ADVANCED HIP FLEXOR STRETCH For the more agile ones, who have a good sense of balance. To use at your own risk! The "standard" hip flexor stretch is very effective and targets the psoas really well. However, if you wish to extend this stretch to the whole fascial chain of the front of the hip, from the quads, through the psoas, into the flank and possibly the diaphragm, this one may be interesting for you.