Movement: Lie on your back on a padded mat of floor. Place one leg over the other, right above the knee on the lower thigh. Now, using either a towel, a stretching band or your hands, grasp the bottom leg, and - with your back flat and without hyperextending - slowly pull the knee of this leg closer to your chest. Keep the top leg fixed and you should feel a stretch in the hips. Go as far as your range of motion will comfortably allow.
Repetitions: Hold for the full prescribed time on one side, then switch sides and repeat. This counts as one set.
Instructions and effects for the Lying Hip External Rotation Stretch exercise 
Movement in Transverse Plane