Learn how to do this amazing release for a chronically tight muscle called your Psoas. Your psoas is a hip flexor muscle that inserts into the lumbar vertebrae and discs then wraps around your leg. Often times tightness here can feel like a "back ache" but it is probably this muscle and not your back. This muscle is a stabilizer of the low back. If the abs are not working or diastasis is happening, the psoas is overactive, leading to compression and pressure on the low back. One more reason to do Pilates and strengthen your core!