IMG White Paper Why and How Chiropractic Works

WHY CHIROPRACTIC WORKS

Motion, Neurology, Function and the Science of the Chiropractic Adjustment

An InterState Medical Group White Paper

Movement is Our Medicine.
Motion Wins.

Introduction: From Clinical Observation to Modern Science

For more than a century, chiropractors have observed something remarkably consistent: when appropriately selected patients with painful or dysfunctional areas of the spine receive skilled manual treatment, many experience meaningful changes in pain, mobility and function.

The explanations for those changes have evolved considerably.

Early chiropractic developed before modern neurophysiology, advanced imaging, pain neuroscience, electromyography and sophisticated biomechanical research existed. Chiropractors therefore described what they were seeing with the terminology and scientific knowledge available at the time.

Today, we can ask a more precise question:

What actually happens when a spinal joint is manipulated, and why can that change how a person feels and moves?

Modern evidence suggests that the answer does not lie in any single mechanism.

A chiropractic adjustment creates a specific mechanical input into a complex biological system. That input can influence joint mechanics, sensory information entering the nervous system, spinal processing, muscle activity, pain modulation and motor control. These effects occur within the much larger biological and psychological environment of the individual patient.

The chiropractic adjustment therefore should not be viewed simply as a method of “putting bones back into place.”

It is better understood as a mechanical intervention capable of producing interacting biomechanical and neurophysiological responses.

That distinction represents an important evolution in chiropractic science.

1. The Original Chiropractic Observation

The early pioneers of chiropractic recognized that the spine was more than a passive column of bones.

It was a dynamic mechanical structure intimately connected with movement, posture, muscles, joints and the nervous system.

Different schools of chiropractic subsequently developed different systems for detecting and treating spinal dysfunction. Palmer chiropractic, Gonstead, Thompson, Diversified, Activator and other approaches varied considerably in examination methods, terminology and adjustment technique.

Yet a common principle ran through much of their work:

Identify an area believed to be functioning abnormally and apply a specific mechanical intervention intended to improve that function.

Modern research allows us to examine that observation independently of some of the historical theories originally used to explain it.

The question is no longer simply whether the vertebra is perfectly aligned.

The more useful questions are:

• Does the joint move normally?
• Does movement provoke pain?
• Has mechanical loading changed?
• Has muscle guarding developed?
• Is sensory information from the region altered?
• Has motor control changed?
• Is the patient avoiding movement?
• Is the nervous system becoming increasingly protective?
• Can an appropriate mechanical intervention change any of these processes?

This transition—from position alone toward motion, loading, sensory processing and function—is one of the most important developments in modern chiropractic thought.

2. The Spine Is a Sensory Organ as Well as a Mechanical Structure

The spine contains joints, ligaments, muscles, tendons, fascia and other tissues rich in sensory receptors.

Every movement generates information.

That information continuously travels toward the spinal cord and brain, helping the nervous system answer fundamental questions:

Where is the body?

How much force is being produced?

Is the joint moving?

How quickly is it moving?

Is the movement threatening?

Should muscles contract, relax or stabilize?

This continuous stream of information contributes to proprioception and sensorimotor control.

Consequently, abnormal movement does not exist solely as a mechanical event.

It also changes the information being generated by the musculoskeletal system.

This is where modern neuroscience begins to provide an intriguing framework for understanding spinal manipulation.

Joel Pickar’s influential review proposed that the biomechanical changes created by spinal manipulation can generate physiological effects through changes in sensory input reaching the central nervous system. This connected the mechanical adjustment with subsequent neurological responses rather than treating the two as separate phenomena.

Later research has continued investigating changes in sensory processing, motor output and sensorimotor integration following spinal manipulation.

This does not mean every chiropractic adjustment “resets the brain.”

It means something more scientifically defensible:

A mechanical intervention to the spine can alter sensory input, and sensory input can influence how the nervous system organizes movement and pain.

3. Motion Changes Information

This leads to a foundational concept:

Motion creates information.

When a spinal joint moves, receptors within and around that joint respond to movement, force and tissue deformation.

When normal movement becomes restricted, painful or guarded, the pattern of sensory information generated by the region may also change.

The nervous system may respond by increasing muscular protection, altering recruitment patterns, modifying movement and sometimes increasing sensitivity to otherwise tolerable mechanical input.

This can create a self-reinforcing cycle:

Pain → guarding → reduced movement → altered loading → altered sensory input → altered motor control → more guarding and reduced function.

Spinal manipulation can potentially interrupt portions of this cycle.

The rapid mechanical input produced by an adjustment stimulates joint and surrounding tissues and creates an unusually strong burst of sensory activity.

Studies investigating spinal manipulation have demonstrated measurable changes in somatosensory processing and sensorimotor integration following manipulation, although the clinical importance and duration of these changes continue to be investigated.

This suggests a more modern interpretation of something chiropractors have observed clinically for generations:

Change the motion, and you may change the information entering the system.

4. The Adjustment as a Mechanical Stimulus

A chiropractic adjustment is usually a controlled mechanical force delivered to a joint or spinal region.

In high-velocity, low-amplitude manipulation, that force is delivered rapidly through a relatively small range of movement.

The adjustment does not necessarily permanently reposition a vertebra.

Contemporary evidence suggests that the immediate biomechanical effects are more nuanced.

A 2024 systematic review examining anatomical, structural and positional changes after spinal manipulation found credible evidence suggesting increases in lumbar facet joint space and reductions in spinal stiffness. The same review found considerably less evidence supporting many other proposed permanent structural changes.

A subsequent systematic review of high-velocity, low-amplitude manipulation examined outcomes including range of motion, facet-joint gapping and spinal stiffness, illustrating the ongoing scientific effort to identify the mechanical effects that accompany manipulation.

This is important.

The benefit of an adjustment does not require us to believe that a vertebra was dramatically displaced and then permanently pushed back into position.

Instead, manipulation may temporarily alter:

joint movement,

joint stiffness,

mechanical loading,

tissue deformation,

muscle activity,

and sensory input.

Those changes can then interact with the nervous system.

5. The Adjustment and Pain

Pain is not simply a direct measurement of tissue damage.

Pain is a protective experience produced by the nervous system after integrating information from tissues with many other factors, including previous injury, inflammation, expectations, stress, movement, context and perceived threat.

That does not make pain imaginary.

It makes pain biological and complex.

Modern research suggests that spinal manipulation can influence some of the neural processes involved in pain modulation.

A 2021 review examining neurophysiological mechanisms of chiropractic spinal manipulation concluded that spinal segmental mechanisms appear to contribute to pain relief. Possible peripheral and supraspinal mechanisms are also being investigated, although the evidence supporting those pathways remains less certain.

This distinction matters enormously.

We should not tell patients:

“Your pain disappeared because the vertebra was put back in place.”

That may occasionally describe part of a mechanical problem, but it is an incomplete explanation of pain.

A more accurate statement is:

The adjustment introduced a mechanical stimulus that may have changed joint mechanics, sensory input and pain processing simultaneously.

6. The Adjustment and Motor Control

Movement requires constant communication between the musculoskeletal system and nervous system.

The brain sends motor commands.

The body moves.

Sensory receptors report what happened.

The brain and spinal cord process that information.

The motor strategy is continuously updated.

This is the sensorimotor system.

Researchers including Haavik, Murphy and colleagues have reported changes in measures of sensory processing and sensorimotor integration following spinal manipulation.

These findings are scientifically interesting because they offer a potential bridge between an adjustment and the changes patients sometimes immediately describe:

“I can turn farther.”

“It doesn’t feel as tight.”

“My movement feels easier.”

“I feel more balanced.”

“The muscles aren’t guarding as much.”

These observations should not automatically be attributed to dramatic cortical “reprogramming.” Research remains incomplete.

But the broader concept is biologically reasonable:

Changing sensory information from a region can potentially change motor output to that region.

That relationship is fundamental to neuroscience, rehabilitation and movement science.

7. Why Patients Often Need More Than an Adjustment

If an adjustment changes movement and sensory input, an important question follows:

What happens next?

This is where chiropractic and rehabilitation should become partners rather than competitors.

An adjustment may create an opportunity.

Rehabilitation teaches the body what to do with that opportunity.

Consider a patient who has avoided cervical rotation because turning the head has hurt for months.

The patient may develop:

joint stiffness,

muscular guarding,

reduced range of motion,

altered movement strategies,

weakness,

fear of movement,

and compensatory patterns.

An adjustment may reduce stiffness or pain and make movement easier.

But if the patient never relearns the movement, strengthens the appropriate musculature or restores normal activity, the underlying functional problem may persist.

The logical sequence becomes:

Improve motion.

Reintroduce movement.

Strengthen the movement.

Build capacity.

Restore confidence.

This is one reason modern multimodal musculoskeletal care often combines manual therapy with exercise, education and active rehabilitation.

Major clinical guidelines also place spinal manipulation among several nonpharmacologic options rather than presenting it as a solitary treatment. The American College of Physicians includes spinal manipulation among nonpharmacologic approaches for acute, subacute and chronic low-back pain.

The World Health Organization likewise states that spinal manipulative therapy may be offered as part of care for adults with chronic primary low-back pain, while emphasizing a broader person-centered treatment model.

The phrase “as part of care” is important.

That is precisely how InterState Medical Group views it.

8. Why Different Chiropractic Techniques Can Work

Chiropractic has produced numerous adjusting systems.

Some emphasize manual palpation.

Some emphasize radiographic analysis.

Some use drop tables.

Some use instruments.

Some use rotational forces.

Others emphasize short-lever adjustments or highly specific contacts.

If these techniques are so different, how can several of them produce clinical benefit?

One plausible explanation is that different techniques can produce variations of the same general phenomenon:

a targeted mechanical stimulus delivered into the neuromusculoskeletal system.

The magnitude, velocity, direction, contact point and mechanical characteristics may differ.

The resulting sensory input will therefore also differ.

The patient’s response will depend on many variables:

their condition,

irritability,

age,

anatomy,

pain sensitivity,

expectations,

movement pattern,

joint characteristics,

and the skill of the practitioner.

This helps explain why chiropractic should never become technique worship.

The technique is not the objective.

Improved function is the objective.

At IMG, technique should therefore serve the patient rather than requiring the patient to fit the technique.

9. The Audible Cavitation Is Not the Treatment

Many patients associate chiropractic with the characteristic “pop” or “crack” that can accompany manipulation.

The sound is generally associated with rapid changes within a synovial joint.

It can provide useful feedback, but it should not be confused with the therapeutic objective.

A joint does not necessarily need to audibly cavitate for a clinically meaningful mechanical or neurological effect to occur.

Likewise, more cavitations do not necessarily mean a better adjustment.

The purpose is not to create noise.

The purpose is to create an appropriate mechanical stimulus capable of improving movement or function.

Sound is an event.

Function is the goal.

10. Why Chiropractic Sometimes Works Quickly

One of the characteristics that has fascinated chiropractors and patients alike is that some responses can occur rapidly.

A patient may enter with painful restricted rotation and immediately demonstrate greater movement following manipulation.

Such rapid changes cannot reasonably be explained by tissue healing.

Ligaments did not regenerate in thirty seconds.

A degenerative disc did not become young again.

Arthritis did not disappear.

Instead, rapid changes strongly suggest contributions from mechanisms capable of changing quickly:

joint stiffness,

muscle guarding,

pain modulation,

sensory input,

motor output,

perception of threat,

and willingness to move.

This distinction is clinically important.

Feeling better is not necessarily the same as being healed.

The adjustment may make improved movement possible.

Rehabilitation and progressive activity then help make improved movement durable.

11. Why Chiropractic Does Not Work for Everything

A scientifically mature chiropractic profession must be equally willing to explain when chiropractic is unlikely to be sufficient.

Spinal manipulation cannot reverse every structural disease.

It cannot cure cancer.

It cannot regenerate every severely degenerated joint.

It cannot eliminate every disc herniation.

It cannot correct every neurological disorder.

It cannot replace appropriate surgery when surgery is genuinely necessary.

And it should not be presented as a universal treatment for systemic disease without compelling evidence.

The strength of chiropractic does not come from claiming that it treats everything.

Its strength comes from becoming exceptionally good at the conditions for which mechanical, neurological and functional approaches make biological and clinical sense.

This requires examination.

Diagnosis.

Clinical reasoning.

Imaging when appropriate.

Recognition of red flags.

Referral when necessary.

And continual reassessment.

Knowing when not to adjust is part of knowing how to adjust.

12. Chiropractic Within Modern Evidence-Based Care

Modern clinical guidelines increasingly recommend beginning many patients with musculoskeletal pain using conservative, nonpharmacological strategies.

The American College of Physicians recommends nonpharmacological approaches for low-back pain and includes spinal manipulation among available treatment options.

The World Health Organization’s chronic primary low-back-pain guideline includes education, exercise, certain physical therapies including spinal manipulation and massage, selected psychological interventions and appropriate medications within a coordinated model of care.

This broader model closely resembles the direction modern chiropractic should continue moving.

Not adjustment versus exercise.

Not chiropractic versus rehabilitation.

Not manual therapy versus medicine.

The more productive question is:

What combination of appropriate interventions gives this individual patient the best opportunity to regain function?

13. From Dependence to Independence

There is another historical criticism of chiropractic worth addressing directly:

Does chiropractic create lifelong dependence on treatment?

It should not.

Some individuals with recurrent musculoskeletal disorders may benefit from periodic care. A randomized trial of selected patients with recurrent or persistent low-back pain who initially responded favorably to chiropractic treatment found that maintenance care reduced the total number of bothersome pain days over one year compared with symptom-guided treatment, although the maintenance group received somewhat more treatment.

Subsequent analysis suggested that the benefit was particularly evident in certain patient subgroups rather than universally across every patient.

That is exactly why maintenance care should be individualized rather than prescribed automatically forever.

Some patients may benefit from periodic supportive care.

Others should graduate.

The objective should remain:

maximum function with minimum necessary dependence on treatment.

At InterState Medical Group, we describe that simply as:

Independence Over Dependence.

14. A Modern Model of Chiropractic

The historical chiropractic model was often described primarily in terms of alignment.

The modern model can be broader.

Consider this sequence:

Dysfunction or Injury

↓

Altered Joint Motion and Mechanical Loading

↓

Altered Sensory Input

↓

Pain, Protective Muscle Activity and Changed Motor Control

↓

Reduced Movement

↓

Further Deconditioning and Functional Loss

Then the intervention:

Appropriate Mechanical Input

↓

Change in Joint Motion / Stiffness

↓

Change in Sensory Input

↓

Modulation of Pain and Muscle Activity

↓

Improved Opportunity for Movement

↓

Rehabilitation and Progressive Loading

↓

Improved Function

↓

Greater Independence

This should not be regarded as a proven universal pathway for every chiropractic patient.

It is a synthesis.

But it integrates much of what is currently known about manipulation, biomechanics, neurophysiology, pain science and rehabilitation without requiring unsupported claims.

15. What the Chiropractic Pioneers May Have Been Observing

The pioneers of chiropractic did not have functional MRI.

They did not have modern EMG.

They could not measure spinal stiffness with contemporary instrumentation.

They could not record somatosensory evoked potentials or directly study modern concepts of central pain processing.

They had their hands.

Their eyes.

Their patients.

And clinical observation.

They recognized that certain patients hurt.

They recognized that areas of the spine moved differently.

They applied a mechanical intervention.

And they repeatedly observed changes.

Their explanations were inevitably limited by the science of their era.

Modern chiropractic should therefore honor its pioneers without becoming imprisoned by nineteenth- or twentieth-century explanations.

The greatest respect we can give early clinical observations is to continue testing them.

Keep what survives.

Modify what needs revision.

Discard what cannot withstand evidence.

Discover what they could never have measured.

That is how a profession matures.

16. Motion Wins

This brings us to the central philosophy of InterState Medical Group.

Human beings were designed to move.

Movement loads bone.

Movement nourishes joints.

Movement maintains muscle.

Movement challenges balance.

Movement produces sensory information.

Movement develops coordination.

Movement maintains independence.

Pain frequently takes movement away.

Injury takes movement away.

Fear takes movement away.

Deconditioning takes movement away.

Our objective is to give movement back.

Sometimes that begins with an adjustment.

Sometimes with decompression.

Sometimes with soft-tissue treatment.

Sometimes with rehabilitation.

Sometimes with strength.

Sometimes with education.

Frequently, it requires several of them.

The adjustment is therefore not the destination.

Movement is the destination.

And restored movement is valuable because movement restores something even more important:

Function.

Function allows the person to work.

To lift a child.

To turn their head while driving.

To walk through a grocery store.

To climb stairs.

To golf.

To garden.

To exercise.

To travel.

To serve.

To live independently.

This is why we believe:

Movement restores function.

Function creates freedom.

We choose freedom.

17. The InterState Medical Group Position

InterState Medical Group believes chiropractic is most powerful when practiced as a modern clinical discipline grounded simultaneously in experience, evidence and humility.

We do not need to choose between the wisdom of chiropractic’s past and the discoveries of modern science.

We can learn from both.

We recognize the clinical importance of spinal motion.

We recognize the relationship between the musculoskeletal and nervous systems.

We recognize that pain is complex.

We recognize that adjustment alone is not always enough.

We recognize the value of rehabilitation, strength, education and progressive movement.

We recognize that some patients require medical intervention.

We recognize that some patients require surgery.

We recognize that every patient deserves an individualized plan rather than a predetermined lifetime treatment schedule.

And above all, we recognize that the purpose of care is not simply to make an X-ray look better or produce an audible adjustment.

The purpose is to improve the human being standing in front of us.

Reduce pain.

Restore motion.

Rebuild function.

Restore confidence.

Encourage independence.

That is modern chiropractic.

That is the philosophy of InterState Medical Group.

Conclusion

More than a century after the founding of chiropractic, science is providing increasingly sophisticated ways to investigate something chiropractors have observed throughout the profession’s history:

Mechanical intervention to the spine can influence pain and function.

We now know that the explanation is considerably more complicated than simply moving a misplaced bone.

The adjustment interacts with a living system.

A mechanical event can influence joint behavior.

Joint behavior influences sensory input.

Sensory information interacts with spinal and brain processing.

The nervous system influences pain, muscle activity and movement.

Movement influences function.

And function influences independence.

There remains much to discover.

Not every proposed chiropractic mechanism has been proven. Some historical concepts will continue to evolve as evidence improves.

That should not threaten chiropractic.

It should strengthen it.

Because the enduring observation is not dependent upon any single theory:

When appropriate patients move better, they frequently function better.

And when function returns, people regain portions of their lives.

That is why at InterState Medical Group:

Movement is Our Medicine.

Motion Wins.

We Keep You Moving.