Your piriformis muscle is responsible for the rotation of the hip. Although it’s very important in activities that frequently change direction, it tends to tighten up in runners. If the piriformis becomes too tight or spasms, it can irritate the sciatic nerve, which causes pain in the glutes, lower back and thighs.
1) Lie on your back with your legs extended and your back straight. Keep your hips level and your lower back down on the floor. Bend your left knee, placing left foot flat on the floor (not pictured).
Cross your right ankle at your left knee. Grab the back of your left thigh and hug your legs towards your chest. Place your right elbow on the inner portion of your right knee and push it slightly to the side. Breathe deeply and hold for 10-30 seconds. Repeat on opposite side. To reduce the intensity of this stretch, don’t bring your legs towards your chest as much.