What I think might be a good stretch from
T-Nation:
Basic Hip Flexor
Now that we’ve loosened up the quads, it’s time to focus on the hip flexors. This is probably the single-most overactive group of muscles, and the benefits of stretching them are numerous: improved firing of the gluteals, decreased incidence of low back injury, etc.
This stretch is identical to the one described before, except your back leg isn't elevated in this version. To increase the stretch on the psoas versus iliacus, laterally flex the body in the opposite direction of the side you're stretching (e.g. if you're stretching the right hip, laterally flex to the left).
