The piriformis is a difficult to reach muscle that runs from your sacrum to your thigh bone. When it begins to push against your sciatic nerve, often due to too much sitting, it can cause excruciating pain. A tight or inflamed piriformis is what is known as piriformis syndrome.

Here are five things you should know about your piriformis, and how to keep it healthy.

Vivian Eisenstadtis a Los Angeles-based physical therapist who specializes in pain prevention.

“Think of your body as a pulley system,” she says. “Muscles cross joints and connect bone to bone, and pull the bones in one direction. If one muscle is too tight, then it creates strain on the next joint over on both sides.”

“A tight piriformis from slouching in a chair with your hips rotated outward puts a lot of strain on your low back and makes your hips so tight that you create an imbalance in the entire system.”

Piriformis syndrome isn’t always caused by inactivity. It can occur after an accident or even after vigorous activity such as running.

Option 1: Seated stretch

The key to a successful piriformis stretch is sitting up straight, says Eisenstadt. “What’s the use of stretching out a muscle if you’re going to keep tightening it back up?”

  1. First, roll up a hand towel into a Tootsie Roll shape.
  2. Next, sit on a firm surface, and find your “butt bones” — the two bones at the lowest part of your posterior.
  3. Sit directly on top of those bones.
  4. Then take the towel and place it behind the bones, under your gluteal muscles.
  5. Once you find that perfect spot perched on the butt bones, contract your abdominals lightly and relax your upper body, especially the shoulders and neck.
  6. Arch your back by sticking your butt back and out and slightly moving your chest forward.
  7. In that posture, with your legs flat on the floor, lift your right leg, and place the ankle on the opposite knee.
  8. Hold for 20 seconds then repeat on the opposite side.

Option 2: Stretch on the floor

Piriformis exercises also can be done on the floor:

  1. Lying flat on your back, put your arms at your sides with palms facing the floor.
  2. 从墙上的位置大约一英尺远,完整模型tely extend your legs upward to rest your heels against the wall.
  3. At that angle, rest one ankle against the opposite knee, just as in the sitting position.
  4. Hold for 20 seconds then repeat on the opposite side.

Doing the piriformis stretch can ease knee and ankle pain as well, Eisenstadt says. “Walking with a tight piriformis puts extra strain on the inside and outside of your knee joint, making the outside too tight and the inside weak, which creates an unstable joint.”

The stretch can also help with symptoms of plantar fasciitis (inflammation of the fascia on the bottom of the feet). People with tight piriformis and hamstring muscles often end up walking a “duck walk,” Eisenstadt says, which puts extra strain on the bottom of their foot.

“Fixing the body mechanics of how you walk by stretching your piriformis can not only help alleviate injuries but prevent you from getting them in the first place,” she says.

Like with any type of exercise, you should stop doing it if it hurts.

Don’t try to “work through” the pain, saysDr. Mark Kovacs, a former tennis professional who has a doctoral degree in sports medicine. “Those pain receptors are there for a reason.”