‘Yoga is just stretching’
Any yin yoga student will argue against this statement, knowing that yin offers much more than the physical ‘stretch’ benefit. We quiet the mind, we attune to our breath, we find physical and mental stillness. However, do we really know what is happening in our bodies when we practice yin yoga? The word ‘stretch’ is used more often than not by a teacher, to a habitual degree in as much as ‘stretch’ becomes attributable to any feeling of sensation in the body. So to a student, the physical side of yoga may be interpreted as only stretching, whereas in reality there is a lot more happening in the body than just stretching. In fact, there is actually minimal stretching happening at all in a yin yoga class. What we are feeling in these cases can be described as stress. With stress, we may have a resulting stretch, but more likely what will result is strength.
The intention of this essay is to find some definition as to what is happening in our physical body during yin yoga, and a distinction between stress, stretch and strengthen - or, as I have come to refer to it, the ‘Three S’s of yin yoga’.
It is important at this stage to distinguish what stress and stretch translate to in the yin yoga room. The two are not synonymous with each other, nor are they interchangeable. According to Bernie Clark (2012), stress is tension and stretch is the elongation that may result from stress. Often we think we are stretching, but what is actually happening is a degree of stress which may or may not be resulting in a stretch. Isometric exercises, for example, are an application of stress but with no stretch or change in length in the outcome (Clark, 2012). In an active, or yang, style of exercise, the focus is predominantly on muscular contraction. Muscles are filled with blood and become much easier to stretch and strengthen due to an increase in elasticity once filled with fluid. In yin yoga, our aim is to stress tissues rather than stretch them. In fact, there is minimal muscular effort required as muscles should be relaxed in order to target the connective tissue around a joint. If muscles are tense, the connective tissue will not receive the appropriate degree of stress.
Unfortunately, in our culture today, stress comes attached with negative connotations and something we use yoga to escape from. This may go some way in explaining why the term is used so little by yoga teachers to describe physical sensation. However, in our physical health as much as our mental health, a certain degree of stress is necessary. There is eustress, for example, a good stress that we can react to
and recover from in order to prevent our body from becoming fragile (Clark, 2019). Like many things in yoga, it’s all about balance. Whilst distress or over-stress can cause problems and damage to our physical and mental health, this shouldn't; mean complete elimination. Bernie Clark (2012) terms this optimal amount as the Goldilock’s position - not too much and not too little. In biomechanical terms, this means if we apply too little stress to our tissues, they deteriorate, but too much stress can cause tissues to degenerate.
Contrary to the muscular engagement of a yin practice, the term ‘tissue’ in yin specifically refers to connective tissues, that being ligaments, tendons and fascia. Tissue of this kind behaves in a different way to muscular tissue, hence needs to be exercised in a different way. Muscles respond well to rhythmic contraction and repetitive movement, as their elasticity allows fibres to elongate and therefore stretch appropriately. Connective tissues, on the other hand, don’t elongate as much due to their plasticity. Instead, these tissues respond best when stressed in a slow and steady manner, such as yin yoga, with a conscious relaxing of the muscular tissue. Myers (2012) found that slow and sustained tensile loads change tissue length more effectively than a quick stretch, and can undergo change under a new load due to their plasticity element. Imagine a plastic ruler, the type you used to use at school. If you bend it repetitively back and forth, it will eventually weaken and snap. Just like the ruler, our ligaments and tendons cannot undergo repetitive forceful movement. The long held static stresses of yin yoga may eventually result in a stretch, but in turn work to make the tissues stronger.
So now alongside the idea of stress and stretch, we add strength to the mix.
Many yoga students come to the practice seeking the physical benefit of strengthening rather than stretching, in particular the more dynamic forms of yoga. However, stability and strength of joints can be best achieved through a regular yin practice due to the concentration of connective tissue in these areas. The highly adaptive connective tissue of our bodies is composed of cells, collagen and elastin, as well as a gel-like fluid called ground substance. Taking fascia as an example, this being the band of integrating mesh that envelopes our bones, muscles and organs. It is key to our ability to move and for the functioning of our internal communication system. The primary cells found in fascia, known as fibroblasts, build fibres which create more fascia, controlled by physiological input (Schleip et al. 2012). Research by Benjamin et al. (2005) has shown that fibroblast cells will adjust the collagen, elastin and ground substance production to create an appropriate architecture for the given demand placed on them through stress. In other words, they will adapt and strengthen to respond to compressive forces and withstand additional forces (Benjamin et al. 1998). Fascia, being a yin like tissue, will respond best to long held, sustained yin-like stress.
That being said, there are many ligaments in the body which do stretch under the right amount of stress. For example, the nuchal ligament, along the back of the neck, has enough elastin to bring our head upright after flexion (Clark, 2012). Every forward fold we make, we rely on the ligaments and fascia of the back to control descent and initiate the return to vertical through stretching (Clark, 2018).
Whilst stress, stretch and strengthen all have distinct properties and definitions, it is easy to see where the lines become blurred and each become codependent. Perhaps a ‘one size fits all’ approach is required; a single word that encompasses all three of these qualities. A more neutral definition such as ‘load’ could fit the bill, although a blanket term of this kind may be rendered too vague.
Why does the correct use of language matter to the student? After all, the practice of yin is suggestive; allowing the practitioner to feel what is happening in their own body without prescription of how it should be. However, with a better physiological understanding, we can work more effectively and even prevent injury. Yin teaches us to pay attention to our bodies, so it’s important that we understand what it is we are paying attention to. Conveying this to our students emphasizes the importance of a yin practice in a somewhat yang world, which can only result in positive outcomes.
Benjamin, M., Putz, R., “Molecular parameters indicating adaption to mechanical stress in fibrous connective tissue.” Advances in Anatomy, Embryology and Cell Biology (2005).
Benjamin, M., Ralphs, J.R., “Fibrocartilage in tendons and ligaments — an adaption to compressive load.” Journal of Anatomy (1998).
Clark, B., “The Complete Guide to Yin Yoga” (2012)
Clark, B., “Your Spine, Your Yoga” (2018)
Clark, B., “In Defense of Yin Yoga.” (https://yinyoga.com/in-defense-of-yin-yoga/) YinYoga.com (2016)
Clark, B., “The Value of Stress” (https://www.elephantjournal.com/2012/09/the-value-of-stress-bernie-clark/) Elephantjournal.com (2012)
Clark, B. “Not Too Much & Not Too Little: The Goldilock’s Position” (https://www.elephantjournal.com/2012/10/not-too-much-not-too-little-the-goldilocks-position-bernie-clark/) Elephanthournal.com (2012)
Schleip, R., Muller, D.G., “Training principles for fascial connective tissues: Scientific foundation and suggested practical applications.” Journal of Bodywork & Movement Therapies (2012).
Myers, T. Frederick, C., “Stretching and Fascia.” Fascia: The Tensional Network of the Human Body (2012).
O’Sullivan, J., “How Yin Yoga Affects Connective Tissue” (https://medium.com/@satiJen/how-yin-yoga-affects-connective-tissue-70ba3867cb23) Medium.com (2017)
Yogaland., “Bernie Clark on the Benefits of Yin Yoga” (https://www.jasonyoga.com/podcast/episode154/) (2019)