Main outcome measurements The dependent variables were the CSAs of the psoas and quadratus lumborum muscles. Results At all three time points, the CSA of the psoas muscle was significantly greater ...

The psoas is an important ribbon-shaped muscle that runs from your lower lumbar spine (the lower back) to the top of the femur (thigh bone), explains Jim White, R.D.N., A.C.S.M. Ex-P, owner of Jim ...