Piriformis Syndrome

A fellow swimmer told me he was being treated for "piriformis syndrome" which was caused by his cycling.  His story made me want to learn about piriformis syndrome, what it is, what causes it and if yoga would be useful in treating it.
    The piriformis is a muscle that runs between the anterior of the sacrum and passes under the sciatic notch, inserting on the top of the greater trochanter. The piriformis functions in lateral rotation of the thigh.  The sciatic nerve either runs under, over or even sometimes through the piriformis muscle.  If the muscle becomes inflamed, goes into spasm, or is  chronically shortened, undue pressure is put upon the sciatic nerve. The sciatic nerve begins with its roots in the spine and runs down our leg. Since the sciatic nerve is affected, symptoms are similar to sciatica including numbness, tingling or weakness in one leg, foot or toes.  According to www.pain.com "the piriformis muscle is shortened  from prolonged sitting at a desk or in a  car, and can easily be overused  by running or cycling."  Another reference mentioned that an ill-fitting bicycle seat may contribute to piriformis syndrome.
    I found a bunch of web references that recommend yoga for working with piriformis syndrome.  AboutSports.com recommended a stretch that in Yoga we call the pigeon pose.  See the picture on the right. Sitting in a chair, rest your ankle just about your knee.  On your exhale, fold forward at your hips just enough to feel a stretch in the hip of the bent leg.  The Livestrong article listed below suggested the bound angle pose.  Sit with feet together, crown toward ceiling.  Grab feet and on exhale hinge forward at hips until your chin is over your ankles.   If you have pain, always seek medical attention before trying any exercises
References: 
* http://www.livestrong.com/article/344676-yoga-sciatica-treatment/
* http://roadcyclinguk.com/how-to/conditioning-for-cyclists-with-jo-mcrae-part-one-piriformis-exhttp://pain.com/archives/2012/12/21-sciatica-piriformis-syndrome-yoga/exercise.html
* http://www.womenfitness.net/top10_yoga_exercises.htm
*http://velonews.competitor.com/2011/05/news/velonews-training-center-piriformis-syndrome-and-cycling_172757

Pigeon Pose from www.bestraleighmassage.blogs

Bound Angle Pose from www.fitbie.com