The Tremor Mechanism
Having explored the history of TRE, let us now examine what actually happens when we tremor. Understanding the tremor mechanism will help you appreciate why TRE works, what to expect during practice, and why the experience can vary so much from session to session.
What Are Neurogenic Tremors?
Neurogenic tremors are involuntary muscular vibrations that originate in the central nervous system. Unlike voluntary movement, which we consciously initiate, neurogenic tremors arise spontaneously when the conditions are right.
The tremor mechanism appears to be an innate biological process: present in all mammals and many other animals. It is part of the body's natural toolkit for managing stress and returning to homeostasis after threat.
Key characteristics of neurogenic tremors:
Involuntary. You do not make the tremors happen through conscious effort. Once initiated, they arise on their own.
Self-regulating. The tremors naturally adjust in intensity and location. They may move through different parts of the body, change speed, or stop on their own.
Safe. Unlike pathological tremors (which indicate nervous system dysfunction), neurogenic stress tremors are a healthy discharge mechanism. They do not damage the body.
Variable. The tremor experience differs widely between people and between sessions. There is no single "correct" way to tremor.
While we often use these terms interchangeably, there is a distinction. Shaking typically refers to voluntary or fear-induced whole-body movement. Tremoring in the TRE context refers specifically to the involuntary neurogenic vibrations that arise from the body's natural discharge mechanism.
Why Animals Shake
Observing animals provides insight into the natural function of tremoring. In the wild, animals face regular threats to their survival. A zebra chased by a lion, a bird startled by a predator, a dog encountering a larger aggressive dog: all experience intense stress responses.
What happens after the threat passes is instructive. Animals typically:
- Orient to ensure safety (looking around, sniffing)
- Tremor or shake often visibly and vigorously
- Rest briefly in a relaxed state
- Return to normal activity fully recovered
This sequence: threat, response, discharge, restoration: is the complete stress cycle. The tremoring phase appears to discharge the energy mobilised during the threat response, allowing the nervous system to return to baseline.
When animals in the wild shake off stress, they are completing what the nervous system began. This is not pathology; it is resolution.
– Peter Levine, In an Unspoken Voice
Peter Levine, developer of Somatic Experiencing, documented this pattern extensively and made it central to his understanding of trauma. When the discharge phase is blocked: as it often is in humans: the mobilised energy remains stuck, and the stress response never fully completes.
The Psoas and Trauma Storage
The psoas muscle plays a central role in TRE and in the body's stress response more broadly. Understanding this muscle illuminates why the TRE exercises are designed as they are.
Anatomical location of the psoas major
The psoas (properly psoas major) is a deep core muscle that:
- Connects the lumbar spine to the femur (thigh bone)
- Is the only muscle connecting the upper and lower body
- Is involved in hip flexion, spinal stabilisation, and postural alignment
- Passes near major nerve plexuses and blood vessels
From a survival perspective, the psoas is crucial. It is involved in:
Fight: The psoas helps generate power in kicking and knee strikes.
Flight: The psoas is a primary hip flexor, essential for running.
Freeze/foetal position: When we curl into a protective ball, the psoas contracts to bring the knees toward the chest.
Because of its involvement in all these survival responses, the psoas tends to be chronically contracted in people living with ongoing stress or unresolved trauma. This chronic tension can contribute to:
- Lower back pain
- Hip tightness
- Restricted breathing (the psoas is near the diaphragm)
- Postural imbalances
- A persistent sense of being braced or guarded
The TRE exercises specifically target the psoas and surrounding muscles, creating the conditions for the tremor mechanism to activate and for this deep-held tension to release.
How Tremoring Facilitates Release
What happens physiologically when we tremor? While the exact mechanisms are still being researched, several processes appear to be involved:
Muscular release. The vibrations of tremoring help tight muscles let go. Just as shaking can help a cramped muscle relax, the tremors facilitate release of chronic muscular tension.
Fascial reorganisation. Fascia: the connective tissue web that permeates the entire body: can become rigid and restricted under stress. The tremoring motion may help fascia regain fluidity and proper sliding function.
Nervous system discharge. The tremors appear to help discharge accumulated activation in the nervous system, shifting the autonomic nervous system toward parasympathetic dominance.
Completion of defensive movements. Sometimes the tremors organise into movements that resemble fight or flight responses: kicking, pushing, running motions. This may represent the completion of defensive responses that were previously thwarted.
Reorganisation of posture and breath. After tremoring, many people notice shifts in how they hold their bodies: shoulders dropping, jaw relaxing, breath deepening. The tremors seem to help the body find a new, more relaxed resting state.
While TRE works through physical mechanisms, the effects are not limited to the physical body. Many practitioners report emotional releases, shifts in mood, improved sleep, and changes in how they relate to stress. The body-mind connection means that physical release often facilitates psychological release.
What Tremoring Feels Like
Describing the experience of tremoring is challenging because it varies so much. However, here are common elements:
The onset. After completing the exercises, you lie in the tremor position. Initially, you may notice your legs feel tired or shaky. Then, often beginning in the thighs or pelvis, vibrations start to arise. For some people this happens immediately; for others it takes several minutes.
The quality. Tremors can be fine and rapid (like a vibration) or larger and slower (like a shaking). They can be gentle or quite vigorous. They may feel like waves moving through the body.
The location. While tremors typically begin in the legs and pelvis, they can spread throughout the body: into the abdomen, chest, arms, shoulders, jaw, and even face. Different areas may tremor in different sessions.
The movement. Sometimes the tremors stay in one place; sometimes they move. The legs might shake, then the pelvis might begin to rock, then the belly might undulate. The body has its own intelligence about where it needs to release.
Associated experiences. Tremoring may be accompanied by:
- Sensations of warmth, tingling, or energy movement
- Emotional feelings: from calm to sadness to joy to fear
- Yawning, sighing, or spontaneous deep breaths
- Stomach gurgles (digestive system activating)
- Memories or images arising
- Simply a sense of pleasant vibration and release
There is wide variation in the tremor experience. Some people tremor vigorously; others experience subtle vibrations. Some have dramatic emotional releases; others simply feel relaxed afterward. All of these are valid. The tremors will be what your body needs them to be.
Why Every Session Is Different
One common observation among TRE practitioners is that no two sessions are alike. The tremors may be strong one day and subtle the next. They may concentrate in the legs one session and spread to the upper body the next. Emotions may arise sometimes and not others.
This variability reflects the intelligence of the body's release process. What needs to be discharged changes from day to day based on:
- Recent stress experiences
- Sleep quality
- Physical activity
- Emotional state
- What was released in previous sessions
Trying to replicate a previous session or achieve a particular experience is counterproductive. The practice invites us to meet whatever arises with curiosity rather than expectation.
The Body's Wisdom
A central principle of TRE: and somatic work more broadly: is that the body has its own wisdom. The tremor mechanism is not something we impose on the body; it is something we allow. We create the conditions (through the exercises) and then step back, letting the body do what it knows how to do.
This requires a shift for many people, especially those accustomed to controlling and directing their bodies. TRE is an invitation to trust: to believe that the body knows what it needs and how to heal, even when we do not consciously understand the process.
We do not make healing happen. We create the conditions for it and then allow it to unfold.
– David Berceli, The Revolutionary Trauma Release Process
In the following sections, we move into the practical details of TRE: how to prepare for practice, how to do the exercises, and: crucially: how to self-regulate during the experience.