Understanding the Structure of Your Lower Back
For many decades, most back pain was explained through a structural lens — especially problems with the discs between your vertebrae. This approach became popular in the 1930s and shaped the way back pain was diagnosed and treated for much of the 20th century. If an MRI showed a disc bulge or degeneration, it was often assumed to be the cause of pain — prompting surgery in many cases.

In recent years, though, research has shown that these changes are surprisingly common — even in people without pain. This doesn’t mean structure doesn’t matter, far from it, but it means we now take a more balanced view.

On this page, we’ll take a closer look at how the structure of the lower back changes over time — to help you understand what might be happening in your own body, especially if you've been told you have a “degenerating disc” or “wear and tear.” These are common age-related changes, not necessarily signs of dysfunction — and even when they do contribute to pain, they often respond well to the right kind of support.
💬 Note: While most low back pain improves without invasive treatment, there are certain symptoms that may indicate a more serious issue and require medical attention. These include loss of bowel or bladder control, progressive weakness, unrelenting or worsening night pain, significant trauma, or pain accompanied by numbness, tingling, or shooting pain down the leg. If any of these are present, or you have any concerns, it’s a good idea to check in with your GP.
Your low back is a strong and flexible structure designed to distribute load and allow movement. It includes vertebrae (the bones), discs (shock absorbers), and facet joints (movement-guiding joints), all supported by layers of muscle and connective tissue. These parts work together to balance strength, flexibility, and control. 
The Disc
Between each pair of vertebrae sits a disc—often described as a “cushion,” but it’s more like a firm, fibrous ring (the annulus) wrapped around a thick, gel-like center (the nucleus pulposus). Think of the outer annulus like the tough rubber of a tire, and the nucleus pulposus like a water-filled gel inside, or like a jelly-filled donut but made of tough collagen surrounding a thick gel. The disc allows for movement, absorbs shock, and helps distribute pressure evenly through the spine.

Everyone’s disc structure is a little different — some people are naturally more flexible, while others are stiffer. As researcher Stuart McGill puts it, we’re a bit like different breeds of dogs: some built for speed and agility, others for power and endurance. Your unique spinal anatomy can influence how your discs respond to different types of movement or load.
What Happens As the Spine Ages:
As we get older—or if we move in ways that repeatedly stress the spine—its parts can gradually wear down. This is a normal part of both aging and an active life. Understanding how these changes occur can help you prevent more serious issues. Think of it like a domino effect:

It often starts in the bone itself
The vertebral body is made of spongy bone called trabecular bone. Living bone, especially inside the spine, is softer and more elastic than people often expect (we're often used to seeing dry, preserved bone, which is much stiffer and more brittle than bone in a living body). 

This inner bone is strong yet porous, designed to absorb force. But like any structure under repeated stress, it needs time to recover. If not, it can develop tiny micro-fractures from repeated compression or high-impact activities. These changes can gradually influence how the spine adapts and shifts with age or cumulative stress.
Left box shows healthy trabecular bone, strong yet porous and designed to absorb load, but also prone to developing micro-fractures with repeated compression, especially without proper recovery.  Right box shows thinner, weakened bone, as seen with age-related changes or conditions like osteoporosis.
Changes in the endplates
​The endplates, which sit between the disc and the bone, act like nutrient gateways. In youth, this gateway is supported by a richer blood supply that gradually recedes with age. In the mature spine, nutrients diffuse more slowly through the endplate into the central disc.
When the vertebral endplates are put under stress—whether from aging, repeated loading, bone density changes, or small injuries—they can develop tiny cracks or weak spots. This can make it harder for nutrients to reach the disc and may allow some of the disc material to press into the vertebral body, creating what’s called a Schmorl’s node. Sometimes, this intrusion or the stress on the endplate can lead to inflammation inside the bone, which shows up on MRI as Modic changes. These inflammatory changes are sometimes linked to low back pain, especially if nearby nerves or other structures are also affected.
Schmorl’s node intrusion
Inflammatory Modic changes
​With endplate damage, it can make it harder for the disc to stay hydrated. And as the disc’s nucleus loses fluid, it becomes thinner and less springy, placing more demand on the surrounding structures such as the facet joints and nearby nerves (as we'll see below).
The outer rings can fray—like a worn sweater
The disc’s tough outer layer, the annulus, is made of layered collagen fibers arranged in alternating directions — like plywood — to provide strength in multiple planes. Some people have stiffer, more resilient collagen, while others are naturally more bendy or flexible.
With age or repeated strain, especially through twisting or bending under load, the disc’s plywood-like outer wall can begin to separate or tear. This process, called delamination, is a bit like the threads of a sweater fraying over time. These changes are more likely if the disc has already lost height or hydration. As the structure weakens, the soft inner gel can start to push into these vulnerable spots, like a filling pressing into a worn seam.
Annulus with a tear
The gel pushes out (bulge or herniation)
​If pressure continues, the gel-like center may shift outward. Sometimes it stays inside the disc wall (a bulge); other times it escapes (a herniation). We may not even be aware this has happened, as it doesn’t always cause pain — unless nearby nerves or sensitive tissues are involved. Often the herniated material is reabsorbed over time, or the area stiffens naturally as part of the body’s way of sealing and stabilizing the disc.
This bulge is getting close to the spinal nerves, and may cause an issue if not managed.
Bending forward through the spine, especially under load or repeated movement, can be problematic because it can push a bulge further into nerve-sensitive areas (as seen in the image above). While bending is a normal and healthy movement, repeatedly loading the spine in deep forward bending — especially under heavy weight — can increase pressure on the disc. This is more relevant for heavy lifters or in certain repetitive jobs, rather than everyday bending like tying your shoes, unless it's currently an issue.
When forward bending is sensitive, learning to hinge from the hips (left), rather than flexing through the spine (right), can reduce pressure on irritated discs and help protect the lower back during daily tasks or lifting.
Facet joints take on more load
As the disc loses hydration and height, the small joints at the back of the spine — the facet joints — begin to bear more of the load that was once distributed through the discs. These joints, which also help guide and limit movement, aren’t primarily designed to carry heavy compressive forces.
Arrows showing the movements of the facet joints between each lumbar vertebra, mainly bending forwards and backwards.
Over time, this extra stress can lead to joint irritation, stiffness, or wear — similar to what we see in knees or hips. Facet joint irritation may not show up clearly on scans, so diagnosis often depends on the pattern of symptoms and response to movement. Irritated facet joints can sometimes refer pain into the buttocks or the back of the thigh, and symptoms are often worse when bending backwards. These are also the joints that often produce a “click” or “pop” during spinal adjustments or manipulations.
When disc height decreases, the facet joints (right) take on more load—rising from around 30% to as much as 70%.
When nerves become affected
As disc height decreases and the spine changes, nearby nerves can be affected in several ways — and in some cases, this can contribute to more intense or persistent symptoms. Sometimes, this starts with inflammation — irritating chemicals from a stressed disc or nearby tissue can spread to nearby nerves, contributing to pain or altered sensation.

Sometimes, bulging disc material presses against a nerve root, leading to symptoms like tingling, numbness, or radiating pain down the leg — often referred to as sciatica. This pattern is more likely to affect the lower lumbar spine, where the discs bear more load. It’s also where the spine transitions into the pelvis — a natural stress point where a mobile structure (your spine) meets a stable one (your sacrum).
In some cases, the disc itself can become more sensitive — a pattern called discogenic pain. When the disc has been irritated over time, the body may start growing new nerves and blood vessels into parts of the disc that usually don’t have them. This can make the disc more reactive than usual, even to everyday movements or pressure.
Over time, the spaces where nerves travel through the spine can gradually narrow — a process called spinal stenosis. This narrowing may happen in the central spinal canal (central stenosis) or in the openings where nerves exit the spine (foraminal stenosis). Central stenosis is usually caused by things like bulging discs, thickened ligaments, or bony overgrowth pressing into the spinal canal. Foraminal stenosis is often linked to loss of disc height, which reduces the space between vertebrae and narrows the openings where nerves exit the spine.
These changes can sometimes affect how signals travel through the nerves, contributing to sensitivity, altered muscle tone, or subtle weakness. They often develop gradually and may or may not cause symptoms — depending on how the nervous system adapts.

Interestingly, people with central spinal stenosis often feel better when bending forward — like leaning over a shopping cart — because that posture opens up the narrowed canal and eases pressure on the nerves. This contrasts with disc-related pain, where bending forward can sometimes make symptoms worse.
Your Spine’s Needs Change Over Time
In younger people, the inner disc is more hydrated and mobile, which makes disc bulges and herniations more likely, especially with repetitive strain or heavy loading. But as we get older and the disc dries out, it becomes stiffer and less likely to herniate. At that stage, symptoms like leg pain or numbness are more often caused by bony changes, such as joint thickening or bony narrowing, rather than a fresh disc injury. This helps explain why some back issues are more common at certain ages, and why certain treatment and management strategies often depend on both your age and your body’s unique response. 

Understanding these patterns can help guide more tailored and realistic care — whether it’s movement, hands-on support, or learning how to avoid common stressors for your spine. Often, the key isn’t just treating the painful spot, but improving how the whole system works together — including things like hip function and core timing.
​What Does 'Degeneration' Really Mean?
Many people hear terms like “degenerative disc disease” and assume the worst. But degeneration simply means change over time. It’s a common part of aging, like wrinkles in the skin or graying hair. Some of these changes may cause pain or stiffness, while many do not. Structural changes aren’t always a problem — it depends on how you and your body adapt and respond, and how severe the issue is. If discomfort does arise, understanding the underlying mechanics can help guide more effective and supportive care.
Pain and the Nervous System:
Some studies show that people with persistent back pain may have changes in their nervous system — including a kind of low-grade inflammation in the nervous system itself. This may help explain why certain pain lingers long after healing, and why approaches that calm the nervous system and reduce sensitivity can be effective. 
Muscles, Movement, and “Core Strength”
When back pain flares up, people often describe feeling muscle tension, spasms, or “knots.” Sometimes these sensations are the body’s protective response to irritation in deeper structures like the discs, joints, or nerves — a way of bracing or guarding. In other cases, pain may come from the muscles themselves, especially if they’ve been overworked or underused. What’s often called a “pulled muscle” or “knot” may involve tiny areas of muscle tension that refer pain elsewhere — sometimes called myofascial trigger points.
Muscle conditioning also plays a role. Research shows that some people with persistent back pain have less endurance or coordination (even fatty build-up) in the deep spinal muscles that help stabilize the back. Teaching these muscles to activate with the right timing can make a meaningful difference. This idea of controlled stiffness can be especially helpful for those with back instability, or are returning to lifting, sports, or physically demanding jobs.

That said, for many people, simply staying active is enough. Gentle strengthening, walking, stretching, or other enjoyable movement can all support recovery — as long as it’s done with attention to how your body responds. For example, if your back feels sore after prolonged sitting, repetitive bending, or deep stretching, that’s useful information. Some people find relief by learning to gently ‘de-brace’ — to move with more ease and less protective tension. The key is learning to move pain-free with confidence and control.
Want to explore more?
Back pain is a complicated and nuanced subject. If you’d like to learn more, you can explore some of our related pages: These resources offer different angles to help make sense of what you're feeling — and to support your path toward relief.
⚠️ Disclaimer:
This page is here to support—not replace—medical advice. If you're experiencing intense, unusual, or worsening symptoms, it's a good idea to check in with your GP.

🩺 For Referrers:
We’re always happy to collaborate with referring providers. Feel free to get in touch to discuss an approach or referral.
Exercises: Podcast
Compiled by Joe Liguori