Looking into the History and Science of Yin Yoga

Yin yoga is a beautiful soft approach to asana yoga and can be a deeply restful and rejuvenating experience. Over the past few decades we have welcomed yin as a needed contrast to the more dynamic practice of Hatha yoga, with one of its main purposes being to help restore our bodies ability to move with ease and fluidity. Yin yoga has its roots both in the traditional practice of yoga that originated in India, yet is much influenced by Traditional Chinese Medicine (TCM). It is a practice that invites us to stillness- stillness of the mind through stillness in our physical bodies. A stillness that, through a persistent practice and devotion may lead to the expansion of consciousness.

The introduction to yin yoga to the western world happened in the 1970s, and is credited to yogi and martial arts practitioner Paulie Zink. Zink introduced yin yoga as an art form more than a collection of teachings, and he inspired his students to explore the practice though their own personal experience:

«Yin yoga is an art form and not an exact science because every person has an individuality that is expressed through her heart as she practices her art. 
«The spontaneous creative expression of art is alive. But when you repeat something and copy it over and over again, the same way your teacher did it, you are just making a replica of somebody else’s method. I don't want my students to mimic me. I want them to discover their own innate expression and ability to flow with movement- differently than I do. In this way it is a moving art that is constantly evolving.
«Science is based on objective observation. It is an intellectual construction. But art, like life, is subjective. Our experience of being alive, of what we feel and perceive, is organic and intuitive. We are organisms and not mechanisms. It is very important to be able to change and adapt.»
-Paulie Zink

The yin yoga we know and practice today, has more Traditional Chinese Medicine and anatomical science to it, and was made popular by Paul Grilley and Sarah Powers. Traditional Chinese Medicine is a system in which the practitioners use herbal medicines and mind-body practices, such as acupuncture and Tai Chi, to treat health ailments and enhance wellbeing. In TCM, we are introduced to Meridians as channels that directs the flow of Qi. Qi (also known as Chi, Ki, Prana or Life Force) is directly translated as ‘air breath’, and is the subtle yet very powerful energy that informs nature. It is the pulsation of the yin and the yang, the meeting of the feminine and the masculine energies. It is the ebb and flow of the universe. The state of our Qi impacts our physical and mental health.
The meridians are an interconnected network of channels that comes together as a complete energetic circuit. Each of the meridians are associated with a different internal organ, and the health of each organ is affected by the way Qi flows through in that area. Just like our physical and emotional health is interconnected, the health of our organs also has a direct impact on our mental and emotional health.

Author of the book «Brightening Our Inner Skies: Yin and Yoga», Norman Blair says:

If the stomach meridian is blocked, we could feel nervous and unable to feel satisfied with receiving support. If there’s an imbalance in the liver meridian this manifests as anger and a feeling of hopelessness.”

Western medicine has been sceptical to the principles of energy maps described by traditional eastern medicine; in chinese medicine, tai chi and ayurveda and yogic philosophy. But recently, groups of resetrches, led by Dr. James Oschman in The United States, and Dr. Hiroshi Motoyama in Japan, have explored the possibility that the connective tissue running throughout the body provides a pathway for the energy flows described by ancient traditions. 

Looking at yin yoga from a scientific point of view, it is important to keep in mind that there are very few studies done on the actual practice of yin yoga, and so instead we have to look into studies and scientific finds on yin-like practices, in search for scientific proof for benefits from a practice of yin. 

One such study looked at what applying distraction (traction) force, which is long held stress that tends to pull our bones apart, may do to our bodies. It found that applying traction to our bones, like we do in the long-held postures in yin, stimulates the growth of bones and their associated ligaments. (‘1) Yoga postures such as Buddha Konasana, often referred to as Butterfly in yin, applies stress along the spine, which may help to strengthen the bones and ligaments in this area. 

In a different study (‘2) , researchers contrasted short intense stresses (that we find in the more dynamic practices of yoga) to milder stretches held over longer periods of time (like we do in yin) in correlation to contracture repair. The results of this study found that the shorter and more intense stretches resulted in «a higher proportion of elastic response, less remodelling, and greater trauma and weakening of tissue» (‘3). The milder stretches that were held for longer periods of time, on the other hand produced «the greatest amount of permanent elongation, with the least amount of trauma and structural weakening of the connective tissue». 

Yin yoga aims to target the deeper tissues in the body, and the internal tissue of fascia. The fascia is a white material that is both flexible and sturdy. It is a structure of continuous material that penetrates every muscle, coats every organ and every bond, and envelops all nerves in the body. The fascia alters its structure according to the postures we find ourselves in the most, to support our body in its daily life and activities. The fascia tissue present in the parts of our body that we use less, or do not move at all, will with time begin to dehydrate, constrict and solidify.

The fascia needs at least 2 minutes of sustained pressure for it to start changing. This is why we, in the practice of yin yoga, hold the postures for longer periods of time (usually 3-5 minutes). The goal is to gradually lengthen and soften the fascia that has begun to constrict and solidify, and to rehydrate the tissues and release stuck spots. As the fascia gains back its flexibility and softness, it in turn becomes stronger and healthier. As with all forms of exercise, the principle here is to stress the tissue, so that the body will respond by strengthening it. 

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Generally, the practice of yin yoga is a tool to assist our body in its ability to relax, and to activate the parasympathetic nervous system. The parasympathetic nervous system is what’s in charge of our bodies ability to ‘rest and digest’. Many forms of modern yoga, that we suggest may have become too dynamic and and too fitness-dominated, instead activates the practitioners sympathetic nervous system; the system responsible for the ‘fight or flight’ mode. 


Simon Borg-Olivier explains: «I believe that if you are doing real yoga, then you should be feeling love, happiness and safety while you are practicing, not only in your relaxation after you exercise.. To generate yoga on a physical level by improving blood-flow without needing to increase heart rate, is not only possible, but it is the way of healthy people and the way of real Hatha yoga». 

I believe yoga is about cultivating a deeper ability to listen, adapt and soften. We are learning to be more aware, tapping into the feminine qualities of fluidity, ease and grace. This helps us adapts to our circumstances and to our surroundings. Like the flow of water, we find power through fluidity, flow and playfulness. This is what I wish to teach and inspire; yoga as a way to moving from, and connecting to, our hearts. 

References:
1- See The biology of distraction osteogenesis for correction of mandibular and craniomaxillofacial defects: A review by Subodh Shankar Natu et al in Dental Research Journal 2014 Jan-Feb; 11(1): 1626.
2- Contracture and Stiff Joint Management with Dynasplint by George R Hepburn.