With that in mind, it's easy to think there's a lot more to the psoas. The psoas is also connected to the diaphragm, where breathing is modulated.

Not only can a psoas stretch reduce lower back pain, but it can also improve knee pain, daily movements, posture, walking and running, sports performance in soccer and football, and potentially ...

The psoas is a hip flexor that connects the spine to the femur, Lettenberger says. It essentially runs from the vertebrae of your lower back to the front of your hip, attaching onto your femur.