Today’s post is a bit different to what we normally cover on this site but appropriate for the situation we find ourselves in at the moment. With schools closed and many people working from home due to the covid-19 virus, many students and others may be spending a lot more time than normal trying to study and work with online resources. So today we will look at some simple biomechanics so you can avoid unnecessary stress and pain.
Text neck happens when people are hunched over looking at their electronic devices, for hours at a time. This puts an extreme load on the spine, and muscles. Your head weighs, 4.5 to 5.5kg on average, about 8% of your total body weight. When you are standing or sitting straight its centre of gravity is directly above your spine and it is well supported. At a normal curvature, the cervical spine is designed to support this weight. There is no excess stress being placed on the spine or surrounding muscles.
But if you lean forward your head’s centre of gravity is no longer in line with your spine and you get a resulting torque or turning force under the influence of gravity. If you lean 15 degrees forward, the this force head is more like 12.2kg. With a 30-degree tilt, 18kg. A 45-degree angle and it feels like 22.2kg. The neck is thoroughly strained at this point, with a dangerous curvature that disrupts nerve pathways and stresses vertebral discs. And when you are hunched over at a 60-degree angle looking at a mobile device your head puts a 27.2kg strain on your neck.
That is puts extra pressure on the discs in the neck and spine, causing increased compression and can lead to chronic neck and shoulder pain and severe headaches.
The lower part of the neck, just above the shoulders, is particularly vulnerable to pain caused by forward head posture. The lower cervical vertebrae, including C5, C6, and C7, already handle the most load from the weight of the head. As the head is held further forward, this load only increases.
With forward head posture, some studies suggest that the compressive forces typically increase the most at the C4-C5 and C5-6 spinal levels. The intervertebral discs and facet joints at these spinal levels may be subject to additional shearing forces with the vertebrae being pulled in different directions relative to one another, as well as repetitive traumas that can cause pain and other symptoms.
While the lower cervical spine may experience greater loads with forward head posture, it should also be noted that compressive forces are increased on all of the discs and joints throughout the cervical spine. Furthermore, the specific cervical levels that experience the largest increase in compressive loads can vary from person to person.
When everything is normal three main forces are at play and balance each other out to give a zero net force and no excess strain. The upper vertebrae supply an upward force that balances out with the torque forces due to the head’s weight and forces exerted by the muscles.
But when you lean forward the centre of gravity is no longer directly above the line of support from the spin. This results in the muscles having to do extra work to counter the extra torque force.
So what can you do?
You can do simple exercises by squeezing your shoulder blades together. You can practice keeping your neck back and keeping your ears over your shoulders. Get up and stretch every now and again.
And when using a mobile device try to keep it in front of you, don’t look down. When using a laptop or desktop computer ensure that the screen is at eye level when you sit up straight. In other words, do not be looking down on your screen for long periods. You could rest your laptop on some hardback books if you need to raise it.
Poor posture over an extended period can lead to life long problems so take the time to set up your computer and use your phone appropriately.