In a yoga class, one is often directed to keep a “long” spine. Teachers will even say that being able to lengthen the spine helps the cerebrospinal fluid to flow more easily.  Well, let’s explain why that is not true and how that kind of false belief can even be potentially harmful.

cool image from wikipedia

First, let’s us really understand what CSF is. Cerebrospinal fluid is a fluid that circulates throughout the spinal canal and across the surfaces of the brain, which at any given moment is about 150 ml (in the subarachnoid space) in volume.  The entire volume of CSF is replaced about every 8 hours and everyday about 500 ml in total is produced.  The contents of this fluid consists of mostly proteinaceous material (proteins) and a concentration of certain simple ions (the distributions of these materials can change depending on which areas of the spine CSF is inhabiting). Its function is to facilitate shock absorption of the brain and spinal cord from mechanical shock. (So if you fall or bump your head the fluid is there to minimize the impact on your brain and spinal cord, yay!), keep the hydrostatic pressure of blood vessels in the brain in a safe zone to prevent aneurysms when changing your relationship with gravity (so wait, inversions don’t increase blood flow to the brain?  whaaaaaa?  Well, it’s a bit more complicated than that, but suffice it to say that no, inversions do not increase blood flow to the brain.) and maintains a constant environment for various brain cells by transferring metabolites in and out of the deeper recesses of the central nervous system.

So we can all agree, based on the information above, that an unobstructed flow of CSF is necessary for optimal health.  No argument there. So then wouldn’t it be natural to assume  that humans have evolved (or were created, if you prefer) to structurally inhabit the movement of CSF in a way that most benefits us without having to consciously create an internal environment for that function.  Why would we assume that?  Well, because, lengthening the spine (axial extension) takes conscious effort and, therefore, muscular work.  Conscious muscular effort uses up excess energy that the body would be using for other things if we were not making that effort.  The human body is an energy conservationist by nature.  It would really prefer to expend as little energy as possible.  So the spine has been constructed in such a way to be functional for our bipedal lives (for most of us, unless there is a disease or structural abnormality), including protecting the spinal cord and allowing for healthy CSF flow (without us having to monitor it) while we are at rest and involved in all kinds of movement.

Ah, movement.  Riiiiiight.  So, if it was true that we needed to consciously manage the optimal flow of our CSF by keeping a lengthened spine then wouldn’t the majority of asana that make up a yoga practice be contraindicated?  What you say to me, bitch?! Think about it.  Wouldn’t twisting (even if you try to do it with a “long spine”), flexing, extreme spinal extension like in…almost every backbend and lateral bending change the space surrounding the spinal canal? No! Actually, since CSF flows through the vertebral foramen, that space would be minimally affected by these movements. foramenSo it is neither true that you need to lengthen the spine for optimal flow, nor is it necessary to be alarmed about CSF flow when changing the shape of your spine.

There is a danger in this kind of misinformation.  The danger of mistrust in the inherent strength and intelligence in the design of the human body.  We need practices that reveal that design to us, so that we may use it to help, not be afraid of it and create beliefs and physical practices that solidify the false understanding the we must control every aspect of our beings.  Try exerting that amount of constant control and you will go insane or just sleep a lot from over exhaustion and not be productive or not be any fun to be around.  This is not to suggest that you shouldn’t sometimes be careful with your body, but you should question everything you are told by anybody, especially in a movement class.  The human body was designed with certain basic functions meant to be outside of the realm of everyday awareness, so that we can put our attention to other things.

But you can, if you choose, create an awareness of almost every biological/physiological process.  We (Mel and Kim) do it all the time!  But we do it with the intention to understand what’s going on inside of us without fear or anxiety.  Unnecessary fear is the last emotion one would want to embody.

1.) Essentials of Anatomy & Physiology, 2nd edition, Martini & Bartholomew.
2.) A Handbook for Yogasana Teachers, Mel Robin.

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  1. Thank you for describing this to me. I went through Ana Forrest function foundation teacher training in October of 2011. I have since gotten other teacher certifications. I always, like the “Forrest Classes” for many reasons. i.e. they create internal heat, without a heated room. The apexes are worked up to following a warm-up, and a warm-down/cool-down to follow. For me this seals a good practice session on my mat. I love to fly, and there are a lot of inversion opportunities in “Forrest”. HOWEVER…. We are constantly told to lengthen the low back, tuck tail bone or sacrum. I look at Ana, and she has NO gluteal area hardly at all.. a.k.a. flat butt, and a form of posterior pelvic tilt. Posterior pelvic tilt is caused by muscle imbalances in the core and legs. Muscle imbalances in the lower body can pull the pelvis down and under, flattening out the lumbar lordosis from the bottom. The typical muscle imbalance scenario that causes posterior pelvic tilt involves tight hamstrings, glutes and lower abdominal muscles coupled with weak quadriceps, psoas and lower back muscles. Tight muscles exert a pull on body structures that is not counterbalanced by the pull of weak muscles. The pelvis is pulled downward by the glutes and hamstrings and under by the lower abdominals.

    Discogenic pain may result from this condition as spinal discs are subjected to uneven pressure. As the anterior sides of the lumbar vertebrae move closer together, the pressure placed on the spinal disc may cause a rupture or bulge on the posterior side. Disc herniation or bulging can irritate the nerves that travel through the lumbar spine to the lower body, causing sciatica pain.

    Muscular pain may be present in any of the muscles involved in posterior pelvic tilt. The muscles that are tight are chronically strained and likely have knots called trigger points. The weaker, overstretched muscles are also strained by the stretching they’ve endured; muscles contract as they’re stretched to protect themselves from tearing. The constant contraction of both the weaker and stronger muscles can cause pain, cramping and spasms. Not to mention, it is not how I want my gluteal area to look.

    At any rate, I will continue my path following what feels good to my body, and keeping conditioned simultaneously. I appreciate your article.. Thanks for sharing.

  2. Hi Tabitha! Wow, awesome anatomy breakdown! THANK YOU for sharing that with us! We’re totally with you. Ana is an awesome warrior-woman and so much of her teaching has been invaluable to the masses. But yeah, that constant cue to “tuck the tailbone” can lead to so many problems (as you described). Happy to clear up myths, connect to individuals like you and present the benefits a bio-mechanically based yoga practice.

  3. Thanks for the little tidbit of info here. As for the comment prior, I have a hard time with telling people to tuck the tailbone under, and get a little growly knowing Pure Barre (not yoga, I know, but it’s very popular and not well-supervised in terms of anatomical knowledge for the certification) is CONSTANTLY, in EVERY class, using the tucking motion.
    When teaching, it’s best to try to analyze or get the students to analyze if they have an anterior tilt to their pelvis. Most people know whether they do or not, and mirrors help. I would rather emphasize an egg shaped curve than see people flatten their low spine completely in an effort to “tuck” the tailbone. I do teach them to tuck, then stick it out, then find the happy medium and try to stay there. It should feel like minimal effort and a certain freedom in the upper glutes/multifidis region.
    Thanks again! Would love to see more articles that focus on the spine/nervous system and lymphatic system.

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