Why Everyday Activities Load Your Spine More Than You Think
The human spine is a remarkable structure — designed to bend, twist, and carry heavy loads. Yet when you're in pain (as many people are when they visit my clinic), it’s easy to feel like your back is weak, fragile, or vulnerable.
In reality, most spines are far stronger than we give them credit for. You might be surprised to learn just how much force your spine handles during everyday movements.
How Much Load Goes Through Your Spine?
A recent research paper measured the compressive force on the lumbar spine — specifically the L4/L5 disc — during common activities. The results are striking:
Walking: ~2.5x your bodyweight
Running: ~6–8x your bodyweight
Bending forward: ~2.5x your bodyweight
Lifting a 20kg weight with poor form: up to 9x your bodyweight
If you weigh 80kg, walking alone can put around 200kg of force through your lower spine. Running or lifting could mean your back is dealing with several hundred kilograms of force.
Sitting isn’t inherently high-load for the spine. In fact, some supported sitting positions can load the discs less than standing or walking.
But for many people with back pain — especially disc-related pain — slumped or unsupported sitting often feels significantly worse. Why?
In clinic, one of the most common diagnoses I see is lumbar disc pathology. A simple clinical assessment I often use is the slump test. The patient sits upright, then slowly slumps forward. If this reproduces lower back pain or leg pain, it strongly suggests disc involvement and nerve sensitivity.
So why does sitting — especially slumped sitting — aggravate disc symptoms?
It comes down to how the load is applied, not just how much load there is:
1. Load Direction
Slumping directs force into the back (posterior) portion of the disc — the exact region most prone to injury and irritation.
This is very different from upright posture, which distributes load more evenly through the disc.
2. Posture
When you sit upright, your spine maintains its natural curves and muscles remain lightly active.
When you slump, the pelvis rolls backwards, the lumbar spine flexes, and pressure shifts directly onto vulnerable disc tissue.
3. Static vs Dynamic Load
Walking and general movement constantly alternate compression and decompression through the spine.
Sitting — especially slumped sitting — creates sustained, unchanging pressure. Discs are far more sensitive to prolonged static loading than to brief dynamic loading.
4. Time Under Load
Most people sit for long, uninterrupted periods, whereas walking or activity naturally breaks into shorter bouts. Extended sitting gives disc tissue no opportunity to recover from sustained pressure.
5. Muscle Activity
Walking keeps the spinal muscles active, sharing load between muscle and disc. Sitting allows many of those muscles to switch off, meaning discs and ligaments end up carrying a greater proportion of the load.
Your Spine is a Spring — Not a Stack of Bricks
When we talk about spinal strength and function, we can’t ignore the spinal engine — a term coined by Serge Gracovetsky. The concept flips the old idea of the spine being just a passive structure.
Instead, it highlights how the spine actively contributes to movement. In walking and running, for example, spinal rotation and pelvic motion work together to create efficient, coordinated movement. It’s a beautifully dynamic system — and it thrives on motion.
The takeaway? Your spine isn’t just something to protect — it’s something to use. Movement isn’t the enemy of pain. It’s often part of the solution.
What This Means For You
Your spine is designed to handle load — but it thrives on movement and variation.
Walking is medicine for your spine. It provides the gentle loading and unloading your discs need.
Sitting isn’t inherently bad, but sitting still for too long, especially in poor posture, can aggravate disc issues.
Three Quick Tips to Ease Spinal Strain When Sitting
Break it up: Stand and move every 30–45 minutes (or sooner if it’s sore).
Sit tall: Avoid slumping; keep a gentle curve in your lower back.
Use support: A small lumbar cushion or engaging your core can help share the load.
Load Tolerance: The Key to Managing Disc Injuries
Most injuries happen when a structure can no longer tolerate the load placed on it — whether that’s a bicep tendon doing too many curls, or a lumbar disc enduring too much pressure in one position.
In acute disc injuries, load tolerance is low, meaning small movements or positions may be painful. In chronic disc issues, the spine can usually handle more — but often still has limits. That’s why gradual exposure and load management are central to recovery.
Final Thought
Your discs are tougher than you think — but they still have limits. If back pain is stopping you from sitting, walking, or doing the things you enjoy, it’s worth getting assessed. Find out how Osteopathy can help in the management of disc injuries.
A tailored osteopathic assessment can help identify what’s going on and guide you with the right movements, support, and advice to get back on track.