I am hoping that Yoga students will be readers of this post and so, I am entering the Yoga Map proper, without regular introductions. I am attempting to very quickly explain the three popular limbs of Yoga, (among the eight limbs of Yoga) and translate them to physiological concepts, or how changes might happen in the body. Once, many years ago, I had planned to write a book on the physiology of Yoga and Yoga Nidra/Yogic Sleep. I will follow this blog up with a book on the physiology of Yogic practice sometime soon. I still feel the need for writing this book and I am satisfying myself for the time being with this blog.
Generally, Yoga, as practiced in western countries, has three main parts namely Pranayama (breathing exercises), Asana (physical postures) and Dhyana (meditation). A yoga session might include all of these three limbs in various doses, according to the teacher’s prerogative. In the following paragraphs I have a quick description of each of these three main parts and in subsequent paragraphs, the probable physiological response from the description.
I have seen from my experiences in western countries that many of you take Yoga very seriously and may give a lot of your time for the practice of Yoga. This blog is addressed primarily for those of you who are serious students. Some of you who are very popular Yoga teachers and conduct many classes during the course of a day also need to understand how Yoga affects the human body in scientific terms. I have hyperlinked corresponding text links to Wikipedia articles on the respective subjects. Please read more about it if you would like further information.
Pranayama is taught during the first part of a yoga class, as preliminary exercises before the physical part of stretches and exercises that we commonly associate with Yoga. The wrong practice of Pranayama is the usual pitfall of Yoga, which might translate into physical dysfunction. You may practice according to what your teacher teaches you. If your teacher’s knowledge is faulty, you suffer the consequence in your Yoga practice. What has been taught and practiced in good faith can be wasted time and worse, cause damage to the body. In short, Pranayama is what you should be most careful about when practicing Yoga.
Physiology of Pranayama
In human physiology, breath rate has a relative 1:4 ratio with the heart rate. When you control the breath rate voluntarily, the heart rate will proportionally change in relation to the breath rate. Since Pranayama focuses on the control of breathing, with practice you may make changes in the brain, with the possibility of having beneficial effects on the heart and other internal organ functions. The benefits of Pranayama are affected primarily through the Hypothalamus and the Brain Stem. Commands from the brain are sent mainly through the Vagus nerve, the Pelvic Splanchnic parasympathetic nerves and ganglia, and nerves of the autonomic/enteric nervous system. The above-mentioned changes will manifest in your body as changes in your heart rate and rhythm, your breath rate, your hormonal balance, and mental and emotional balance. The map of the full benefits of Pranayama is still not clear due to lack of adequate scientific studies. Your practicing Pranayama is similar to your taking medicine and is as potent.
Pranayama practice should be tailored to your body, your health, your job, and personality, which a good Yoga teacher will do. The dosage required by one person is like a map. The teacher will help make the Yoga map for the practitioner, which might be different from one student to another; the same timing and regimen may work on people differently, as well.
Asanas involve stretching into certain predetermined poses and constitute one of eight limbs of Yoga. Stretching into the poses and holding on to the physical poses are important for positive gains from your Yoga practice. These exercises are repeated a number of times to gradually educate and train the body. Asanas build the muscle strength and flexibility. These poses bestow upon you major physiological benefits and require more studies for us to fully understand. Many in the Yoga field think that these exercises are the most important part of their practice and might ignore the seven other – equally important – aspects or limbs of the practice.The physical exercise aspect is significant in keeping the body in top shape and condition, but it is not the most important part of a Yoga practice. Please read my previous post for more on my views on the philosophy of Yoga.
Physiology of Asanas
The Asana limb of Yoga maximizes muscle efficiency and streamlines the body structure. Your body gains flexibility in the joints, adding to the range of motion. According to Indian wisdom, a continuing Yoga practice will optimize internal visceral functions. From a physiological point of view, a muscle fiber has a specific length when it contracts with maximum force. Any measurement that is above or below this particular length will reduce muscle efficiency. Yoga helps muscle fibers to be close to the ideal length as possible, thereby improving its functions. Yoga exercises are set and structured in such a manner that the group of agonist muscles and its antagonist muscles, (Agonist muscles cause a movement to occur through their own contraction and Antagonist muscles oppose that specific movement,) equally get exercised, stretched and optimized. This helps you to keep your posture in the best possible position and increases your postural and body awareness.
Many Yoga postures are recommended as curative poses to help rebalance the body and to get rid of non-contagious physical ailments. Yoga Asanas, when practiced incorrectly, may hurt the physical body, and may result in joint pain, muscle tears, and sprains. This is an area of Yoga physiology that warrants more research from many angles.
Dhyana or meditation is usually practiced towards the tail end of a Yoga session and is the seventh limb of Yoga. The preferred pose in simple meditation is Shavasana, or corpse position. From this posture, one relaxes and consciously breathes in and out. Though the Shavasana position is the preferred position to meditate after your physical activities, there are many other positions, including the Lotus or Half Lotus that could be used to meditate.
Physiology of Dhyana
Dhyana up-regulates the parasympathetic system and down-regulates the sympathetic system. In a person who is generally in the stressed mode, Dhyana practice can have very positive benefits, reducing emotional, mental and physical stress. Dhyana relaxes the body-mind and advances peace in the practitioner. Since the result of Dhyana is also physical in nature, it is good to tailor it to the individual. Meditation increases the count of gray matter cells in the nerve system, thereby increasing capabilities for higher brain function and intellect. Please remember, the goal of the whole meditation practice is to balance the practitioner’s life and living, which is translated to health and happiness. Any practice that exceeds the required or ideal time frame for that practitioner may be counterproductive.
Yoga is a very important practice to have as a means to balance your body and life. The practice of Yoga should be tailored to the individual's need and requirement and that is the job of a good Yoga teacher. My deepest respect and regards to all the great Yogis and Yoginis!