The Back Pain Your Scan Won't Show: Understanding Segmental Overstrain

All information in this blog is supported by NICE guidelines and peer-reviewed research. Reference numbers appear throughout, the full list can be found at the bottom of the page.

Have You Been Told There Is Nothing Wrong?

You have had back pain for weeks, months, or even years. You have had an X-ray or an MRI. The report comes back saying the scan is normal, or that there are only age-related changes. Your GP tells you there is nothing structurally wrong. And yet you are still in pain, sometimes significant, persistent, debilitating pain.

This is one of the most frustrating and confusing experiences a person can have, and it is far more common than you might think. The aetiology of chronic low back pain is, in most cases, up to 85%, unknown or non-specific, meaning no specific structural cause is identified on imaging. ¹

But "non-specific" does not mean "nothing is wrong." In many cases it means the problem is functional; a problem with how the spine is moving, loading, and being controlled, rather than structural. And one of the most common functional causes of persistent, localised back pain is a condition known as segmental overstrain.

What Is Segmental Overstrain?

To understand segmental overstrain, it helps to first understand what a spinal motion segment is. The spine does not move as one single unit, it is made up of approximately 24 individual motion segments, each consisting of two adjacent vertebrae, the intervertebral disc between them, two facet joints at that level, the surrounding ligaments and muscles, and the nerve root that exits the spine at that level.

Each motion segment has a specific job; to allow controlled, smooth movement whilst protecting the spinal cord and nerve roots. When all segments are working well and sharing the load of movement equally, the spine functions efficiently and pain-free.

Segmental overstrain occurs when one or more of these motion segments is repeatedly subjected to excessive, abnormal, or poorly controlled mechanical stress, beyond what it is designed to handle over time. Pain at the segmental level arises from a multifactorial combination of factors including mechanical, nociceptor-mediated pain from structures within the affected segment, instability, and local inflammatory processes. ² The surrounding muscles respond by going into protective spasm to guard the irritated segment, which provides short-term protection but creates its own cycle of tension, stiffness, and pain.

The key point, and the reason scans so often come back normal, is that segmental overstrain is a movement and loading problem, not a structural one. The bones, discs, and joints may look perfectly normal on imaging, whilst the segment itself is being chronically overloaded, irritated, and guarded.

Why Does a Segment Become Overloaded?

There are several common reasons why a specific spinal segment ends up bearing more load than it should:

Compensatory mechanics: This is one of the most important and underappreciated causes. If one part of the spine is stiff or restricted, perhaps from a previous injury, a postural habit, or muscle tightness, the segments above and below it are forced to work harder to compensate. Over time, these adjacent segments become progressively overloaded. This is why the most painful level is not always the original source of the problem.

Muscle imbalance patterns: Postural syndromes such as lower crossed syndrome, where the deep abdominals and gluteal muscles are weak and the hip flexors and lumbar erectors are overactive, place disproportionate compressive and shear load on specific lumbar segments, particularly L4/L5 and L5/S1. The segment takes the strain that the muscles are no longer sharing efficiently.

Repetitive occupational or sporting movements: Repeated loading in the same direction; prolonged forward bending, repetitive twisting, sustained sitting, or overhead work, can overload a specific segment through cumulative mechanical stress, even when individual loads are modest.

Sustained poor posture:Long hours in a flexed seated posture increase disc pressure and facet joint loading at specific levels. Over time, the chronically loaded segment becomes sensitised and painful.

Previous injury with incomplete rehabilitation: An old sprain, a minor disc injury, or even a previous episode of back pain that appeared to resolve can leave altered movement patterns and muscle recruitment behind. Multifidus dysfunction; where the small, deep segmental stabilising muscles of the spine undergo reflex inhibition following an initial injury, decreases spinal stability and predisposes patients to further injury and recurrence at the same segment. ³ This is one of the most important reasons why back pain that "went away on its own" so frequently returns.

The Role of the Multifidus: Your Spine's Most Important Stabiliser

The multifidus is a deep, segmental muscle running along the spine that most people have never heard of. Unlike the larger, more superficial back muscles, which move the spine in broad directions, the multifidus operates at the level of individual vertebrae, providing precise, moment-to-moment control of each motion segment during movement.

The lumbar multifidus is crucial for maintaining both lumbar segmental stability and dynamic stability of the spine, and growing evidence suggests that individuals with chronic low back pain frequently exhibit impairments in this muscle, characterised by morphological changes including fatty infiltration and atrophy. ⁴

What makes this clinically significant is that multifidus muscle recovery is not automatic after resolution of acute low back pain, meaning that even when pain settles, the deep segmental stabilisers may remain inhibited and dysfunctional, leaving the segment vulnerable to repeated overstrain. ³ This is why simply waiting for back pain to go away, without targeted rehabilitation, so frequently leads to recurrence.

In October 2024, the ICD-10 code M62.85 was issued for dysfunction of the multifidus muscle in the lumbar spine, providing formal clinical classification and allowing more specific diagnosis of this important contributor to chronic low back pain. ³

What Does Segmental Overstrain Feel Like?

Segmental overstrain has a fairly characteristic pattern of symptoms, though it varies between individuals:

• Localised, specific pain: often the person can point to the exact location with one finger, rather than describing a broad, diffuse ache

• Pain that is worse with sustained postures: sitting for long periods, prolonged standing, or being in one position for too long

• Stiffness at a specific level: particularly first thing in the morning or after rest, easing with gentle movement

• A feeling of instability, weakness, or "giving way" at the painful area

• Protective muscle spasm: tightness in the muscles either side of the spine around the affected level that feels like it needs to be constantly stretched but never quite releases

• Pain that returns repeatedly: appearing to settle with rest, only to come back quickly with activity or prolonged posture

• No leg pain, tingling, or numbness: in uncomplicated cases, symptoms stay in the back and possibly the buttock or thigh, but do not travel below the knee

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The pain is often described as a deep, persistent ache that is difficult to get comfortable with, and that is disproportionate to what imaging suggests should be there. This brings us to one of the most important aspects of understanding segmental overstrain.

Why Does the Pain Feel So Significant When the Scan Looks Normal?

This is one of the most common questions, and one of the most important to answer clearly, because misunderstanding it leads people to catastrophise, to fear movement, and to delay seeking the right treatment.

The answer lies in a process called pain sensitisation. When a spinal segment is repeatedly overloaded and irritated over a prolonged period, the nervous system undergoes changes that make it progressively more sensitive to pain signals from that area. In the 21st century, the development of knowledge about central sensitisation has allowed for a better understanding of the pathomechanism of pain and the transformation of low back pain into a chronic form; patients with chronic pain often experience accompanying symptoms such as fatigue, sleep disturbance, and heightened pain responses that go beyond what the local tissue damage alone would predict. ⁵

In practical terms this means the affected segment can become hypersensitive, responding to normal everyday loads and postures with a pain signal that feels far more significant than the underlying mechanical problem would warrant. This is not imagined or exaggerated pain. It is a real, neurological process that explains why people with perfectly normal-looking scans can be in considerable discomfort. ⁵

Understanding this is liberating, because it means that with the right treatment, addressing both the mechanical loading problem and the sensitised nervous system, significant improvement is very achievable, even in long-standing cases.

What to Look Out For

In the vast majority of cases, segmental overstrain is a benign, mechanical condition. However, UK guidelines advise seeking urgent medical attention if any of the following are present, as they may indicate a more serious underlying cause: ⁶

• Loss of bladder or bowel control

• Numbness or tingling in the inner thighs or saddle area

• Rapidly worsening weakness in the legs

• Severe, constant pain not relieved by any position, particularly at night

• Unexplained weight loss alongside back pain

• Back pain following significant trauma

• A history of cancer alongside new or worsening back pain

Myths vs Facts

"My scan is normal so nothing is wrong.": A normal scan means there is no significant structural damage, it does not mean the spine is functioning well. Segmental overstrain is a functional problem that imaging is simply not designed to detect. ¹

"I just need to rest and it will settle.": Short-term relative rest during an acute flare can help, but prolonged rest allows the multifidus and deep stabilisers to further weaken and decondition, making recurrence more likely. UK guidelines recommend staying as active as possible and beginning appropriate treatment early. ⁶

"If the pain keeps coming back, there must be something seriously wrong.": Recurrent back pain at the same level is a very common pattern in segmental overstrain, not because something is seriously wrong, but because the underlying instability and muscle dysfunction has not been addressed. Once it is, recurrence rates drop significantly. ³

"I need to protect this area and avoid anything that hurts it.": Avoiding movement and loading the spine entirely is counterproductive. Graded, progressive loading through the right exercise programme actually promotes healing, restores multifidus function, and reduces pain sensitisation over time. ⁴

How We Can Help

At our clinic, we take a thorough assessment approach to identify the specific segment or segments involved, the movement patterns and muscle imbalances contributing to the overstrain, and the degree to which pain sensitisation is playing a role. All treatment is delivered in line with UK guidelines and current research evidence. ⁶

Osteopathic manual techniques and spinal manipulation / mobilisation: UK guidelines recommend manual therapy, including spinal manipulation, mobilisation, and soft tissue techniques, as part of a treatment package for low back pain. ⁶ For segmental overstrain specifically, targeted mobilisation and manipulation of the affected segment is particularly effective, restoring normal joint movement, reducing facet joint irritation, breaking the cycle of protective muscle spasm, and improving the proprioceptive (position sense) feedback from the segment. The contemporary model of vertebral dysfunction recognises that spinal adjustments directed at a dysfunctional segment alter neuromuscular function through peripheral mechanisms involving the paravertebral tissues, improving motor control and reducing pain. ⁷

Deep tissue and sports massage: The protective muscle spasm that develops around an overloaded segment, particularly in the thoracolumbar fascia, multifidus, and erector spinae, responds very well to targeted soft tissue release. Reducing this spasm allows the joint to move more freely and prepares the segment to respond better to both manipulation and corrective exercise.

Medical acupuncture: We use medical acupuncture as part of a broader multimodal treatment plan. Acupuncture is particularly useful for addressing pain sensitisation at the segmental level, stimulating inhibitory pain pathways, reducing the heightened nerve sensitivity around the affected segment, and breaking the pain-spasm-pain cycle. Whilst UK guidance does not recommend acupuncture as a standalone treatment for low back pain, a growing body of peer-reviewed research supports its use within a multimodal approach. ⁸

Cupping and gua sha: Used as complementary tools within a broader plan. Cupping and gua sha are effective at releasing stubborn paraspinal muscle tension, particularly the deep tension that often persists around an overloaded segment despite other treatment, improving local circulation and reducing tissue sensitivity.

Exercise and Rehabilitation: The Key to Long-Term Recovery

Treating the painful segment manually is essential, but without restoring the deep segmental stability that has been lost, the same overstrain pattern will return. Exercise is therefore not optional, it is the foundation of lasting recovery. ⁴

Exercise therapy is the primary endorsed form of conservative treatment for chronic low back pain, and there is growing evidence that targeted exercise programmes aimed at restoring multifidus function produce significant improvements in pain and disability. ⁴ Frontiers

Phase 1: Early stage: reduce irritation and restore basic movement

• Gentle walking: the most underrated and evidence-based early intervention for back pain

• Frequent position changes: avoid sustained loading of the affected segment in any one position

• Pelvic tilts: lying on your back with knees bent, gently flatten the lower back to the floor. Begins to activate the deep stabilisers without loading the segment

• Cat-cow: on all fours, slowly arch and round the spine in a flowing motion. Maintains segmental mobility and reduces stiffness

Phase 2: Building segmental stability

• Bird-dog: on all fours, slowly extend one arm and the opposite leg, holding for 5 to 10 seconds before returning. One of the most evidence-based exercises for multifidus activation and segmental control

• Dead bug: lying on your back with arms pointing to the ceiling and knees bent to 90 degrees, slowly lower one arm and the opposite leg toward the floor whilst keeping your lower back flat. Excellent for deep abdominal and segmental stabiliser co-activation

• Side-lying clam: lying on your side with knees bent, lift the top knee whilst keeping the feet together. Activates the gluteus medius and reduces pelvic instability that loads the lumbar segments

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Phase 3: Progressive loading and return to full activity

• Glute bridges progressing to single-leg glute bridges

• Plank progressions building endurance of the deep stabilisers

• Gradual return to walking, swimming, and low-impact exercise

• Sport or work-specific movement retraining where relevant

  
  

Your practitioner will guide the exact exercises appropriate for your specific presentation and stage of recovery.

Living With Segmental Overstrain: Practical Day-to-Day Tips

UK guidelines emphasise self-management advice as a core component of care for low back pain. ⁶ Here are practical steps to reduce segmental loading day to day:

• Sitting: Set a timer to stand and move every 20 to 30 minutes. The affected segment accumulates load rapidly in sustained sitting. A small lumbar support can reduce flexion load on the segment.

• Standing: Avoid prolonged standing in one position. Shift weight, use a foot rest, and move regularly.

• Sleeping: Side lying with a pillow between the knees is often most comfortable, as it reduces rotational stress on the lumbar segments. Avoid sleeping on your front.

• Lifting: Keep loads close to your body, bend at the knees, and avoid combining lifting with twisting, this places significant shear stress on individual segments.

• Heat: A warm heat pack over the affected area can reduce muscle spasm and improve comfort, particularly in the morning when stiffness is typically worst.

• Keep moving: Counterintuitive as it feels, gentle, consistent movement is one of the most powerful things you can do. The spine needs movement to distribute nutrients, maintain disc health, and keep the deep stabilisers active.

What to Expect at Your First Appointment

At your first appointment, we will take a thorough case history, including how and when your pain started, what makes it better or worse, whether it has recurred before, and what your daily loading looks like at work and at home. We will carry out a detailed movement assessment and hands-on examination to identify the affected segment, assess the surrounding muscle function, and establish the degree of sensitivity. We will then explain exactly what we find in plain language and build a personalised, evidence-based treatment plan with you — one that addresses not just the pain, but the underlying cause. ⁶

Frequently Asked Questions

How long will it take to recover? This depends on how long the overstrain has been present and how well the deep stabilisers respond to rehabilitation. Many people notice significant improvement in pain within two to four sessions of treatment. Restoring full segmental stability typically takes six to twelve weeks of consistent exercise, but most people are functioning much better well before then.

Will it come back? If the underlying causes, muscle imbalance, movement habits, and segmental instability — are addressed and maintained through exercise, recurrence rates are significantly reduced. Many people have no further significant episodes after completing a full course of rehabilitation.

Do I need a scan? In most cases, no. UK guidelines advise against routine imaging for non-specific low back pain, as scans frequently show changes that are either normal for age or unrelated to the current symptoms. Your practitioner will advise if a referral for imaging is appropriate. ⁶

Is this the same as a "trapped nerve"? Not quite. Segmental overstrain does not necessarily involve nerve compression. However, if the segment becomes significantly inflamed and irritated, it can occasionally produce referred pain into the buttock or thigh, which is sometimes described as a "trapped nerve." True nerve compression with leg symptoms below the knee is a different presentation requiring a different approach.

Think this sounds familiar? Get in touch using the contact form and we will carry out a thorough assessment to find out exactly what is driving your back pain — and put together a plan to do something about it.

References

1. Vlaeyen JWS, et al. Central sensitization in chronic low back pain: a narrative review. European Spine Journal. 2016. Available at: https://pubmed.ncbi.nlm.nih.gov/27062464/

2. The Diagnosis and Treatment of Degenerative Changes of the Lumbar Spine. Deutsches Arzteblatt International. PMC. 2025. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12516344/

3. Bess S, et al. Multifidus Dysfunction and Chronic Low Back Pain: Systematic Review and Meta-analysis. International Journal of Spine Surgery. 2025. Available at: https://www.ijssurgery.com/content/ijss/early/2025/11/12/8814.full.pdf

4. Deodato M, et al. The effects of a 12-week combined motor control exercise and isolated lumbar extension intervention on lumbar multifidus muscle stiffness in individuals with chronic low back pain. Frontiers in Physiology. 2024. Available at: https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2024.1336544/full

5. Yücel F, et al. Is the Central Sensitization in Chronic Nonspecific Low Back Pain a Structural Phenomenon or Psychological Reaction? A Narrative Review. Journal of Clinical Medicine. 2025;14(2):577. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC11765779/

6. National Institute for Health and Care Excellence (NICE). Low Back Pain and Sciatica in Over 16s: Assessment and Management. NICE Guideline [NG59]. Published November 2016, last updated December 2020. Available at: https://www.nice.org.uk/guidance/ng59

7. Haavik H, Murphy B. The contemporary model of vertebral column joint dysfunction and impact of high-velocity, low-amplitude controlled vertebral thrusts on neuromuscular function. PMC. 2021. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8416873/

8. Qu Z, et al. Effectiveness of acupuncture in the treatment of chronic sciatica from herniated discs: a systematic review and meta-analysis. Frontiers in Medicine. 2026. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12872920/