What is Sciatica?

Sciatica is a general term for pain radiating along the course of the sciatic nerve. The sciatic nerve is the largest nerve in the body (as big around as the pinky finger) and supplies nerve input to the back of the thigh and the entire leg below the knee. Sciatica is a general description of the pain, not a diagnosis. It usually begins in the lower back and radiates down the posterior thigh to the knee or foot.

A common cause is strain of the piriformis muscle called "Piriformis Syndrome." The piriformis muscle (figure 1) crosses both sacroiliac and hip joints. It is one of a group of muscles called the deep lateral rotators because they help laterally or externally rotate the hip. The piriformis muscle lies overtop the sciatic nerve while the others lie below the nerve. Irritation to the piriformis muscle can cause it to clamp down on the sciatic nerve, creating pain along the distribution of the sciatic nerve (false sciatica).

When running, our heel strikes the ground with a force that is two to five times our body weight, depending on whether running on level ground or downhill. Your gluteal (butt) muscles help maintain an upright posture and prevent your trunk from buckling (flexing forward) at heel strike. Gluteal weakness causes the hip to collapse and rotate inward, and the knee to move in towards the midline of the body. This internal rotation places a lot of stress on the piriformis muscle, which can lead to irritation. Excessive pronation (flat feet) contributes to even more internal rotation, placing further stress on the muscle.

What to do?

The first line of defense against piriformis syndrome is footwear that provides the correct shock absorption at the heel while providing enough arch support to limit

overpronation and help reduce internal rotation at the hip. Strengthening exercises for the gluteal muscles, such as lunges and single leg squats, can be beneficial as well. These are designed to isolate the glutes on the weakened side and can be found in a variety of strength training books.

Stretching the piriformis is easy and can be done while sitting in your desk chair. Simply cross the ankle of the affected side over the opposite knee, sit up straight, and bend forward at the waist keeping your head up and back straight (figure 2). The stretch you feel in your buttocks is your piriformis muscle. This stretch, like all stretches, should be held for 20-30 seconds, and if performed while sitting throughout your workday, should reduce your discomfort. It can also be very helpful to do this stretch before and after running.

Another way of stretching the piriformis before and after your run can be done on the floor as follows: Start on your hands and knees, slide the foot of the side to be stretched between the hand and knee of the opposite side and let the knee go to the floor (Figure 3). Slide the opposite foot and leg back until you feel a comfortable stretch in the buttocks. Repeat on the opposite side.

If you have limited time for stretching, it is more important to stretch after running than before, although both are optimal. If continued running causes the leg pain to radiate further down the leg, a visit to a qualified medical professional is recommended.

Dr. Ken Sheridan is a local road and trail runner who enjoys competing in a variety of events from marathons to duathlons. He practices at ActiveCare Chiropractic & Rehab in Golden, a clinic specializing in sports injuries. To learn more, log onto www.getactivecare.com.