Protect Your Back
Hi everybody, my name is Tracy Secombe.
I am a physiotherapist and I have been doing manual handling training now for about 15 years.
My experience comes from initially spending seven years in a private practice treating people, including people who have injured themselves at work and what I found was that the people that had injured themselves, I felt probably shouldn't have injured themselves in the first place, had they been given some important information to help them avoid that injury.
So what I am going to do today is give you some general information that can be applied to any kind of industry. So no matter what type of work you do, you can apply these principles and if you do apply them you will find things more comfortable and really reduce your risk of injuring yourself.
Don't forget that all the principles that we talk about can be applied to things that you do at home. If you are the person that does housework at home for example, that is definitely a manual handling task and these principles will be extremely useful.
So lets get started. First thing you need to know is that our spine is shaped like an 'S' curve, so when you have a look at somebody standing from side on, what you will notice is that the lower back curves forward, the middle back area or the thoracic spine, where the shoulder blades are, curves in the opposite direction and then the neck curves forward.
Now that 'S' curve is different from person to person because we are all different.
So some of us are taller, some of us are shorter and the shape of our 'S' curve is also different. So what you need to know is what your normal 'S' curve is like, so that you can try and maintain that normal 'S' curve for most of the time.
So when you are maintaining your 'S' curve, the disc at every level is in its ideal position. So what's the disc? Well you may already know about the disc and may have heard of the old saying 'I have slipped a disc'. Well you can't actually slip a disc, because the disc is firmly attached to the bone below and the bone above. So what can happen is the jelly inside of the disc can move, as we move and that is normal. That allows the movement through the spine and the disc acts as a shock absorber.
So what can happen with the disc with time, is if we are bending forward a lot or we are losing our 'S' curve a lot by flattening it out through the lower back area, then the jelly on the inside of the disc is pushing against the fibres around the outside of the disc. So if these fibres are elastic in nature, you can imagine what's going to happen if they continually get pushed or stretched. So as the jelly pushes against the fibres, the fibres get stretched and they can lose their elasticity and stay stretched.
Now the interesting thing about the fibres surrounding the disc, is that the fibres that are closest to the jelly don't actually have a nerve supply. So what does that mean? Well what that means, is that if you tear those initial fibres on the inside of the disc, they don't send a message to your brain saying 'ouch, you have hurt yourself, something's broken', and they don't give you a pain message. So a lot of us can have the start of a disc bulge without actually having any pain in our back.
....so you end up with a baggy disc or a disc bulge.
Now the interesting thing about the fibres surrounding the disc, is that the fibres that are closest to the jelly don't actually have a nerve supply. So what does that mean? Well what that means, is that if you tear those initial fibres on the inside of the disc, they don't send a message to your brain saying 'ouch, you have hurt yourself, something's broken', and they don't give you a pain message. So a lot of us can have the start of a disc bulge without actually having any pain in our back.
What's the problem with that you might think, 'if I don't have any pain, I don't need to worry'. Well the problem with that is, if we have torn through say for example, half the thickness of those fibres around the disc and we continue to lose our 'S' curve or slightly bend forward in the lower back, then we can eventually tear through all of those fibres. Now the fibres on the outside do have a nerve supply and it will be painful once you have caused those outside fibres to tear and of course close to the disc is the nerve root, that comes of each level from the spinal cord and it supply's the legs in the lower back and the arms in the upper back and neck. So this is how we can end up with leg pain. So the disc has burst all the way through those fibres around the jelly and is pressing on the nerve root.
Now when jelly from the disc presses on the nerve root, you can experience pain, you can experience tingling and you can experience numbness and you can even get weakness associated with this nerve root compression.
So it's really important to avoid a disc injury from getting to that point. Sometimes you may even need surgery to the back if you injure your disc to this extent. So how can we prevent our disc bulge that may already be there and we don't know about it, from becoming what's called a disc protrusion, which means the jelly has burst all the way through the fibres and is out in the spinal canal area, possibly causing irritation to the nerve root. Well put very simply, we need to make sure that most of the jelly stays in the very centre of the disc by maintaining as normal pressure as possible.
So thinking again about the structure of the disc, I don't know if you remember or whether you did this when you were little, but I know when I was little I would be playing on the beach and I used to love picking up those tiny little jellyfish and popping them into a bucket. I promised that I threw them back out to sea, but that consistency is a little bit similar to your disc or even a marshmallow.
So there is pressure inside a disc depending on the position that you are in and the activity that you are performing. Now the pressure is affected by your body weight. For example, for a person who weighs 70kg, when that person is standing up straight and maintaining his or her ideal 'S' curve, the pressure in the disc is equal to 70kg. So you can work that out for yourself, if you know how much you weigh, whatever your body weight is, that is how much pressure is going on in the disc, in your lower back when you are standing up straight. Now when you sit down the pressure in that disc increases to 100kg if you weigh 70kg. Now this is sitting down with a good posture, so sitting up straight, possibly with a little cushion behind your lower back so that you maintaining your 'S' curve, you do have increased pressure in your disc when you are sitting down. So this will explain why if you have got a sore back, you can't actually tolerate sitting for very long periods of time. Now here's the big one, if you are not sitting up straight, but you are actually sitting slouched in your chair, then you lose that curve in your back and the pressure increases from 100kg to 180kg. So that's a huge difference and that's a huge lot of pressure for you to have on that disc.
So if you can imagine a disc with increased pressure on it, you can imagine what's going to happen. The jelly is going to be pushing out at every angle towards those fibres around the outside. If the pressure is increased because you are slumping, then the fibres that will take the brunt of it are the ones at the back and those are the ones that can tear and then possibly cause irritation to the nerve root.
The other activities that really increases pressure in the spine, in the disc in particular, is a very simple activity that we do quite a lot without really noticing until we do have a sore back and that is the stoop. Now what I mean by the stoop is just slightly bending forward from the back, not bending all the way over, but just that little lean forward that we do. Now you might do this when a bench for example, is a little bit too low, when you are washing the dishes reaching into the bottom of the sink or when you are cleaning your teeth and bending forward to spit out the toothpaste. So it's a very light activity, there is no weight attached to it, but it is the actual stoop that increases the pressure in the disc.
Now using the example again of somebody who weighs about 70kgs, if you lean forward in this position the pressure in your disc will be about 120kg. Now the reason that this particular movement has such a huge impact on the disc, is because it is such a common one and its one that we certainly don't notice until we have a back pain.
During my years as a treating physiotherapist, I had many people come to me for treatment who said they were doing something as simple as cleaning their teeth and then they just couldn't stand up straight. Now the injury hasn't just occurred on the day that they were cleaning their teeth and just bend forward.
For probably months or years leading up to that day, they have slightly bent forward over and over again or they have done other activities such as heavy lifting that has torn most of the fibres and then on the day they were literally down to a few fibres that tore at the time.
The other activity of course that will increase the pressure in your disc is lifting and there is great awareness now about safe lifting and reducing the amount of lifting that you have to do at work and at home, share the load all of that and in fact rather than having a set safe lifting limit, most occupational health and safety regulations now recommend that it depends on the individual. And this is a good recommendation because it really is an individual thing in terms of how much you are able to lift. It is determined by your own body weight and definitely determined by your strength.
What do you think needs to be strong to help you lift safely?
Well your quadriceps absolutely need to be strong. That is your thigh muscles. When your thigh muscles are strong, it's going to be your legs that perform the lift and that's what should be lifting, not your back,...
and of course your upper limbs. Your abdominal's are really important too. The transverses abdominis forms your own internal brace. So if you can switch this on, you can actually activate muscles that are going to support your back during lifting.
However as a general guide in terms of the pressure that is placed on the disc when you lift, lifting 20kgs with your back straight or maintaining your 'S' curve and using your legs to lift, for a 70kg person the pressure in your disc is 180kgs. Now the interesting thing about that is lifting 20kgs puts the same pressure on your back as sitting slouched in your couch or on the sofa. You wouldn't think that. You would think that lifting is going to put more pressure on your back, but it can obviously be better to be active than to be sitting with a poor posture for a lot of the time.
Now the big difference comes if you accidentally bend a little bit through the lower back losing that 'S' curve when you lift. So lifting 20kgs with your back bent increases the pressure in your disc if you weigh 70kgs to 340kgs. So you can see why you can significantly injure your back when you lift with poor technique. And the problem is, that when you don't have a back injury you can spend years in your youth lifting poorly with bad technique just because you can and then after some years of doing this and the fibres have all been torn, you end up with a severe back injury fairly easily. So I guess that is the 'why' behind why you should lift safely. I think we all know, how to lift safely but that certainly gives you a little bit of background information about why it is actually so important to lift safely and what can happen if you don't.
So that gives you a little bit of information about the disc, but there is not just a disc in our back is there. The discs are between every single vertebra in your spine. So you have the lumbar vertebra, which is in your lower back. You have the thoracic vertebra, which is in your middle back and then the cervical vertebra, which is in your neck. So in between every single bone is a disc. It's firmly attached to the bone below it and the bone above it, so it can't actually slip anywhere as such.
But what other structures have we got? Well you've got the ligaments, which are between the bones and of course the joint capsules, which is the soft tissue around the joint. But the one thing that we actually have some control over in our body from a structural point of view, of course is our muscles. This is what sets people apart in terms of preventing a back injury. So muscles start off in great nick when we are kids and they usually remain pretty active during our adolescent years when we are involved in sport and other activities, but often as people get older they become more seventry, which mean they sit down more basically. And if you have a look at technology and what's going on in terms of the way we do our job now, a lot of us spend a lot more time sitting. So if we are sitting more, we have increased disc pressure for more of the time because we are spending more time in sitting. But what's happening to our muscles when we are sitting around? They of course are becoming weak. So it is really important to be involved in physical activity, ideally every day so that you can maintain your muscle strength.
Most importantly is your core strength when we talk about preventing a back injury. Core strength has really become a bit of catch phrase lately. Everybody is very aware of core strength and you may have also heard of pilates, which is a method of teaching you how to activate your deep abdominal muscles so that they can protect your spine. Now you can do specific exercises to target these muscles groups and get your transverses abdominis activated and correct all of those internal muscles and maintain a good posture. But do you know that if you're active in general that these muscles kick in and work anyway. So anything that you love to do, if you love to go for a brisk walk, do that. If you love running, do that. Riding a bike. All of these activities are activating your core muscles and increasing the protection for your back. So I can't recommend regular exercise enough. In this audio file we are specifically talking about manual handling and that is that obvious benefit for this session, but there a millions of other benefits that you are going to get from regular exercise anyway. And just to name a few, you are going to feel a lot better. For those of who are already fit, you will know that you are full of energy and you feel happier because you are fit and that is a proven scientific fact, that is just not here say. But if you want to prove it, the best way to do it is try it out yourself. So start getting active as soon as you can. If you are not doing anything at all at the moment, then just start by walking out of your front door in some comfortable shoes. If you haven't done anything in a while, walk for five minutes in one direction and turn around and walk back and gradually build up from there. But there are lots of fantastic ways that you can exercise that are going to increase that support through the spine and protect your discs and your back so that you can use it for the rest of your life.
So do we just need to protect our discs in our back? Well no of course not. We need to protect our muscles in our back from injury as well.
Now if you were to go off and do an aerobics class tonight and you haven't done one for a long time, how do you think you might feel tomorrow? A little bit sore possibly. And why do you feel that way? Well the muscles are fatigued because you haven't used them like that for a long time. Now a lot of the aches and pains that we feel, not only in our back, but in our shoulders, our neck, our joints, throughout the body really, can be related to overusing certain muscle groups and this comes down to our technique.
You may be in a job where you actually have to do something quite repetitively. That can be the nature of people's jobs. So whether you develop an injury or not is dependant on a few things. First of all, the ergonomic set up of the job that you are doing. So naturally you want things to be set up so that you can maintain an upright posture. If you are sitting, you should be sitting up straight. If you are standing, you should be standing up straight maintaining your 'S' curve. You want your task to be in close to your body so that you are not over reaching. The other thing that can contribute to over using your muscles is the way you perform the task. Now if you are in an ideal posture and you're in close to your task, then you're going to be using your muscles at the optimal length. So our body likes its 'S' curve. Ok, my body likes my 'S' curve and your body likes your 'S' curve. So once you know what that is, you want to maintain that so that it is easy for you to do your job and your muscles don't have to work too hard. If I lose my curve in my back, lets say for example the curve in my lower back, that is naturally going to affect the curves in the rest of my spine. So for me, I have what is called a sway back, which is quite an exaggerated curve in the lower back. That's ok, that is normal for me. It's actually caused by years of callisthenics for any of you that know what that is. I used to do marching and rods and all of these crazy things. Anyway we used to stand up so straight that we really kind of stuck our stomach out forward and increased that curve in the lower back and I am kind of stuck with that now. So for me, I actually need to make sure that that curve is maintained and if its not, what happens is, if I become flatter through the lower back then I become more round shouldered. My shoulders come forward and my head comes forward. So if you think about the muscles and where they are positioned. We obviously have muscles at the front of the spine and we have muscles at the back of the spine. So when we have our ideal 'S' curve, all of that is in balance. The muscles at the front are balanced with the muscles at the back and they are at the correct length. But if I spend a lot of time too flat through the lower back and therefore rounded through the upper back, what's going to happen is, I am going to cause a muscle imbalance. So I will become tight through the chest. Those chest muscles will get tighter and the muscles between the shoulder blades will get longer or weaker. Now if I do an activity in this posture, I will be using muscles when they are either on stretch or too tight and that is how I can get an overuse injury.
I can even get an overuse injury just by having the poor posture. For example, the trapezius muscles. Now these guys start in the base of the skull, come down and insert into the tip of the shoulder, so the ones along the side of your neck and they also come down in a kite shape in between the shoulder blades and into the middle of your back. So if I am always sitting a little bit slouched, so I am 'C' curved or rounded through the lower back and shoulders forward, you can see how weak the muscles are going to get that are stretched and how tight the muscles will get that are in the forward position or holding on at the front. So if you think back to the example of us going off to do some aerobics and then feeling really sore. That soreness is caused by muscles being tight. So often the first sign you are going to get before you actually get pain for any type of muscular injury can be tightness. Lets use an example of going for a run. Lets say you decide, 'yep I am going to get fit, I used to run, let's go running'. You may have not sought any advice about how to gradually introduce running and you might go off for example and run 6kms, after not doing any running at all for a few years. Now naturally you are going to feel very sore the next day, but if you don't actually get pain, you're definitely going to feel tight. Those muscles are going to be tight. This is the same with overuse injury's that can be caused by work activities. For example, if you think about the tennis elbow. Now some of you may have experienced tennis elbow before or know somebody who has. Tennis elbow is hardly ever caused by tennis. Naturally it can be, that is where the name comes from. The technical name for it is lateral epicondylitis, but you can forget that because that is not important. So with a tennis elbow what happens is, you overuse the muscles on the outside of the elbow and you overuse them by continuously extending your wrist. Which means, if you imagine your arm out stretched in front of you, you can do it now if you like with your palm facing down. If you pull your hand back towards you so that the back of your palm is coming up towards you, that is wrist extension. So when you pull your wrist back in that position, you use the muscles on the outside of your elbow and if you are always doing that activity then you are going to over use the muscles in the elbow. So how do we avoid that? Well what you will notice is, how much you use those muscles varies depending on your posture. So don't try this if you have actually got tennis elbow or if you have any aches or pains at the moment but if you sit in a slouch position, so you are in a chair and you let your bum slide forward a little bit in the seat, so you are slightly rounded through the lower back and then reach out straight in front of you with a straight elbow and grip the air really strongly, so hold on tight. Now put your hand over your forearm just underneath the elbow, so just lower than the elbow. You'll feel that the muscle works quite tightly when you grip in this position. So that is, arm out stretched with a poor posture. Now if you sit up straight with a good posture, bring your elbow into your waist and face your palm towards the other palm. OK, so you look like a robot now, you have got your elbows into your waist, elbows bent 90 degrees and your palms are facing each other. Now grip strongly, release one arm from that position so that you can feel the muscle in your forearm and you will see that it doesn't work so hard. So by correcting your posture you are actually reducing how hard that muscle works. Pretty good huh?
So this is the first principle that I want you to remember and that is to get as close to the task as you can. It doesn't matter if the task is heavy or light, you need to get as close as you can. So how close do you need to be? Well you need to be so close that you can maintain your 'S' curve really well, perfectly, your perfect 'S' curve. So that means that you don't need to put your shoulders forward at all. You can actually keep your shoulders in the neutral position for you, so the comfortable position that feels right for you. It also means that whatever you are doing is inside your base of support. Now what do I mean by that? What is your base of support? Well when I am standing up straight with my feet together, the base of support is the rectangle that I can draw if I trace a line around my shoes, with my feet in my shoes. So it's a very small base of support. I am standing up straight with my feet together. Now obviously what I can do is step to the side and now I have a wider base of support. But where do you think my task might be? Often, if not always, my task is in front of me. So where do you think I should put my foot, so that I can increase my base of support in the direction I need too and get the task inside my base of support? Out the front. So I put my foot forward, now I am in a lunge position or I may just have knees comfortably, not too straight, not too bent, with one foot in front of the other and now I bring my task inside my base of support.
So lets use an example, I'll use one that is not work related so that no matter what kind of work you do you will be able to relate to this if you have ever washed the dishes. If you haven't ever washed the dishes, shame on you! Ok if you haven't done it yourself you have probably watched somebody in your house do it. So we are washing the dishes and usually there is a cupboard under the sink. So you are standing with feet side by side on the ground and you are bending over so that you can reach into the sink. Where is your task and where is your base of support? Well your base of support is the line you can draw around your two feet on the floor next to the kitchen cupboard. The task that you are doing is in front of you, in the sink where you are washing the dish. Not a heavy task, but if you have a sore back you will know this will hurt. So the task is outside your base of support. So how do we fix that? Well unless you have got shelves underneath your sink then unfortunately you cant do this. But if you have got cupboard space, you open the cupboard door, clear a space for your foot, put your foot inside the cupboard so that your front foot is underneath the task. Now if you are not touching, if your body is not touching the edge of the sink or the bench, you may find that your foot wont go in far enough to be under the task. So the task is still slightly outside of your base of support. So what you do now is, you increase your base of support significantly by adding your workbench to your base of support by bracing. So if you now with your foot in this position, in the cupboard, press your hips against the bench, then you actually merge with the bench and the bench becomes part of your base of support. Now the activity, which is washing the dishes, is inside your base of support.
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