Static Magnetic Fields, PEMF, Photobiomodulation, TENS and Acupuncture: Why the Physics Matters Clinically

Static magnets, pulsed electromagnetic field therapy (PEMF), red and near-infrared photobiomodulation (PBM), transcutaneous electrical nerve stimulation (TENS) and acupuncture may all appear in pain management, rehabilitation or integrative clinical practice.

That does not make them variations of the same treatment.

They apply fundamentally different physical inputs to the body. Those inputs interact with tissue through different—and differently established—physiological pathways. They also require different ways of thinking about dose, treatment duration, placement, risk, practicality and cost.

For health professionals, these distinctions matter.

The useful question is not simply:

Which modality is more effective?

Effectiveness only has meaning in relation to a particular clinical objective, patient population, treatment protocol and outcome.

In some situations, two modalities may reasonably be alternatives. In others, they may address different aspects of the clinical problem—or one modality may be suited to a therapeutic objective that another is not designed to address.

The more useful questions are:

What physical input is being applied, what does that input appear to do physiologically, what clinical outcomes does the evidence support, and where might that modality fit within patient care?

That framework provides a more rational basis for comparing therapies—and for understanding when different modalities might be alternatives, complementary, or simply intended to do different jobs.

The Physics Comes First: What Is Actually Being Applied to the Body?

Before considering mechanisms or clinical outcomes, it helps to identify what is physically being applied.

A static magnet produces a persistent magnetic field.

PEMF produces a magnetic field that changes with time and can therefore induce electrical effects.

Photobiomodulation delivers red or near-infrared electromagnetic radiation in the form of photons.

TENS passes pulsed electrical current through tissue using electrodes.

Manual acupuncture introduces and manipulates needles within tissue, producing mechanical and sensory stimulation. Electroacupuncture adds electrical stimulation through inserted needles.

These distinctions may sound elementary, but they prevent one of the most common mistakes when comparing physical modalities: treating measurements that describe entirely different physical quantities as though they were interchangeable.

Static Magnetic Fields: Persistent Fields and Spatial Gradients

Q Magnets are permanent magnets.

Their applied magnetic field does not intentionally pulse or oscillate with time as it does with PEMF. For a stationary permanent magnet, the applied field is essentially static:

frequency of field variation = 0 Hz

Magnetic flux density is expressed in tesla (T) or gauss (G):

1 T = 10,000 G

But field strength alone does not completely describe the magnetic exposure.

Magnetic flux density also varies with position.

The spatial rate of change can be expressed as a magnetic field gradient:

∇B = dB/dx

where B is magnetic flux density and x is position.

This becomes particularly relevant with multipolar magnetic configurations.

Alternating neighbouring poles can produce substantial spatial variation over relatively short distances. Two magnetic devices reporting similar maximum surface gauss values may therefore expose nearby tissue to quite different field distributions.

This is one reason why describing a therapeutic magnet only by its maximum surface gauss value is incomplete.

PEMF: A Magnetic Field Changing With Time

PEMF is sometimes grouped with static magnets because both involve magnetic fields.

Physically, however, the distinction is fundamental.

PEMF intentionally produces a magnetic field that varies with time.

Faraday’s law describes electromagnetic induction:

ℰ = −dΦB/dt

where:

• ℰ = induced electromotive force
• ΦB = magnetic flux
• dΦB/dt = rate of change of magnetic flux with time

A changing magnetic flux can therefore produce an induced electric field.

For a stationary static magnet:

dΦB/dt ≈ 0

unless the magnet or tissue moves relative to the field.

PEMF is therefore not adequately characterised by peak magnetic flux density alone. Pulse frequency, waveform, pulse duration, rise and fall characteristics, coil geometry and exposure duration also matter.

Static magnetic fields and PEMF should not be treated as interchangeable merely because both involve magnetism.

Photobiomodulation: Electromagnetic Radiation and Photons

Red and near-infrared light are also electromagnetic phenomena, but they are physically very different from static magnetic fields.

Light propagates as electromagnetic radiation.

Photon energy is described by:

E = hf

and, because:

c = fλ

photon energy can also be written as:

E = hc/λ

where:

• E = photon energy
• h = Planck’s constant
• f = optical frequency
• c = speed of light
• λ = wavelength

This is why wavelength matters in photobiomodulation.

A photon at one wavelength carries a different amount of energy from a photon at another wavelength.

Importantly, the optical frequency described by these equations should not be confused with the pulse rate of a light-therapy device.

A red or near-infrared device may pulse its output at a few hertz or hundreds of hertz, while the electromagnetic radiation itself oscillates at frequencies of hundreds of trillions of hertz.

Those are different physical quantities.

TENS: Electrical Current Through Tissue

TENS introduces another physical input again.

Electrical current is applied through electrodes placed on the skin.

The basic electrical relationship is described by Ohm’s law:

V = IR

where:

• V = voltage
• I = current
• R = electrical resistance or, more generally in biological tissue, impedance

Relevant treatment variables include current intensity, pulse frequency, pulse width, waveform, electrode position, tissue impedance and treatment duration.

Unlike PEMF, the electrical effect is not being produced indirectly through magnetic induction.

The electrical stimulation is applied through electrodes.

Acupuncture: Mechanical and Sensory Input

Manual acupuncture does not fit neatly into an electromagnetic comparison—and it should not be forced into one.

A fine needle is inserted into tissue and may subsequently be manipulated.

The initial physical interaction is therefore mechanical and sensory rather than photonic, electrical or magnetic.

Calling acupuncture simply a “mechanical energy therapy,” however, would be too reductive because the clinically relevant response extends beyond the local mechanical interaction.

Electroacupuncture is different again. Once electrical stimulation is applied through acupuncture needles, another physical input has been introduced.

Why Gauss Cannot Be Compared With Joules, Watts or Milliamps

Once the physical inputs are separated, another common comparison problem becomes apparent.

Different units measure different physical quantities.

• Gauss and tesla describe magnetic flux density.
• Joules describe energy.
• Watts describe power:

P = E/t

Joules of energy transferred per second

• Volts describe electric potential difference.
• Amperes describe electrical current.
• Nanometres describe wavelength.
• Hertz describe frequency.

Consequently, questions such as:

“How many gauss is equivalent to 10 joules of red light?”

have no direct physical answer.

It is comparable to asking how many kilograms equal a kilometre.

The units describe different things.

This also explains why words such as stronger or more powerful can be misleading when comparing modalities.

A high-gauss magnet is not “more powerful” than a PBM device delivering a particular optical dose in any simple universal sense.

They are producing different physical exposures.

Physics Comparison

The next question for a clinician is more important:

So what does each of these physical inputs do physiologically?

From Physics to Physiology

Physics tells us what is being applied.

Physiology asks what happens when that physical exposure interacts with a biological system.

This distinction is important because the strength of mechanistic evidence is not equal across these modalities.

Static Magnetic Fields: Proposed Effects on Neuronal and Nociceptive Function

The physics of static magnetic fields is well established.

The precise biological mechanism by which therapeutic-strength static magnetic fields might influence pain is not.

Experimental findings nevertheless provide several important lines of investigation.

McLean and colleagues exposed cultured mouse dorsal-root-ganglion neurons to particular static magnetic-field configurations and reported substantial inhibition of action-potential firing under some exposure conditions. Importantly, higher magnetic flux density did not simply produce a larger effect; some stronger configurations produced no significant inhibition. The authors concluded that field strength alone could not account for the observed action-potential blockade. PMID: 7748200

That observation is particularly relevant when comparing multipolar magnetic configurations with simpler magnets.

A 2021 review by Fan and colleagues examined the analgesic literature on static magnetic fields and identified several potential mechanistic pathways under investigation, including TRPV1/capsaicin-sensitive pathways, opioid receptors, P2X3 receptors, C-fibres, membrane proteins and ion channels. PMID: 33508148

The authors were also explicit that mechanistic evidence remained limited and that direct molecular-level evidence was still lacking.

A scientifically cautious summary is therefore:

Static magnetic fields have demonstrated effects on neuronal and nociceptive behaviour under some experimental conditions, but the mechanism by which particular therapeutic field configurations might influence pain remains unresolved.

Photobiomodulation: Photon Absorption and Cellular Signalling

PBM begins with photon absorption.

Red and near-infrared photons reaching tissue may be absorbed by biological photoacceptors, initiating cellular responses.

Mitochondrial cytochrome-c oxidase has been extensively investigated as one photoacceptor, with downstream effects proposed to involve mitochondrial electron transport, ATP production, reactive oxygen species signalling, nitric oxide and other cellular signalling pathways.

The biology is more complex than a single mitochondrial pathway, but the important physical-to-physiological sequence is:

photons → absorption by biological molecules → photochemical and cellular signalling

PBM is therefore a dose-dependent photobiological intervention.

TENS: Electrical Stimulation and Pain Modulation

TENS applies electrical pulses capable of activating peripheral neural structures.

Its analgesic mechanisms involve more than one pathway, with evidence supporting peripheral afferent stimulation, spinal inhibitory mechanisms and descending pain-modulatory systems.

The sequence can therefore be simplified as:

electrical stimulation → peripheral neural activation → modulation of nociceptive processing

Stimulation intensity and other treatment parameters can materially affect that response.

Acupuncture: From Needling to Neural Processing

Acupuncture also involves multiple interacting physiological processes.

The Acupuncture Now Foundation’s review of acupuncture in pain management, authored by Matthew Bauer and John McDonald, discusses ascending sensory pathways involving Aδ, Aβ and C fibres, descending pain-modulatory pathways, endogenous opioid and non-opioid mediators, neurotransmitters and neuroplastic changes.

For the purposes of this comparison, a useful simplified sequence is:

needle insertion/manipulation → local mechanical and sensory stimulation → peripheral neural signalling → spinal and central processing

That is not intended as a complete explanation of acupuncture.

It demonstrates why acupuncture cannot be adequately described merely as mechanical energy.

PEMF: Time-Varying Fields and Induced Electrical Effects

PEMF introduces a time-varying magnetic exposure.

Because changing magnetic flux can induce electric fields, its biological interaction cannot simply be inferred from the behaviour of a static magnet.

The physiological response will depend upon factors including field amplitude, waveform, frequency, pulse characteristics, coil geometry and tissue exposure.

This is another reason why evidence concerning PEMF cannot automatically be used as evidence for static magnetic-field therapy, or vice versa.

Mechanism Is Not the Same as Clinical Evidence

A plausible mechanism does not prove that an intervention produces a clinically meaningful outcome.

Conversely, clinical benefit can be demonstrated even when the complete biological mechanism remains uncertain.

These are different levels of evidence:

Physics → physiological interaction → clinical outcome

Each needs to be considered separately.

Static Magnetic Fields: What Does the Clinical Evidence Show?

Fan and colleagues reviewed 28 sham-controlled human and animal studies investigating static magnetic fields and pain. PMID: 33508148

They reported positive analgesic findings in 64% of the human studies and all six mouse studies included in their review.

Their meta-analysis of seven human trials produced a pooled effect of:

SMD = −0.39

95% CI = −0.78 to −0.00

with substantial heterogeneity:

I² = 78%

That heterogeneity matters.

The authors identified magnetic-field intensity, treatment duration, pain type and field characteristics among factors potentially contributing to different results. They also emphasised the importance of properly defining magnetic exposure, including field strength, spatial distribution, magnet configuration, treatment duration and distance between the magnet and target tissue.

The appropriate conclusion is therefore not that every static magnet should be expected to produce the same analgesic response.

It is almost the opposite.

“Static magnetic-field therapy” is not a single uniform exposure.

A weak magnetic insole, a homogeneous static field and a multipolar magnet producing steep local spatial gradients should not automatically be regarded as equivalent biological exposures simply because all use permanent magnets.

This becomes important when interpreting both positive and negative clinical trials.

Photobiomodulation: Broad Evidence, Variable Certainty

PBM has been investigated across a wide range of clinical conditions.

A 2025 umbrella review by Son and colleagues examined 15 meta-analyses encompassing 204 randomised controlled trials, more than 9,000 participants and 35 health endpoints across 15 disease conditions. PMID: 40770824

Statistically significant effects were identified for multiple outcomes, but certainty ranged from very low to moderate, and none of the outcomes was supported by high-certainty evidence. Moderate-certainty evidence was found for selected outcomes including pain reduction in burning mouth syndrome and disability improvement in knee osteoarthritis.

That is important clinically.

PBM has a substantial evidence base, but “red light works” is still too broad a conclusion.

Indication, wavelength, dose and treatment protocol matter.

TENS: Evidence for Analgesia During or Immediately After Treatment

The 2022 meta-TENS study provides one of the largest evidence syntheses for TENS. PMID: 35144946

It included 381 randomised controlled trials involving 24,532 participants.

Moderate-certainty evidence showed lower pain intensity during or immediately after TENS compared with placebo. Evidence concerning other outcomes and longer-term effects was more limited.

This helps define its clinical role.

TENS is primarily an active electrical neuromodulation intervention used for symptomatic analgesia, particularly during or around the period of stimulation.

That exposure model is very different from wearing a passive static magnetic device for prolonged periods.

Acupuncture: Substantial Evidence for Chronic Pain

Acupuncture has a substantial clinical literature for chronic pain.

The Acupuncture Trialists’ Collaboration individual-patient-data meta-analysis included 20,827 patients across 39 trials involving musculoskeletal pain, osteoarthritis, chronic headache and shoulder pain. PMID: 29198932

Acupuncture produced better pain outcomes than both sham acupuncture and no-acupuncture controls. The difference compared with sham was considerably smaller than the difference compared with no-acupuncture controls, indicating that the overall treatment effect cannot simply be reduced to one component of needling.

Acupuncture also illustrates a broader lesson relevant to this entire article:

clinical evidence can exist even when the complete physiological mechanism remains debated or incompletely characterised.

Dose Means Something Different for Every Modality

Once the physics and physiology are understood, the idea of a universal therapeutic “dose” becomes difficult to defend.

Each modality requires its own dosing vocabulary.

Static Magnetic Fields

Relevant variables can include:

• magnetic flux density
• spatial field gradients
• polarity and field geometry
• magnet dimensions
• distance from the magnet
• target depth
• duration of exposure
• anatomical placement

For Q Magnets, these considerations are organised through:

Field | Dose | Placement

Photobiomodulation

Relevant variables include:

• wavelength
• irradiance
• fluence or energy density
• exposure duration
• beam area
• tissue optical properties
• anatomical location
• treatment frequency

TENS

Relevant variables include:

• current intensity
• pulse frequency
• pulse width
• waveform
• electrode dimensions
• electrode placement
• tissue impedance
• treatment duration

PEMF

Relevant variables include:

• magnetic flux density
• pulse frequency
• waveform
• pulse duration
• rise and fall characteristics
• coil geometry
• distance
• treatment duration

Acupuncture

Relevant variables can include:

• anatomical or acupuncture-point selection
• needle depth
• needle manipulation
• stimulation technique
• treatment duration
• treatment frequency
• number of treatment sessions

The underlying principle is the same:

Biological tissue responds to the exposure it actually receives—not simply to the name of the modality.

Why Field | Dose | Placement Matters for Static Magnetic Fields

This issue is especially important when discussing permanent magnets because they are frequently compared primarily by maximum gauss rating.

That can be misleading.

Field

What magnetic-field geometry is being produced?

Is the field relatively homogeneous or highly spatially varying?

What gradients are produced around neighbouring poles?

Dose

What magnetic flux density and gradient reach the intended tissue?

How does that exposure change with distance?

How long is the tissue exposed?

Placement

Where is the magnet positioned relative to the anatomical target?

What tissue depth separates the device from that target?

Is the intended structure actually within the relevant field distribution?

Fan et al. similarly argued that static magnetic-field studies should report factors such as field strength, magnet configuration, distance from tissue, spatial field distribution and duration of exposure. PMID: 33508148

That does not mean Fan validated the Q Magnets FDP framework.

It means the review independently reinforces the broader scientific principle underlying it:

magnetic exposure must be characterised more completely than by surface gauss alone.

Penetration Is Not the Same as Therapeutic Dose

“Which modality penetrates deepest?” sounds like a useful clinical question.

But penetration means something different for each modality.

Static Magnetic Fields

A permanent magnet’s field extends into surrounding space and through biological tissue, but field strength and spatial gradients decrease with distance.

A field being detectable at a particular depth does not demonstrate that the exposure at that depth is biologically sufficient to produce a clinical effect.

Photobiomodulation

Red and near-infrared photons entering tissue undergo absorption and scattering.

Near-infrared wavelengths generally reach deeper than visible red wavelengths, but the presence of some photons at depth does not demonstrate that an adequate therapeutic optical dose has reached the target.

TENS

Electrical current distribution depends upon electrode geometry, tissue conductivity, impedance and the electrical parameters applied.

The concept of optical “penetration depth” therefore does not transfer directly to TENS.

Acupuncture

A needle can physically reach deeper tissue, but needle depth alone does not define the physiological dose or clinical effect.

PEMF

Magnetic-field distribution and induced electric fields depend upon coil geometry, field characteristics and distance.

The more clinically useful question is therefore not:

How far does it go?

It is:

What exposure reaches the intended target, and is that exposure biologically meaningful?

Which Modality Fits the Clinical Objective?

There is no scientifically meaningful general answer to which modality is “more effective.”

Effectiveness depends on the clinical objective, condition being treated, patient population, treatment parameters and outcome being measured.

In some circumstances, modalities may be reasonable alternatives.

In others, they may address different aspects of the clinical problem or be suited to quite different therapeutic objectives.

The more useful clinical questions are:

• What is the treatment objective?
• What tissue or physiological system is being targeted?
• What evidence supports the modality for this particular clinical problem?
• What dose and application parameters were used in the supporting research?
• Is the aim immediate analgesia, longer-duration exposure, tissue recovery, neuromodulation or another outcome?
• What are the known risks, precautions and contraindications?
• How simple is the intervention to apply correctly and consistently?
• Does treatment require practitioner time, specialised equipment or repeated clinic visits?
• Can treatment continue outside the clinic, or does it require supervised sessions?
• What is the cost to the practitioner and patient?
• Could another modality address a different component of the clinical problem?
• Is there a rational role for combining modalities rather than treating them as alternatives?

These questions move the discussion beyond physics and device comparison toward clinical decision-making.

Clinical Effectiveness Is Only One Part of Clinical Utility

Two modalities could theoretically produce similar improvements in a particular outcome while imposing very different practical demands.

Acupuncture inherently requires practitioner involvement during treatment.

PBM may be delivered in a clinic or, depending upon the device and treatment protocol, in another setting.

TENS can often be self-administered after appropriate instruction.

A wearable static magnetic device can provide prolonged passive exposure once appropriately positioned.

PEMF generally requires powered equipment and defined treatment sessions.

These differences do not establish that one modality is superior.

They affect clinical utility.

For a health professional, clinical utility may involve a combination of:

A therapy that is effective under trial conditions may be less useful in a particular clinical setting if it is difficult, expensive or impractical to deliver appropriately.

Conversely, convenience does not compensate for lack of evidence for the intended clinical objective.

Both considerations matter.

Alternatives, Different Jobs or Complementary Modalities?

Once these therapies are understood as different physical inputs, another possibility becomes apparent.

They do not necessarily have to compete.

A practitioner might use acupuncture for one therapeutic purpose, TENS when short-term electrical analgesia is appropriate, or PBM when a photobiological intervention is relevant to the treatment objective.

A passive static-field device could potentially occupy another part of the treatment pathway because its exposure continues while the device remains appropriately positioned.

This distinction is particularly interesting when considering Q Magnets alongside photobiomodulation.

PBM delivers photons during a defined exposure.

Q Magnets establish a persistent local static magnetic-field environment while they remain positioned on the body.

The two therefore differ in:

• physics
• proposed physiological interaction
• dose
• application
• treatment duration

That makes different or potentially complementary clinical roles conceptually plausible.

It does not establish clinical synergy.

Whether combining two modalities produces better outcomes than either alone is a separate clinical research question.

The same caution applies to combinations involving acupuncture, TENS or PEMF.

Different mechanisms can provide a rationale for investigating combination therapy. They do not prove that the combination is more effective.

From Physics to Practice

The most useful way to compare Q Magnets, PEMF, photobiomodulation, TENS and acupuncture is to follow the same reasoning sequence:

That prevents several common mistakes.

Gauss cannot be converted into joules.

Static magnets are not simply low-powered PEMF.

Red and near-infrared light are not simply another “frequency” of magnetic therapy.

TENS does not act like PBM merely because both devices require electrical power.

Acupuncture should not be reduced to mechanical energy simply because needles mechanically interact with tissue.

And none of these therapies should be considered clinically effective merely because a plausible mechanism can be described.

For Q Magnets, the distinguishing physical exposure is a persistent, spatially varying static magnetic field, rather than a time-varying magnetic field, photon exposure, electrode-delivered electrical current or needle stimulus.

Experimental research has identified possible effects on neuronal and nociceptive behaviour under particular static magnetic-field conditions, while the precise therapeutic mechanism remains unresolved. Clinical research reviewed by Fan and colleagues also suggests that field parameters, exposure duration and pain type may contribute to different outcomes.

That uncertainty is not a reason to abandon physics.

It is a reason to describe the physics more precisely.

For health professionals, the objective should therefore not be to determine which technology sounds most powerful.

It is to understand:

What is being applied to the patient?

What does that exposure appear to do physiologically?

What outcomes does the evidence actually support?

What dose and application were studied?

What are the risks, costs and practical requirements?

And where does the modality reasonably fit within this patient’s care?

That is where physics becomes clinically useful.

Key Research and Further Reading

Scientific Note

The physiological mechanisms and clinical effects described in this article do not have equal levels of certainty.

Established physical principles, experimental biological effects, proposed mechanisms and demonstrated clinical outcomes are different categories of evidence and should not be treated as interchangeable.

Evidence concerning one magnetic-field configuration should also not automatically be generalised to another.

For Q Magnets, application and therapeutic statements should be interpreted according to current approved product information and directions for use.