Spinal Disc Loading: Why Sitting Is Harder on Your Back Than You Think
As osteopaths, we often hear patients say, “I don’t know what I did — my back flared up after sitting.”
What many don’t realise is that sitting actually places more pressure on your spinal discs than standing — especially in the lower back.
In this blog, I want to share some lesser-known facts about how your spinal discs work, what contributes to disc-related back pain, and how lifestyle factors like posture, nutrition, and seating choices affect your spinal health — sometimes more than you think.
Understanding Spinal Discs: What Are They?
Each of your spinal discs sits between the vertebral bones of your spine and acts like a shock absorber to cushion movement. A healthy disc has two main parts:
Nucleus Pulposus – a soft, gel-like centre designed to absorb compressive forces (like sitting, lifting, or carrying weight).
Annulus Fibrosus – a tough outer layer made up of concentric rings of collagen fibres. These fibres are specifically oriented to resist torsional (twisting) forces and keep the nucleus contained.
Together, they allow for flexible, stable movement — but over time, or under sustained load, this delicate structure can begin to break down.
Discs Are Fused to Bone — They Don’t ‘Slip’
Let’s clear up a common myth: discs don’t “slip” out of place.
They are firmly fused to the vertebral endplates above and below them and are immobile by design. What can happen is a disc herniation or rupture.
This occurs when the nucleus pulposus pushes through a weakened or torn part of the annulus fibrosus, usually due to repetitive strain, degeneration, or sudden load. The result? Local inflammation, pressure on spinal nerves, and often symptoms like sciatica or sharp lower back pain.
💡 Think of the disc like a jelly doughnut — if the outer layer cracks, the inner jelly can squeeze out.
(Source: Adams MA, Roughley PJ. What is intervertebral disc degeneration, and what causes it? Spine. 2006)
Sitting Loads Your Spine More Than Standing
This surprises many patients: sitting increases the pressure on your lumbar discs far more than standing.
Study on disc pressures by Dr. A Nachemson The lumbar spine: an orthopaedic challenge. Spine. 1976;1(1):59–71. doi:10.1097/00007632-197603000-00004
This was shown in classic research by Dr. Alf Nachemson, who measured intradiscal pressure in various postures:
Standing upright = baseline pressure
Sitting upright = ~40% increase in pressure
Sitting slouched = up to 85% more pressure on the discs
(Source: Nachemson A. The lumbar spine: an orthopaedic challenge. Spine. 1976)
If you sit for long periods — at your desk, in the car, on the sofa — your discs are under constant load. Combine that with poor posture or an unsupportive seat, and your lower lumbar spine (L4–L5 and L5–S1) takes the brunt of it.
Disc Degeneration Starts in Your 20s
Another surprising fact: disc degeneration can begin in your mid-twenties — often without any pain.
Over time, discs begin to lose water content and become less elastic, reducing their ability to cushion and move. This process, if severe enough can lead to disease of the spinal discs: known as Degenerative Disc Disease (DDD), can lead to:
Localised or chronic back pain
Reduced disc height (seen on imaging)
Facet joint strain
Higher risk of disc bulge or herniation
While some degeneration is normal with age, factors like inactivity, smoking, poor posture, and excess sitting can accelerate it.
(Source: Boos N et al. Classification of age-related changes in lumbar intervertebral discs. Spine. 2002)
Could Your Chair Be Part of the Problem?
One question I often ask patients is: What are you sitting on most of the day?
Office chairs without lumbar support?
Car seats that force you into a slouched position?
Sofa lounging with poor alignment?
When your lower back flattens or rounds, your disc pressure increases, and the annulus fibres work harder to stabilise your spine. Over time, this constant load can create micro-injuries or worsen existing degeneration.
Nutrition and Hydration Matter, Too
Your spinal discs don’t have a direct blood supply. They rely on diffusion from nearby vertebral tissue to receive nutrients — meaning hydration, movement, and good nutrition all play a role in keeping them healthy.
In your 20s and 30s: support disc cell turnover with plenty of water, protein, and colourful, anti-inflammatory foods.
In your 40s and beyond: nutrients like vitamin C, magnesium, omega-3s, and possibly collagen peptides(emerging evidence) may help support tissue resilience.
(Source: Grunhagen T et al. Nutritional pathways for intervertebral disc cells: physiology and pathophysiology. J Appl Physiol. 2006)
How to Support Your Spinal Discs Daily
✅ Move frequently – Break up long sitting periods with walking, stretching, or standing.
✅ Hydrate well – Discs need water to maintain height and shock absorption.
✅ Use lumbar support – Especially when driving or sitting for long periods.
✅ Eat for tissue health – Think whole, anti-inflammatory foods with good hydration.
✅ Strengthen your core – A stable spine loads discs more efficiently.
✅ Seek early assessment – Don’t wait for severe symptoms to arise.
Final Thoughts
Your spinal discs work hard — all day, every day. But they don’t complain until they’ve been under strain for too long. By understanding how pressure builds on your spine, and what you can do to protect it, you can stay active and maintain good disc health.
If you’re dealing with persistent low back stiffness, disc-related symptoms, or postural fatigue — don’t ignore it. We’re here to help.
📅 Book your spinal assessment online today:
👉 thewatersidepractice.janeapp.co.uk
References
(we do our research!)
Nachemson A. The lumbar spine: an orthopaedic challenge. Spine. 1976;1(1):59–71. doi:10.1097/00007632-197603000-00004
Adams MA, Roughley PJ. What is intervertebral disc degeneration, and what causes it? Spine. 2006;31(18):2151–2161. doi:10.1097/01.brs.0000231761.73859.2c
Boos N, Weissbach S, Rohrbach H, Weiler C, Spratt KF, Nerlich AG. Classification of age-related changes in lumbar intervertebral discs: 2002 Volvo Award in basic science. Spine. 2002;27(23):2631–2644. doi:10.1097/00007632-200212010-00002
Grunhagen T, Shirazi-Adl A, Fairbank JCT, Urban JPG. Nutritional pathways for intervertebral disc cells: physiology and pathophysiology. J Appl Physiol. 2006;100(1):153–161. doi:10.1152/japplphysiol.00981.2005