Written with Sarah Campbell
Why stretch in yoga?
It is an undeniable fact that the poses that make up yoga sequences require a high degree of flexibility and strength, even if you are not interested in sticking your leg behind your head. Life off the mat, in contrast, is largely sedentary and encourages chronic inflexibility, tension, and discomfort. A lack of flexibility not only prevents you from practicing compass pose but can also decrease muscular performance and strength and can contribute to poor circulation[i]. Both on and off the mat there is a practical need for a reasonable amount of flexibility. Of course, we are almost always stretching as we practice, but we can be more deliberate about how and why we do it. Yoga classes provide an ideal environment to develop this balanced and mindful flexibility and strength that can help us feel more joyfully embodied, awake, and alive.
What to stretch in yoga?
The target muscle is the muscle or group of muscles you aim to stretch due to disproportionate tightness or limited range of motion. The target muscle and its tightness may be what is limiting you from progressing in a group of yoga poses or is just tight in general. In addition to knowing the target muscle or muscle group, you must find its opposing muscle or muscle group. This will be the muscle that upon its contraction will aid in lengthening your target muscle. In anatomical language this is the agonist/antagonist relationship. This opposing muscle can be productively contracted to aid the release of your target muscle. For example, the opposing muscle group for the hamstrings are the quadriceps and can be contracted in poses like triangle pose to help lengthen the hamstrings.
Additionally, you will want to know the muscles that blend with or connect to your target muscle from above, below, or to the sides. The body is not as segmented as anatomical texts will lead you to believe and you are never stretching just one muscle in isolation. If you work with the muscles close to your target muscle you can further aid an increase of range of motion. For example, the calf muscles and one of the adductor muscles blend with the hamstrings and can be stretched to help release the hamstrings. Do your homework before you start getting out the straps and sandbags.
Yoga and the stretch reflex
Fundamental to understanding stretching is that the nervous system, in simple terms, utilises reflex actions to manage the contraction and release of muscles. These reflex actions can be highly sensitive and influenced by your psycho-emotional states.
Most stretching theory and practice works in relationship to the stretch reflex. The name of ‘stretch reflex’ is misleading, as it is actually a reflex that leads to muscular contraction. You will have experienced this reflex in medical check-ups with a sharp pound on the knee leading to a ‘knee jerk.’ In everyday function it stabilises the body as we move and confront the forces of gravity, making sure that as we lean and stretch forward, backwards, or sideways as we move through space that a compensatory contraction arises to maintain an equilibrium (i.e. so we don’t fall over). Repetitive stimulation through activities like jogging wherein the stretch reflex has to repeatedly activate to stabilise the body thousands of times can lead to diminished flexibility. Importantly, quick, sharp, and bouncy movements in yoga practice can also stimulate the stretch reflex and diminish our capacity to stretch and release, therefore the general advice is to move patiently and slowly while avoiding bouncy movements[ii]. The stretch reflex also prevents muscles from stretching too far and tearing by protectively signalling to the muscle to contract if it thinks we are going too far[iii]. If you move carefully into a pose and hold for a prolonged period the stretch reflex will reduce its signalling and allow a release.
Another reflex to work with is the lengthening reaction (also known as the clasped-knife reflex) that in a simplistic view can be seen as the opposite of the stretch reflex. When muscles are contracted, especially by the stretch reflex, tension is produced at the tendon. When this tension exceeds a certain threshold over time, sensors within the tendon signal back to cease contraction and the muscle lets go[iv]. We will discuss how long to hold in Part Three. Some stretching techniques involve manual stimulation of the tendon and/or further contraction of the muscle while trying to stretch to activate this lengthening reaction. We will examine these techniques in Part Two.
If all of this is starting to sound a bit overwhelming, you are not alone! But re-examining these reflexes in the light of what they can teach us about yoga can be mightily reassuring. You’ve surely been told or have instructed in class to move slowly, patiently, and to work with and not against your body. You may have even wrapped this up in spiritual words and well-chosen quotes. The reality of these reflexes we feel is the secular and mechanical reassurance and proof that we do have to work slowly, patiently, and with our bodies otherwise we will meet a slamming door of resistance. Working with the stretch reflex can be the working metaphor of yoga, reinforcing philosophy with biomechanics. The stretch reflex can be seen as the muscular ego, holding on to past habitual patterns and future fears both real and imagined. It doesn’t want you to change. It wants the status quo.
Knowing this can we meet our physical and emotional edges with sanity? Can we stay with an unpleasant sensation and develop a new relationship with it? Can we breathe through challenge? Can we find ways to grow and change through repeated practice? Working with the stretch reflex can begin to teach us this.
How to stretch in yoga
When you stretch in yoga you are working with both the nervous system and the musculoskeletal system and must adopt strategies to work with the challenges that both present. Fundamentally, you must work with the body as a whole and not seek limitless flexibility in one region at the possible expense of the healthy function of the rest of you[v]. Furthermore, flexibility should not be developed in the absence of strength, to make sure your body can still support itself within the everyday world[vi]. The musculoskeletal system is robust and resists quick change, requiring time and reasonable force to work through layers of connective tissue and muscular fibres and create an environment in which they can reorganise and lengthen.
Stretching occurs by placing a tensile load, i.e. a pulling force, on your target muscle through a variety of techniques[vii]. We will explain these techniques in Part Two. The effect of the pulling force and the duration of the stretch takes the target muscle through the following stages.
Stretch tolerance
Stretch tolerance is an individual’s ability to withstand more stretching force and the associated discomfort without the muscles contracting in response (the stretch reflex). Stretch tolerance is gained through repeated practice wherein through time and patience while working carefully with the body’s natural reflexes both passively and actively, the target muscle will release its active tension and temporarily elongate for a chosen movement or shape[viii] [ix]. Over time this tolerance can grow, but the actual length of the muscle does not change[x].
Permanent elongation and elasticity
Once muscles have released active tension and temporary range of motion has begun to open up, stretching technique begins to address the connective tissue, or fascia, and in some cases (and controversially) the ligaments that support joints to permanently elongate for lasting effect. Through active and passive practices, in most cases working with much longer holds, these stretches seek to elongate both the fascia and muscle fibres[xi]. The mechanics and safety of this are debated and can vary widely.
Practise these concepts with my 90-minute online workshop, ‘Beyond Stretching’ available on-demand. 
2019 Update: Fascia is not separate from muscles. There is new information about the composition and role of fascia coming out consistently. We should be more critical in our acceptance of ‘facts’ than I was when I wrote this in 2016. At this moment I do not intend to rewrite this with a more nuanced understanding of the role of fascia, so I refer you to Jules Mitchell’s Yoga Biomechanics: Stretching Redefined (2019). Mitchell notes “the idea that fascia can become more fit, more pliable, or less restrictive in response to certain methods of movement or massage is most usually met with either blind acceptance or staunch skepticism.” This reminds us to keep our critical thinking hats on and continue to experiment and survey new research studies as they emerge.
On the issue of permanent elongation, Mitchell summarises that “we cannot confidently conclude tissue changes in length as a response to stretching.”
Stay tuned for Part Two, which will address how to use a variety of stretching techniques in your yoga practice and teaching.
Photos by Karen Yeomans
Works Cited:
[i] Walker, B. (2011). The Anatomy of Stretching. Berkeley: North Atlantic Books.
[ii] Coulter, H. D. (2001). Anatomy of Hatha Yoga. Honesdale: Body and Breath.
[iii] Walker, B. (n.d.). Understanding the Stretch Reflex. Retrieved October 25, 2016, from Stretch Coach: http://stretchcoach.com/articles/myotatic-stretch-reflex/
[iv] Appleton, B. (2009). Stretching and Flexibility: Everything You Never Wanted to Know. Retrieved November 1, 2016, from http://www.mit.edu/activities/tkd/stretch/stretching_toc.html
[v] Coulter, D. (2015, June 14). Stretching: What Does it Really Mean? Retrieved October 26, 2016, from Yoga International: https://yogainternational.com/article/view/stretching-what-does-it-really-mean
[vi] Mitchell, J. (2014, November 18). Stretching Does Improve Flexibility. Retrieved October 26, 2016, from Jules Mitchell Yoga: http://www.julesmitchell.com/stretching-does-improve-flexibility/
[vii] Mitchell, J. (2016, June 26). Loading and Stretching. Retrieved from Jules Mitchell Yoga: http://www.julesmitchell.com/loading-and-stretching/
[viii] Coulter, D. (2015)
[ix] Page, P. (2012). Current Concepts in Muscle Stretching for Exercise and Rehabilitation. International Journal of Sports Physical Therapy , 7 (1), 109-119.
[x] Appleton, B. (2009)
[xi] Appleton, B. (2009)
