Published on – 7 minute read
By Guest Writer Nell Mead
BSc (Hons) PG Dip SEM APSKM MCSP
The spine is an incredible piece of living machinery. It looks like an S-shaped column of alternating vertebrae (bones) and discs.
At the front of the spine are the vertebral bodies — the bony building blocks of the spine — stacked between discs (the shock absorbers). It’s this front part of the spine that’s designed to take load, and it’s the part I want to discuss today.
The discs are really interesting. They are tough, rubbery cylinders with a liquid gel centre, a bit like a jam doughnut. The “jam” is filled with chemicals called proteoglycans. These attract water, which is how the centre stays liquid.
When the disc is healthy, there is plenty of liquid in the centre of the disc (nucleus) and this is the part of the disc that bears load, a bit like a water balloon. The outer wall of the disc (annulus) is much harder but instead of being designed to bear load, it controls stretch. So when your disc is working optimally, the nucleus stops the disc from getting squashed flat, and the annulus stops it from being pulled apart.
It's vital that liquid flows in and out of the nucleus. Like every other tissue in the body, the nucleus is a live structure, so it needs nutrients to flow in and waste products to flow out; and they do this in liquid form. This process is much slower for discs than it is for other tissues such as muscles or organs, because the annulus is so dense and tough, so it’s hard for the liquid to find a path through.
However, the metabolic process – liquid nutrients in, liquid waste out - is significantly affected by our behaviour.
This is why we are shorter when we go to bed than we are when we get up in the morning: our discs tend to get progressively squashed throughout the day, and plump up again when we are asleep.
Problems arise when the amount of liquid flowing out exceeds the amount of liquid flowing in, causing the discs to dehydrate and stiffen. You see, spinal segments (each segment consisting of a vertebra and the disc that sits on top of it) are barely viable at the best of times, because the journey that fluid and nutrients have to take, from the edge of the disc to the nucleus and back again, is so arduous.
The many potential obstacles to the nutrients reaching the nucleus and waste products then being expelled include:
The problem in all of these scenarios is that the disc becomes compressed (thus squeezing out fluid) and is then prevented from stretching out again. It’s therefore not able to suck in fluid and nutrients to replace the fluid that has been lost. Unhelpfully, when this happens, the nucleus stops producing proteoglycans as efficiently, so the nucleus stops attracting as much water – and thus the disc begins to become dehydrated and to flatten. In turn, the spinal joints then become stiff (which is the point at which you are likely to notice it) because stiff joints hurt when you try to make them do perfectly normal everyday activities, such as putting your socks on.
Manual therapists such as physiotherapists can feel these stiff joints when we palpate, or poke, your spine. (That’s the bit where we make noises like a car mechanic finding a dodgy spark plug and you start to worry for the safety of your wallet!)
The good news is that — possibly with a bit of manual therapy and definitely a lot of home exercise — a stiff spinal segment is a reversible condition. That is, it is possible to get the joints moving again, and thus to promote better disc metabolism; it may in some cases even be possible for the discs to rehydrate.
The key points about the best exercises to stretch the discs and suck the fluid in are that
There are lots of ways of stretching the discs to suck fluids in:
With the big stretches, we need to get both the front and the back of the discs stretched out, so good exercises would encourage flexion (such as touching your toes, which is a combination of flexion and inversion; or positions such as the child’s pose, or knees to chest) and extension (such as the cobra pose, or draping yourself backwards over a yoga brick or swiss ball).
However, please bear in mind that just as you wouldn’t try to run a marathon as your first run and you’d start with a short jog, if your back is already feeling stiff or vulnerable, you may need to start with smaller movements before you tackle really dramatic ones like toe touching or the crab pose, and work up to it! Don’t exercise into pain, and if you’ve got any concerns, see a professional first – even during the lockdown, I and many other physios are offering online assessment sessions to make sure you are stretching safely.
NB — Please note that although I am an experienced physiotherapist, unless I have examined you, I am unable to give individual advice about your specific case. Every case is different, and this article is not a substitute for individual medical advice. You should never delay seeking medical advice, disregard medical advice or discontinue medical treatment because of information in this article. However, if you would like individual advice from me, please do call 0207 175 0150 to arrange an online assessment.