Several exercises stretch the piriformis muscle, and an introductory stretch involves sitting cross-legged on the floor for several minutes each day. As piriformis flexibility grows, other stretches that involve a greater degree of movement continue to help the muscle strengthen and become more flexible, according to About.com.
Another piriformis muscle stretch involves crossing one leg on top of the other, resting an ankle on the knee of the opposite leg. Pushing down on the interior of the knee while leaning forward slowly yields a mild stretch in the piriformis, according to About.com.
The lying piriformis stretch is a more extreme stretch, and it is carried out while lying on the back on the floor. Cross the left leg over the right, leaving the left ankle on the right knee. Pick up the right foot, and bring it towards the head while gently pressing on the inside of the left knee. Hold this position for up to 30 seconds before repeating it, according to About.com.
The piriformis is actually located beneath the gluteus muscles. Its purpose is to laterally stabilize and rotate the hips. Athletes who enjoy running sports can experience a tight piriformis. When the piriformis muscle compresses the sciatic nerve, pain runs deep through the buttocks and hips, as stated by About.com.