First, Set up for the pandangusthasana one by lying flat on a yoga mat. If your back is sensitive, bend your knees and place your feet flat on the mat.
Second, Loop a yoga strap over your right foot, holding the ends in either hand. Lift your leg straight up toward the sky until you feel a stretch in your hamstrings. Keep your
leg fully extended and your shoulder blades on the mat
Third, Modify this pose by setting yourself up in a doorway with one leg extended vertically along the door frame
Source: http://www.livestrong.com/article/34323 ... z1nXZO44ge
In addition, you should do the Yogo poses on professional Yago mat