The single joint Hip flexors primarily compose of the Psoas Major (originating from vertebrate T12-L4) & the Iliacus (originating from the Iliac fossa) these muscles come together forming the Illiopsoas inserting down into the lesser trochanter of the femur. Both of these muscles FLEX & EXTERNALLY ROTATE the hip. When the Iliopsoas is limited in length it can lead to an anterior pelvic tilt/excessive lordosis (aka Lower Cross Syndrome) — low back dysfunction.
Here I am primarily focus on releasing the Psoas (pronounced “So ASS”). You can feel this muscle just medial of the pelvis, and with the amount of time most people spend in hip flexion during sitting (when the hip flexors are shortened), it is not a surprise that this muscle is often limited. Here I pin the Psoas down in a shortened position (hip flexion) and I actively lengthen the muscle into hip extension and internal rotation. This may reduce the neural tone of the hip flexors which will give more length to this muscle.
NOTE- The hip flexors just like the subscapular muscle are surrounded by many neurovascular structures. If you are not a healthcare practitioner or thoroughly familiar with your anatomy we would recommend you see a local skilled PT before beginning to work on the soft tissue in this region.