When the Model Is Challenged, Does the Method Still Hold?

THE BOTTOM LINE

Polyvagal Theory — developed by Stephen Porges — has been widely used to explain how the nervous system shifts between states of safety and protection.

More recently, it has come under scientific challenge, particularly from researchers like Paul Grossman, who question some of its underlying biological claims.

So where does that leave approaches — like the Lyno Method® — that have used this framework to guide treatment?

Here’s the important distinction:

The model may be debated.
The clinical observations are not.

We consistently see that:
• when the body feels safe, movement improves.
• when the body feels threatened, the body protects.

HOW TO

Let’s step away from theory for a moment and look at what’s happening in practice.

In Lyno-informed work, we use three tools, usually simultaneously:

• Breathwork to help the body settle.
• Touch to provide sensory input.
• Movement through the joint’s range.

Why this combination matters

Breath is one of the most direct ways we can influence the state of the nervous system.

When the body is more settled:
• touch is more easily tolerated (and often reassuring).
• movement is more likely to expand.
• resistance begins to reduce.

When the body is more defensive, the opposite tends to happen — the same input can be interpreted as threat, and movement remains limited.

In simple terms:

State changes how the body responds to input.

What the intervention is doing

By combining breath, touch, and movement, the same range is explored in a more settled state, allowing the nervous system to begin recognising that the new range is safe.

Where Polyvagal Theory fits

Polyvagal Theory offers a language for describing this — for example,

“shifts toward a more regulated or ‘safe’ state.”

But the practical takeaway is simpler:

When the body perceives safety, protective responses reduce and movement becomes available.

THE SCIENCE

Traditionally, the Autonomic Nervous Systems (ANS) has been described as having two branches:

1. The sympathetic nervous system — which mobilises us (the fight-or-flight response).
2. The parasympathetic nervous system — which supports rest, recovery, and digestion.

The Polyvagal Theory (Porges, 2007) expands on this, suggesting that the ANS is constantly scanning our environment — a process referred to as neuroception — in order to determine how we respond:

These responses are typically described as:

• A calm, socially engaged state.
• A mobilised (fight-or-flight) state.
• An immobilised state (often described as a “freeze” response).

The “poly” in Polyvagal refers to the idea that the vagus nerve — the main communication pathway between brain and body — has multiple functional pathways:

• the ventral vagal pathway is associated with calm regulation, connection, and social engagement
• the sympathetic nervous system, which supports mobilisation (fight-or-flight)
• the dorsal vagal pathway, associated with immobilisation and low-mobilisation protective states

One of the key tenets of Polyvagal Theory is that our behaviour is strongly influenced by our underlying physiological state, often outside of conscious awareness. Put more simply, our responses are often shaped by what we feel, before that which we consciously think.  

It is proposed that patterns in heart rate linked to breathing — referred to as respiratory sinus arrhythmia (RSA) — can give an indication of how the vagus nerve is influencing the heart. Higher RSA is often interpreted as reflecting a greater capacity for regulation and calm engagement.

Finally, Polyvagal Theory proposes that these response patterns developed over time in an evolutionary sequence, with immobilisation (freeze) being the most primitive response, followed by mobilisation (fight-or-flight), and the more recent capacity for social engagement and regulation.

Paul Grossman (2023) examined the physiological claims underlying Polyvagal Theory and raised challenges to several of its key premises. 

He argues that the available evidence suggests heart rate regulation in mammals is primarily mediated by the ventral vagal pathway, rather than by separate ventral and dorsal vagal systems acting independently.

In line with this, he argues there is limited evidence to support the claim that the dorsal vagal pathway is responsible for the kind of marked heart rate slowing proposed by Polyvagal Theory, and more broadly questions whether these responses can be cleanly attributed to distinct vagal pathways in the way the theory suggests.

Grossman further questions the use of RSA as a measure of vagal tone, noting that RSA is influenced by multiple physiological factors and may not provide a clean or specific measure of “vagal tone”.

He also challenges the evolutionary framing of Polyvagal Theory, particularly the idea that these systems emerged in a fixed hierarchical sequence.

Lyno works primarily with the body’s fascia system — the connective tissue network in which muscles, joints, nerves, and organs are embedded.

When fascia moves well, the structures embedded within it can function more effectively. When it becomes restricted or less mobile, movement, comfort, and overall function may be affected.

Fascia may be restricted due to:

• Physical factors – injury, surgery, overload, repetitive strain, or periods of immobility.

• Emotional and physiological stressors – stress, overwhelm, or prolonged periods of heightened demand on the system.

These factors rarely exist in isolation: a physical injury is also a stressor, and prolonged emotional load can have physical effects.

From this perspective, fascial restriction can be understood not just as a structural response, but as part of the body’s broader protective response.

A prolonged or unresolved stressor may shift the system toward a protective, low-mobilisation state. Within a Polyvagal framework, this is often described as a “dorsal vagal” response.

The primary aim of the Lyno intervention is to restore movement in areas where fascia is restricted. As movement improves, the system often becomes more settled and adaptable. Within a Polyvagal framework, this may be understood as a shift toward a more regulated, ventral vagal state.

In practice, this is supported through gentle hands-on work, guided movement, and breathwork — all of which help promote a sense of safety within the system while improving movement.

Short answer — no, not in terms of abandoning the framework, but yes in how precisely we interpret and explain it.

 The critiques are questioning:

• How functionally distinct the different vagal pathways are in regulating behaviour and physiology.
• The extent to which different vagal pathways exert distinct and separable influences on heart rate.
• How reliably RSA reflects vagal activity, particularly as a marker of specific pathways.
• The evolutionary hierarchy, particularly the idea that these response systems developed in a fixed, stepwise sequence.

They are not disputing that:

• The nervous system influences how your body (or even parts of it) move.
• Our responses to perceived threat are often shaped by sensation before conscious thought.
• Our response state influences our physical reactions and/or behaviour.
• Breathing is well-established to influence autonomic regulation and perceived state.

This is where the distinction becomes important in practice.

Lyno works with how the body moves by identifying and addressing areas of fascial restriction.

The gentle, hands-on approach stimulates sensory receptors in the skin and fascia, sending information back to the nervous system. Since much of the communication along the vagus nerve travels from the body to the brain, this sensory input helps shape how the body responds.

In simple terms:

What the body feels influences how it reacts.

The aim isn’t to force change, but to provide the body with safer, more useful input so it can adjust its response.

Through gentle touch, together with intentional breathwork, Lyno works with the relationship between sensation, nervous system response, and movement — creating the conditions for the body to become more settled and less defensive.

Because the body doesn’t respond well to being argued with — but it does respond to being understood.

Lyno does not depend on Polyvagal Theory being anatomically correct.
It uses it as a functional, organising framework for understanding observable patterns in how the body responds.

Emerging perspectives are beginning to bridge the gap between Stephen Porges’ framework and Paul Grossman’ critiques — particularly in practical, body-based approaches such as fascia work and somatic therapies.

Across both research and clinical practice, there is growing recognition that Polyvagal Theory offers a useful language and framework, while Grossman’s work highlights important limitations in the underlying physiological claims.

In practice, this allows a shift in focus — away from needing precise explanations of specific mechanisms, and toward what is observable: how the system regulates, adapts, and responds.

It is this focus on observable change that speaks to the credibility of Benita Bester, founder of the Lyno Method. Her willingness to continually question the “why” behind the results allows the method — and the framework that supports it — to evolve as new ways of understanding those results emerge.

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