Karim in London asks:
"Could you provide some advice to prevent back and neck pain while I'm working on the computer?"
T J Salih, Senior Chartered Physiotherapist at the back2normal back and neck clinic, London, replies:
"Preventing back and neck pain whilst sitting is not an exact science, as there are always new ideas and differing opinions. There are various recommendations as to the ideal distance between your eyes and the monitor, or the perfect angle for your elbows and knees. Depending on which study you read, you will be given different recommendations.
"When it comes to prevention, there are some common denominators on which most experts agree:
"Whilst you are sitting using a PC there are a number of things you can do you prevent back and neck problems. If, for example, your neck and shoulder on the side that you use the mouse gets sore, it's probably due the position of your arm when you use the mouse. When muscles become fatigued, they ache.
"A good stretching exercise for these neck and shoulder muscles is shown here. This should be done intermittently throughout the day to help prevent those muscles from aching.
"If you get soreness across the base of your neck and across your shoulder blades, it is likely that you start to slump forwards as the day goes on. Tiredness and poor posture causes your pelvis to tilt backward, your lower back flattens, and your head comes forward, in other words you become 'C' shaped, or sit in a 'slumped' position.
"This 'poking chin' posture creates a lever system in the neck, with the pivot point of the lever being the base of the neck, in this 'poking chin' position the force through the neck is multiplied 3 x, and so your neck and shoulder muscles have to work 3 x harder to hold your head up.
"The average weight of an adult head weighs between 8-12lb, so 12lbs of force need to be generated by the neck and shoulder muscles to hold your head up. If your head falls forward as described, the muscles now need to generate 36lbs of force to hold your head up. After a period of time, this amount of force generation will cause fatigue and pain.
"To prevent this from occurring, move your chair in close to the PC to avoid over reaching, sit back in your chair properly. This will prevent your pelvis from tilting backwards as the backrest opposes it. If your feet cannot reach the floor comfortably, either lower your chair or use a foot rest.
"Another very good neck exercise to stretch is neck 'retraction' or the chin tuck. This is performed by looking straight ahead and pulling your head straight back in, like trying to give yourself a double chin. This stretches the muscles at the base and back of the neck and opens and lubricates the neck joints. This is a particularly good stretch to do throughout the day. If this exercise causes pain discontinue it and consult a chartered physiotherapist.
"If sitting for too long causes back pain or soreness, it may be due to the forces that occur in the spine. When you sit in the 'slumped' position as described above, the normal curve of the spine is lost and the lower spine straightens. In so doing, the force distribution is lost. For example, when sitting in the 'slumped' position there is approximately 1.5 times the amount of compressive force through your spine than in standing. This increased force may, over a period of time, fatigue the spinal muscles and cause pain, or may lead to early degenerative changes.
"When you sit, it is best to sit in an upright neutral posture as shown in the diagram. This maintains the natural curve of the spine and so preventing excessive loading of the lower back.
"To prevent stiffness of the lower spine in sitting, you can gently rock the pelvis forwards and backwards - sit upright and then slowly allow the pelvis to drop backwards, and then slowly sit upright again. Then can be done whilst sitting, but you must move away from the chair backrest to allow you to drop your pelvis backwards.
"It is also beneficial to stand frequently (every hour say) to 're-set' the spinal tension that has built up over the last hour of sitting, and to allow the spine to regain it's normal curvature. Gentle extension exercises may help the spine to regain its normal curve.
"However, should this or any other exercise provoke any increase in lower back pain, discontinue it and consult a Chartered Physiotherapist."
Note - In the UK, workplace ergonomics and the use of visual display units are governed by legislation in Health and Safety (Display Screen Equipment) Regulations 1992. All employers must comply with this. It is the employers' responsibility to undertake a risk assessment of the workplace to ensure that it is a safe working environment.