The science of tremoring

This section explores the physiological mechanisms behind tremoring. Understanding the science is not necessary for effective practice, but it can help demystify the experience.

The tremor mechanism operates through ancient pathways in the brainstem and spinal cord. It doesn’t require conscious understanding or verbal processing. Several body systems work together to produce and regulate tremors:

System	Role in TRE™
Brainstem	Coordinates survival responses and autonomic state
Central pattern generators	Generate rhythmic tremor patterns
Muscular system	Stores and releases tension
Fascial system	Holds and transmits tension patterns
Autonomic nervous system	Shifts from stress to restoration states

This page covers each of these systems and how they contribute to the tremoring process.

The brainstem’s role

The brainstem sits at the base of the skull where the brain meets the spinal cord. This ancient part of the brain handles survival functions and operates largely outside conscious awareness.

Its responsibilities include:

• Autonomic regulation — heart rate, blood pressure, respiration, and digestion
• Muscle tone — baseline level of tension in muscles throughout the body
• Defensive reflexes — flinching, freezing, and bracing
• Survival response coordination — fight, flight, and freeze responses

Trauma and chronic stress create patterns held in the brainstem. When survival responses become stuck, the brainstem holds patterns of defensive tension.

Because the brainstem operates below conscious awareness, its patterns cannot be changed through thinking or talking alone. You cannot reason your way out of a brainstem-level freeze response.

This is why body-based approaches like TRE™ can access patterns that psychotherapy may not reach. The tremor mechanism operates at this deeper level of the brain.

Central pattern generators

Central pattern generators (CPGs) are networks of neurons in the spinal cord and brainstem. They generate coordinated, rhythmic movements autonomously, and are central to how neurogenic tremoring works. Once activated, they produce their characteristic pattern without needing moment-to-moment control from the brain.

Examples of CPG-driven movements include:

CPG function	Location	Movement pattern
Chewing	Brainstem	Jaw movement
Locomotion	Spinal cord	Walking, running
Respiration	Brainstem	Breathing rhythm
Swallowing	Brainstem	Coordinated throat muscles

These rhythmic movements don’t require conscious thought: you don’t have to think about each step when walking or each breath when breathing. The CPG handles the pattern; higher brain centres simply initiate, modulate, or stop the activity.

CPGs and tremors

The tremor mechanism appears to involve CPG-like circuits. When conditions are right (muscle fatigue, relaxation, safety), these circuits activate and produce rhythmic oscillations.

Evidence for CPG involvement:

• Tremors are rhythmic and patterned, characteristic of CPG output
• They continue without conscious effort once initiated
• They can be modulated (slowed or intensified) but not directly controlled
• They originate from subcortical neural structures
• Similar tremor patterns appear across all mammals

The brain can facilitate, inhibit, or voluntarily suppress tremors, but it doesn’t create the rhythmic pattern itself. This is why you cannot make yourself tremor through willpower, but you can allow tremors to arise when the conditions are right.

Why the exercises work

The TRE™ exercises are designed to activate the tremor mechanism by targeting the muscles where chronic stress and trauma are held.

The interior muscle pattern

Chronic stress creates a characteristic pattern of tension in the flexor muscles that curl us into a protective foetal position. The interior muscle pattern includes the jaw, neck, anterior spine, hip flexors (psoas and iliacus), and inner thighs.

The TRE™ exercises systematically fatigue these muscles:

Exercise	Target
Exercises 1–3 (ankles, calves, thighs)	Lower legs (preparing the body)
Exercise 4 (inner thigh stretch)	Adductors
Exercise 5 (hip flexor stretch)	Psoas and iliacus
Exercise 6 (wall sit)	Quadriceps
Exercise 7 (tremoring)	Release of all fatigued muscles

The muscle fatigue pathway

The exercises create specific conditions that invite tremors to arise:

1. Muscle fatigue — The exercises progressively tire the leg muscles, particularly the quadriceps, adductors, psoas, and gluteals. When muscles are fatigued, the threshold for activating the tremor mechanism lowers. The protective bracing patterns that normally suppress tremoring are temporarily weakened.
2. Positioning — The tremoring position places the fatigued muscles in a slightly stretched position. This combination of fatigue and stretch creates ideal conditions for tremors to emerge. The position also supports the body fully, opens the front of the body (signalling safety), and allows gravity to assist.
3. Cortical inhibition relaxes — The cortex (thinking brain) actively suppresses many reflexive processes. We hold back yawns, suppress tears, and keep our bodies still when needed. This is called cortical inhibition. In the tremoring position, with fatigued muscles and a supported body, this inhibition naturally relaxes.
4. CPG activation — Once cortical inhibition relaxes sufficiently, the tremor CPG activates. Initial tremors typically appear in the legs (where fatigue is greatest) and may gradually spread through the body.

Why tremors travel

Tremors typically begin in the legs and pelvis but often spread to the belly, chest, shoulders, neck, and jaw. This is not random. It follows the deep front line, a continuous myofascial meridian described by fascia researcher Tom Myers.

Because the fascial system is continuous, releasing tension in one area affects distant areas. When the psoas releases, the jaw may relax. The body releases along lines of connected tissue.

The autonomic shift

One of the most consistent effects of TRE™ is a shift in autonomic nervous system state.

Before tremoring

Many people arrive in a state of chronic sympathetic activation:

• Elevated muscle tension
• Shallow, rapid breathing
• Increased heart rate and blood pressure
• Digestive suppression
• Hypervigilance

During tremoring

As tremors progress, the nervous system begins to discharge accumulated activation. Signs include:

• Warming of extremities (blood flow returning to periphery)
• Deepening and slowing of breath
• Spontaneous sighs or yawns
• Stomach gurgles (digestion reactivating)
• Softening of facial muscles

After tremoring

Following tremoring, practitioners commonly notice:

• Deep relaxation
• Slower heart rate
• Improved digestion
• Sense of calm or wellbeing
• Increased body awareness
• Better sleep (when practising in evening)

This represents a shift toward parasympathetic dominance: the ‘rest and digest’ state that allows recovery and restoration.

Integration and rest

Tremoring initiates changes that continue after the session ends. This is why rest afterward is important; it’s when much of the physiological benefit consolidates.

• Neural reorganisation — The nervous system needs time to consolidate the shift from sympathetic to parasympathetic dominance
• Muscular recalibration — Released muscles need time to establish new resting lengths and tone
• Fascial rehydration — Fascia that has been mobilised needs time to settle into new patterns
• Metabolic processing — The biochemical byproducts of muscle contraction and release need to be cleared