Short answer: Lower back pain when sitting usually happens because long, slumped sitting flattens the low back's natural curve, increases sustained load on the discs and stretches the tissues at the back of the spine. Stiff hips, weak trunk muscles and an irritated disc or joint can make sitting even less comfortable.
What sitting does to your lower back
When you stand, your low back (the lumbar spine) has a natural inward curve. The five lumbar vertebrae and their discs share load with the facet joints at the back, and your muscles do relatively little work.
When you sit, especially in a soft couch or low car seat, a few things change:
- Your pelvis rolls backwards. That flattens, or even reverses, the low back curve.
- Load shifts onto the discs. Bending forward, which a slump is, pushes more of the load through the front of the spine and squeezes the discs towards the back, towards where the nerves sit.
- The back of the spine is held on stretch. Ligaments and joint capsules stay lengthened for as long as you sit.
- Muscles switch off. The deep trunk muscles stop working much, and the hip flexors at the front sit in a shortened position.
None of this is harmful in short bursts. The trouble is time. An hour or more without changing position keeps load on the same tissues, and sensitive ones start to complain.
Common reasons your lower back hurts when you sit
| Possible cause | Typical clues |
|---|---|
| Disc irritation | Deep ache that builds the longer you sit; worse bending forward; may spread into the buttock or leg. See disc bulge. |
| Irritated nerve root | Pain, burning or tingling down the leg that sitting or driving aggravates. See sciatica. |
| Ligament and joint strain | Ache that comes on with slumping, eases quickly when you stand and move |
| SI joint or pelvis | Pain low and to one side, near the dimple at the back of the pelvis; worse sitting on one hip. See SI joint pain. |
| Muscle fatigue | Dull tiredness across the low back, especially on stools or seats without support |
Most people have a mix. The patterns are clues, not a diagnosis, which is why a proper assessment matters.
Why does it hurt more when I stand up?
Many people with lower back pain when sitting find the worst moment is getting up. After sitting, the tissues at the back of the spine have been held on stretch and the hip flexors have been held short. Standing asks the spine to move back into its curve, and the hips to straighten, all at once. Stiff, sensitised tissue doesn't like that. It often takes a few steps to "unfold". If that's you, it's a sign your back would like you to move more often.
Sitting still and your spine's sensors
There's a nervous-system side to lower back pain when sitting, too. Your spine is a sensory organ: the deep muscles around each lumbar vertebra carry movement sensors that keep your brain updated on where your back is and what it's doing. Movement keeps that information flowing. A long, still stretch in a chair gives those sensors far less to report.
That matters more when a segment is already sore or stiff. In the current research model, pain, injury or ongoing stress can change how the brain controls a spinal segment. The segment moves less, the feedback gets patchier, and the brain's control of the area becomes less precise, a loop that can keep things stiff. Chiropractors call this a vertebral subluxation.1
An adjustment is designed to send a burst of fresh information from a specific segment to the brain. In one study, a single session changed how the brain processed sensory input from the body.2 When you adjust the spine, the nervous system responds. More in chiropractic and your nervous system.
Things that make sitting harder on your back
- Soft, deep couches and low seats that tip the pelvis back
- Laptops on your lap or a low screen, which pull you into a slump
- Long drives without breaks
- Sitting on a wallet or phone in your back pocket
- Crossing the same leg every time
- Stiff hips or tight hamstrings, which pull the pelvis back
- Low overall activity: backs that move more through the day tend to tolerate sitting better
How we approach this at MPCC
Sitting-related low back pain is something we see every day, from office workers to tradies who spend hours driving between jobs. Your new patient appointment takes 30 to 40 minutes. We hear your story, take posture pictures, and do a thorough chiropractic, orthopaedic and neurological check of your spine, joints and nerves. That helps us tell disc, joint, nerve and pelvis problems apart.
At your report of findings appointment we explain what we found in plain English and what we'd do. Depending on your case, care may include specific chiropractic adjustments to the low back and pelvis, work on our flexion-distraction table (a gentle, rhythmic, table-assisted technique for low back and disc problems), and home exercises. We'll also look at your workstation, car and daily routine. Read more on our low back pain page.
What helps lower back pain when sitting
- Move every 30 to 45 minutes. Even a minute standing or walking resets the load.
- Support your curve. A small rolled towel behind your low back, at belt height, helps many people.
- Sit back in the chair. Use the backrest rather than perching forward.
- Hips level with or slightly above the knees. A firmer seat or cushion can help.
- Raise your screen. Looking down pulls the whole spine into a slump.
- Build strength. Exercises such as glute bridges help the hips and trunk share the load.
If you're worried about it, call us and we'll talk it through.
References (2)
- Haavik H, et al. (2021). Contemporary model of vertebral column joint dysfunction. Eur J Appl Physiol. doi:10.1007/s00421-021-04727-z
- Lelic D, et al. (2016). Sensorimotor integration in the prefrontal cortex after spinal manipulation. Neural Plast. doi:10.1155/2016/3704964