I teach a class sometimes called 'emotional hips' which is centred around the tenet that high stress and tight hips sometimes correlate. Here is what I mean by emotional hips, and why the Psoas in particular, needs to EMOTIONALLY relax.
You may already understand your fight/flight response, and how the 2 branches of our nervous system control, and are controlled by, emotional stress and relaxation. The Sympathetic nervous system is active when we are in a high stress, or 'active' situation. Your hearth rate will increase, pupils dilate, muscles contract and prepare you to flee or fight, and digestion halts among other things. All of these homeostatic ('self-regulatory') responses are instigated by the sympathetic nervous system, sometimes the response is mild, and sometimes, when we're really stressed, or chronically stressed, the response is big, and can have an unwanted and maladaptive effect.
The part of the stress response that effects the Psoas muscle, is, of course, muscle contraction. The sympathetic nervous system causes muscles to contact to prepare for fight or flight, and the Psoas is one of the main muscles involved in walking, running, and and also stabilising your core and kicking (ie. preparing to fight, and defend oneself) So it is very active in your fight/flight response.
This is all an entirely normal natural bodily function, but when we experience extreme or chronic stress, our Psoas is in a constant state of contraction, ie. it never gets to rest (our rest and recover responses occur when our Parasympathetic nervous system is active). This overuse causes tightness, weakness, and a generally unhappy muscle that's unwilling to relax and open up through physical exercise alone.
Your Psoas muscle
Enter Yoga! Or all mindful movement modalities that encourage us to explore the mindscape as well as the bodyscape. If we can up-regulate our Parasympathetic nervous system enough (balance all the stress responses from the Sympathetic...) then we can reduce these unwanted contractions and relax, and open up those tight pesky hip flexors.
The how do we up-regulate the Parasympathetic nervous system? Simple - we relax. We ACTIVELY relax. That means time off work, meditation, gentle movement, good nutrition, and plenty of sleep. I guarantee when you de-stress emotionally, your hips will be happier.
So treat your Psoas like it has feelings - it's an emotional muscle, and it needs care, rest, and kindness to keep it happy, open and healthy.
Laura Pearce, Senior Yoga Teacher (SYT YA) and chief Yogi @ Yoga Collective London