I suffered a serious tear of the psoas (hip flexor) about 2 years ago. I compete and train at a national caliber level every season. My sport of choice is ultimate frisbee which consists of constant change of direction sprinting. I've had 2 relapses in the same hip flexor area and its quite debilitating and frustrating. Do you know of any 'magical' (proven) stretches or strengthening exercises that could help me address my psoas problem?
Magic, Alex, is unlikely to help your psoas. On the other hand, since the psoas, or more correctly the iliopsoas, is a combination hip and lumbar muscle, you need to address exercise through a series of activites that challenge the muscle in various different directions.Although it is primaril a sagital plane muscle across the hip, promarily associated with hip flexion, at the spine, it's insertion is lateral, and so it functions more in the frontal plane across the lower back joints. Together, if the muscles on either side of the spine contract, they assist either lumbar flexion or extension depending on the starting point of the spine. One significant consideration is that the muscle are themselves twisted, and as such, contribute to motions in more than one plane at a time - in fact, they are quite complex muscles and that goes a long way to explaining why the are so hard to help when hurt.
The obvious stretches apply. A common one from soccer is to position yourself in a great big forward lunge, and keeping your trunk erect, getover your front foot with your knee on the ground behind you. A variation is to rotate your trunk left and right in the lunge position. A further variatio is to stay in the same position, but pick your knee up just off the ground as you continue to rotate.
Sprinting is good training for the psoas, so wind sprints are where you need to go eventually - work up to it.