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How sitting can cause lower back pain

Updated: Feb 17, 2023

It’s really important to understand that the act of sitting, as such, is NOT bad for your back. It is only when you sit for too long or on bad chairs or in bad positions that it becomes a problem. This article only focusses on the lower back, but your sitting position can also influence your upper back and neck.

This is why sitting may cause your back to hurt.

In this article:

  • Why slouching in a chair can cause trouble

  • Sitting upright without support can also cause problems

  • Time is an issue

  • The problem with soft chairs

  • What’s the best surface to sit on?

Why slouching in a chair can cause trouble

When you slouch in a chair, you’re putting all the muscles and ligaments in your lower back under strain. If you keep them in that position for long enough, they will start to stretch and they may even reach a point where they cannot stretch any further. At this point you will start putting strain on your muscles, ligament or discs in your lower back.

You can even aggravate the nerves in your legs if you slouch in a chair and put your legs up on a chair in front of you (like in the picture above). This position potentially puts a lot of strain on your sciatic nerve and you may find that your leg goes to sleep or your toes/foot tingles.

I’ve seen patients in my practice where the sole cause of their lower back injury could be traced back to sitting in bad positions for a long time.

How long you will be able to sustain poor sitting postures for before you cause yourself discomfort will all depend on your previous injuries and even your genetics.

For example, my boyfriend and I find ourselves on the opposite extremes of the flexibility scale. I’m one of those annoying people who can get their heads all the way flat on their knees in yoga while he breaks out in a sweat just trying to sit upright with his knees out straight. But he seems to be able to sit in bad postures (e.g. slouching on our couch) for a very long time whereas I usually have to prop myself up with pillows while watching TV.

Sitting upright without support can also cause problems

Sitting upright is definitely preferred to slouching. But if you spend large parts of the day sitting, I would strongly advise that you sit in a chair that supports your lower back.

When you sit upright without support, your back and hip muscles have to work very hard to maintain the position. That is fine and good for shorter periods in the day, but they will become tired, overworked and painful if you do it for prolonged periods in the day.

The key is to use a chair that allows you to sit nice and upright and that supports the small of your back.

Time is an issue

It is obvious from the above that if you sit in a bad posture for a long time you’ll find yourself in trouble. But you’ll also find that your back can stiffen up and feel uncomfortable even while sitting on a good chair, if you don’t take regular breaks during the day.

Our bodies are built for movement. Our joints don’t have arteries and veins that go directly into them. They rely on the changes in pressure, that happens with movement, to force fluid in and out of them. So your joints will not get all the nutrients they need if you don’t move enough during the day. You can read more about the negative effect of prolonged sitting on hip joints in this article.

The problem with soft chairs

When you sit in a soft chair the seat usually sinks in and causes the same effect as when you’re slouching in a chair. It is nearly impossible to sit in a good position on a very soft surface.

Over time this will cause the ligaments and muscles will stretch to a point where they can hurt and if you have any discs that’s a little bit worn they will also start to moan.

Slouching in a chair can hurt your back.

What’s the best surface to sit on?

I always suggest a firm surface that’s not too hard or too soft. Every person is different so it's a bit of trial and error, but make sure that you don’t sink into it.

Make sure that you sit with your bottom right back into the seat and that you can feel it supporting your lower back. The woman in the picture above can actually do with a pillow behind her back as you can see a gap between her and the back of the chair. This doesn't mean that you have to always sit on an upright chair. You can further support your lower back by placing pillows behind you when sitting on a coach or chair.

The height of the chair is also important. Your knees should be at right angles when you sit. If the chair is too low, your knees will be higher than your pelvis and force your back into flexion. If it is too high you will tend to sit forward to get your feet on the floor and will not use the back support. You can compensate for a chair that is too high by placing a small step or book under your feet.

Finally, get into the habit of taking regular breaks and not sitting for too long so that your joints can stay well-nourished. The evidence suggests that short bursts of exercise can also improve your mental function so now you have 2 reason to get up and do an extra set of stairs every hour!

Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.

About the Author

Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Masters Degree in Sports Injury Management. Follow her on LinkedIn or ReasearchGate.


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