All stretching should be pain-free
This technique simultaneously stretches the hip flexors on one side and the hip extensors on the other side.
Have your client sit at the end of the table so that one leg hangs off the end of the table and the other leg is up so that their foot presses into your shoulder or upper chest.
Place a hand on your client’s knee and press the knee toward the floor. Move forward so that the other knee goes toward their chest. Bring your client to a position of maximum stretch, then ask them to press with 10% of their strength for 10 seconds, pushing their foot into your shoulder, and their other knee up toward the ceiling. After they push for 10 seconds have the move in the opposite direction into a greater stretch, and assist them with that stretch.
Treatment for Pelvic Torsion
If one leg appears longer than the other, a common cause is torsion of the pelvis in which one side of the pelvis is rotated forward compared to the other side. This makes the acetabulum lower and the leg appear longer.
To use this technique for pelvic torsion we want the pelvis on the long leg side to rotate back, so we would stretch the hip extensors. The pelvis on the short leg side needs to rotate forward, so we stretch the hip flexors.
I also will do some stretching in the opposite way, so my client will feel balanced, but I will do most of the stretching in the direction that is needed.