Reflections on Stretching

Reflections on Stretching, Stabilizing, and Forceful Yoga

by Mark Stephens

What is Asana? Sthira Sukham Asanam – “Steadiness, Ease, Present”

– Patanjali, Yoga Sutra (325CE)

Hatha: “forceful”

Example: Hatha Yoga Pradipika (Light on Forceful Yoga)

– Swami Swatmarama (early 15^th century)

These reflections flow to you in waves:

• Wave One. This sets the table. I wrote it somewhat playfully, colloquially, and maybe a little provocatively. I do like to stir the pot! It considers notions about stretching in the vastly different practices of Ashtanga Vinyasa (which the foundational practice from which most “flow” style of yoga are derived) and Yin Yoga.

• Wave Two. This sets forth basic – and conventional – information on joint stability and mobility.

• Wave Three. This takes a much deeper dive into the kinesiology of stretching, ROM, stability, the nature of fascia, and related matters.

Wave One

Let’s imagine a student who’s in good overall health. They have no acute or chronic joint injuries, ligament sprains, or muscle strains. They feel good in their body, have a positive outlook on life, and seem emotionally balanced. They love doing yoga and say it’s an important part of their sense of health and wellbeing. Their practice appears to embody contentment, patience, presence of mind, conscious breathing and personal devotion. They don’t seem competitive or possessed of a go-for-it attitude.

What a wonderful student!

They’re also really flexible, even hypermobile in their knees and elbows. And while they’re strong, it’s very hard for them to keep their knees and elbows from hyperextending when bearing weight in poses such as Triangle, Extended Hand-to-Foot Pose, Down Dog and Handstand.

But not to worry! They’re doing Ashtanga Vinyasa six days a week (switching between primary and second series on alternate days), and Yin Yoga on the seventh day, religiously committed to staying in their practice. In both styles, they’re going far beyond what the sciences of anatomy, biomechanics and kinesiology define as full range of motion; it’s part and parcel of these prescribed practices.

In Ashtanga, they’re “led” (unless it’s Mysore-style, where they somewhat lead themselves) into not just the weight-bearing poses just mentioned, but extreme contortionist forms such as Marichyasna D, Janu Sirsasana C and Setu Bandhasana – all in the primary series, the one for beginners. The more formal name given to primary series by its founder, Tirumalai Krishnamacharya, is “Yoga Chikitsa,” meaning yoga therapy. In second series, they’re doing things like deep forward bends with both legs wrapped around behind their back. Almost the entire practice is done with fairly quick movement through a succession of poses, some of which are never held (Chaturanga and Up Dog) and most of which are held for exactly five breaths and never longer. It only gets more complex and contortionist from there. I know because I completed primary, second, and third series, having started in 1994, before jumping off the Ashtanga train in 2006.

On Saturdays (the Ashtanga “rest day”), our wonderful student goes to Yin Yoga, originally described by its founder, Paul Grilley, as “a quieter practice.” Now they’re invited to move to into poses far more slowly, and rather than holding for the mere five breaths mandated in most Ashtanga poses, they’re guided to stay in the poses for several minutes. Amid these long-held often complex poses (in terms of joint angles), most either seated or lying on the floor, it’s still an active practice in which one gradually moves into a deeper and deeper stretch and greater range of motion. It’s a different sort of yoga chikitsa, now targeting “the fascia,” which Grilley and other Yin theorists describe as “the primary organizing principle of the body,” as well as Meridians, the energy channels at the heart of ancient Chinese medicine. Paul adapted Yin Yoga from Paulie Zink’s Taoist Yoga (yin/yang), which we took along with Sarah Powers and other early Yin devotees in the early 1990s when Paulie taught in Santa Monica, California.)

The underlying idea in Yin is that our fascia is said to hold tension, and we can effectively release it by stretching really far and for a long time, which other yoga methods don’t do. Yin goes further, asserting that we must stress the ends of bones to maintain their health, an original and rather esoteric expression of Wolff’s Law, which states that bone develops in proportion to the force placed upon it. (Put aside for a moment that Wolff’s law doesn’t require bone-to-bone pressure; simply walking will stress the skeleton plenty. It’s the couch potatoes that are in trouble.)

“Theorists” is apropos because some of Yin’s leading visionaries and influencers see their work as part of a “paradigm change” in understanding the human body, even invoking Thomas Kuhn’s The Structure of Scientific Revolutions to underline their sense of a grand new synthesis. To be clear, Kuhn saw such paradigm shift occurring through the gradual accumulation of evidence-based research that eventually brought new understandings to light. A classic example is found in centuries of work in math and classical (Newtonian) physics that gradually brought forth a quantum revolution, a new paradigm expressed in the general (and later, special) theories of relativity. It’s not like Einstein woke up one day with a stroke of insight to proclaim the new paradigm. He and all other physicists in the 17^th to 19^th century were working within and on the immediate periphery of Newtonian physics, gradually developing new insights, eventually coming to a place where it was apparent that Newton didn’t quite explains things as well as cold now be explain.

 

Odd as it can seem coming from a devoted yogi, I’ll suggest that “mainstream” or “conventional” science does a pretty good job explaining human tissues and the forces involved in physical posture and movement. (At the risk of losing some readers, for now I’ll reserve matters of chakras and nadis for metaphysics and spiritual philosophy. Namaste, namago!)

Wave Two

So, let’s get back to matters of stretching, flexibility, range of motion, fascia and other tissues. I’ll first give a succinct overview of joint stability and mobility, helping to ensure we’re all clear on at least some basic concepts.

All joints are relatively stable and relatively mobile, with these qualities typically in inverse proportion to each other: more stability generally yields more mobility and vice-versa. However, this is not always true: one can have both great stability and mobility depending on the condition of their muscles and ligaments (think of the adept yogi who is capable of calmly stabilizing in fantastically open asanas, or most high-level gymnasts). We can define stability as the ability of a joint to move through its range of motion free of injury to the joint itself and to its stabilizing tissues (primarily ligaments and muscles). We find even greater stability when a joint can withstand shock from high-impact movements, such as catching a fall by placing one’s hand on the ground without separating joints in the shoulder girdle. When lacking stability, one is more prone to dislocation, sprained ligaments, or undue pressure on surrounding muscle and nerve tissues.

There are three sources of joint stability, with weakness in any compromising the support of the others and making the joint less stable:

A snug fit in the joint articulation: The glenohumoral joint of the shoulder is relatively shallow and thus not stable, whereas the hip joint—both are ball and socket structures—has a deep recession in the receiving acetabulum and is therefore generally more stable.

A robust and well-structured set of ligaments: The quality and quantity of ligaments surrounding the hip joint help prevent its potential dislocation, whereas ligaments around the shoulder joint are far less sufficient to prevent dislocation.

Strong muscular support: Rather than merely strong muscles, the key to the muscular stability of a joint is in the opposing forces that muscle can create to maintain the proximity of the bones comprising the joint. For example, there are four muscles in the shoulder joint that provide opposing directions of force that help maintain its stability (together they form the shoulder rotator cuff, which we explore later).

Mobility is the ability to fully and naturally move a joint without disturbing or being limited by surrounding tissues. Many joints are capable of multiple movements. We define these movements as range of motion (ROM), a common measure of flexibility. Joint ROM ranges from hypomobility, in which different structures limit full ROM, to hypermobility, in which one can create movement beyond the joint’s normal maximum extension as defined in anatomy and orthopedics. Whatever one’s ROM in any joint, it is ultimately limited either by bony structures (one bone hits another), ligaments (which have very little elasticity), and/or muscular tension.

Although ROM in any joint varies across the landscape of humanity, kinesiologists (informed by anatomy, biomechanics, neurology and physiology) provide us with average normal ranges of motion that are good starting points for considering generally safe ROM. Although it may seem that greater flexibility is associated with weakness—and as discussed earlier flexibility is typically associated with instability—strength can be developed in tandem with flexibility to allow for greater range of stable movement. Still, moving beyond normal range of motion into hypermobility, particularly when a joint is bearing weight or other tension, can further destabilize the joint by causing injury to the supportive ligaments, muscles, and other tissues such as cartilage.

Before exploring all of this more deeply – the Third Wave – here’s an excerpt from the second edition (2024) of Teaching Yoga on “The Natures of Fascia.” It’s relevant to play in the waves.

The Natures of Fascia

            Fascia is one of the trendiest topics in yoga and bodywork. Typically referred to in the singular (“the fascia”), it is said by some to be the source of “myofascial meridans” that most influence the body, “the primary organizing principle of the human body,” or the foundation of a “bio-tensegrity” explained with concepts taken from Buckminster Fuller’s architectural theories. (See See Myers (2020), Grilley (2012), Scarr (2018). Despite having questionable validity and confusing application, these and related pseudoscientific notions are widely asserted across the yoga landscape, leading many yoga teachers to express them without understanding their factual reality and giving us both ahimsa and satya issues.

            In attempting to establish the supreme role of fascia, a few researchers have found very limited evidence about a some aspects of certain types fascia that subsequently have been greatly exaggerated by others, such as taking scant evidence of fascial contractility only in the thoraco-lumbar fascia of rats as evidence that human being’s fascia can be contracted or relaxed, then using that assertion to defend the imaginative but unfounded assertion that fascia is the primary organizing tissue in the human body and primarily responsible for force transmission in specific “bio-tensegrity” patterns. Even the very limited root evidence regarding active facial contractility has never been found in humans.

            Going further, some imagine that the fascia constitutes a distinctive physiological system. Predicated upon these and other speculative notions, we are then given specific prescriptions ranging from how to do yoga (and how not to do yoga) to how to address persistent pain, psychological issues, and rehabilitation from injury.

            The most fundamental error in this body of gross and specific assertions is that our fascia is anything but singular. To suggest otherwise leads to practices that are misinformed and potentially injurious. To be clear, fascia matters. But it is not a “system,” not an irreducible tissue, and not in any measure the primary tissue of the body around we should develop a yoga anatomy and yoga practice. Fascia is diverse, which the most basic histographical, structural, and neurological analysis reveals. Its diversity in structure and function invites us to relate to it in its specificity. Consider these unique qualities of different types of fascia:

• Dense connective tissue – Connective tissue containing closely packed, irregularly aligned collagen fibers (in many directions) that form tendons and ligaments.

• Non-dense (areolar) connective tissue – Connective tissue containing sparse, irregularly arranged collagen fibers, it is found in the linings of the body’s inner surfaces and ducts.

• Superficial fascia – Enveloping layer directly beneath the skin containing dense and areolar connective tissue and fat.

• Deep fascia – Continuous sheet of mostly dense, irregularly arranged connective tissue that limits the changes in shape of underlying tissues. Surrounding muscles, bones, nerves, and blood vessels, it may be continuous with epimysium and intermuscular septa and may also contain layers of areolar connective tissue.

• Intermuscular septa – A thin layer of closely packed bundles of collagen fibers, possibly with several preferential directions predominating, arranged in various layers. The septa separate different, usually antagonistic, muscle groups (for example, flexors and extensors), but may not limit force transmission.

• Interosseal membrane – Two bones in a limb segment can be connected by a thin collagen membrane with a structure similar to the intermuscular septa, such as between the tibia and fibula.

• Periosteum – Surrounding each bone and attached to it is a bi-layered collagen membrane similar in structure to the epimysium.

• Intra- and extramuscular aponeurosis – A multilayered structure with densely laid down bundles of collagen with major preferential directions. The epimysium also covers the aponeuroses, but is not attached to them. Muscle fibers are attached to intramuscular aponeuroses by their myotendinous junctions.

• Epimysium – A multi-layered, irregularly arranged collagen fiber sheet that envelopes muscles and that may contain layers of both dense and areolar connective tissue.

• Perimysium – A dense, multi-layered, irregularly arranged collagen fiber sheet that envelopes muscle fascicles. Adjacent fascicles share a wall of the tube (like the cells of a honeycomb).

• Endomysium – Fine network of irregularly arranged collagen fibers that form a tube enveloping and connecting each muscle fiber. Adjacent muscle fibers share a wall of the tube (like the cells of a honeycomb).

• Neurovascular tract – The extramuscular collagen fiber reinforcement of blood and lymph vessels and nerves. This complex structure can be quite stiff. The diameter and, presumably, the stiffness of neurovascular tracts decrease along limbs from proximal to distal parts. Their stiffness is related to the angle or angles of the joints that they cross.

There’s often weird contentiousness when trying to converse about questions for which there are conflicting answers. We all need to find better ways to listen and consider other views.

Regarding fascia, we can move toward a more balanced perspective.

Here, I’ll try:

While fascia is an essential component of the connective tissue system and plays significant roles in mechanical force transmission and structural integration, it is part of a broader system of interdependent components that together organize and regulate body functions. The assertion that it is the "primary organizing principle" may be more a reflection of a shift towards appreciating its roles rather than a literal statement about its primacy (I hope so!).

Force transmission, similarly, is a shared function across multiple tissue types, with fascia playing a significant but not exclusive or primary role. While fascia is integral to the body's structural network and contributes to the distribution and efficiency of force transmission, it is not as primary in this role as bones and muscles. The dynamic and complex interplay of all these elements allows for the diverse range of movements and activities human bodies are capable of performing, including in yoga where we explore, well, everything! I think this perspective aligns with a more holistic understanding of human anatomy, where multiple systems are recognized for their contributions to the body's optimal functioning and wellbeing

Onwards!

Wave Three

Let’s back up to refocus on the risks and benefits, if any, of stretching the ligaments that stabilize that joint, especially if a student is capable of full range of motion in a joint.

Let’s be clear that stretching really deeply can have benefits.

If someone’s goal is greater flexibility, stretching ligaments will help. Even if a student has a full range of motion, increasing ligament flexibility through stretching might contribute to greater ease and fluidity of movement, especially in activ