Sarah Key’s Back Blocks.
Yoga Leaflet 22
Sarah Key is a well-known physiotherapist from Australia who established her own centre in London in 1976. She is now back in Sydney. She has written several books on how to treat back problems. She introduced the use of a back-block to ease spinal contraction.
We tend to have stiff spinal segments or vertebrae randomly spread throughout the spine.
Some areas of the spine are naturally less mobile than others. Our neck can move relatively freely, while our lower back is a more rigid area of support. The thoracic region cannot bend very far sideways, but rotates with ease. The lower back does forward bending best. In the lower back the least mobile and most mobile lumbar segments are vertically adjacent. The fifth lumbar(L5) at the bottom of the spine, is the least mobile. Immediately above is L4; the most mobile lumbar segment. (Sarah Key’s Back Sufferers’ ‘Bible. 2000. p.27).
L4 is the most likely lumbar segment to suffer from over-mobility problems, such as segmental instability, while L5 is the most likely spinal segment to be too stiff.
Causes of segmental stiffness.
1 The disc loses water and becomes thinner.
. Gravity squeezes fluid from the discs.
. Poor movement prevents fluid replacements.
. The disc breaks down.
2 Other factors make it worse.
. Sitting compresses the base of the spine.
. Abnormal postures increase neurocentral compression.
. Tummy weakness allows spine to sink.
. Injury can rupture the cartilage plate between vertebra and disc. (ditto: p.29).
The lowering of intradiscal pressure which occurs when you stand upright with raised arms and the higher intradiscal pressure which happens when you bend forward create a circulation in the disc. The intra vertebral disc has no blood supply. It relies heavily on push-me-pull-me forces throughout the spine to shunt fluids in and out of the discs through the end plates from the rich capillary beds in neighbouring vertebral bodies. As the spine pulls out-elongates- nutrients and oxygen are sucked into the discs. As the spine squashes down again, carbon dioxide and metabolites are pushed back out through the end-plates. (p.!2).
In this way a dynamic pump is provided by routine spinal activity.
The spine relies on a dynamic support system of muscles which contribute to its functioning.
The muscles play a dynamically synchronised role in keeping the skeleton upright and controlled. E G. a strong contraction of the tummy and back muscles lifts the spine vertically. Spinal nerves carry messages to the muscles to make the legs work and carry messages back inside relaying information from the outside back to the brain. We may move with ease but the underlying structures are complicated and awe-inspiring as well as beyond the purpose of this leaflet.
Sarah Key developed the progressive stages of the back block as a simple way of getting the low vertebral segments to separate. (A more relaxed and easier way then hanging upside down or from a beam).
Because our spine carries itself upright, over time the lower end telescopes into itself(contracts). This compression flattens the discs and fluid is pressed out. More irreversibly, the binding soft tissues pucker as the spine shortens and becomes brittle and unresilient.
Image source: Nancy Nelson Yoga |
The back block can be an Iyengar yoga wood block and remedies some of these problems with regular use. When lying on the floor with your knees bend, lift your pelvis and slide the block under your sacrum with the wide side up and across. Allow both legs to straighten and relax, feet dropped to the side and if possible your heels touching and arms over head. Completely let go and you may feel some discomfort, a pulling out feeling in the lower back and across the front of both hips. Allow gravity to do the work passively.
|
Much later in her practice Sarah Key introduced the thoracic back block to deal with our incessant computer activities added now to our other sitting positions such as driving or watching TV. At the end of the day we have lost as much as 20% of our discal fluids. The thoracic block can be the same wooden block or a yoga foam block. Lie down with knees bend and place the block a few inches below your neck or shoulder line between the shoulder blades and release your legs. She suggests bringing your arms above your head inverting your hands for extra length. Do it without any sense of urgency at the end of the day visualising the fluids moving back into the spine. As you get used to the practice it will be something you enjoy doing and it will ease the spine. With regular use the thoracic block will correct your posture. The proof of the pudding is in the eating.
Books by Sarah Key:
Back in Action 1986 Bantam Press
Back sufferers Bible 2000 Vermillion
Keep your JOINTS young 2006 Allen & Unwin
Marjolein Gamble (March 2020)
