What are the best poses to do if you have a really tight back and problems with the psoas muscle?
Awakening the psoas muscle is one the most beneficial things a yoga aspirant can do. A tight psoas muscle can cause lower-back weakness and add to compression and tightness of spinal joints. If you are a professional sitter, that is, your employment requires long hours sitting at a desk each day, then chances are you will have a tight psoas muscles unless you are doing the work to reopen and awaken the powerful muscles.
The muscles of the psoas basically attach from the upper leg to lower vertebra and the crest of the hip. They are responsible for flexing the hip (lifting the leg) and are the only muscles attached to your spine from your leg, so it's pretty important.
The good news is that most hatha yoga routines focus on opening the psoas and specifically any lunge poses, such as the crescent lunge or warriors pose, will awaken the front side of the body by extending the hip and taking the attachment points of the psoas muscle further apart.
But, "What we lengthen we must strengthen", as one of my teachers used to say. So it is also important to strengthen the psoas muscle by activating the leg at full range and contracting the psoas muscle in the lunge poses. Usually this can be done by pressing the back foot firmly into the floor. Other great poses would be triangle, half pigeon, dancers, etc.
The key to maintaining a healthy psoas muscle is a complete practice done regularly at an intensity that challenges but does not strain the body. Namaste.
Duncan Peak yoga expert