Piriformis Exercise

The piriformis muscle lies underneath the large gluteus maximus muscle within your buttocks, attaching to the sacrum of your pelvis on the inside and to the greater trochanter -- the bony protrusion just outside your hip joint -- on the outside. The piriformis facilitates outward rotation of the femur, or thighbone, within the hip socket and helps abduct your thighs, or spread your legs apart, when your hips are flexed. Stretching and strengthening the piriformis through regular exercise helps keep the muscle generally healthy, allowing it to perform its functions effectively.

Stretching Exercises

Stretching the piriformis involves lengthening the muscle by inwardly rotating and adducting your hip until you feel gentle tension through your buttock on the same side. You can accomplish this by lying on your back or sitting upright with your knees flexed and feet on the floor, crossing your left leg over your right, so your right knee rests just below the outside of your left knee, and then pulling your right knee toward your chest with both hands. Hold the stretch for 10 to 30 seconds, pulling your knee slightly closer to your chest with each exhalation as you breathe normally. Repeat the exercise with your right leg crossed over your left as well.

Isometric Exercises

Exercising the piriformis isometrically involves contracting the muscle for five to 10 seconds at a time without actually moving your legs, which typically requires pressing against an immobile object. Sit erect on the floor with your legs extended and heels on the floor. Have a partner stand with the insides of her feet against the outsides of your ankles and press your legs into hers, attempting to spread your legs apart, for five to 10 seconds. Relax briefly, then move your legs about 6 inches apart and repeat the exercise. Perform the exercise a third, fourth and fifth time as well with your legs approximately 12 inches, 18 inches and 24 inches apart, respectively.

Strengthening Exercises

Traditional strengthening exercises that target the piriformis require repeated muscle contractions against external resistance. The seated hip abduction exercise, which is performed on a weight machine that has a chair and two levers attached to a stack of weights, is one example of such an exercise. Sit on the chair and extend your legs forward, placing the outsides of your lower legs against the pads on the levers, then repeatedly spread your legs apart to lift the stack of weights and return to the starting position slowly. Complete two to six sets of six to 15 repetitions, depending on the amount of weight you use, on two to three nonconsecutive days per week. Progressively increase the number of sets and the amount of weight and decrease the number of repetitions to build your strength gradually.

Piriformis Syndrome and Exercise

The piriformis muscle is associated with piriformis syndrome -- a condition that occurs when the muscle irritates the sciatic nerve, causing numbness, pain and/or tingling in your buttocks and radiating down your leg. A physical therapist will likely recommend performing these stretching exercises or similar stretches to help treat the condition, along with other pain-relieving interventions. He may also suggest that you discontinue any exercises that might aggravate the condition, such as biking or running, until your symptoms subside. Consult your doctor if the condition persists.