Multifidus Dysfunction: A Hidden Cause of Chronic Low Back Pain

Low back pain is often blamed on a disc, arthritis, a strained muscle, or simply getting older. But there is another problem that can develop after a back injury and may help explain why pain keeps returning.

It is called multifidus dysfunction.

The multifidus is one of the most important stabilizing muscles of the lumbar spine. After an injury or repeated episodes of back pain, this muscle can become inhibited, weak, and eventually begin to shrink.

The pain may improve, but normal muscle function does not always return automatically.

That can leave the spine with less muscular support and control, potentially contributing to recurring episodes of low back pain.

At The Center for Total Back Care in Mesa, we evaluate spinal function as well as symptoms. When appropriate, we use MedX lumbar strength testing and rehabilitation to objectively measure spinal strength and progressively rebuild function.

What Is the Multifidus Muscle?

The multifidus is a series of small, deep muscles that run along the back of the spine and connect individual vertebral segments.

Unlike the larger muscles you can see and feel, the multifidus is primarily involved in spinal stabilization and precise control of movement.

The multifidus helps:

• Stabilize individual spinal segments
• Control small movements between vertebrae
• Support the spine during bending, lifting, and twisting
• Maintain posture and spinal control
• Work with other trunk muscles to manage loads placed on the spine

In a healthy neuromuscular system, the deep stabilizing muscles coordinate with other trunk muscles to prepare the spine for movement.

The problem is that pain or injury can disrupt this system.

What Is Multifidus Dysfunction?

Multifidus dysfunction occurs when the multifidus no longer activates or functions normally.

This may occur following:

• An acute low back injury
• A herniated or degenerative disc
• Repeated episodes of low back pain
• Irritation of the spinal joints
• Back surgery
• Prolonged inactivity or deconditioning

Following an injury, changes in the nervous system can reduce activation of muscles surrounding the affected area.

Car accidents, falls, and long hours of sitting are a common way this starts. That side of the story is in why the multifidus fails.

One mechanism involved in this process is known as arthrogenic muscle inhibition, or AMI.

What Is Arthrogenic Muscle Inhibition?

Arthrogenic muscle inhibition is a neurological response in which signals coming from an injured or irritated joint can alter the nervous system's ability to fully activate the muscles associated with that joint.

In simple terms:

The problem may not be just that the muscle is weak. The nervous system may not be activating the muscle normally.

Over time, reduced activation and reduced use can contribute to weakness, muscle atrophy, and changes in muscle composition.

This can create a difficult cycle:

Pain or injury, then muscle inhibition, then weakness and reduced control, then altered spinal loading, then recurring irritation.

This is one reason simply waiting for the pain to disappear may not completely restore normal spinal function.

Think of It Like a Circuit Breaker

A useful way to understand muscle inhibition is to think about the circuit breaker in your house.

If an electrical circuit becomes overloaded, the breaker trips. Electricity is reduced or shut off to protect the system.

Something conceptually similar can occur following a spinal injury.

When a disc, facet joint, ligament, or other spinal structure becomes irritated, sensory information from the injured area changes. The nervous system may respond by altering activation of the muscles responsible for controlling that area.

It is as though the body's protective system has partially tripped the breaker.

The original pain may eventually settle down, but that does not necessarily mean normal muscle activation, strength, and control have completely returned.

Feeling better and being fully rehabilitated are not always the same thing.

Why Does This Happen?

Your spine contains an extensive network of sensory receptors that constantly provide information about pain, position, movement, and loading.

These include:

• Mechanoreceptors that help detect movement and position
• Nociceptors that respond to potentially damaging stimuli
• Receptors within spinal joints, ligaments, and joint capsules

Following an injury, this sensory information can change the way the nervous system controls the muscles surrounding the affected spinal segments.

The result can include:

• Reduced muscle activation
• Changes in motor control
• Weakness
• Reduced endurance
• Delayed muscle activation
• Altered spinal stability

Importantly, these changes can sometimes persist even after the original episode of pain has improved.

Why Is the Multifidus Particularly Important?

The multifidus has a specialized role in controlling the lumbar spine.

Research involving people with low back pain has identified changes in the multifidus that may include:

• Reduced muscle size
• Side-to-side asymmetry
• Reduced activation
• Altered timing of muscle contraction
• Muscle atrophy
• Increased fatty infiltration in chronic cases

These findings are important because the multifidus is not simply another large back muscle.

It contributes to the precise control of individual spinal segments.

When that control is reduced, larger muscles may compensate, but compensation is not necessarily the same as restoring normal deep spinal muscle function.

The Pain May Be Gone, but Is the Weakness?

This is one of the most important concepts for patients with recurring low back pain.

Pain is a symptom.

Strength, endurance, motor control, and spinal stability are functions.

The two do not always recover at the same rate.

A patient may feel considerably better and still have measurable weakness or impaired spinal muscle function.

This may help explain a familiar pattern:

You hurt your back.

You rest or receive treatment.

The pain improves.

You return to normal activity.

Several weeks or months later, the pain returns.

The question should not only be, "How do we make the pain go away?"

We should also be asking, "Has normal spinal function been restored?"

Multifidus Dysfunction and Segmental Stability

The lumbar spine is made up of multiple vertebrae, discs, joints, ligaments, and muscles working together.

The deep spinal muscles help control movement between these individual segments.

When this system is impaired, the spine may have less precise muscular control during everyday activities.

Larger muscles such as the erector spinae can help generate force and movement, but they cannot completely duplicate the multifidus muscle's segmental role.

This distinction is important.

A person can have strong abdominal and back muscles and still have deficits in the deeper stabilizing system.

Why General Core Exercise May Not Be Enough

Planks, bridges, abdominal exercises, and general strengthening can all be useful components of an exercise program.

But they do not tell us whether a patient has restored normal lumbar extensor strength or whether compensation is occurring. A back extension can be part of home care, and it still does not show whether that strength has returned.

During many traditional back exercises, movement can come from several areas at once, including the:

• Hips
• Pelvis
• Gluteal muscles
• Hamstrings
• Abdominal muscles
• Larger spinal muscles

A patient can therefore become better at performing an exercise without necessarily correcting the specific weakness we are trying to address.

That is why we believe measurement and isolation are important components of spinal rehabilitation.

Why Pelvic Stabilization Matters

One of the challenges in lumbar rehabilitation is separating true lumbar movement from movement of the pelvis and hips.

If the pelvis is allowed to move freely during an exercise, powerful hip and leg muscles can contribute substantially to the movement.

This makes it difficult to determine how much work is actually being performed by the lumbar muscles.

Stabilizing the pelvis reduces compensation and allows lumbar extension to be trained more specifically.

This principle is an important part of the MedX approach to lumbar testing and rehabilitation.

The Role of MedX in Lumbar Rehabilitation

At The Center for Total Back Care, we use MedX lumbar equipment in selected patients because it allows us to approach spinal rehabilitation differently from a typical gym exercise program.

Objective Strength Testing

Instead of simply asking whether your back feels stronger, MedX testing can objectively evaluate lumbar extension strength through different positions in the available range of motion.

This gives us measurable information that can help:

• Identify significant weakness
• Establish a baseline
• Compare performance over time
• Guide rehabilitation
• Document improvement

What gets measured can be managed.

Pelvic Stabilization

One of the defining features of the MedX lumbar system is stabilization.

The equipment is designed to restrict movement of the pelvis and reduce contribution from the hips and thighs.

This allows us to more specifically evaluate and train the lumbar extensor musculature.

Without adequate stabilization, a back exercise can easily become a hip and leg exercise.

Specific, Progressive Exercise

Once a patient's ability has been evaluated, resistance can be introduced in a controlled and progressive manner.

The goal is not simply to lift more weight.

The goal is to progressively improve:

• Lumbar strength
• Muscular endurance
• Movement control
• Functional capacity
• Confidence with activity

Measurable Progress

Patients can be retested during rehabilitation.

That allows us to compare objective measurements rather than relying entirely on symptoms.

This is particularly important because pain reduction does not necessarily mean strength has returned to normal.

What Can Happen If Weakness Is Never Addressed?

When spinal weakness and impaired muscle function persist, some patients may continue to experience:

• Recurring episodes of low back pain
• Reduced tolerance for lifting or prolonged activity
• Deconditioning
• Stiffness
• Guarded movement
• Reduced confidence
• Avoidance of activities
• Difficulty returning to normal work, exercise, or recreation

This can become a self-perpetuating cycle.

Pain causes people to move less.

Moving less contributes to weakness and deconditioning.

Weakness makes normal activities more difficult.

The person becomes increasingly cautious about movement.

Eventually, the goal becomes avoiding pain rather than restoring function.

We want to break that cycle.

What Happens When Spinal Function Improves?

Effective rehabilitation should do more than temporarily reduce symptoms.

The objective is to restore as much normal function as possible.

Depending on the individual patient, improvements in spinal strength and function may help them:

• Move with greater confidence
• Increase activity tolerance
• Return to normal activities
• Improve strength and endurance
• Reduce physical deconditioning
• Better tolerate the demands placed on their back

The long-term goal is not simply a back that hurts less. It is a back that functions better.

Do You Have Multifidus Dysfunction?

You cannot diagnose multifidus dysfunction simply by how your back feels.

However, it may be worth evaluating spinal muscle function if:

• Your low back pain repeatedly returns
• Your pain improved, but your back still feels weak
• You have difficulty returning to normal activity
• You have had a lumbar disc injury
• You have become deconditioned after an injury
• You have completed general exercise but continue to have problems
• Your back fatigues easily
• You are concerned that something other than pain has not fully recovered

A comprehensive examination can help determine whether weakness or impaired function should be part of your treatment and rehabilitation plan.

Treat the Function, Not Just the Pain

Chronic and recurring low back pain is rarely explained by one factor alone.

Discs, joints, nerves, movement patterns, activity levels, conditioning, and the nervous system can all play a role.

Multifidus dysfunction and lumbar muscle weakness are important pieces of that picture that can sometimes be overlooked when treatment focuses only on reducing pain.

At The Center for Total Back Care, our approach is to determine what is contributing to the problem and then develop treatment around the findings.

For appropriate patients, this can include:

• A comprehensive spinal examination
• Objective lumbar strength testing
• Pelvic stabilization
• Specific lumbar rehabilitation
• Progressive resistance exercise
• Periodic retesting to document improvement

After more than 40 years of treating spinal conditions, one principle remains especially important:

Pain relief is important, but restoring function is what helps you get back to living your life.

Multifidus Dysfunction Treatment in Mesa, Arizona

The Center for Total Back Care provides evaluation and rehabilitation for patients with acute and chronic lower back pain in Mesa and throughout the East Valley, including Chandler, Gilbert, and Tempe.

If your back pain keeps returning, or if previous treatment helped the pain but never seemed to restore your strength, it may be time to look beyond the symptoms and evaluate how your spine is actually functioning.

Schedule your evaluation at The Center for Total Back Care in Mesa, Arizona.