The psoas is a core muscle with a big job to do — and most people don't even know what it is! Traditionally categorized as a hip flexor, the psoas is attached to the lower spine and the thigh, and runs through the pelvis and over the hip joint. Every time you stand, walk, or run, your psoas is engaged.
If you're dealing with a sore back or knee pain, it could very well be a problem with your psoas; this muscle is often exhausted and shortened from overuse, or from sitting all day. Work to lengthen this elusive muscle and relieve tension in your whole body with the following poses.