Back pain & sitting posture:

How to keep your back healthy and pain free

Sitting slouched minimizes muscle activity - the main reason that most people will adopt a slouched or curled up position when sitting if left to their own volition. Unfortunately, that slouched position, or flexion, of the lumbar spine increases stress on the vulnerable, posterior parts of the disc annulus. 

On the other hand, prolonged upright sitting leads to higher activation of the psoas and back extensors, which impose their own compressive stresses on the lumbar spine. 

Changing lumbar postures causes a migration of loads from one tissue to another (...) and suggests that no single, ideal posture exists; rather, a variable posture is recommended as a strategy to minimize the risk of tissue overload [McGill 2002]. This advice, of course, could be extended to the whole spine, neck and head position, as well as arms and legs - take note those who sit cross-legged... 

Get Fit to Sit

So what can you do to improve your sitting posture? Well, you need to be Fit to Sit!

• General body fitness is arguably even more important when you are in a sedentary occupation. This means active walking, cycling, dancing, climbing stairs... anything that raises your heart and breathing rate enough to make it a little difficult to hold a conversation, for preferably for a minimum of 20 minutes a day. (Look out for a post coming soon about recommended exercise levels, a little preview: it’s no longer 10,000 steps a day...)
• Strengthening your core stability muscles helps you to be able to sit in a wide variety of postures and positions, including standing. But take care, sit-ups are not the way to strengthen your abdominals and core: sit-ups will damage the backs of most people. Much better are the bird-dog, side-bridge and single-leg pelvic bridge. (More about core stability exercises coming soon).
• Perform a back and disc relieving stretch when getting up from sitting: standing with knees very slightly bent, imagine that there is a high shelf up in front of you, but don’t look up at it, aim the top of your head at it. Slowly bring both arms up in front of you until you are reaching up to that shelf. Take good note of your back - your back should feel slightly stretched; and of the front of your rib cage - your rib cage should not raise up, but rather stay held down by an automatic activation of your abdominal oblique muscles. 
• Change your position regularly. Use your chair to help: either have two or more different chairs, preferably at different positions to your desk, or make sure you use your adjustable office chair to its full!
• Use a rolled or folded towel, cushion or cushions to help support you and take the strain off your muscles.
• Try standing for short periods to work - maybe use the top of a filing cabinet to do some work.
• Experiment with a wobble cushion #dynaircushion for your desk chair or even a gym ball (but build up usage times slowly).
• Most importantly, get up and do something else for at least 5 minutes in every hour.