The Value of Stress. ~ Bernie Clark

Via Bernie Clark
on Sep 20, 2012
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The Two Biggest Challenges in Yoga Today (Part One)

Frequently I receive emails or postings from yoga teachers and students asking for an opinion about some other teacher’s statement that a certain yoga pose is really harmful for students and should never be taught, or certain movements of the body in a yoga class should be outlawed.

Dogma is dangerous! To say that something is always wrong or something should never be done feeds into fear and is, at best, unhelpful and, at worst, harmful. There are two big reasons why some teachers will render these prejudicial statements:

  1. A common misperception about the nature and value of stress
  2. Ignorance of skeletal variations

Let’s investigate how these deficiencies manifest in a yoga class and why they’re not serving students well. We’ll begin first by reciting a few of the most recent questions I have received.

Please comment on this blog wherein a teacher claims that Pigeon Pose should be forever outlawed in yoga classes. (He says the lying forward version should be renamed “Dead Pigeon.”)

Please comment on this video blog where a teacher claims that we should never allow any flexion of the spine (forward folds) during a Yin Yoga class.

Please comment on the following statement made by a yoga teacher, “Yin Yoga is especially bad for pregnant students because it could lead to a thrombosis or an embolism leading to a stroke or heart attack!”

This is not a complete list of dogmatic assertions that you may come across in a yoga studio, but it’s a good representation of the two biggest challenges we have in yoga today. Let’s dive right in and shine a light first on “stress.”

The Value of Stress

Stress has a negative reputation in our culture: we seem to think that stress is bad but this cannot be—without stress we would all die. Problems occur when we over-stress the body and do not allow enough rest to recover from the stress.

In a yoga class we can divide stress into three types: we stretch our tissues, compress our tissues or twist them (technically referred to as “shear”)—this is basically all we do to our body in yoga. For some reason yoga teachers have decided that stretching is an okay form of stress but compression is not.

You’ll often hear even very experienced teachers warn students against compression, for example for the lower back they’ll use very negative imagery to hammer home the point: “Don’t jam into your lower back!” Another example: we’re not allowed to let our shoulders ride up towards the ears because that would mean we are compressing the neck.

The idea is—compression is bad. But is it?

If compression were bad, every massage therapist would be out of work and walking would be one of the worst forms of exercise. We need to compress tissues in order to stimulate the body at a cellular level. Compression stimulates healing.

We can take the example of bones: we’ve known for over 100 years that bones can be coaxed into growing thicker and stronger if the bones are subjected to compressive stress. If we take the stress away, the bones atrophy. Space studies have shown that astronauts who experience no stress on their bones will lose significant amount of calcium and their bones atrophy to the point that many astronauts cannot walk after coming back to earth. (This is known as “disuse osteoporosis.”)

Joints are comprised of bones, cartilage and the ligaments comprising the joint capsule—all these tissues need stress to be healthy. Usually the stress comes through compression. Stressing the ligaments causes cells called fibroblasts to be active: they secrete hyaluronic acid to help lubricate the joint’s movement and collagen to thicken and reinforce the joint capsule. Stressing the cartilage stimulates chondrocytes to secrete collagen used to strengthen and repair the cartilage.

We need to stress our joints!

But we need to stress them appropriately: being yin-like tissues, bones, cartilage and ligaments do best when stressed in a long held, static way. Repeated, rhythmic stress could damage these tissues in the same way a credit card is damaged by repeatedly bending it back and forth. Our back vertebrae and our sacroiliac joints need stress! Without it they decay.

The Goldilocks' Position

However! We can do too much of anything. Too much stress can lead to a degeneration of tissues. As described in The Complete Guide to Yin Yoga, we need to find the Goldilocks’ position: not too much and not too little. This can be shown graphically: on the right is a classic n-shape curve that illustrates the danger of being outside the optimal bounds.

If we apply too little stress to our tissues, they atrophy. All living things require some stress to be healthy! If we apply too much stress, however, tissues degenerate. There have been many scientific studies verifying the n-shaped curve shown in the graph on the right (see Lower Back Disorders by McGill: page 32 for several references).

Some stress is good, a lot of stress can be bad—how do we know the difference?

Pain! The body will generally warn you when you’re going too deep or holding the stress for too long. Stressing tissue brings down the tolerance level of that tissue. This is what exercise is all about—we stress tissues to make them weaker, at least initially. Once we release the stress, the tissues recover and become stronger. If we apply too much stress, or hold for too long or do not allow enough rest, then we’re in danger.

The graph below on the left shows how these three variables work together. The curve at the top of the graph shows the level of tolerance the tissue can take before becoming damaged. The lower peaks show the degree of tension or stress being applied through either repetitive stresses or one prolonged steady stress. The horizontal axis represents time.

Our Tolerance to Stress Declines

Notice how the amount of stress that our tissues can tolerate decreases with total stress and increased time. Eventually, if we continue to stress the tissues to the point where the two lines cross, damage will occur. This is known as the “last straw effect.” It’s a classic occurrence with low back injuries—you bend over at home to pick up your socks and you throw your back out. Worker’s compensation refuses to cover your injury because it occurred at home.

What actually happened was that years of a repetitive stress at work reduced the tolerance of your tissues to the point that one last little stress created a serious injury. This “last straw effect” can also show up in yoga studios: this same person who has for years been reducing the tolerance of her tissues comes into a class, does one particular pose, say Pigeon Pose, and “snap!”—her hip or knee gives her searing pain. She then decides to sue the yoga studio for the injury when it was all the other stresses she had been applying to the area over the years that set up the conditions for the injury to occur.

Our Tolerance Increases with Rest

However, notice the next graph (right). Here we see the recuperative effect of rest.

If we stress and then rest the tissue, the tissue’s tolerance level increases above what it was before. The key then is to not over stress the tissue either by having too much stress or holding the stress for too long, but rather allow the tissue enough time to recover and grow stronger.

All tissues need stress. Let’s emphasize that! All tissues. This includes our joints, our bones, our fascia, our muscles, our nerves and so on. This means that we cannot afford to ignore some areas of the body out of fear of injury. To say as many teachers do that we should never stress our sacroiliac joint is not helpful—no stress there will cause the joint to atrophy, tighten and lose range of motion. Yes, too much stress could lead to arthritis and hyper mobility, but this does not mean that we should avoid stressing the area totally.

The two cases cited earlier of teachers warning students to “never flex your spine when you do a forward fold because you will be stressing the vertebral joints,” or “never do Pigeon Pose because you will stress the sacroiliac joint too much” betrays a misunderstanding of the nature and necessity of stress.

More helpful is to warn students to avoid stressing any area of the body if they are feeling pain—even little tweaks are to be noticed and avoided because little tweaks lead to big tweaks and big tweaks lead to expensive operations, time off work, no yoga practice, which leads to yoga studios going out of business and yoga teachers being out of work… So the moral is—don’t ignore little tweaks! This is a warning against any stress that causes pain: stretching, twisting or compression. But do not be afraid of compression! Tissues need to be compressed to stay healthy.

Now that we understand the nature of stress, in part two we’ll look at how this is applied to individuals. We need to understand the nature of skeletal variation.


Editor: Lynn Hasselberger

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About Bernie Clark

Bernie Clark is an author, yoga teacher, creator of the website and author of The Complete Guide to Yin Yoga. He has been teaching yoga and meditation since 1998 and has a degree in Science from the University of Waterloo. Combining his intense interest in yoga with a scientific approach to investigating the nature of things, his ongoing studies have taken him deeply inside mythology, comparative religions, psychology and physiology. All of these avenues of exploration have clarified his understanding of the ancient Eastern practices of yoga and meditation. Bernie’s teaching, workshops and books have helped many students broaden their understanding of health, life and the practice of yoga. His latest book, Your Body, Your Yoga goes beyond any other “anatomy for yoga” book, which focus on the muscles while ignoring the fascia, bones, the nervous system and human variations. It is "Required reading!” according to Drs Timothy McCall, Loren Fishman, Gil Hedley, Stu McGill, Robert Schleip and many others


9 Responses to “The Value of Stress. ~ Bernie Clark”

  1. tjyoga says:

    I think that stress and compression are 2 different things. Certainly compression of the lumbar spine in a backbend is different than jamming into the lumbar by, say having the hands too far forward and not engaging the abdomen and gluts properly and forcefully pressing back. Compression is the bone to bone contact which just means you can't go farther by stretching anything, your anatomy dictates the ability to move or stop movement in that case. Like for some flexible people who cannot get their heels to the floor in downward facing dog. They don't feel a hamstring stretch, it's just the bones in the ankle joint don't allow their feet to go any further. And some types of pain may not show up at the time of the stretch. Your body might feel good while you are stretching and you can be unaware of the message the golgi tendons are sending to the brain resulting in tightness and pain the next day. That leads you to want to continue stretching, which leads to tightening. Similarly, when people have a muscle injury and they put heat on it. It feels good when they do it but leads to more inflamation which will cause pain.

  2. flynnsamya says:

    Thank you for a different perspective on a very common concept for us yoga teachers and practitioners (and as a lawyer we hear the word every now and again too) and the invitation to research the issue of stress further!

  3. Bernie says:

    We are using the term "stress" here in a way that includes compression (squeezing two things together) and tension (pulling something apart) and shear (a twisting action that actually combines compression and tension), but these are arbitrary definitions and you can define them differently. I just find it helpful to explain the differences if we are more specific about what we mean by 'stress.'

    When we engage muscles we often do so to reduce or remove compression while increasing tension: in your example, engaging the stomach muscles while in a backbend will help 'stretch' the stomach tissues while it reduces 'compression' of the lumbar spine. In a Yin Yoga practice, we deliberately want to compress the bones in the lumbar so we deliberately don't engage the stomach muscles: this many teachers would say results in 'jamming' as if to imply jamming is bad. Jamming may be bad, for some people in some situations, but jamming (or compression to use the less emotive term) may be exactly what some students need. Compression may be caused when a bone hits another bone, as you mention, but it can also occur when flesh hits flesh (stomach to thighs in Child's Pose for example) or when bone hits flesh (again in Child's Pose, some people reach compression when the front/top of the pelvis (called the ASIS) contacts their upper thighs.)

  4. Seth Daley says:

    Great post Bernie!

    I think that there are some assertions made that I might disagree with from a physiology point of view when it comes to the effects of different types of stress on different types of tissues in the body, but disagreement and discussion are the very soul of learning.
    I think the most important comment you made in your text was the bit about dogma, and its dangers. Dogmatic teachings are creeping more and more into yoga classes, and this is going to create far more issues then any debate had about more esoteric theory.

    I should mention that I am the guy who wrote the dead pigeon blog that your student asked you about. (Although oddly not the one that is linked above)

    If I gave the impression that I thought the pose should be outlawed, then that was done mistakenly. My main issue with the posture is the perceived level of its difficulty. The variations of pigeon done in classes are for the most part intermediate if not advanced poses, and yet they are done in a wide range of classes, often in the first yoga class someone attends.

    It is not my intent to defend my position, but I wanted to be clear that the worst thing I think I could do as a teacher is assume I am always right. While I do not allow the forward folding version of the pose to be taught in my studio (except in advanced classes, or with props) I am much more concerned with keeping dogma out of my yoga room.


    – Seth

  5. Bernie says:

    Hi Seth – thanks for taking the time to comment: you are right that debate is healthy – the philosophy of science demands it, and if yoga is meant to help open us up and make us more flexible, how can dogmatic demands to do poses only one way ever be right? I am not sure if you read the second part of this article as it was being published around the same time you were replying here. You might want to check it out:…. Cheers! Bernie

  6. […] A common misperception about the nature and value of stress […]

  7. Leah says:

    There’s a great RadioLab (WNYC/ NPR) podcast called ” Stress” that brings light on the evolution of stress in humans, and how stress helps us survive. Well worth a listen 🙂

  8. […] we apply too little stress to our tissues, they atrophy. All living things require some stress to be healthy! If we apply too […]