Sitting in one position means your muscles are working to maintain that position. Working muscles produce a waste product called lactic acid which is normally taken away by circulation. Getting up and moving around after 20 minutes or so causes muscles to contract sufficiently to move joints and also pumps the circulation and hence the waste products out.
In sedentary jobs muscles are working in a static manner to maintain your upright working posture at the desk or keyboard, but they are not contracting enough to act as a pump. The waste products therefore build up, the joints get stiffer and you get sore.
How to avoid postural pain.
You can save yourself undue pain by:
- Understanding which postures are kind to your muscles, ligaments, joints and discs.
- Understanding how to adapt your current chair or how to buy a new chair that suits you and your job; and taking the time to adjust it.
- Moving regularly helps to reverse sustained postures thereby preventing stiffness, decreasing ligament stretch, allowing certain muscles to relax and pumping nutrition into the muscles and discs.
Avoiding sitting indefinitely throughout the day despite the ideal seating arrangement.
The best posture for sitting.
In most circumstances, the best position for the lower back when sitting is that which maintains the normal curve (lordosis) that is seen in standing. This position enables less pressure on the discs than the slumped position and therefore the discs are less prone to stress and strain.
Similarly, the back joints and their surrounding ligaments are also less likely to be stressed in this lordotic position. Muscles are also working minimally because the line of gravity allows the body to be balanced.
When trying to improve the way you sit, it will take time becoming used to a new posture. The new posture itself will cause some discomfort in the waist areas initially over the first few days. However, rewards will follow as you realize a less painful existence. There are two different methods one can use to find the correct amount of lordosis for sitting. We recommend you try both to see which is easier for you.
- Sit forward on your chair so that the back does not interfere while you learn this position, or use a stool.
- Allow the body to slouch to its maximum. Hold for a few seconds.
- Reverse the position so the body is sitting totally erect, at the limit of lordosis (arched lowerback, stomach forward). Hold for a few seconds.
- Repeat several times so you understand the difference between the two extreme positions.
- Take the totally erect position, then allow the body to relax 10%.
- This is the best position for the lumbar spine. Never maintain the two extreme positions, as they will cause pain.
If you have trouble determining a position 10% off extreme, then try this method.
- Place palms under the buttocks, so you can fee the ‘sitting bones’ – the two bony points which contact the chair.
- Sit up as erect as possible. Feel the sitting bones move backwards over the hands.
- Allow the body to slump to the maximum. Feel the sitting bones move forwards over the hands.
- That position where the sitting bones are directly over the hands is the correct sitting posture.
- The lower back is now in the best position to avoid pain because this degree of lordosis is the position with the least load on the discs, ligaments and joints.
At the Keyboard
Good sitting posture at the keyboard is when:
- the lumbar lordosis is 10% off maximum;
- the hip and trunk angle is 110 – 115° (thighs sloping downwards);
- the head and neck are in the neutral position (not bent or rotated);
- shoulders are relaxed (not hunched under ears);
- upper arms are vertical by sides (not held forward or out to sides);
- elbows are 90° and level with the middle of the keyboard;
- wrists are in mid position, with hands in line with forearms.
For further information or postural assessment speak to one of our practitioners on your next visit or make an appointment with Steve who specializes in the area.
References: Pynt, Jenny (1998), The Seat of Your Pain May Be Your Chair, Kangaroon Press, NSW, Aust.