Muscle Minute TUESDAY -Hamstrings

Woman practicing yoga forward bend indoors

The hamstring muscle group gets a lot of press when it comes to low back pain and for good reason. Normal hamstring flexibility is required for protection from excessive lumbar flexion forces too early in the range. What do I mean by that?

Physiotherapist measures knee joint flexibility.

This is the 90/90 hamstring flexibility test. It is used to determine the length of the hamstrings. The patient lies supine with one hip flexed to 90˚and the other leg extended. Then he is asked to extend the knee as far as he can. A normal measurement is -20-0˚ of knee extension. Notice in this measurement, the lumbar spine is in neutral, stabilized by the table and the opposite hip in extension.

How does this translate to function?

That means in standing, one should be able to stand with their knees unlocked (15-20˚ of flexion) and hinge at the hips to 90˚ before any contribution from the lumbar spine (see the picture above). Early onset lumbar flexion during forward bending results in overload to the lumbar spine, specifically the intervertebral discs.

A study determined that patients with herniated lumbar discs displayed larger forces on all lumbar vertebral discs with various lifting postures, primarily due to early flexion of the lumbar spine during forward bending. And the answer to preventing early lumbar flexion during forward bending is normal hamstring flexibility.

But it isn’t just about touching your toes. You should aim to be able to hinge at your hip to 90˚ before your lumbar spine bends. Keeping your chest up during the hip hinge will ensure a neutral lumbar spine.

And then make one more observation. As you bend forward, do your knees want to fall in (medial hamstring tightness) or fall out (lateral hamstring tightness)? If they want to fall in, add a triangle pose to our stretching regime to target the medial hamstring. If they want to fall out, add a revolving triangle pose to target the lateral hamstring.