The piriformis stretch stretches your hip rotator muscles. Improving the flexibility of your hip rotator muscles makes your hips feel less stiff and makes it easier for you to move your hips during your everyday activities.
Get into a comfortable position lying on your back with one leg up on an exercise ball in front of you. Your hip and knee should both be at a 90 degree angle.
Cross your other foot over your knee so that your foot is resting on your knee. Once in position, you should feel a gentle stretch in the hip of the leg that is crossed over. If you do not, you can roll the ball closer to you to increase the stretch. Hold the static stretch for 30 seconds. Then relax back to the starting position.