Get Hip About Flexors

Stretching hip flexors can relieve the tension built up from too much sitting.

By Julie Gudmestad

Too much sitting: You probably know it can contribute to serious health problems like obesity and osteoporosis. But did you know it also contributes significantly to back woes, including lower back pain in yoga poses? Fortunately, you can use your yoga practice to offset the effects of a sedentary lifestyle, relieve associated back pain, and set the stage for safe practice of intermediate poses like backbends.

The connection between a sedentary lifestyle and lower back discomfort in yoga poses is the hip flexor muscles across the front of the hips. If left unstretched, shortened hip flexors affect the position of the pelvis, which in turn affects the position and movement of the lower back.

Several muscles cross the front of the hip and create hip flexion, pulling the thigh and trunk toward each other, but probably the most important is the iliopsoas. It is actually composed of two muscles, the iliacus and the psoas, which lie deep in the back of the abdomen. If you looked at the front of a body with the internal organs removed, you would see the psoas lying alongside the spine, attached to the sides of the lumbar vertebrae. The iliacus originates on the inner bowl of the pelvis. Both muscles cross the floor of the pelvis, emerge at the outer edges of the pubic bones, and finally insert on the inner upper femur (thighbone). Because the muscles are buried so deep, we can't see or touch them, so it's easy to understand why there is much confusion about their location and action.

If you are standing, the hip flexors lift your leg when you step up on a stool. If you are lying flat on your back, the hip flexors can either lift your leg or lift your torso into a sit-up. In yoga, Navasana (Boat Pose) is especially good at strengthening the iliopsoas because it demands that the muscle isometrically contract to hold up the weight of the legs and torso.

Use It or Lose It
Most problems with the hip flexors, however, don't originate in a lack of strength but in a lack of flexibility. To understand how these muscles lose their flexibility, imagine someone with a broken arm, her bent elbow encased in a plaster cast. When the cast is removed after six or eight weeks, the soft tissues around the elbow (muscles, tendons, ligaments, and even skin) will have shortened, and the elbow won't straighten out. It will take patient stretching over several weeks to restore the range of motion. Similarly, if the hip is constantly kept in a flexed position—like sitting—for hours every day, day after day, the hip flexors will shorten and shrink, limiting your ability to fully extend (straighten) the hip.

If the iliopsoas and other hip flexors are tight, they pull down and forward on the pelvis, which tilts the pelvis forward and compresses the lower back. Picture a man standing with the front of his pelvis tilting forward and his tailbone lifting. To stand upright, he has to overarch his lower back. Anatomically, this is called hyperextension; commonly, it's called "swayback." Prolonged standing or sitting in this position increases pressure on the facet joints of the lower spine, which can contribute to arthritis in those joints.

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