Lumbar Disc...or Jam Donut?
Unfortunately, we all assume poor postures, for greater volumes of time than we used to, predominantly due to hi tech gadgets. Sitting a lot in bad positions is an unnatural load for the lumbar discs, the building blocks of our spine in our lower back. Issues with lumbar discs are debilitating, yet surprisingly simple to avoid.
Anatomy Made Easy
The spine is made up of a stack of blocks of bone, called vertebrae. They are categorised into three sections – cervical (neck), thoracic (mid back), and lumbar (lower back).
Looking at the spine from side on, it is built with natural mild curves – in at the neck, out over our shoulder blades, and back in again at our lower back. Looking from the front or back, however, our spine should be nice and straight.
We have discs sandwiched in between each of the vertebrae in our spine. They are fused to the vertebra above and below. The discs act like a cushion, or shock absorber. The presence of these discs, combined with the natural curves of our spine, work like a spring to absorb the impacts and shocks that are imposed on our body with natural movement. The ultimate role of all of this shock absorbing is to protect our brain.
The discs in the spine are made up of concentric rings of fibrous tissue, surrounding a pocket of jelly in the centre. Picture a jam donut, the sort without the hole – a sugary dough casing, and in the middle, a heart full of jam. This is similar to our disc structure (though I’d imagine they don’t taste nearly as good). The discs are flexible, and the ‘jam’ in the middle allows the disc to compress slightly if the spine is loaded.
When our spine is in the upright or straight position, the lumbar spine (lower back) has its ‘natural inward curve’. With the lumbar spine positioned with its natural inward curve, the discs are loaded evenly with the jam centered in the middle. In this upright or ‘neutral’ position, our spine, and the discs within it, can withstand considerable loads. This could include holding bags full of shopping, or carrying a heavy backpack. This neutral position is generally the position we get into when we stand and ‘think tall’.
If you have been to an Asian or African country you may have seen locals gracefully carrying heavy produce and containers on their heads. They are always standing very straight – if they let their head or body bend forward even slightly, they would either drop their load, or create injuries that could threaten their livelihoods. This vision is true testament to the enormous strength of our spines if they are loaded in an upright or neutral position.
What Goes Wrong
Unfortunately, most of what we do in modern times is not in an upright or neutral spinal position, but rather one in which we are bent in the middle. We sit at a desk, we sit in a car, we pick up a child’s toys, we lift groceries out of trolleys, we slump on the couch. When we bend, our lumbar spine loses its natural inward curve. The front part of the disc compresses. This causes the ‘jelly’ in the centre of the disc to move.
Picture this: You raise the enticing jam donut to your mouth. It is full of sweet, warm jam. You take a big bite. This squashes the front half of the donut, compressing the space available for the jam. Where does the jam go? It squeezes out the back wall of the donut, and runs down your hand…
This mouth-watering analogy is reminiscent of what happens to our discs when we bend a lot.
In reality, the jelly doesn’t burst out of the back of the disc straight away. Over time, the jelly pushes on the back wall of the disc so much, that it creates little fissures, or tears on the inside of the disc back wall. Then, each time you continue to bend or sit, the jelly keeps pushing back into those fissures, making them a bit bigger.
This process can be happening to your discs right now without you even being aware of it. The nerves (and therefore your pain warning system), only supplies the very outer layer of the disc wall, so internal damage can go undetected until…
You bend over to pick up a pen and BANG - sudden pain and spasm in your back. The cumulative disc load has finally caused the outside layer of the disc to become swollen and distended. It therefore registers a pain response via the nerves. For some people, the onset of pain is less dramatic (a small niggle that builds), but can also escalate to a debilitating level.
Disc issues can become recurrent and ongoing. Once you have suffered once, you are ever vulnerable. Some people can correct these issues with rehab, and others end up under the surgeon’s knife, with a range of outcomes.
The management of these issues once they have occurred is not the focus of this book. We wish to address prevention. This prevention advice can still be relevant to you if you have already suffered from a lumbar disc issue, however this should be in consultation with your health professional. A Comprehensive Injury Analysis from www.physios-online.com could help.
Take Action Before You Break
There are just three main things you need to remember in order to protect your lumbar discs. The first is that discs are by far happiest when the spine is in a neutral position, and the lumbar area has its natural inward curve. This means maintaining that small inwards curve in your lower back while you sit, lift, garden and pave that path at home. It can help to use a lumbar support in your chair, and make sure you always sit right at the back of the seat with your back supported. When doing more physical activities, think of sticking your butt out and keeping your shoulders back.
No-one is perfect, and we live in a real world, so it is impossible to avoid bending your back all day everyday. In fact, it is healthy for us to move constantly, including into bent positions, but our predominant, default spinal position should be neutral. These days, the volume of bending we are in the habit of doing is far too much for our lumbar discs to bear.
The message here, is that bending is inevitable, but it should be in small doses only.
Changing flexed spine habits into neutral spine habits takes time and effort, but the time and effort required pales dramatically into insignificance when compared with the time and effort associated with a disc injury if you don’t make changes. If you can decrease the time you spend slumped in your chair (or flexing your lumbar spine over the herb garden) by just 5% each day, you will eventually find that the healthier positions become the new habits, and therefore automatic, and less effort.
The second thing to remember is to find any excuse possible to frequently move from a prolonged position. For example, make a cup of tea, walk to the Post Office, hand deliver a message and stand for morning tea during your day of desk-based work.
Clearly, the less sitting and computer work you do the better, but this is difficult if your work relies on it. As an ideal rule, a maximum of half a day at a time should be spent locked into computer use.
The third thing to remember is that you can compensate your lumbar discs for all of the bending forwards by
arching back the other way! This can be done in both a standing and a lying position. As compression of the front of the disc by bending forwards or sitting causes the jelly to push to the back of the disc, arching backwards helps to coax the jelly back into the centre of the disc. By moving the jelly away from the back wall of the disc, the pressure is relieved, allowing the back wall of the disc to recover and heal. Put your hands on your hips in standing and arch your back (keep your head straight though, if you throw your head back you could fall over!). Lie on your tummy on the floor and use your arms to push your upper body up, leaving your hips on the floor. The Yogis call it a Cobra.
If you have any questions or comments about this article, feel free to
email me
Karen Finnin
Musculoskeletal Physiotherapist
BAppSc(Physio), MMuscPhys