Difference between the Neurophysiological Postural Model and the Biomechanical Postural Model

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The difference between the Neurophysiological postural model and the Biomechanical postural model lies in their primary focus when explaining how the body maintains posture.

The Biomechanical Postural Model views posture as a result of the body's physical structure and the mechanical forces, particularly gravity, acting on it. This model often considers the body as a system of levers and segments, where the alignment of these segments determines stability and efficiency

I ascribed and published on this model, up until approximately 2012.

In contrast, the Neurophysiological Postural Model highlights the active, dynamic control mechanisms orchestrated by the brain, specifically, the cerebellum. It focuses on how sensory information is gradient codified (Foot's Sensory Feedback) and transmitted to the cerebellum where it is decoded into motor commands that maintain balance in various terrain deformations.

As a result of my current postural research, this is the postural model that I now propose.

Rothbart B.A., 2025. PreClinical Clubfoot Deformity: Neurophysiological Postural Model. Positive Health Online. Issue 305, September

 

The use of orthotics or insoles to reverse postural distortions depends on the clinical paradigm followed, e.g., Biomechanical or Neurophysiological.

If one follows the Biomechanical Postural Model, the rationale for using orthotics is to support the collapsing foot, which in turn reverses the postural distortions above the feet, e.g., in the knees, pelvis, spine, shoulders, neck, head and jaw. The analogy would be stabilizing the foundation of a building to eliminate continual cracks in the ceiling.

If one follows the Neurophsiological Postural Model, the rationale for using insoles is to reprogram the CNS in order to reverse postural distortions.
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Hence, in the former, one uses orthotics to support the feet. In the latter, one uses insoles to reprogram the CNS.

 

The Foot Neurophysiological Postural Model explains how the brain uses sensory input from the feet to maintain balance and posture. This model proposes that:

• Specialized receptors in the feet send a continuous stream of sensory data (Foot's Sensory Feedback) to the brainstem and cerebellum.
• If the sensory pattern from the foot on a given surface matches the brainstem's stored "engram," balance is maintained automatically by the brainstem
• If there's a mismatch (e.g., walking on a slope), the cerebellum intervenes to make necessary postural adjustments.

The Biomechanical Postural Model is a theory that attributes posture solely to the effects of gravity, with no central nervous system processing. This "bottom-up" model suggests that:

• The body's posture is a passive reaction to gravity, much like a building's structure is affected by its foundation.

 

In summation:

The Foot Neurophysiological Postural Model explains how the brain utilizes sensory input from the feet to maintain balance and posture.

Rothbart's model proposes that:

1. Specialized receptors in the feet:

Meissner Corpuscules (activated when walking)
Merkel disks (activated when standing)​

send a continuous stream of sensory data (Foot's Sensory Feedback) to the brainstem.

2. If the sensory pattern from the foot matches the brainstem's stored "engram," balance is maintained automatically by the brainstem, e.g., no cerebellum intervention

3. If there's a mismatch (e.g., resulting from Rothbarts, the PreClinical Clubfoot deformity or walking on uneven ground surfaces), the cerebellum intervenes to make the necessary postural adjustments.

 

Firing properties of muscle spindle afferents in the intrinsic foot muscles and tactile afferents from the sole of the foot during upright stance

Thomas P. Knellwolf, Alex Burton, Elie Hamman, Vaughan G. Macefield
First published: 10 April 2025
https://doi.org/10.1113/EP092348


"Moreover, selective anaesthesia of cutaneous afferents of the sole of the foot increases postural sway by only ∼11% (Meyer et al., 2004), whereas increases of ∼40%–60% occur in diabetic neuropathy, in which both muscle and cutaneous afferents are affected (Boucher et al., 1995; Simoneau et al., 1994). Accordingly, it is likely that muscle afferents from the foot contribute more to the control of postural sway than do cutaneous afferents, but in the absence of direct data this is speculation."

 

If my memory serves me correctly, you had previously quoted this study, which we discussed.