreted as indicating that meditation helps to alleviate stress.
  2. There was an increase in the acetylcholine level.

These findings correlate with a physically calm and quiet body while mentally and neuro-physiologically they were more active, alert and creative. Corresponding findings in the EEG readings seem to confirm this. It appears that by keeping the body still and practising the technique, energy is made available for inner awareness.

Combined techniques

The effects of asana and pranayama on the body when compared with meditation are opposite. Therefore it is possible that by combining the two groups we can achieve a third state which blends the two components and creates balance and harmony in the body. Udupa states:

"The combined practice of selected asanas, pranayama and relaxation appear to be more useful... most of the asanas and pranayama produce bodily effects like vitalisation of endocrine functions and metabolic corrections. On the other hand meditation makes an individual more alert and aware as is evident from increased blood levels of different neuro-humors (chemicals secreted by the nervous system) and the related enzymes... (meditation) reduces the bodily stress which is evident from the reduced blood level of Cortisol and a lowered rate of urinary excretion of nitrogen. Therefore such practices may prove useful for persons suffering from anxiety states and depression."*6

By combining the three groups of practices into our daily sadhana we not only affect the muscles and joints but we stretch and massage our body in the process, even at the molecular level. Thereby we exercise and keep our body fit, well tuned and oiled. This research provides a good first step for our exploration deeper into the mechanisms of yoga.


*1-*6. K. N. Udupa, "A Manual of Science and Philosophy of Yoga", 'Journal of Research in Indian Medicine, Yoga and Homoeopathy', vol. II, no. I, 1976, pp. 1-103.