Yoga - A Medical Analysis

The following is excerpted from the wonderful 'Iyengar, The Yoga Master: Essays and Appreciations'. In this book, many students share their experiences having spent time under the tutelage of B.K.S Iyengar. One of them Dr. Krishna Raman, was a graduate in Medicine from Madras Medical College, Chennai in India. Dr Raman has spent much of his life researching the clinical and medical benefits of hatha yoga.


As I have explained many times to our Teacher Trainee students, the modern way to approach standing and balancing poses (take triangle and warrior 3 for examples) is with a bend in the front or balancing leg. The theory being that this is 'safer'. Even though there is no actual research to support this. All the research available tells us to work our knee joint to 'full' extension. Dr Raman explains the medical reasons why a straight leg is the preferred technique in all standing and balancing poses. Anyway, enough from me, below Dr Raman explains his findings and on some points I have made comments in blue.


A Brief Analysis of Lower Limb Arterial Blood Flow in Standing Poses D R . K RISHNA R AMAN


To the hatha yogi, the body is an exercise in concentration, its subtle inner workings an opportunity to develop the most sophisticated and deepest levels of knowledge and awareness. Dr. Krishna Raman gives an indication of the complexities of interaction of which a discriminating awareness is capable.



I started practicing yoga in school at fourteen. One of my teachers presented me with a book, and liking challenges, I attempted the poses and felt great. Being a student of karate, I was already quite flexible. I attempted the more difficult asanas, and although I could achieve them, my incorrect technique eventually caused problems. Years later, I could not cross my legs while seated in a chair. Persistent backaches and hip pain were my companions. Yet the most advanced poses remained possible. By God’s grace, I met Sri B. K. S. Iyengar, and the pains of years disappeared within a week! This new approach to practicing yoga made me ponder whether there was more to it. I continued to visit the Ramamani Iyengar Memorial Yoga Institute and followed up on patients being treated there. Dr. Suresh, a highly regarded and dedicated sonologist, was a friend of mine. I became curious about the ultrasound details of yoga poses. Dr Suresh started analyzing arterial blood flow patterns while I practiced asanas. The research continues even now, and we discover more about yogic physiology.


Hatha yoga is often filled with concepts that cannot be ratified. What we think happens does not happen, while the opposite is also true. For example, our eyes may feel very comfortable while in headstand. We therefore may not appreciate that eye pressure rises to twice its resting levels no matter how well the pose is performed (with or without a bandage around the eyes). The pressure rises even if the pose is performed on the ropes.


It is very important to be unbiased and recognise that our assumptions on the effects of yoga poses may well be incorrect. We tend to focus only on what yoga can do. Many yoga practitioners think that yoga poses lead entirely to positive effects. It is difficult to accept that negative effects could occur. As an example, we may think that standing poses increase blood supply to the legs. But they can produce minimal change and sometimes actually reduce blood flow.


Is it harmful if blood flow is reduced? The body does need to shut off its own resources at times. This helps to give “relief” from the effects of the constant hematological traffic within the body. It is important to understand the different effects on blood flow that different poses can have.


In tadasana (standing mountain pose), the force of blood flow is slightly greater than it is in dandasana (seated on your backside, legs stretched out, back straight). One need not execute a perfect asana to get this slight change in effect. The moment we stand up, gravity will ensure certain hemodynamic changes. Sri Iyengar once mentioned that it is possible to consciously direct blood flow to the center of the vessel—and that is what I have seen using ultrasonography (medical ultrasound). He also stated that a slight change in the position of the legs in prasarita padottanasana (wide legged forward fold) will change the direction of flow. This was also ratified by ultrasound.


It is necessary to appreciate the medical importance of keeping the knees locked in standing poses. Failure to do so will weaken the supporting ligaments (medial and lateral) and the menisci will be massaged improperly. Taking utthita trikonasana (triangle) as a specific example, it has been observed that the blood flow in the popliteal artery, located in the back of the knee, shows greater increases when the knees are not locked! But this does not mean that we should not engage the knees in these poses. In the end, the locking provides a greater overall blood supply than merely standing erect, since the popliteal artery is enveloped by the leg muscles and is massaged more thoroughly when the knees are locked.


This indirect “touch” on the artery maintains the elasticity of the vessel, which in turn maintains healthy blood flow.


(TT students will recall we spoke of the need for the bottom 'ends' of the femur (thigh bone) to sit snuggly into the meniscus. This is why the meniscus is designed the way it is. To accommodate the curved ends (condyles) of the thigh bone. This is what Dr Raman refers to as 'massaging' the meniscus - Zahir)


Back to Dr Raman....


Inverted poses (upside down poses), unlike standing ones, are restful for the legs, yet they actually deliver a greater quantity of fresh blood to these extremities. Many yoga students feel better if they practice inverted poses after standing poses, as this relieves the fatigue sometimes caused by standing asanas. However, if the standing poses are done with “buoyancy,” no difference is felt in the legs while doing inverted poses. But if they are held to the point of exhaustion and done with “heaviness,” the blood flow in the legs reduces almost to zero.


It is easier to lock the quadriceps in sirsasana (headstand) than in sarvangasana (shoulderstand), because in the latter, we need to align and lift the pelvis. Against that lift, we need to press back onto the hamstring muscles. Thus, the legs must be very active in sirsasana. If beginners feel a little fatigued in the legs, it is then incorrect to advise them, and even fairly advanced practitioners, to precede their standing poses with a headstand.


(For TT students, this creates an interesting argument about when you should plan a headstand in your sequence. Too late and the legs that are required to 'engage' and reach up may be too fatigued. It's food for thought - Zahir)



If “high-speed” athletes practice yoga regularly, their running speed might well decrease as the fast-twitch muscle fibers seen in sprinters are replaced by slow-twitch ones. They must therefore practice yoga prudently. There is a subtle tendency among yoga practitioners to “thump” other systems of exercise, and in all fairness to both systems, this is not justified. Every system of exercise gives some benefit to the body. While yoga does not involve wear and tear, a yoga student cannot engage in recreational sports as effectively as do professionals, because yoga does not build the stamina to face that kind of strain. However, yoga does offer methods of recuperation and protection against injuries.


D R . K RISHNA R AMAN holds a Bachelor of Medicine and Surgery (MBBS) degree, Madras; is a Fellow of the College of Chest Physicians (FCCP), Delhi; and is a certified Iyengar teacher who has assisted extensively in the medical classes held at the Ramamani Iyengar Memorial Yoga Institute in Pune, India. He has given lecture-demonstrations at medical conferences and institutions in India and the United States. He has authored A Matter of Health: Integration of Yoga and Western Medicine for Prevention and Cure and Yoga and Medical


Science: FAQ. __________ 1 . Krishna Raman Baskaran et al., “Intra-ocular Pressure Changes and Ocular Biometry during Sirsasana (Headstand Posture) in Yoga Practitioners,” Ophthalmology 113, no. 8 (August 2006): 1327–32. 2 . “Longevity of Men Capable of Prolonged Vigorous Physical Exercise,” British Medical Journal 301, no. 6766 (December 22–29, 1990): 1409–11.

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