The fight and flight muscle

I've got a little absorbed in the 'River' series particularly the answers and responses to step 3 and remained seated too long. The soft tissues I'm my lower back and pelvis area are partially calcified (only mild) from arthritis, so I can get discomfort from it. It's only recently that I have become more aware of both the Polyvagal Theory and the body keeping score, this searchbon AI also links in benefits of deep breathing too, well worth a read : )

The psoas major is often dubbed the "fight-or-flight muscle" because it is the primary muscle group activated by the sympathetic nervous system during times of stress. 

Connecting the lower spine to the thigh bone, it is the only muscle that links the upper and lower body, making it essential for the rapid movement required to survive. 

The Psoas-Stress Connection

• Instant Activation: When you perceive a threat, the brain signals the psoas to contract immediately. This prepares you to run (fleeing), kick (fighting), or curl into a protective ball (the fetal position).

• The Stress Loop: Because the psoas is deeply intertwined with the nervous system, a chronically tight psoas can send signals back to the brain that the body is still in danger, trapping you in a cycle of low-grade anxiety and hypervigilance.

• Breath and Diaphragm: The psoas is connected to the diaphragm via fascia and ligaments. Tension in the psoas can restrict the diaphragm, leading to shallow "chest breathing" that further stimulates the stress response. 

Physical & Emotional Symptoms of a Tight Psoas

If the fight-or-flight response never "switches off," the psoas remains in a state of high alert, potentially leading to: 

• Physical: Chronic lower back pain, hip stiffness, digestive sluggishness, and poor posture.

• Emotional: Persistent anxiety, irritability, a sense of "bracing" for impact, and unresolved trauma stored in the body's core. 

How to Release the "Stress" Muscle

Experts recommend gentle, passive approaches rather than aggressive stretching, which can sometimes trigger further defensive tightening. 

• Constructive Rest: Lie on your back with knees bent and feet flat on the floor (hip-width apart). This allows the psoas to relax passively.

• Somatic Exercises (TRE): Tension & Trauma Releasing Exercises use mild tremors to discharge stored energy and tension directly from the psoas.

• Diaphragmatic Breathing: Deep belly breathing massages the vagus nerve and signal to the nervous system that it is safe to soften.